National Library of Energy BETA

Sample records for out-perform single crystals

  1. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Platinum Nanoclusters Out-Perform Single Crystals Platinum Nanoclusters Out-Perform Single Crystals Print Wednesday, 27 October 2010 00:00 When it comes to metal catalysts, platinum is the standard. However, at about $2,000 an ounce, the high cost of the raw material presents major challenges for the future wide-scale use of platinum in fuel cells. Berkeley Lab research suggests that one possible way to meet these challenges is to think small. Researchers from Berkeley Lab's Materials Sciences

  2. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Platinum Nanoclusters Out-Perform Single Crystals Print When it comes to metal catalysts, platinum is the standard. However, at about $2,000 an ounce, the high cost of the raw material presents major challenges for the future wide-scale use of platinum in fuel cells. Berkeley Lab research suggests that one possible way to meet these challenges is to think small. Researchers from Berkeley Lab's Materials Sciences Division have found that under high pressure-comparable to the pressures at which

  3. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Platinum Nanoclusters Out-Perform Single Crystals Print When it comes to metal catalysts, platinum is the standard. However, at about $2,000 an ounce, the high cost of the raw material presents major challenges for the future wide-scale use of platinum in fuel cells. Berkeley Lab research suggests that one possible way to meet these challenges is to think small. Researchers from Berkeley Lab's Materials Sciences Division have found that under high pressure-comparable to the pressures at which

  4. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Platinum Nanoclusters Out-Perform Single Crystals Print When it comes to metal catalysts, platinum is the standard. However, at about $2,000 an ounce, the high cost of the raw material presents major challenges for the future wide-scale use of platinum in fuel cells. Berkeley Lab research suggests that one possible way to meet these challenges is to think small. Researchers from Berkeley Lab's Materials Sciences Division have found that under high pressure-comparable to the pressures at which

  5. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Platinum Nanoclusters Out-Perform Single Crystals Print When it comes to metal catalysts, platinum is the standard. However, at about $2,000 an ounce, the high cost of the raw material presents major challenges for the future wide-scale use of platinum in fuel cells. Berkeley Lab research suggests that one possible way to meet these challenges is to think small. Researchers from Berkeley Lab's Materials Sciences Division have found that under high pressure-comparable to the pressures at which

  6. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Platinum Nanoclusters Out-Perform Single Crystals Print When it comes to metal catalysts, platinum is the standard. However, at about $2,000 an ounce, the high cost of the raw material presents major challenges for the future wide-scale use of platinum in fuel cells. Berkeley Lab research suggests that one possible way to meet these challenges is to think small. Researchers from Berkeley Lab's Materials Sciences Division have found that under high pressure-comparable to the pressures at which

  7. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Platinum Nanoclusters Out-Perform Single Crystals Print When it comes to metal catalysts, platinum is the standard. However, at about $2,000 an ounce, the high cost of the raw material presents major challenges for the future wide-scale use of platinum in fuel cells. Berkeley Lab research suggests that one possible way to meet these challenges is to think small. Researchers from Berkeley Lab's Materials Sciences Division have found that under high pressure-comparable to the pressures at which

  8. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Platinum Nanoclusters Out-Perform Single Crystals Print When it comes to metal catalysts, platinum is the standard. However, at about $2,000 an ounce, the high cost of the raw material presents major challenges for the future wide-scale use of platinum in fuel cells. Berkeley Lab research suggests that one possible way to meet these challenges is to think small. Researchers from Berkeley Lab's Materials Sciences Division have found that under high pressure-comparable to the pressures at which

  9. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Platinum Nanoclusters Out-Perform Single Crystals Print When it comes to metal catalysts, platinum is the standard. However, at about $2,000 an ounce, the high cost of the raw material presents major challenges for the future wide-scale use of platinum in fuel cells. Berkeley Lab research suggests that one possible way to meet these challenges is to think small. Researchers from Berkeley Lab's Materials Sciences Division have found that under high pressure-comparable to the pressures at which

  10. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Platinum Nanoclusters Out-Perform Single Crystals Print When it comes to metal catalysts, platinum is the standard. However, at about $2,000 an ounce, the high cost of the raw material presents major challenges for the future wide-scale use of platinum in fuel cells. Berkeley Lab research suggests that one possible way to meet these challenges is to think small. Researchers from Berkeley Lab's Materials Sciences Division have found that under high pressure-comparable to the pressures at which

  11. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Platinum Nanoclusters Out-Perform Single Crystals Print When it comes to metal catalysts, platinum is the standard. However, at about $2,000 an ounce, the high cost of the raw material presents major challenges for the future wide-scale use of platinum in fuel cells. Berkeley Lab research suggests that one possible way to meet these challenges is to think small. Researchers from Berkeley Lab's Materials Sciences Division have found that under high pressure-comparable to the pressures at which

  12. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Platinum Nanoclusters Out-Perform Single Crystals Print When it comes to metal catalysts, platinum is the standard. However, at about $2,000 an ounce, the high cost of the raw material presents major challenges for the future wide-scale use of platinum in fuel cells. Berkeley Lab research suggests that one possible way to meet these challenges is to think small. Researchers from Berkeley Lab's Materials Sciences Division have found that under high pressure-comparable to the pressures at which

  13. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    automobile catalytic converters, and the degradation of platinum electrodes in hydrogen fuel cells. As the carbon monoxide coverage of the platinum surfaces increased, the...

  14. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    The next steps will be to determine whether other adsorbed reactants, such as oxygen or hydrogen, also result in the creation of nanoclusters in platinum. Exploring metals that...

  15. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    have found that under high pressure-comparable to the pressures at which many industrial technologies operate-platinum surfaces can change their structure dramatically in response...

  16. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    could be replaced with less expensive alternatives, lowering the cost of the final products. Researchers have discovered that the presence of high densities of carbon...

  17. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    High-pressure scanning tunneling microscopes (STM) and ambient-pressure x-ray ... structured as a series of flat terraces about six atoms wide separated by atomic steps. ...

  18. Platinum Nanoclusters Out-Perform Single Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    in platinum. Exploring metals that catalyze other important reactions-such as palladium, silver, copper, rhodium, iron, and cobalt-might also help researchers determine...

  19. Jefferson Lab Builds First Single Crystal Single Cell Accelerating Cavity |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Jefferson Lab Builds First Single Crystal Single Cell Accelerating Cavity Single Cell Cavity This single cell cavity was made from a single crystal of niobium. Made in the same shape as the low-loss design proposed as an improvement to the baseline for the International Linear Collider (ILC), this cavity performs much better than the ILC design goal. Jefferson Lab Builds First Single Crystal Single Cell Accelerating Cavity May 18, 2005 Jefferson Lab's Institute for Superconducting

  20. Jefferson Lab Builds First Single Crystal Single Cell Accelerating Cavity |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Jefferson Lab Builds First Single Crystal Single Cell Accelerating Cavity Single Cell Cavity This single cell cavity was made from a single crystal of niobium. Made in the same shape as the low-loss design proposed as an improvement to the baseline for the International Linear Collider (ILC), this cavity performs much better than the ILC design goal. Jefferson Lab Builds First Single Crystal Single Cell Accelerating Cavity Jefferson Lab's Institute for Superconducting Radiofrequency Science

  1. Epitaxial Single Crystal Nanostructures for Batteries & PVs ...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    for Lithium Sulfur Batteries Better Ham & Cheese: Enhanced Anodes and Cathodes for Fuel Cells Epitaxial Single Crystal Nanostructures for Batteries & PVs High Performance ...

  2. Ultratough single crystal boron-doped diamond

    DOE Patents [OSTI]

    Hemley, Russell J [Carnegie Inst. for Science, Washington, DC ; Mao, Ho-Kwang [Carnegie Inst. for Science, Washington, DC ; Yan, Chih-Shiue [Carnegie Inst. for Science, Washington, DC ; Liang, Qi [Carnegie Inst. for Science, Washington, DC

    2015-05-05

    The invention relates to a single crystal boron doped CVD diamond that has a toughness of at least about 22 MPa m.sup.1/2. The invention further relates to a method of manufacturing single crystal boron doped CVD diamond. The growth rate of the diamond can be from about 20-100 .mu.m/h.

  3. Ames Lab 101: Single Crystal Growth

    ScienceCinema (OSTI)

    Schlagel, Deborah

    2014-06-04

    Ames Laboratory scientist Deborah Schlagel talks about the Lab's research in growing single crystals of various metals and alloys. The single crystal samples are vital to researchers' understanding of the characteristics of a materials and what gives these materials their particular properties.

  4. World's largest single crystal of gold verified by Los Alamos...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Los Alamos verifies largest single gold crystal World's largest single crystal of gold verified by Los Alamos instruments Using Lujan Center's HIPPO instrument, researchers probed ...

  5. Synthesis of platinum single-crystal nanoparticles in water vapor...

    Office of Scientific and Technical Information (OSTI)

    of platinum single-crystal nanoparticles in water vapor Citation Details In-Document Search Title: Synthesis of platinum single-crystal nanoparticles in water vapor Authors: ...

  6. World's largest single crystal of gold verified at Los Alamos

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    World's largest single crystal of gold verified at Los Alamos World's largest single crystal of gold verified at Los Alamos The SCD instrument is used to determine the periodic atomic arrangement or crystal structure of single crystals, both natural and synthetic. April 7, 2014 Neutron diffraction data collected on the single-crystal diffraction (SCD) instrument at the Lujan Center, from the Venezuelan gold sample, indicate that the sample is a single crystal. Neutron diffraction data collected

  7. Neutron detection with single crystal organic scintillators

    SciTech Connect (OSTI)

    Zaitseva, N; Newby, J; Hamel, S; Carman, L; Faust, M; Lordi, V; Cherepy, N; Stoeffl, W; Payne, S

    2009-07-15

    Detection of high-energy neutrons in the presence of gamma radiation background utilizes pulse-shape discrimination (PSD) phenomena in organics studied previously only with limited number of materials, mostly liquid scintillators and single crystal stilbene. The current paper presents the results obtained with broader varieties of luminescent organic single crystals. The studies involve experimental tools of crystal growth and material characterization in combination with the advanced computer modeling, with the final goal of better understanding the relevance between the nature of the organic materials and their PSD properties. Special consideration is given to the factors that may diminish or even completely obscure the PSD properties in scintillating crystals. Among such factors are molecular and crystallographic structures that determine exchange coupling and exciton mobility in organic materials and the impurity effect discussed on the examples of trans-stilbene, bibenzyl, 9,10-diphenylanthracene and diphenylacetylene.

  8. Magnetoelasticity of Fe-Si single crystals

    SciTech Connect (OSTI)

    Xing, Q; Wu, D.; Lograsso, T. A.

    2010-04-20

    The tetragonal magnetostriction constant, (3/2){lambda}{sub 100}, of Fe-Si single crystals was measured and was found to be structure dependent. Similar to that of Fe-Ge single crystals, (3/2){lambda}{sub 100} is positive in the single phase A2 regime, becomes negative in the single phase D0{sub 3} regime, and changes from positive to negative between the two regimes. Short-range order in the A2 regime decreases the magnetostriction prior to the onset of long range order. In the single phase regions of both A2 and D0{sub 3}, thermal history does not show any obvious effect on the magnetostriction, contrary to that found for Fe-Ga alloys. However, in the regions of phase mixture involving A2, B2, and D0{sub 3} phases, quenching pushes the change in magnetostriction from positive to negative to higher Si contents.

  9. World's largest single crystal of gold verified at Los Alamos

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    World's largest single crystal of gold verified at Los Alamos World's largest single crystal of gold verified at Los Alamos The SCD instrument is used to determine the periodic ...

  10. Solar cell structure incorporating a novel single crystal silicon material

    DOE Patents [OSTI]

    Pankove, Jacques I.; Wu, Chung P.

    1983-01-01

    A novel hydrogen rich single crystal silicon material having a band gap energy greater than 1.1 eV can be fabricated by forming an amorphous region of graded crystallinity in a body of single crystalline silicon and thereafter contacting the region with atomic hydrogen followed by pulsed laser annealing at a sufficient power and for a sufficient duration to recrystallize the region into single crystal silicon without out-gassing the hydrogen. The new material can be used to fabricate semiconductor devices such as single crystal silicon solar cells with surface window regions having a greater band gap energy than that of single crystal silicon without hydrogen.

  11. Submicron diameter single crystal sapphire optical fiber

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hill, Cary; Homa, Daniel; Liu, Bo; Yu, Zhihao; Wang, Anbo; Pickrell, Gary

    2014-10-02

    In this work, a submicron-diameter single crystal sapphire optical fiber was demonstrated via wet acid etching at elevated temperatures. Etch rates on the order 2.3 µm/hr were achievable with a 3:1 molar ratio sulfuric-phosphoric acid solution maintained at a temperature of 343°C. A sapphire fiber with an approximate diameter of 800 nm was successfully fabricated from a commercially available fiber with an original diameter of 50 µm. The simple and controllable etching technique provides a feasible approach to the fabrication of unique waveguide structures via traditional silica masking techniques. The ability to tailor the geometry of sapphire optical fibers ismore » the first step in achieving optical and sensing performance on par with its fused silica counterpart.« less

  12. Multifunctional Charge-Transfer Single Crystals through Supramolecular

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Assembly | Argonne National Laboratory Multifunctional Charge-Transfer Single Crystals through Supramolecular Assembly Title Multifunctional Charge-Transfer Single Crystals through Supramolecular Assembly Publication Type Journal Article Year of Publication 2016 Authors Xu, B, Luo, Z, Wilson, AJ, Chen, K, Gao, W, Yuan, G, Chopra, HD, Chen, X, Willets, KA, Dauter, Z, Ren, S Journal Advanced Materials Date Published 05042016 Abstract Centimeter-sized segregated stacking TTF-C60 single crystals

  13. Single Crystal Preparation for High-Pressure Experiments in the...

    Office of Scientific and Technical Information (OSTI)

    Experiments in the Diamond Anvil Cell Citation Details In-Document Search Title: Single Crystal Preparation for High-Pressure Experiments in the Diamond Anvil Cell You are ...

  14. Ultratough CVD single crystal diamond and three dimensional growth thereof

    DOE Patents [OSTI]

    Hemley, Russell J.; Mao, Ho-kwang; Yan, Chih-shiue

    2009-09-29

    The invention relates to a single-crystal diamond grown by microwave plasma chemical vapor deposition that has a toughness of at least about 30 MPa m.sup.1/2. The invention also relates to a method of producing a single-crystal diamond with a toughness of at least about 30 MPa m.sup.1/2. The invention further relates to a process for producing a single crystal CVD diamond in three dimensions on a single crystal diamond substrate.

  15. Preparation and characterization of single crystal samples for...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Preparation and characterization of single crystal samples for high-pressure experiments Citation ... Here we report new procedures to produce extremely ...

  16. Large single domain 123 material produced by seeding with single crystal rare earth barium copper oxide single crystals

    DOE Patents [OSTI]

    Todt, Volker; Miller, Dean J.; Shi, Donglu; Sengupta, Suvankar

    1998-01-01

    A method of fabricating bulk YBa.sub.2 Cu.sub.3 O.sub.x where compressed powder oxides and/or carbonates of Y and Ba and Cu present in mole ratios to form YBa.sub.2 Cu.sub.3 O.sub.x are heated in the presence of a Nd.sub.1+x Ba.sub.2-x Cu.sub.3 O.sub.y seed crystal to a temperature sufficient to form a liquid phase in the YBa.sub.2 Cu.sub.3 O.sub.x while maintaining the seed crystal solid. The materials are slowly cooled to provide a YBa.sub.2 Cu.sub.3 O.sub.x material having a predetermined number of domains between 1 and 5. Crack-free single domain materials can be formed using either plate shaped seed crystals or cube shaped seed crystals with a pedestal of preferential orientation material.

  17. Method for harvesting single crystals from a peritectic melt

    DOE Patents [OSTI]

    Todt, Volker R.; Sengupta, Suvankar; Shi, Donglu

    1996-01-01

    A method of preparing single crystals. The method of preparation involves preparing precursor materials of a particular composition, heating the precursor material to achieve a peritectic mixture of peritectic liquid and crystals, cooling the peritectic mixture to quench directly the mixture on a porous, wettable inert substrate to wick off the peritectic liquid, leaving single crystals on the porous substrate. Alternatively, the peritectic mixture can be cooled to a solid mass and reheated on a porous, inert substrate to melt the matrix of peritectic fluid while leaving the crystals unmelted, allowing the wicking away of the peritectic liquid.

  18. Method for harvesting single crystals from a peritectic melt

    DOE Patents [OSTI]

    Todt, V.R.; Sengupta, S.; Shi, D.

    1996-08-27

    A method of preparing single crystals is disclosed. The method of preparation involves preparing precursor materials of a particular composition, heating the precursor material to achieve a peritectic mixture of peritectic liquid and crystals, cooling the peritectic mixture to quench directly the mixture on a porous, wettable inert substrate to wick off the peritectic liquid, leaving single crystals on the porous substrate. Alternatively, the peritectic mixture can be cooled to a solid mass and reheated on a porous, inert substrate to melt the matrix of peritectic fluid while leaving the crystals unmelted, allowing the wicking away of the peritectic liquid. 2 figs.

  19. Method for harvesting rare earth barium copper oxide single crystals

    DOE Patents [OSTI]

    Todt, Volker R.; Sengupta, Suvankar; Shi, Donglu

    1996-01-01

    A method of preparing high temperature superconductor single crystals. The method of preparation involves preparing precursor materials of a particular composition, heating the precursor material to achieve a peritectic mixture of peritectic liquid and crystals of the high temperature superconductor, cooling the peritectic mixture to quench directly the mixture on a porous, wettable inert substrate to wick off the peritectic liquid, leaving single crystals of the high temperature superconductor on the porous substrate. Alternatively, the peritectic mixture can be cooled to a solid mass and reheated on a porous, inert substrate to melt the matrix of peritectic fluid while leaving the crystals melted, allowing the wicking away of the peritectic liquid.

  20. Growth of Sb-Bi gradient single crystals

    SciTech Connect (OSTI)

    Kozhemyakin, G. N. Lutskiy, D. V.; Rom, M. A.; Mateychenko, P. V.

    2008-12-15

    The growth conditions and structural quality of Sb-Bi gradient single crystals with Bi content from 2 to 18 at %, grown by the Czochralski method with solid phase feed, are investigated. Bi distribution in the crystals along their pulling direction are studied by electron probe microanalysis and the change in the interplanar spacing is analyzed by double-crystal X-ray diffraction. It is established that the pulling rate and feed mass affect the Bi distribution in Sb-Bi single crystals.

  1. Single crystal Processing and magnetic properties of gadolinium nickel

    SciTech Connect (OSTI)

    Shreve, Andrew John

    2012-11-02

    GdNi is a rare earth intermetallic material that exhibits very interesting magnetic properties. Spontaneous magnetostriction occurs in GdNi at T{sub C}, on the order of 8000ppm strain along the c-axis and only until very recently the mechanism causing this giant magnetostriction was not understood. In order to learn more about the electronic and magnetic structure of GdNi, single crystals are required for anisotropic magnetic property measurements. Single crystal processing is quite challenging for GdNi though since the rare-earth transition-metal composition yields a very reactive intermetallic compound. Many crystal growth methods are pursued in this study including crucible free methods, precipitation growths, and specially developed Bridgman crucibles. A plasma-sprayed Gd{sub 2}O{sub 3} W-backed Bridgman crucible was found to be the best means of GdNi single crystal processing. With a source of high-quality single crystals, many magnetization measurements were collected to reveal the magnetic structure of GdNi. Heat capacity and the magnetocaloric effect are also measured on a single crystal sample. The result is a thorough report on high quality single crystal processing and the magnetic properties of GdNi.

  2. Growth and characterization of diammonium copper disulphate hexahydrate single crystal

    SciTech Connect (OSTI)

    Siva Sankari, R.; Perumal, Rajesh Narayana

    2014-03-01

    Graphical abstract: Diammonium copper disulphate hexahydrate (DACS) is one of the most promising inorganic dielectric crystals with exceptional mechanical properties. Good quality crystals of DACS were grown by using solution method in a period of 30 days. The grown crystals were subjected to single crystal X-ray diffraction analysis in order to establish their crystalline nature. Thermo gravimetric, differential thermal analysis, FTIR, and UV–vis–NIR analysis were performed for the crystal. Several solid state physical parameters have been determined for the grown crystals. The dielectric constant and the dielectric loss and AC conductivity of the grown crystal were studied as a function of frequency and temperature has been calculated and plotted. - Highlights: • Diammonium copper disulphate is grown for the first time and CCDC number obtained. • Thermal analysis is done to see the stability range of the crystals. • Band gap and UV cut off wavelength of the crystal are determined to be 2.4 eV and 472.86 nm, respectively. • Dielectric constant, dielectric loss and AC conductivity are plotted as a function of applied field. - Abstract: Diammonium copper disulphate hexahydrate is one of the most promising inorganic crystals with exceptional dielectric properties. A good quality crystal was harvested in a 30-day period using solution growth method. The grown crystal was subjected to various characterization techniques like single crystal X-ray diffraction analysis, thermo gravimetric, differential thermal analysis, FTIR, and UV–vis–NIR analysis. Unit cell dimensions of the grown crystal have been identified from XRD studies. Functional groups of the title compounds have been identified from FTIR studies. Thermal stability of the samples was checked by TG/DTA studies. Band gap of the crystal was calculated. The dielectric constant and dielectric loss were studied as a function of frequency of the applied field. AC conductivity was plotted as a function

  3. Growing intermetallic single crystals using in situ decanting

    SciTech Connect (OSTI)

    Petrovic, Cedomir; Canfield, Paul; Mellen, Jonathan

    2012-05-16

    High temperature metallic solution growth is one of the most successful and versatile methods for single crystal growth, and is particularly suited for exploratory synthesis. The method commonly utilizes a centrifuge at room temperature and is very successful for the synthesis of single crystal phases that can be decanted from the liquid below the melting point of the silica ampoule. In this paper, we demonstrate the extension of this method that enables single crystal growth and flux decanting inside the furnace at temperatures above 1200C. This not only extends the number of available metallic solvents that can be used in exploratory crystal growth but also can be particularly well suited for crystals that have a rather narrow exposed solidification surface in the equilibrium alloy phase diagram.

  4. Large single domain 123 material produced by seeding with single crystal rare earth barium copper oxide single crystals

    DOE Patents [OSTI]

    Todt, V.; Miller, D.J.; Shi, D.; Sengupta, S.

    1998-07-07

    A method of fabricating bulk YBa{sub 2}Cu{sub 3}O{sub x} where compressed powder oxides and/or carbonates of Y and Ba and Cu present in mole ratios to form YBa{sub 2}Cu{sub 3}O{sub x} are heated in the presence of a Nd{sub 1+x}Ba{sub 2{minus}x}Cu{sub 3}O{sub y} seed crystal to a temperature sufficient to form a liquid phase in the YBa{sub 2}Cu{sub 3}O{sub x} while maintaining the seed crystal solid. The materials are slowly cooled to provide a YBa{sub 2}Cu{sub 3}O{sub x} material having a predetermined number of domains between 1 and 5. Crack-free single domain materials can be formed using either plate shaped seed crystals or cube shaped seed crystals with a pedestal of preferential orientation material. 7 figs.

  5. Elasticity of single-crystal olivine at high pressures and temperature...

    Office of Scientific and Technical Information (OSTI)

    Elasticity of single-crystal olivine at high pressures and temperatures Citation Details In-Document Search Title: Elasticity of single-crystal olivine at high pressures and ...

  6. SINGLE CRYSTAL NIOBIUM TUBES FOR PARTICLE COLLIDERS ACCELERATOR CAVITIES

    SciTech Connect (OSTI)

    MURPHY, JAMES E

    2013-02-28

    The objective of this research project is to produce single crystal niobium (Nb) tubes for use as particle accelerator cavities for the Fermi laboratorys International Linear Collider project. Single crystal Nb tubes may have superior performance compared to a polycrystalline tubes because the absence of grain boundaries may permit the use of higher accelerating voltages. In addition, Nb tubes that are subjected to the high temperature, high vacuum crystallization process are very pure and well annealed. Any impurity with a significantly higher vapor pressure than Nb should be decreased by the relatively long exposure at high temperature to the high vacuum environment. After application of the single crystal process, the surfaces of the Nb tubes are bright and shiny, and the tube resembles an electro polished Nb tube. For these reasons, there is interest in single crystal Nb tubes and in a process that will produce single crystal tubes. To convert a polycrystalline niobium tube into a single crystal, the tube is heated to within a few hundred ?C of the melting temperature of niobium, which is 2477 ?C. RF heating is used to rapidly heat the tube in a narrow zone and after reaching the operating temperature, the hot zone is slowly passed along the length of the tube. For crystallization tests with Nb tubes, the traverse rate was in the range of 1-10 cm per hour. All the crystallization tests in this study were performed in a water-cooled, stainless steel chamber under a vacuum of 5 x10-6 torr or better. In earliest tests of the single crystal growth process, the Nb tubes had an OD of 1.9 cm and a wall thickness of 0.15 mm. With these relatively small Nb tubes, the single crystal process was always successful in producing single crystal tubes. In these early tests, the operating temperature was normally maintained at 2200 ?C, and the traverse rate was 5 cm per hour. In the next test series, the Nb tube size was increased to 3.8 cm OD and the wall thickness was

  7. Perpendicular Magnetism Unparalleled Find in Single Crystal ...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    order coexisting in a single sample. Article Title: Itinerant Ferromagnetism in the As 4p Conduction Band of Ba0.6K0.4Mn2As2 Identified by X-Ray Magnetic Circular Dichroism...

  8. Single-Crystal Structure of a Covalent Organic Framework

    SciTech Connect (OSTI)

    Zhang, YB; Su, J; Furukawa, H; Yun, YF; Gandara, F; Duong, A; Zou, XD; Yaghi, OM

    2013-11-06

    The crystal structure of a new covalent organic framework, termed COF-320, is determined by single-crystal 3D electron diffraction using the rotation electron diffraction (RED) method for data collection. The COF crystals are prepared by an imine condensation of tetra-(4-anilyl)methane and 4,4'-biphenyldialdehyde in 1,4-dioxane at 120 degrees C to produce a highly porous 9-fold interwoven diamond net. COF-320 exhibits permanent porosity with a Langmuir surface area of 2400 m(2)/g and a methane total uptake of 15.0 wt % (176 cm(3)/cm(3)) at 25 degrees C and 80 bar. The successful determination of the structure of COF-320 directly from single-crystal samples is an important advance in the development of COF chemistry.

  9. Method for harvesting rare earth barium copper oxide single crystals

    DOE Patents [OSTI]

    Todt, V.R.; Sengupta, S.; Shi, D.

    1996-04-02

    A method of preparing high temperature superconductor single crystals is disclosed. The method of preparation involves preparing precursor materials of a particular composition, heating the precursor material to achieve a peritectic mixture of peritectic liquid and crystals of the high temperature superconductor, cooling the peritectic mixture to quench directly the mixture on a porous, wettable inert substrate to wick off the peritectic liquid, leaving single crystals of the high temperature superconductor on the porous substrate. Alternatively, the peritectic mixture can be cooled to a solid mass and reheated on a porous, inert substrate to melt the matrix of peritectic fluid while leaving the crystals melted, allowing the wicking away of the peritectic liquid. 2 figs.

  10. Growth and characterization of lithium yttrium borate single crystals

    SciTech Connect (OSTI)

    Singh, A. K.; Singh, S. G.; Tyagi, M.; Desai, D. G.; Sen, Shashwati

    2014-04-24

    Single crystals of 0.1% Ce doped Li{sub 6}Y(BO{sub 3}){sub 3} have been grown using the Czochralski technique. The photoluminescence study of these crystals shows a broad emission at ? 420 nm corresponding to Ce{sub 3+} emission from 5d?4f energy levels. The decay profile of this emission shows a fast response of ? 28 ns which is highly desirable for detector applications.

  11. Lithium niobate single-crystal and photo-functional device

    DOE Patents [OSTI]

    Gopalan, Venkatraman; Mitchell, Terrence E.; Kitamura, Kenji; Furukawa, Yasunori

    2001-01-01

    Provided are lithium niobate single-crystal that requires a low voltage of not larger than 10 kV/nm for its ferroelectric polarization inversion and of which the polarization can be periodically inverted with accuracy even at such a low voltage, and a photo-functional device comprising the crystal. The crystal has a molar fraction of Li.sub.2 O/(Nb.sub.2 O.sub.5 +Li.sub.2 O) of falling between 0.49 and 0.52. The photo-functional device can convert a laser ray being incident thereon.

  12. Fuel Performance Experiments on the Atomistic Level, Studying Fuel Through Engineered Single Crystal UO2

    SciTech Connect (OSTI)

    Burgett, Eric; Deo, Chaitanya; Phillpot, Simon

    2015-05-08

    Fuel Performance Experiments on the Atomistic Level, Studying Fuel Through Engineered Single Crystal UO2

  13. Synthesis, spectral characterization, and single crystal structure studies

    Office of Scientific and Technical Information (OSTI)

    of (2-nitro-ethene-1,1-diyl)-bis-((4-isopropyl-benzyl)sulfane) (Journal Article) | SciTech Connect Synthesis, spectral characterization, and single crystal structure studies of (2-nitro-ethene-1,1-diyl)-bis-((4-isopropyl-benzyl)sulfane) Citation Details In-Document Search Title: Synthesis, spectral characterization, and single crystal structure studies of (2-nitro-ethene-1,1-diyl)-bis-((4-isopropyl-benzyl)sulfane) The title compound (2-nitro-ethene-1,1-diyl)-bis-(4-isopropylbenzyl)sulfane)

  14. Apparatus And Method For Producing Single Crystal Metallic Objects

    DOE Patents [OSTI]

    Huang, Shyh-Chin; Gigliotti, Jr., Michael Francis X.; Rutkowski, Stephen Francis; Petterson, Roger John; Svec, Paul Steven

    2006-03-14

    A mold is provided for enabling casting of single crystal metallic articles including a part-defining cavity, a sorter passage positioned vertically beneath and in fluid communication with the part-defining cavity, and a seed cavity positioned vertically beneath and in fluid communication with the sorter passage. The sorter passage includes a shape suitable for encouraging a single crystal structure in solidifying molten metal. Additionally, a portion of the mold between the sorter passage and the part-defining cavity includes a notch for facilitating breakage of a cast article proximate the notch during thermal stress build-up, so as to prevent mold breakage or the inclusion of part defects.

  15. Experiences in Large Grain-Single Crystal Cavity Fabrication

    SciTech Connect (OSTI)

    Pekeler, Michael; Schwellenbach, Johannes; Tradt, Marco

    2007-08-09

    At ACCEL instruments several single cell and 9-cell cavities have been produced out of large grain niobium sheets from different suppliers. The fabrication experience and difference to the production out of fine grain niobium sheets will be described. In addition two cavities were produced using single crystal niobium sheets. The final cavities showed no grain boundaries at all in the cavity cell, even not in the electron beam welding seam.

  16. Growth of large single crystals of MgO

    SciTech Connect (OSTI)

    Boatner, L.A.; Urbanik, M.

    1997-06-12

    The progressive identification of new high-technology applications and requirements for MgO single crystals in the commercial realm, as well as in DOE and other government-agency project areas, has resulted in an increased demand and international market for this material. Specifically, the demand for MgO crystals in large sizes and quantities is presently increasing due to existing and developing applications that include: (a) MgO substrates for the formation of electro-optic thin films and devices, (b) epitaxial substrates for high-temperature thin-film superconducting devices MgO optical components - including high-temperature windows, lenses, and prisms, and (d) specialty MgO crucibles and evaporation sources for thin-film production. In the course of CRADA ORNL92-0091, carried out with Commercial Crystal Laboratories of Naples, Florida as the commercial participant, we have made major progress in increasing the size of single crystals of MgO produced by means of the submerged-arc-fusion technique-thereby increasing the commercial utility of this material. Prior to the accomplishments realized in the course of this CRADA, the only commercially available single crystals of MgO were produced in Japan, Israel, and Russia. The results achieved in the course of CRADA ORNL92-0091 have now led to the establishment of a domestic commercial source of MgO single-crystal substrates and components, and the U.S. is no longer totally dependent on foreign sources of this increasingly important material.

  17. Properties of salt-grown uranium single crystals.

    SciTech Connect (OSTI)

    Cooley, J. C.; Hanrahan, R. J.; Hults, W. L.; Lashley, J. C.; Manley, M. E.; Mielke, C. H.; Smith, J. L.; Thoma, D. J.; Clark, R. G.; Hamilton, A. R.; O'Brien, J. L.; Gay, E. C.; Lumpkin, N. E.; McPheeters, C. C.; Willit, J.; Schmiedeshoff, G. M.; Touton, S.; Woodfield, B. F.; Lang, B. E.; Boerio-Goates, Juliana

    2001-01-01

    Recently single crystals of {alpha}-uranium were grown from a liquid salt bath. The electrical, magnetic and thermal properties of these crystals have been surveyed. The ratio of the room temperature resistivity of these crystals to the saturation value at low temperature is three times larger than any previously reported demonstrating that the crystals are of higher purity and quality than those in past work. The resistive signatures of the CDW transitions at 43, 37 and 22 K are obvious to the naked eye. The transition at 22 K exhibits temperature hysteresis that increases with magnetic field. In addition the superconducting transition temperature from resistivity is 820 mK and the critical field is 80 mT. Contrary to earlier work where the Debye temperature ranged from 186 to 218 K, the Debye temperature extracted from the heat capacity is 254 K in good agreement with the predicted value of 250 K. Magnetoresistance, Hall effect and magnetic susceptibility measurements are underway. In time, measurements made on these crystals may help us to understand the origin of superconductivity and its relation to the CDW transitions in pure uranium.

  18. Method for thermal processing alumina-enriched spinel single crystals

    DOE Patents [OSTI]

    Jantzen, C.M.

    1995-05-09

    A process for age-hardening alumina-rich magnesium aluminum spinel to obtain the desired combination of characteristics of hardness, clarity, flexural strength and toughness comprises selection of the time-temperature pair for isothermal heating followed by quenching. The time-temperature pair is selected from the region wherein the precipitate groups have the characteristics sought. The single crystal spinel is isothermally heated and will, if heated long enough pass from its single phase through two pre-precipitates and two metastable precipitates to a stable secondary phase precipitate within the spinel matrix. Quenching is done slowly at first to avoid thermal shock, then rapidly. 12 figs.

  19. Diamond turning of Si and Ge single crystals

    SciTech Connect (OSTI)

    Blake, P.; Scattergood, R.O.

    1988-12-01

    Single-point diamond turning studies have been completed on Si and Ge crystals. A new process model was developed for diamond turning which is based on a critical depth of cut for plastic flow-to-brittle fracture transitions. This concept, when combined with the actual machining geometry for single-point turning, predicts that {open_quotes}ductile{close_quotes} machining is a combined action of plasticity and fracture. Interrupted cutting experiments also provide a meant to directly measure the critical depth parameter for given machining conditions.

  20. Method for thermal processing alumina-enriched spinel single crystals

    DOE Patents [OSTI]

    Jantzen, Carol M.

    1995-01-01

    A process for age-hardening alumina-rich magnesium aluminum spinel to obtain the desired combination of characteristics of hardness, clarity, flexural strength and toughness comprises selection of the time-temperature pair for isothermal heating followed by quenching. The time-temperature pair is selected from the region wherein the precipitate groups have the characteristics sought. The single crystal spinel is isothermally heated and will, if heated long enough pass from its single phase through two pre-precipitates and two metastable precipitates to a stable secondary phase precipitate within the spinel matrix. Quenching is done slowly at first to avoid thermal shock, then rapidly.

  1. Interfacial dislocation motion and interactions in single-crystal superalloys

    SciTech Connect (OSTI)

    Liu, B.; Raabe, D.; Roters, F.; Arsenlis, A.

    2014-10-01

    The early stage of high-temperature low-stress creep in single-crystal superalloys is characterized by the rapid development of interfacial dislocation networks. Although interfacial motion and dynamic recovery of these dislocation networks have long been expected to control the subsequent creep behavior, direct observation and hence in-depth understanding of such processes has not been achieved. Incorporating recent developments of discrete dislocation dynamics models, we simulate interfacial dislocation motion in the channel structures of single-crystal superalloys, and investigate how interfacial dislocation motion and dynamic recovery are affected by interfacial dislocation interactions and lattice misfit. Different types of dislocation interactions are considered: self, collinear, coplanar, Lomer junction, glissile junction, and Hirth junction. The simulation results show that strong dynamic recovery occurs due to the short-range reactions of collinear annihilation and Lomer junction formation. The misfit stress is found to induce and accelerate dynamic recovery of interfacial dislocation networks involving self-interaction and Hirth junction formation, but slow down the steady interfacial motion of coplanar and glissile junction forming dislocation networks. The insights gained from these simulations on high-temperature low-stress creep of single-crystal superalloys are also discussed.

  2. Single crystal plasticity by modeling dislocation density rate behavior

    SciTech Connect (OSTI)

    Hansen, Benjamin L; Bronkhorst, Curt; Beyerlein, Irene; Cerreta, E. K.; Dennis-Koller, Darcie

    2010-12-23

    The goal of this work is to formulate a constitutive model for the deformation of metals over a wide range of strain rates. Damage and failure of materials frequently occurs at a variety of deformation rates within the same sample. The present state of the art in single crystal constitutive models relies on thermally-activated models which are believed to become less reliable for problems exceeding strain rates of 10{sup 4} s{sup -1}. This talk presents work in which we extend the applicability of the single crystal model to the strain rate region where dislocation drag is believed to dominate. The elastic model includes effects from volumetric change and pressure sensitive moduli. The plastic model transitions from the low-rate thermally-activated regime to the high-rate drag dominated regime. The direct use of dislocation density as a state parameter gives a measurable physical mechanism to strain hardening. Dislocation densities are separated according to type and given a systematic set of interactions rates adaptable by type. The form of the constitutive model is motivated by previously published dislocation dynamics work which articulated important behaviors unique to high-rate response in fcc systems. The proposed material model incorporates thermal coupling. The hardening model tracks the varying dislocation population with respect to each slip plane and computes the slip resistance based on those values. Comparisons can be made between the responses of single crystals and polycrystals at a variety of strain rates. The material model is fit to copper.

  3. Acquisition of Single Crystal Growth and Characterization Equipment

    SciTech Connect (OSTI)

    Maple, M. Brian; Zocco, Diego A.

    2008-12-09

    Final Report for DOE Grant No. DE-FG02-04ER46178 'Acquisition of Single Crystal Growth and Characterization Equipment'. There is growing concern in the condensed matter community that the need for quality crystal growth and materials preparation laboratories is not being met in the United States. It has been suggested that there are too many researchers performing measurements on too few materials. As a result, many user facilities are not being used optimally. The number of proficient crystal growers is too small. In addition, insufficient attention is being paid to the enterprise of finding new and interesting materials, which is the driving force behind much of condensed matter research and, ultimately, technology. While a detailed assessment of this situation is clearly needed, enough evidence of a problem already exists to compel a general consensus that the situation must be addressed promptly. This final report describes the work carried out during the last four years in our group, in which a state-of-the-art single crystal growth and characterization facility was established for the study of novel oxides and intermetallic compounds of rare earth, actinide and transition metal elements. Research emphasis is on the physics of superconducting (SC), magnetic, heavy fermion (HF), non-Fermi liquid (NFL) and other types of strongly correlated electron phenomena in bulk single crystals. Properties of these materials are being studied as a function of concentration of chemical constituents, temperature, pressure, and magnetic field, which provide information about the electronic, lattice, and magnetic excitations at the root of various strongly correlated electron phenomena. Most importantly, the facility makes possible the investigation of material properties that can only be achieved in high quality bulk single crystals, including magnetic and transport phenomena, studies of the effects of disorder, properties in the clean limit, and spectroscopic and scattering

  4. Ultrafast Dynamic Response of Single Crystal PETN and Beta-HMX...

    Office of Scientific and Technical Information (OSTI)

    Conference: Ultrafast Dynamic Response of Single Crystal PETN and Beta-HMX Citation Details In-Document Search Title: Ultrafast Dynamic Response of Single Crystal PETN and Beta-HMX...

  5. Single-Crystal Elasticity of the Deep-Mantle Magnesite at High...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Single-Crystal Elasticity of the Deep-Mantle Magnesite at High Pressure and Temperature Citation Details In-Document Search Title: Single-Crystal Elasticity of the ...

  6. World's largest single crystal of gold verified by Los Alamos instruments

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Los Alamos verifies largest single gold crystal World's largest single crystal of gold verified by Los Alamos instruments Using Lujan Center's HIPPO instrument, researchers probed the specimen with neutrons to gather critical information December 22, 2014 World's largest single crystal of gold verified by Los Alamos instruments Neutron diffraction data collected on the single-crystal diffraction (SCD) instrument at the Lujan Center, from the Venezuelan gold sample, indicate that the sample is a

  7. Shock response of He bubbles in single crystal Cu

    SciTech Connect (OSTI)

    Li, B.; Wang, L.; E, J. C.; Luo, S. N.; Ma, H. H.

    2014-12-07

    With large-scale molecular dynamics simulations, we investigate shock response of He nanobubbles in single crystal Cu. For sufficient bubble size or internal pressure, a prismatic dislocation loop may form around a bubble in unshocked Cu. The internal He pressure helps to stabilize the bubble against plastic deformation. However, the prismatic dislocation loops may partially heal but facilitate nucleation of new shear and prismatic dislocation loops. For strong shocks, the internal pressure also impedes internal jetting, while a bubble assists local melting; a high speed jet breaks a He bubble into pieces dispersed among Cu. Near-surface He bubbles may burst and form high velocity ejecta containing atoms and small fragments, while the ejecta velocities do not follow the three-dimensional Maxwell-Boltzmann distributions expected for thermal equilibrium. The biggest fragment size deceases with increasing shock strength. With a decrease in ligament thickness or an increase in He bubble size, the critical shock strength required for bubble bursting decreases, while the velocity range, space extension and average velocity component along the shock direction, increase. Small bubbles are more efficient in mass ejecting. Compared to voids and perfect single crystal Cu, He bubbles have pronounced effects on shock response including bubble/void collapse, Hugoniot elastic limit (HEL), deformation mechanisms, and surface jetting. HEL is the highest for perfect single crystal Cu with the same orientations, followed by He bubbles without pre-existing prismatic dislocation loops, and then voids. Complete void collapse and shear dislocations occur for embedded voids, as opposed to partial collapse, and shear and possibly prismatic dislocations for He bubbles. He bubbles lower the threshhold shock strength for ejecta formation, and increase ejecta velocity and ejected mass.

  8. Single crystal NMR studies of high temperature superconductors

    SciTech Connect (OSTI)

    Pennington, C.H.; Durand, D.J.; Zax, D.B.; Slichter, C.P.; Rice, J.P.; Bukowski, E.D.; Ginsberg, D.M.

    1989-01-01

    The authors report Cu NMR studies in the normal state of a single crystal of the T/sub c/ = 90 K superconductor YBa/sub 2/Cu/sub 3/O/sub 7/minus/delta/. The authors have measured the magnetic shift tensor, the electric field gradient tensor, the nuclear spin-lattice relaxation rate tensor, and the time dependence and functional form of the transverse decay. From these data they obtain information about the charge state and magnetic state of the Cu atoms, and the existence and size of the electronic exchange coupling between spins of adjacent Cu atoms. 18 refs., 3 figs., 2 tabs.

  9. Growth and properties of Lithium Salicylate single crystals

    SciTech Connect (OSTI)

    Zaitseva, N; Newby, J; Hull, G; Saw, C; Carman, L; Cherepy, N; Payne, S

    2009-02-13

    An attractive feature of {sup 6}Li containing fluorescence materials that determines their potential application in radiation detection is the capture reaction with slow ({approx}< 100 keV) neutrons: {sup 6}Li + n = {sup 4}He + {sup 3}H + 4.8MeV. The use of {sup 6}Li-salicylate (LiSal, LiC{sub 6}H{sub 5}O{sub 3}) for thermal neutron detection was previously studied in liquid and polycrystalline scintillators. The studies showed that both liquid and polycrystalline LiSal scintillators could be utilized in pulse shape discrimination (PSD) techniques that enable separation of neutrons from the background gamma radiation. However, it was found that the efficiency of neutron detection using LiSal in liquid solutions was severely limited by its low solubility in commonly used organic solvents like, for example, toluene or xylene. Better results were obtained with neutron detectors containing the compound in its crystalline form, such as pressed pellets, or microscopic-scale (7-14 micron) crystals dispersed in various media. The expectation drown from these studies was that further improvement of pulse height, PSD, and efficiency characteristics could be reached with larger and more transparent LiSal crystals, growth of which has not been reported so far. In this paper, we present the first results on growth and characterization of relatively large, a cm-scale size, single crystals of LiSal with good optical quality. The crystals were grown both from aqueous and anhydrous (methanol) media, mainly for neutron detection studies. However, the results on growth and structural characterization may be interesting for other fields where LiSal, together with other alkali metal salicylates, is used for biological, medical, and chemical (as catalyst) applications.

  10. Modal reduction in single crystal sapphire optical fiber

    SciTech Connect (OSTI)

    Cheng, Yujie; Hill, Cary; Liu, Bo; Yu, Zhihao; Xuan, Haifeng; Homa, Daniel; Wang, Anbo; Pickrell, Gary

    2015-10-12

    A new type of single crystal sapphire optical fiber (SCSF) design is proposed to reduce the number of guided modes via a highly dispersive cladding with a periodic array of high and low index regions in the azimuthal direction. The structure retains a “core” region of pure single crystal (SC) sapphire in the center of the fiber and a “cladding” region of alternating layers of air and SC sapphire in the azimuthal direction that is uniform in the radial direction. The modal characteristics and confinement losses of the fundamental mode were analyzed via the finite element method by varying the effective core diameter and the dimensions of the “windmill” shaped cladding. The simulation results showed that the number of guided modes were significantly reduced in the “windmill” fiber design, as the radial dimension of the air and SC sapphire cladding regions increase with corresponding decrease in the azimuthal dimension. It is anticipated that the “windmill” SCSF will readily improve the performance of current fiber optic sensors in the harsh environment and potentially enable those that were limited by the extremely large modal volume of unclad SCSF.

  11. Modal reduction in single crystal sapphire optical fiber

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Cheng, Yujie; Hill, Cary; Liu, Bo; Yu, Zhihao; Xuan, Haifeng; Homa, Daniel; Wang, Anbo; Pickrell, Gary

    2015-10-12

    A new type of single crystal sapphire optical fiber (SCSF) design is proposed to reduce the number of guided modes via a highly dispersive cladding with a periodic array of high and low index regions in the azimuthal direction. The structure retains a “core” region of pure single crystal (SC) sapphire in the center of the fiber and a “cladding” region of alternating layers of air and SC sapphire in the azimuthal direction that is uniform in the radial direction. The modal characteristics and confinement losses of the fundamental mode were analyzed via the finite element method by varying themore » effective core diameter and the dimensions of the “windmill” shaped cladding. The simulation results showed that the number of guided modes were significantly reduced in the “windmill” fiber design, as the radial dimension of the air and SC sapphire cladding regions increase with corresponding decrease in the azimuthal dimension. It is anticipated that the “windmill” SCSF will readily improve the performance of current fiber optic sensors in the harsh environment and potentially enable those that were limited by the extremely large modal volume of unclad SCSF.« less

  12. Synthesis of millimeter-scale transition metal dichalcogenides single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gong, Yongji; Ye, Gonglan; Lei, Sidong; Shi, Gang; Vajtai, Robert; Pantelides, Sokrates T.; Zhou, Wu; Li, Bo; Ajayan, Pullikel M.

    2016-02-10

    The emergence of semiconducting transition metal dichalcogenide (TMD) atomic layers has opened up unprecedented opportunities in atomically thin electronics. Yet the scalable growth of TMD layers with large grain sizes and uniformity has remained very challenging. Here is reported a simple, scalable chemical vapor deposition approach for the growth of MoSe2 layers is reported, in which the nucleation density can be reduced from 105 to 25 nuclei cm-2, leading to millimeter-scale MoSe2 single crystals as well as continuous macrocrystalline films with millimeter size grains. The selective growth of monolayers and multilayered MoSe2 films with well-defined stacking orientation can also bemore » controlled via tuning the growth temperature. In addition, periodic defects, such as nanoscale triangular holes, can be engineered into these layers by controlling the growth conditions. The low density of grain boundaries in the films results in high average mobilities, around ≈42 cm2 V-1 s-1, for back-gated MoSe2 transistors. This generic synthesis approach is also demonstrated for other TMD layers such as millimeter-scale WSe2 single crystals.« less

  13. Design and analysis of large-core single-mode windmill single crystal sapphire optical fiber

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Cheng, Yujie; Hill, Cary; Liu, Bo; Yu, Zhihao; Xuan, Haifeng; Homa, Daniel; Wang, Anbo; Pickrell, Gary

    2016-06-01

    We present a large-core single-mode “windmill” single crystal sapphire optical fiber (SCSF) design, which exhibits single-mode operation by stripping off the higher-order modes (HOMs) while maintaining the fundamental mode. The “windmill” SCSF design was analyzed using the finite element analysis method, in which all the HOMs are leaky. The numerical simulation results show single-mode operation in the spectral range from 0.4 to 2 μm in the windmill SCSF, with an effective core diameter as large as 14 μm. Such fiber is expected to improve the performance of many of the current sapphire fiber optic sensor structures.

  14. Compensation mechanism of bromine dopants in cadmium telluride single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bolotnikov, A. E.; Fochuk, P. M.; Verzhak, Ye. V.; Parashchuk, T. O.; Freik, D. M.; Panchuk, O. E.; James, R. B.; Gorichok, I. V.

    2015-01-02

    We grew single crystals of cadmium telluride, doped with bromine by the Bridgman method, annealed them under a cadmium overpressure (PCd = 10² - 10⁵ Pa) at 800-1100 K, and investigated their electrical properties at high- and low-temperature. The influence of impurities on the crystals' electrical properties were analyzed using the defect subsystem model; the model includes the possibility of the formation of point intrinsic defects (V²⁻Cd, Cd²⁺i, V²⁺Te, Te²⁻i), and substitutional ones (Br⁰Te, Br⁺Te), as well as complexes of point defects, i.e., (Br⁺Te V²⁻Cd)⁻ and (2Br⁺Te V²⁻Cd)⁰. We established the concentration dependence between free charge carriers and themore » parameters of the annealing process. Here, n(T) and n(PCd) are determined by two dominant defects – Br⁺Te and (2Br⁺Te V²⁻Cd)⁰. Their content varies with the annealing temperature and the vapor pressure of the component; the concentration of other defects is much smaller and almost does not affect the electron density.« less

  15. Compensation mechanism of bromine dopants in cadmium telluride single crystals

    SciTech Connect (OSTI)

    Bolotnikov, A. E.; Fochuk, P. M.; Verzhak, Ye. V.; Parashchuk, T. O.; Freik, D. M.; Panchuk, O. E.; James, R. B.; Gorichok, I. V.

    2015-01-02

    We grew single crystals of cadmium telluride, doped with bromine by the Bridgman method, annealed them under a cadmium overpressure (PCd = 10² - 10⁵ Pa) at 800-1100 K, and investigated their electrical properties at high- and low-temperature. The influence of impurities on the crystals' electrical properties were analyzed using the defect subsystem model; the model includes the possibility of the formation of point intrinsic defects (V²⁻Cd, Cd²⁺i, V²⁺Te, Te²⁻i), and substitutional ones (Br⁰Te, Br⁺Te), as well as complexes of point defects, i.e., (Br⁺Te V²⁻Cd)⁻ and (2Br⁺Te V²⁻Cd)⁰. We established the concentration dependence between free charge carriers and the parameters of the annealing process. Here, n(T) and n(PCd) are determined by two dominant defects – Br⁺Te and (2Br⁺Te V²⁻Cd)⁰. Their content varies with the annealing temperature and the vapor pressure of the component; the concentration of other defects is much smaller and almost does not affect the electron density.

  16. Shock compression experiments on Lithium Deuteride single crystals.

    SciTech Connect (OSTI)

    Knudson, Marcus D.; Desjarlais, Michael P.; Lemke, Raymond W.

    2014-10-01

    S hock compression exper iments in the few hundred GPa (multi - Mabr) regime were performed on Lithium Deuteride (LiD) single crystals . This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17 - 32 km/s. Measurements included pressure, density, and temperature between ~200 - 600 GPa along the Principal Hugoniot - the locus of end states achievable through compression by large amplitude shock waves - as well as pressure and density of re - shock states up to ~900 GPa . The experimental measurements are compared with recent density functional theory calculations as well as a new tabular equation of state developed at Los Alamos National Labs.

  17. Single crystal metal wedges for surface acoustic wave propagation

    DOE Patents [OSTI]

    Fisher, E.S.

    1980-05-09

    An ultrasonic testing device has been developed to evaluate flaws and inhomogeneities in the near-surface region of a test material. A metal single crystal wedge is used to generate high frequency Rayleigh surface waves in the test material surface by conversion of a slow velocity, bulk acoustic mode in the wedge into a Rayleigh wave at the metal-wedge test material interface. Particular classes of metals have been found to provide the bulk acoustic modes necessary for production of a surface wave with extremely high frequency and angular collimation. The high frequency allows flaws and inhomogeneities to be examined with greater resolution. The high degree of angular collimation for the outgoing ultrasonic beam permits precision angular location of flaws and inhomogeneities in the test material surface.

  18. Single crystal metal wedges for surface acoustic wave propagation

    DOE Patents [OSTI]

    Fisher, Edward S.

    1982-01-01

    An ultrasonic testing device has been developed to evaluate flaws and inhomogeneities in the near-surface region of a test material. A metal single crystal wedge is used to generate high frequency Rayleigh surface waves in the test material surface by conversion of a slow velocity, bulk acoustic mode in the wedge into a Rayleigh wave at the metal-wedge test material interface. Particular classes of metals have been found to provide the bulk acoustic modes necessary for production of a surface wave with extremely high frequency and angular collimation. The high frequency allows flaws and inhomogeneities to be examined with greater resolution. The high degree of angular collimation for the outgoing ultrasonic beam permits precision angular location of flaws and inhomogeneities in the test material surface.

  19. Single-crystal X-ray diffraction at extreme conditions: a review...

    Office of Scientific and Technical Information (OSTI)

    Title: Single-crystal X-ray diffraction at extreme conditions: a review Authors: Ballaran, Tiziana Boffa ; Kurnosov, Alexander ; Trots, Dmytro 1 + Show Author Affiliations ...

  20. Investigation on crystalline perfection, mechanical, piezoelectric and ferroelectric properties of L-tartaric acid single crystal

    SciTech Connect (OSTI)

    Murugan, G. Senthil Ramasamy, P.

    2014-04-24

    Polar organic nonlinear optical material, L-tartaric acid single crystals have been grown from slow evaporation solution growth technique. Single crystal X-ray diffraction study indicates that the grown crystal crystallized in monoclinic system with space group P2{sub 1}. Crystalline perfection of the crystal has been evaluated by high resolution X-ray diffraction technique and it reveals that the crystal quality is good and free from structural grain boundaries. Mechanical stability of the crystal has been analyzed by Vickers microhardness measurement and it exhibits reverse indentation size effect. Piezoelectric d{sub 33} co-efficient for the crystal has been examined and its value is 47 pC/N. The ferroelectric behaviour of the crystal was analyzed by polarization-electric field hysteresis loop measurement.

  1. Deterministically Polarized Fluorescence from Single Dye Molecules Aligned in Liquid Crystal Host

    SciTech Connect (OSTI)

    Lukishova, S.G.; Schmid, A.W.; Knox, R.; Freivald, P.; Boyd, R. W.; Stroud, Jr., C. R.; Marshall, K.L.

    2005-09-30

    We demonstrated for the first time to our konwledge deterministically polarized fluorescence from single dye molecules. Planar aligned nematic liquid crystal hosts provide deterministic alignment of single dye molecules in a preferred direction.

  2. Mechanism of relaxation polarization in lithium fluoride single crystals

    SciTech Connect (OSTI)

    Annenkov, Yu.M.; Boev, S.G.; Kozhemyakin, V.A.; Fursa, T.V.

    1988-12-01

    The authors have compared the thermally stimulated currents and the pulsed electromagnetic radiation of thermoelectrets and mechanoelectrets made from lithium fluoride single crystals grown without specially introduced impurities. The samples with platinum electrodes applied to the surface by cathodic sputtering were deformed along the largest face up to relative strain /var epsilon/ equal to 1.4%. Then the thermally stimulated currents were registered upon heating the samples at the rate of 3-4 deg/min. In other experiments, after deformation of the samples under analogous conditions they registered the pulsed electromagnetic signals for the samples upon nonisothermal annealing. Plane-parallel samples were polarized at the temperature 473 K and electric field intensity 5 kV/cm for 10-15 min. Since thermally stimulated currents and pulsed electromagnetic signals at 363-383 K decreased substantially over the course of several hours after polarization or deformation of the samples and were practically unregistered after one day, while the volume charge in LiF can be retained over the course of many months, they may conclude that the first relaxation maximum is not connected with disruption of the volume charge. It is possible due to localization of cationic vacancies on individual dislocations, while the second maximum may be due to such dislocation pile-ups.

  3. Radiation tolerance of piezoelectric bulk single-crystal aluminum nitride

    SciTech Connect (OSTI)

    David A. Parks; Bernhard R. Tittmann

    2014-07-01

    For practical use in harsh radiation environments, we pose selection criteria for piezoelectric materials for nondestructive evaluation (NDE) and material characterization. Using these criteria, piezoelectric aluminum nitride is shown to be an excellent candidate. The results of tests on an aluminumnitride-based transducer operating in a nuclear reactor are also presented. We demonstrate the tolerance of single-crystal piezoelectric aluminum nitride after fast and thermal neutron fluences of 1.85 × 1018 neutron/cm2 and 5.8 × 1018 neutron/cm2, respectively, and a gamma dose of 26.8 MGy. The radiation hardness of AlN is most evident from the unaltered piezoelectric coefficient d33, which measured 5.5 pC/N after a fast and thermal neutron exposure in a nuclear reactor core for over 120 MWh, in agreement with the published literature value. The results offer potential for improving reactor safety and furthering the understanding of radiation effects on materials by enabling structural health monitoring and NDE in spite of the high levels of radiation and high temperatures, which are known to destroy typical commercial ultrasonic transducers.

  4. DEVELOPMENT OF PROTECTIVE COATINGS FOR SINGLE CRYSTAL TURBINE BLADES

    SciTech Connect (OSTI)

    Amarendra K. Rai

    2006-12-04

    Turbine blades in coal derived syngas systems are subject to oxidation and corrosion due to high steam temperature and pressure. Thermal barrier coatings (TBCs) are developed to address these problems. The emphasis is on prime-reliant design and a better coating architecture, having high temperature and corrosion resistance properties for turbine blades. In Phase I, UES Inc. proposed to develop, characterize and optimize a prime reliant TBC system, having smooth and defect-free NiCoCrAlY bond layer and a defect free oxide sublayer, using a filtered arc technology. Phase I work demonstrated the deposition of highly dense, smooth and defect free NiCoCrAlY bond coat on a single crystal CMSX-4 substrate and the deposition of alpha-alumina and yttrium aluminum garnet (YAG) sublayer on top of the bond coat. Isothermal and cyclic oxidation test and pre- and post-characterization of these layers, in Phase I work, (with and without top TBC layer of commercial EB PVD YSZ) revealed significant performance enhancement.

  5. Growth and characterization of 4-chloro-3-nitrobenzophenone single crystals using vertical Bridgman technique

    SciTech Connect (OSTI)

    Aravinth, K. Babu, G. Anandha Ramasamy, P.

    2014-04-24

    4-chloro-3-nitrobenzophenone (4C3N) has been grown by using vertical Bridgman technique. The grown crystal was confirmed by Powder X-ray diffraction analysis. The crystalline perfection of the grown crystal was examined by high-resolution X-ray diffraction study. The fluorescence spectra of grown 4C3N single crystals exhibit emission peak at 575 nm. The micro hardness measurements were used to analyze the mechanical property of the grown crystal.

  6. Arc-melting preparation of single crystal LaB.sub.6 cathodes

    DOE Patents [OSTI]

    Gibson, Edwin D.; Verhoeven, John D.

    1977-06-21

    A method for preparing single crystals of lanthanum hexaboride (LaB.sub.6) by arc melting a rod of compacted LaB.sub.6 powder. The method is especially suitable for preparing single crystal LaB.sub.6 cathodes for use in scanning electron microscopes (SEM) and scanning transmission electron microscopes (STEM).

  7. The growth of Ho:YAG single crystals by Czochralski method and investigating the formed cores

    SciTech Connect (OSTI)

    Hasani Barbaran, J. Ghani Aragi, M. R.; Javaheri, I.; Baharvand, B.; Tabasi, M.; Layegh Ahan, R.; Jangjo, E.

    2015-12-15

    Ho:YAG single crystals were grown by Czochralski technique, and investigated by the X-ray diffraction (XRD) and optical methods. The crystals were cut and polished in order to observe and analyze their cores. It was found that the deviation of the cores formed in the Czochralski grown Ho:YAG single crystals are resulted from non-symmetrical status of thermal insulation around the Iridium crucible.

  8. The crystal structure of {pi}-ErBO{sub 3}: New single-crystal data for an old problem

    SciTech Connect (OSTI)

    Pitscheider, Almut [Institut fuer Allgemeine, Anorganische und Theoretische Chemie, Leopold-Franzens-Universitaet Innsbruck, Innrain 52a, A-6020 Innsbruck (Austria); Kaindl, Reinhard [Institut fuer Mineralogie und Petrographie, Leopold-Franzens-Universitaet Innsbruck, Innrain 52, A-6020 Innsbruck (Austria); Oeckler, Oliver [Department Chemie, Ludwig-Maximilians-Universitaet Muenchen, Butenandtstrasse 5-13, D-81377 Muenchen (Germany); Huppertz, Hubert, E-mail: Hubert.Huppertz@uibk.ac.a [Institut fuer Allgemeine, Anorganische und Theoretische Chemie, Leopold-Franzens-Universitaet Innsbruck, Innrain 52a, A-6020 Innsbruck (Austria)

    2011-01-15

    Single crystals of the orthoborate {pi}-ErBO{sub 3} were synthesized from Er{sub 2}O{sub 3} and B{sub 2}O{sub 3} under high-pressure/high-temperature conditions of 2 GPa and 800 {sup o}C in a Walker-type multianvil apparatus. The crystal structure was determined on the basis of single-crystal X-ray diffraction data, collected at room temperature. The title compound crystallizes in the monoclinic pseudowollastonite-type structure, space group C2/c, with the lattice parameters a=1128.4(2) pm, b=652.6(2) pm, c=954.0(2) pm, and {beta}=112.8(1){sup o} (R{sub 1}=0.0124 and wR{sub 2}=0.0404 for all data). -- graphical abstract: The first satisfying single-crystal structure determination of {pi}-ErBO{sub 3} sheds light on the extensively discussed structure of {pi}-orthoborates. The application of light pressure during the solid state synthesis yielded in high-quality crystals, due to pressure-induced crystallization. Research highlights: {yields} High-quality single crystals of {pi}-ErBO{sub 3} were prepared via high-pressure-induced crystallization. {yields} At least five different space groups for the rare-earth {pi}-orthoborates are reported. {yields} {pi}-ErBO{sub 3} is isotypic to the pseudowollastonite-type CaSiO{sub 3}. {yields} Remaining ambiguities regarding the structure of the rare-earth {pi}-orthoborates are resolved.

  9. Single Particle Database of Natural Ice Crystals: Dimensions

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Particle Database of Natural Ice Crystals: Dimensions and Aspect Ratios For original submission and image(s), see ARM Research Highlights http:www.arm.govsciencehighlights...

  10. Single-Crystal Sapphire Optical Fiber Sensor Instrumentation

    SciTech Connect (OSTI)

    Pickrell, Gary; Scott, Brian; Wang, Anbo; Yu, Zhihao

    2013-12-31

    This report summarizes technical progress on the program “Single-Crystal Sapphire Optical Fiber Sensor Instrumentation,” funded by the National Energy Technology Laboratory of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. This project was completed in three phases, each with a separate focus. Phase I of the program, from October 1999 to April 2002, was devoted to development of sensing schema for use in high temperature, harsh environments. Different sensing designs were proposed and tested in the laboratory. Phase II of the program, from April 2002 to April 2009, focused on bringing the sensor technologies, which had already been successfully demonstrated in the laboratory, to a level where the sensors could be deployed in harsh industrial environments and eventually become commercially viable through a series of field tests. Also, a new sensing scheme was developed and tested with numerous advantages over all previous ones in Phase II. Phase III of the program, September 2009 to December 2013, focused on development of the new sensing scheme for field testing in conjunction with materials engineering of the improved sensor packaging lifetimes. In Phase I, three different sensing principles were studied: sapphire air-gap extrinsic Fabry-Perot sensors; intensity-based polarimetric sensors; and broadband polarimetric sensors. Black body radiation tests and corrosion tests were also performed in this phase. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. At the beginning of Phase II, in June 2004, the BPDI sensor was tested at the Wabash River coal gasifier

  11. Single shot ultrafast dynamic ellipsometry (UDE) of laser-driven shocks in single crystal explosives

    SciTech Connect (OSTI)

    Whitley, Von H; Mcgrane, Shawn D; Moore, David S; Eakins, Dan E; Bolme, Cindy A

    2009-01-01

    We report on the first experiments to measure states in shocked energetic single crystals with dynamic ellipsometry. We demonstrate that these ellipsometric techniques can produce reasonable Hugoniot values using small amounts of crystalline RDX and PETN. Pressures, particle velocities and shock velocities obtained using shocked ellipsometry are comparable to those found using gas-gun flyer plates and molecular dynamics calculations. The adaptation of the technique from uniform thin films of polymers to thick non-perfect crystalline materials was a significant achievement. Correct sample preparation proved to be a crucial component. Through trial and error, we were able to resolve polishing issues, sample quality problems, birefringence effects and mounting difficulties that were not encountered using thin polymer films.

  12. Demonstration of single crystal growth via solid-solid transformation of a glass

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Savytskii, Dmytro; Knorr, Brian; Dierolf, Volkmar; Jain, Himanshu

    2016-03-18

    Many advanced technologies have relied on the availability of single crystals of appropriate material such as silicon for microelectronics or superalloys for turbine blades. Similarly, many promising materials could unleash their full potential if they were available in a single crystal form. However, the current methods are unsuitable for growing single crystals of these oftentimes incongruently melting, unstable or metastable materials. Here we demonstrate a strategy to overcome this hurdle by avoiding the gaseous or liquid phase, and directly converting glass into a single crystal. Specifically, Sb2S3 single crystals are grown in Sb-S-I glasses as an example of this approach.more » In this first unambiguous demonstration of an all-solid-state glass → crystal transformation, extraneous nucleation is avoided relative to crystal growth via spatially localized laser heating and inclusion of a suitable glass former in the composition. Lastly, the ability to fabricate patterned single-crystal architecture on a glass surface is demonstrated, providing a new class of micro-structured substrate for low cost epitaxial growth, active planar devices, etc.« less

  13. Growth and characterization of new semiorganic nonlinear optical and piezoelectric lithium sulfate monohydrate oxalate single crystals

    SciTech Connect (OSTI)

    Yadav, Harsh; Sinha, Nidhi; Kumar, Binay

    2015-04-15

    Highlights: • A new semiorganic single crystal of LSO grown by slow evaporation technique. • Morphological studies of the LSO crystal deduced by BFDH law. • In the UV–vis spectrum wide transparent region and large band gap were found. • SHG is equal to KDP crystal and d{sub 33} was found to be equal to 6pC/N. • Grown crystal belongs to softer category. - Abstract: New semiorganic crystal of lithium sulfate monohydrate oxalate (LSO) for nonlinear application was synthesized by controlled slow evaporation method. The growth rate of various planes of the grown crystal was estimated by morphological study. Single crystal XRD analysis confirmed that the crystal belongs to triclinic lattice with space group P1. High transparency (∼95%) with large band gap (4.57 eV) was analyzed by UV–vis studies. FTIR and Raman spectroscopy were used to identify various functional groups present in the LSO crystal. SHG efficiency was found to be equal to the KDP crystal. Thermal stability (up to 117.54 °C) and melting point (242 °C) of the crystal were studied by TG-DTA. In dielectric measurements, the value of dielectric constant decreases with increase in frequency. Hardness studies confirmed soft nature of crystals. The piezoelectric coefficient was found to be 6pC/N along [0 0 1].

  14. Growth of mercuric iodide single crystals from dimethylsulfoxide

    DOE Patents [OSTI]

    Carlston, Richard C.

    1976-07-13

    Dimethylsulfoxide is used as a solvent for the growth of red mercuric iodide (HgI.sub.2) crystals for use in radiation detectors. The hygroscopic property of the solvent allows controlled amounts of water to enter into the solvent phase and diminish the large solubility of HgI.sub.2 so that the precipitating solid collects as well-defined euhedral crystals which grow into a volume of several cc.

  15. Effect of indium and antimony doping in SnS single crystals

    SciTech Connect (OSTI)

    Chaki, Sunil H. Chaudhary, Mahesh D.; Deshpande, M.P.

    2015-03-15

    Highlights: • Single crystals growth of pure SnS, indium doped SnS and antimony doped SnS by direct vapour transport (DVT) technique. • Doping of In and Sb occurred in SnS single crystals by cation replacement. • The replacement mechanism ascertained by EDAX, XRD and substantiated by Raman spectra analysis. • Dopants concentration affects the optical energy bandgap. • Doping influences electrical transport properties. - Abstract: Single crystals of pure SnS, indium (In) doped SnS and antimony (Sb) doped SnS were grown by direct vapour transport (DVT) technique. Two doping concentrations of 5% and 15% each were employed for both In and Sb dopants. Thus in total five samples were studied viz., pure SnS (S1), 5% In doped SnS (S2), 15% In doped SnS (S3), 5% Sb doped SnS (S4) and 15% Sb doped SnS (S5). The grown single crystal samples were characterized by evaluating their surface microstructure, stoichiometric composition, crystal structure, Raman spectroscopy, optical and electrical transport properties using appropriate techniques. The d.c. electrical resistivity and thermoelectric power variations with temperature showed semiconducting and p-type nature of the as-grown single crystal samples. The room temperature Hall Effect measurements further substantiated the semiconducting and p-type nature of the as-grown single crystal samples. The obtained results are deliberated in detail.

  16. Method for preparing homogeneous single crystal ternary III-V alloys

    DOE Patents [OSTI]

    Ciszek, Theodore F.

    1991-01-01

    A method for producing homogeneous, single-crystal III-V ternary alloys of high crystal perfection using a floating crucible system in which the outer crucible holds a ternary alloy of the composition desired to be produced in the crystal and an inner floating crucible having a narrow, melt-passing channel in its bottom wall holds a small quantity of melt of a pseudo-binary liquidus composition that would freeze into the desired crystal composition. The alloy of the floating crucilbe is maintained at a predetermined lower temperature than the alloy of the outer crucible, and a single crystal of the desired homogeneous alloy is pulled out of the floating crucible melt, as melt from the outer crucible flows into a bottom channel of the floating crucible at a rate that corresponds to the rate of growth of the crystal.

  17. Growth of large naphthalene and anthracene single-crystal sheets at the liquid–air interface

    SciTech Connect (OSTI)

    Postnikov, V. A.; Chertopalov, S. V.

    2015-07-15

    The growth of organic single crystals of naphthalene (C{sub 10}H{sub 8}) and anthracene (C{sub 14}H{sub 10}) at the liquid‒air interface from a mixture of solvents has been investigated. The growth technique used in the study makes it possible to obtain single-crystal sheets up to 10 mm in size for 24 h. The surface morphology and structure of the crystals have been analyzed by optical microscopy and X-ray diffraction. C{sub 10}H{sub 8} and C{sub 14}H{sub 10} single crystals grow coplanarly along the (001) plane. A thermodynamic model of the flat-crystal nucleus formation at the liquid‒air interface, based on the analysis of the change in the free Gibbs energy, is considered.

  18. Spin-orbit tuned metal-insulator transitions in single-crystal...

    Office of Scientific and Technical Information (OSTI)

    Title: Spin-orbit tuned metal-insulator transitions in single-crystal SrIr1-xRhxO (0x1) SrIrO is a magnetic insulator driven by spin-orbit interaction (SOI) ...

  19. Welding and Weldability of Directionally Solidified Single Crystal Nickel-Base Superalloys

    SciTech Connect (OSTI)

    Vitek, J M; David, S A; Reed, R W; Burke, M A; Fitzgerald, T J

    1997-09-01

    Nickel-base superalloys are used extensively in high-temperature service applications, and in particular, in components of turbine engines. To improve high-temperature creep properties, these alloys are often used in the directionally-solidified or single-crystal form. The objective of this CRADA project was to investigate the weldability of both experimental and commercial nickel-base superalloys in polycrystalline, directionally-solidified, and single-crystal forms.

  20. OPTIMIZATION OF THE PARAMETERS IN THE RHIC SINGLE CRYSTAL HEAVY ION COLLIMATION.

    SciTech Connect (OSTI)

    BIRYUKOV,V.M.; CHESNOKOV,Y.A.; KOTOV,V.I.; TRBOJEVIC,D.; STEVENS,A.

    1999-03-29

    In the framework of the project to design and test a collimation system prototype using bent channeling crystal for cleaning of the RHIC heavy ion beam halo, we have studied the optimal length and bending angle of a silicon (110) single crystal proposed to be a primary element situated upstream of the traditional heavy amorphous collimator. Besides the matters of the channeling and collimation efficiency, we also looked into the impact the crystal may have on the non-channeled particles that go on circulating in the ring, so as to reduce the momentum offset of the particles scattered of the crystal.

  1. Surface Binding and Organization of Sensitizing Dyes on Metal Oxide Single Crystal Surfaces

    SciTech Connect (OSTI)

    Parkinson, Bruce

    2010-06-04

    Even though investigations of dye-sensitized nanocrystalline semiconductors in solar cells has dominated research on dye-sensitized semiconductors over the past two decades. Single crystal electrodes represent far simpler model systems for studying the sensitization process with a continuing train of studies dating back more than forty years. Even today single crystal surfaces prove to be more controlled experimental models for the study of dye-sensitized semiconductors than the nanocrystalline substrates. We analyzed the scientific advances in the model sensitized single crystal systems that preceded the introduction of nanocrystalline semiconductor electrodes. It then follows the single crystal research to the present, illustrating both their striking simplicity of use and clarity of interpretation relative to nanocrystalline electrodes. Researchers have employed many electrochemical, photochemical and scanning probe techniques for studying monolayer quantities of sensitizing dyes at specific crystallographic faces of different semiconductors. These methods include photochronocoulometry, electronic spectroscopy and flash photolysis of dyes at potential-controlled semiconductor electrodes and the use of total internal reflection methods. In addition, we describe the preparation of surfaces of single crystal SnS2 and TiO2 electrodes to serve as reproducible model systems for charge separation at dye sensitized solar cells. This process involves cleaving the SnS2 electrodes and a photoelectrochemical surface treatment for TiO2 that produces clean surfaces for sensitization (as verified by AFM) resulting in near unity yields for electron transfer from the molecular excited dyes into the conduction band.

  2. Fabrication of triangular nanobeam waveguide networks in bulk diamond using single-crystal silicon hard masks

    SciTech Connect (OSTI)

    Bayn, I.; Mouradian, S.; Li, L.; Goldstein, J. A.; Schröder, T.; Zheng, J.; Chen, E. H.; Gaathon, O.; Englund, Dirk; Lu, M.; Stein, A.; Ruggiero, C. A.; Salzman, J.; Kalish, R.

    2014-11-24

    A scalable approach for integrated photonic networks in single-crystal diamond using triangular etching of bulk samples is presented. We describe designs of high quality factor (Q = 2.51 × 10{sup 6}) photonic crystal cavities with low mode volume (V{sub m} = 1.062 × (λ/n){sup 3}), which are connected via waveguides supported by suspension structures with predicted transmission loss of only 0.05 dB. We demonstrate the fabrication of these structures using transferred single-crystal silicon hard masks and angular dry etching, yielding photonic crystal cavities in the visible spectrum with measured quality factors in excess of Q = 3 × 10{sup 3}.

  3. Precise orientation of single crystals by a simple x-ray diffraction rocking curve method

    SciTech Connect (OSTI)

    Doucette, L.D.; Pereira da Cunha, M.; Lad, R.J.

    2005-03-01

    A simple method has been developed for accurately measuring the crystallographic orientation of a single crystal boule, employing a conventional four-circle x-ray diffraction arrangement in the rocking curve mode which relaxes the need for precise instrument and/or reference alignment. By acquiring a total of eight rocking curve measurements at specific orientations about the specimen azimuth, the absolute miscut angle between a crystal surface and the desired crystallographic plane can be resolved to within {+-}0.01 deg.

  4. Electrodynamic Properties of Single-Crystal and Thin-Film Strontium Titanate

    SciTech Connect (OSTI)

    Findikoglu, A.T.; Jia, Q.; Reagor, D.W.; Kwon, C.; Rasmussen, K.O.

    1999-05-13

    The authors present a comparative study of broadband electrodynamic properties of coplanar waveguides made from nonlinear dielectric single-crystal and thin-film SrTiO{sub 3} (STO) with high-temperature superconducting thin-film YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} electrodes. The waveguides that use single-crystal STO exhibit a monotonic increase in refractive index, dielectric nonlinearity, and dissipation with decreasing temperature (from 80 K to 20 K), whereas those based on thin-film STO show similar but weaker effects with increasing temperature. Under dc bias, both types of waveguides show reduced refractive index, but dissipation increases in the case of single-crystal STO, while it decreases in the case of STO thin-films.

  5. Intrinsic stage I crack propagation in Al-Zn-Mg single crystals

    SciTech Connect (OSTI)

    Petit, J.; Kosche, K.; Gudladt, H.J. Daimler-Benz AG, Stuttgart, Max-Planck-Institut fuer Metallforschung, Stuttgart, )

    1992-04-01

    A clear identification has been achieved for intrinsic stage I fatigue-crack propagation in single crystals of a high-purity Al-Zn-Mg alloy. The intrinsic stage I regime is noted to be much faster than intrinsic stage II for comparable loading conditions. The 'shielding' effect related to stage I-like propagation is significantly more important than anticipated on the basis of the conventional comparison to stage II. The propagation of a small surface crack growing in stage I is comparable to that of intrinsic stage I in single crystals rather than to either stage I or stage II in polycrystals. 11 refs.

  6. Bulk single crystal ternary substrates for a thermophotovoltaic energy conversion system

    DOE Patents [OSTI]

    Charache, G.W.; Baldasaro, P.F.; Nichols, G.J.

    1998-06-23

    A thermophotovoltaic energy conversion device and a method for making the device are disclosed. The device includes a substrate formed from a bulk single crystal material having a bandgap (E{sub g}) of 0.4 eV < E{sub g} < 0.7 eV and an emitter fabricated on the substrate formed from one of a p-type or an n-type material. Another thermophotovoltaic energy conversion device includes a host substrate formed from a bulk single crystal material and lattice-matched ternary or quaternary III-V semiconductor active layers. 12 figs.

  7. Iron-based composition for magnetocaloric effect (MCE) applications and method of making a single crystal

    DOE Patents [OSTI]

    Evans, III, Boyd Mccutchen; Kisner, Roger A.; Ludtka, Gail Mackiewicz; Ludtka, Gerard Michael; Melin, Alexander M.; Nicholson, Donald M.; Parish; , Chad M.; Rios, Orlando; Sefat, Athena S.; West, David L.; Wilgen, John B.

    2016-02-09

    A method of making a single crystal comprises heating a material comprising magnetic anisotropy to a temperature T sufficient to form a melt of the material. A magnetic field of at least about 1 Tesla is applied to the melt at the temperature T, where a magnetic free energy difference .DELTA.G.sub.m between different crystallographic axes is greater than a thermal energy kT. While applying the magnetic field, the melt is cooled at a rate of about 30.degree. C./min or higher, and the melt solidifies to form a single crystal of the material.

  8. Ultrafast Dynamic Response of Single Crystal PETN and Beta-HMX (Conference)

    Office of Scientific and Technical Information (OSTI)

    | SciTech Connect Dynamic Response of Single Crystal PETN and Beta-HMX Citation Details In-Document Search Title: Ultrafast Dynamic Response of Single Crystal PETN and Beta-HMX Authors: Zaug, J M ; Armstrong, M R ; Crowhurst, J C ; Feranti, L ; Swan, R ; Gross, R ; Teshlich, N E ; Wall, M ; Austin, R A ; Fried, L E Publication Date: 2014-06-30 OSTI Identifier: 1149550 Report Number(s): LLNL-CONF-656341 DOE Contract Number: DE-AC52-07NA27344 Resource Type: Conference Resource Relation:

  9. Bulk single crystal ternary substrates for a thermophotovoltaic energy conversion system

    DOE Patents [OSTI]

    Charache, Greg W.; Baldasaro, Paul F.; Nichols, Greg J.

    1998-01-01

    A thermophotovoltaic energy conversion device and a method for making the device. The device includes a substrate formed from a bulk single crystal material having a bandgap (E.sub.g) of 0.4 eVsingle crystal material and lattice-matched ternary or quaternary III-V semiconductor active layers.

  10. Structures with three dimensional nanofences comprising single crystal segments

    DOE Patents [OSTI]

    Goyal, Amit; Wee, Sung-Hun

    2013-08-27

    An article includes a substrate having a surface and a nanofence supported by the surface. The nanofence includes a multiplicity of primary nanorods and branch nanorods, each of the primary nanorods being attached to said substrate, and each of the branch nanorods being attached to a primary nanorods and/or another branch nanorod. The primary and branch nanorods are arranged in a three-dimensional, interconnected, interpenetrating, grid-like network defining interstices within the nanofence. The article further includes an enveloping layer supported by the nanofence, disposed in the interstices, and forming a coating on the primary and branch nanorods. The enveloping layer has a different composition from that of the nanofence and includes a radial p-n single junction solar cell photovoltaic material and/or a radial p-n multiple junction solar cell photovoltaic material.

  11. Solid-state syntheses and single-crystal characterizations of three tetravalent thorium and uranium silicates

    SciTech Connect (OSTI)

    Jin, Geng Bang Soderholm, L.

    2015-01-15

    Colorless crystals of ThSiO{sub 4} (huttonite) (1) and (Ca{sub 0.5}Na{sub 0.5}){sub 2}NaThSi{sub 8}O{sub 20} (2) have been synthesized by the solid-state reactions of ThO{sub 2}, CaSiO{sub 3}, and Na{sub 2}WO{sub 4} at 1073 K. Green crystals of (Ca{sub 0.5}Na{sub 0.5}){sub 2}NaUSi{sub 8}O{sub 20} (3) have been synthesized by the solid-state reactions of UO{sub 2}, CaSiO{sub 3}, and Na{sub 2}WO{sub 4} at 1003 K. All three compounds have been characterized by single-crystal X-ray diffraction. Compound 1 adopts a monazite-type three-dimensional condensed structure, which is built from edge- and corner-shared ThO{sub 9} polyhedra and SiO{sub 4} tetrahedra. Compounds 2 and 3 are isostructural and they crystallize in a steacyite-type structure. The structure consists of discrete pseudocubic [Si{sub 8}O{sub 20}]{sup 8−} polyanions, which are connected by An{sup 4+} cations into a three-dimensional framework. Each An atom coordinates to eight monodentate [Si{sub 8}O{sub 20}]{sup 8−} moieties in a square antiprismatic geometry. Na{sup +} and Ca{sup 2+} ions reside in the void within the framework. Raman spectra of 1, 2, and 3 were collected on single crystal samples. 1 displays more complex vibrational bands than thorite. Raman spectra of 2 and 3 are analogous with most of vibrational bands located at almost the same regions. - Graphical abstract: A Raman spectrum and crystal structures of (Ca{sub 0.5}Na{sub 0.5}){sub 2}NaAnSi{sub 8}O{sub 20} (An=Th, U), which contain pseudocubic [Si{sub 8}O{sub 20}]{sup 8−} polyanions and eight-coordinate An{sup 4+} cations. - Highlights: • Single crystal growth of three tetravalent actinide silicates from melts. • Single-crystal structures and Raman spectra of (Ca{sub 0.5}Na{sub 0.5}){sub 2}NaAnSi{sub 8}O{sub 20} (An=Th, U). • First report of Raman spectrum of huttonite on single crystal samples.

  12. Divalent europium doped and un-doped calcium iodide scintillators: Scintillator characterization and single crystal growth

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Boatner, L. A.; Ramey, J. O.; Kolopus, J. A.; Neal, John S.

    2015-02-21

    Initially, the alkaline-earth scintillator, CaI2:Eu2+, was discovered around 1964 by Hofstadter, Odell, and Schmidt. Serious practical problems quickly arose, however, that were associated with the growth of large monolithic single crystals of this material due to its lamellar, mica-like structure. As a result of its theoretically higher light yield, CaI2:Eu2+ has the potential to exceed the excellent scintillation performance of SrI2:Eu2+. In fact, theoretical predictions for the light yield of CaI2:Eu2+ scintillators suggested that an energy resolution approaching 2% at 662 keV could be achievable. Like the early SrI2:Eu2+ scintillator, the performance of CaI2:Eu2+ scintillators has traditionally suffered due, atmore » least in part, to outdated materials synthesis, component stoichiometry/purity, and single-crystal-growth techniques. Based on our recent work on SrI2:Eu2+ scintillators in single-crystal form, we have developed new techniques that are applied here to CaI2:Eu2+ and pure CaI2 with the goal of growing large un-cracked crystals and, potentially, realizing the theoretically predicted performance of the CaI2:Eu2+ form of this material. Calcium iodide does not adhere to modern glassy carbon Bridgman crucibles - so there should be no differential thermal-contraction-induced crystal/crucible stresses on cooling that would result in crystal cracking of the lamellar structure of CaI2. Here we apply glassy carbon crucible Bridgman growth, high-purity growth-charge compounds, our molten salt processing/filtration technique, and extended vacuum-melt-pumping methods to the growth of both CaI2:Eu2+ and un-doped CaI2. Moreover, large scintillating single crystals were obtained, and detailed characterization studies of the scintillation properties of CaI2:Eu2+ and pure CaI2 single crystals are presented that include studies of the effects of plastic deformation of the crystals on the scintillator performance.« less

  13. Strain-relief by single dislocation loops in calcite crystals grown on self-assembled monolayers

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ihli, Johannes; Clark, Jesse N.; Côté, Alexander S.; Kim, Yi-Yeoun; Schenk, Anna S.; Kulak, Alexander N.; Comyn, Timothy P.; Chammas, Oliver; Harder, Ross J.; Duffy, Dorothy M.; et al

    2016-06-15

    Most of our knowledge of dislocation-mediated stress relaxation during epitaxial crystal growth comes from the study of inorganic heterostructures. In this study, we use Bragg coherent diffraction imaging to investigate a contrasting system, the epitaxial growth of calcite (CaCO3) crystals on organic self-assembled monolayers, where these are widely used as a model for biomineralization processes. The calcite crystals are imaged to simultaneously visualize the crystal morphology and internal strain fields. Our data reveal that each crystal possesses a single dislocation loop that occupies a common position in every crystal. The loops exhibit entirely different geometries to misfit dislocations generated inmore » conventional epitaxial thin films and are suggested to form in response to the stress field, arising from interfacial defects and the nanoscale roughness of the substrate. In conclusion, this work provides unique insight into how self-assembled monolayers control the growth of inorganic crystals and demonstrates important differences as compared with inorganic substrates.« less

  14. Method of forming single crystals of beta silicon carbide using liquid lithium as a solvent

    DOE Patents [OSTI]

    Lundberg, Lynn B.

    1982-01-01

    A method of growing single crystals of beta SiC from solution using molten lithium as a solvent for polycrystalline SiC feed material. Reasonable growth rates are accomplished at temperatures in the range of about 1330.degree. C. to about 1500.degree. C.

  15. Optical characteristics of ZnO single crystal grown by the hydrothermal method

    SciTech Connect (OSTI)

    Chen, G. Z.; Yin, J. G. E-mail: yjg@siom.ac.cn; Zhang, L. H.; Zhang, P. X.; Wang, X. Y.; Liu, Y. C.; Zhang, C. L.; Gu, S. L.; Hang, Y.

    2015-12-15

    ZnO single crystals have been grown by the hydrothermal method. Raman scattering and Photoluminescence spectroscopy (PL) have been used to study samples of ZnO that were unannealed or annealed in different ambient gases. It is suggested that the green emission may originate from defects related to copper in our samples.

  16. Epitaxial single-crystal thin films of MnxTi1-xO2-δ grown on...

    Office of Scientific and Technical Information (OSTI)

    Epitaxial single-crystal thin films of MnxTi1-xO2- grown on (rutile)TiO2 substrates with ... Title: Epitaxial single-crystal thin films of MnxTi1-xO2- grown on (rutile)TiO2 ...

  17. Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals

    SciTech Connect (OSTI)

    Michael J. Mills

    2009-03-05

    Cast nickel-based superalloys are used for blades in land-based, energy conversion and powerplant applications, as well as in aircraft gas turbines operating at temperatures up to 1100 C, where creep is one of the life-limiting factors. Creep of superalloy single crystals has been extensively studied over the last several decades. Surprisingly, only recently has work focused specifically on the dislocation mechanisms that govern high temperature and low stress creep. Nevertheless, the perpetual goal of better engine efficiency demands that the creep mechanisms operative in this regime be fully understood in order to develop alloys and microstructures with improved high temperature capability. At present, the micro-mechanisms controlling creep before and after rafting (the microstructure evolution typical of high temperature creep) has occurred have yet to be identified and modeled, particularly for [001] oriented single crystals. This crystal orientation is most interesting technologically since it exhibits the highest creep strength. The major goal of the program entitled ''Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals'' (DOE Grant DE-FG02-04ER46137) has been to elucidate these creep mechanisms in cast nickel-based superalloys. We have utilized a combination of detailed microstructure and dislocation substructure analysis combined with the development of a novel phase-field model for microstructure evolution.

  18. Photoelectrochemical Stability and Alteration Products of n-Type Single-Crystal ZnO Photoanodes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Paulauskas, I. E.; Jellison, G. E.; Boatner, L. A.; Brown, G. M.

    2011-01-01

    The photoelectrochemical stability and surface-alteration characteristics of doped and undoped n-type ZnO single-crystal photoanode electrodes were investigated. The single-crystal ZnO photoanode properties were analyzed using current-voltage measurements plus spectral and time-dependent quantum-yield methods. These measurements revealed a distinct anodic peak and an accompanying cathodic surface degradation process at negative potentials. The features of this peak depended on time and the NaOH concentration in the electrolyte, but were independent of the presence of electrode illumination. Current measurements performed at the peak indicate that charging and discharging effects are apparently taking place at the semiconductor/electrolyte interface. This result is consistent with themore » significant reactive degradation that takes place on the ZnO single crystal photoanode surface and that ultimately leads to the reduction of the ZnO surface to Zn metal. The resulting Zn-metal reaction products create unusual, dendrite-like, surface alteration structural features that were analyzed using x-ray diffraction, energy-dispersive analysis, and scanning electron microscopy. ZnO doping methods were found to be effective in increasing the n-type character of the crystals. Higher doping levels result in smaller depletion widths and lower quantum yields, since the minority carrier diffusion lengths are very short in these materials.« less

  19. Polarized Neutron Studies on Antiferromagnetic Single Crystals: Technical Report No. 4

    DOE R&D Accomplishments [OSTI]

    Nathans, R.; Riste, T.; Shirane, G.; Shull, C.G.

    1958-11-26

    The theory of neutron scattering by magnetic crystals as given by Halpern and Johnson predicts changes in the polarization state of the neutron beam upon scattering which depend upon the relative orientation of the neutron polarization vector and the crystal magnetic axis. This was investigated experimentally with a polarized beam spectrometer using single crystals of Cr{sub 2}O{sub 3} and alpha - Fe{sub 2}O{sub 3} in which reside unique antiferromagnetic axes. Studies were made on several different reflections in both crystals for a number of different temperatures both below and above the Neel point. Results support the theoretical predictions and indicate directions for the moments in these crystals consistent with previous work. A more detailed study of the polarization changes in the (111) reflection in alpha - Fe{sub 2}O{sub 3} at room temperature on application of a magnetic field was carried out, The results indicate that the principal source of the parasitic ferromagnetism in hematite is essentially independent of the orientation of the antiferromagnetic domains within the crystal.

  20. Metal oxide superconducting powder comprised of flake-like single crystal particles

    DOE Patents [OSTI]

    Capone, Donald W.; Dusek, Joseph

    1994-01-01

    Powder of a ceramic superconducting material is synthesized such that each particle of the powder is a single crystal having a flake-like, nonsymmetric morphology such that the c-axis is aligned parallel to the short dimension of the flake. Nonflake powder is synthesized by the normal methods and is pressed into pellets or other shapes and fired for excessive times to produce a coarse grained structure. The fired products are then crushed and ground producing the flake-like powder particles which exhibit superconducting characteristics when aligned with the crystal lattice.

  1. Metal oxide superconducting powder comprised of flake-like single crystal particles

    DOE Patents [OSTI]

    Capone, D.W.; Dusek, J.

    1994-10-18

    Powder of a ceramic superconducting material is synthesized such that each particle of the powder is a single crystal having a flake-like, nonsymmetric morphology such that the c-axis is aligned parallel to the short dimension of the flake. Nonflake powder is synthesized by the normal methods and is pressed into pellets or other shapes and fired for excessive times to produce a coarse grained structure. The fired products are then crushed and ground producing the flake-like powder particles which exhibit superconducting characteristics when aligned with the crystal lattice. 3 figs.

  2. Anisotropic shock sensitivity and detonation temperature of pentaerythritol tetranitrate single crystal

    SciTech Connect (OSTI)

    Yoo, C. S.; Holmes, N. C.; Souers, P. C.; Wu, C. J.; Ree, F. H.; Dick, J. J.

    2000-07-01

    Shock temperatures of pentaerythritol tetranitrate (PETN) single crystals have been measured by using a nanosecond time-resolved spectropyrometric system operated at six discrete wavelengths between 350 and 700 nm. The results show that the shock sensitivity of PETN is strongly dependent on the crystal orientation: Sensitive along the shock propagation normal to the (110) plane, but highly insensitive normal to the (100) plane. The detonation temperature of PETN is, however, independent from the crystal orientation and is determined to be 4140 ({+-}70) K. The time-resolved data yielding the detonation velocity 8.28 ({+-}0.10) mm/{mu}s can be interpreted in the context of a modified thermal explosion model. (c) 2000 American Institute of Physics.

  3. Single-crystal sapphire microstructure for high-resolution synchrotron X-ray monochromators

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Asadchikov, Victor E.; Butashin, Andrey V.; Buzmakov, Alexey V.; Deryabin, Alexander N.; Kanevsky, Vladimir M.; Prokhorov, Igor A.; Roshchin, Boris S.; Volkov, Yuri O.; Zolotov, Dennis A.; Jafari, Atefeh; et al

    2016-03-22

    We report on the growth and characterization of several sapphire single crystals for the purpose of x-ray optics applications. Structural defects were studied by means of laboratory double-crystal X-ray diffractometry and white beam synchrotron-radiation topography. The investigations confirmed that the main defect types are dislocations. The best quality crystal was grown using the Kyropoulos technique with a dislocation density of 102-103 cm-2 and a small area with approximately 2*2 mm2 did not show dislocation contrast in many reflections and has suitable quality for application as a backscattering monochromator. As a result, a clear correlation between growth rate and dislocation densitymore » is observed, though growth rate is not the only parameter impacting the quality.« less

  4. Advances in the growth of alkaline-earth halide single crystals for scintillator detectors

    SciTech Connect (OSTI)

    Boatner, Lynn A; Ramey, Joanne Oxendine; Kolopus, James A; Neal, John S; Cherepy, Nerine; Payne, Stephen A.; Beck, P; Burger, Arnold; Rowe, E; Bhattacharya, P.

    2014-01-01

    Alkaline-earth scintillators such as strontium iodide and other alkaline-earth halides activated with divalent europium represent some of the most efficient and highest energy resolution scintillators for use as gamma-ray detectors in a wide range of applications. These applications include the areas of nuclear nonproliferation, homeland security, the detection of undeclared nuclear material, nuclear physics and materials science, medical diagnostics, space physics, high energy physics, and radiation monitoring systems for first responders, police, and fire/rescue personnel. Recent advances in the growth of large single crystals of these scintillator materials hold the promise of higher crystal yields and significantly lower detector production costs. In the present work, we describe new processing protocols that, when combined with our molten salt filtration methods, have led to advances in achieving a significant reduction of cracking effects during the growth of single crystals of SrI2:Eu2+. In particular, we have found that extended pumping on the molten crystal-growth charge under vacuum for time periods extending up to 48 hours is generally beneficial in compensating for variations in the alkaline-earth halide purity and stoichiometry of the materials as initially supplied by commercial sources. These melt-pumping and processing techniques are now being applied to the purification of CaI2:Eu2+ and some mixed-anion europium-doped alkaline-earth halides prior to single-crystal growth by means of the vertical Bridgman technique. The results of initial studies of the effects of aliovalent doping of SrI2:Eu2+ on the scintillation characteristics of this material are also described.

  5. Flux growth and magnetic properties of FeVO{sub 4} single crystals

    SciTech Connect (OSTI)

    He Zhangzhen Yamaura, Jun-Ichi; Ueda, Yutaka

    2008-09-15

    FeVO{sub 4} (I) single crystals are grown by the flux method using V{sub 2}O{sub 5} as the self-flux. The grown crystals exhibit a characteristic morphology with natural facets. The quality of the crystals is confirmed by X-ray diffraction and EPMA techniques. Magnetic properties are investigated by means of magnetic susceptibility, magnetization, and heat capacity measurements. Two magnetic phase transitions are observed at {approx}13 and {approx}20 K. Such unusual magnetic behaviors are suggested to originate from two different Fe ligand environments of octahedral FeO{sub 6} and trigonal bipyramidal FeO{sub 5} in a six-column doubly bent chain. - Graphical abstract: FeVO{sub 4} (I) single crystals are grown by the flux method using V{sub 2}O{sub 5} as the self-flux. Magnetic properties are investigated by means of magnetic susceptibility, magnetization, and heat capacity measurements, showing two magnetic phase transitions at {approx}13 and {approx}20 K.

  6. Enhancing ionic conductivity of bulk single-crystal yttria-stabilized zirconia by tailoring dopant distribution

    SciTech Connect (OSTI)

    Lee, E.; Prinz, F. B.; Cai, W.

    2011-02-11

    We present an ab initiobased kinetic Monte Carlo model for ionic conductivity in single-crystal yttria-stabilized zirconia. Ionic interactions are taken into account by combining density functional theory calculations and the cluster expansion method and are found to be essential in reproducing the effective activation energy observed in experiments. The model predicts that the effective energy barrier can be reduced by 0.150.25 eV by arranging the dopant ions into a superlattice.

  7. Dependence of dynamic fracture resistance on crack velocity in tungsten: Pt. 1. Single crystals

    SciTech Connect (OSTI)

    Liv, J.M.; Shen, B.W.

    1984-06-01

    The dependence of dynamic fracture resistance on crack propagation velocity on (100) in tungsten has been examined. A correlation is obtained between the measured local crack velocity with the surfac and subsurface deformations. Based on the experimental results on one pass, two passes, and prestrained, electron beam zone refined single crystals, a discussion is given on the slip modes activated at the crack tip, the contributions to the dynamic fracture resistance from dislocations and surface features and from the preexisting deformed microstructure.

  8. Characterization of single-crystal diamond grown from the vapor phase on substrates of natural diamond

    SciTech Connect (OSTI)

    Altukhov, A. A.; Vikharev, A. L.; Gorbachev, A. M.; Dukhnovsky, M. P.; Zemlyakov, V. E.; Ziablyuk, K. N.; Mitenkin, A. V.; Muchnikov, A. B. Radishev, D. B.; Ratnikova, A. K.; Fedorov, Yu. Yu.

    2011-03-15

    The results of studies of single-crystal diamond layers with orientation (100) grown on substrates of IIa-type natural diamond by chemical-vapor deposition and of semiconductor diamond obtained subsequently by doping by implantation of boron ions are reported. Optimal conditions of postimplantation annealing of diamond that provide the hole mobility of 1150 cm{sup 2} V{sup -1} s{sup -1} (the highest mobility obtained so far for semiconductor diamond after ion implantation) are given.

  9. Spin glass in semiconducting KFe1.05Ag0.88Te2 single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ryu, H.; Lei, H.; Klobes, B.; Warren, J. B.; Hermann, R. P.; Petrovic, C.

    2015-05-26

    We report discovery of KFe1.05Ag0.88Te2 single crystals with semiconducting spin glass ground state. Composition and structure analysis suggest nearly stoichiometric I4/mmm space group but allow for the existence of vacancies, absent in long range semiconducting antiferromagnet KFe1.05Ag0.88Te2. The subtle change in stoichometry in Fe/Ag sublattice changes magnetic ground state but not conductivity, giving further insight into the semiconducting gap mechanism.

  10. DIRECT OBSERVATION OF THE ALPHA-EPSILON TRANSITION IN SHOCKED SINGLE CRYSTAL IRON

    SciTech Connect (OSTI)

    Kalantar, D H; Collins, G W; Colvin, J D; Davies, H M; Eggert, J H; Hawreliak, J; Lorenzana, H E; Meyers, M A; Rosolankova, K; Schneider, M S; Sheppard, J; Stolken, J S; Wark, J S

    2005-08-23

    In-situ x-ray diffraction was used to study the response of single crystal iron under shock conditions. Measurements of the response of [001] iron showed a uniaxial compression of the initially bcc lattice along the shock direction by up to 6% at 13 GPa. Above this pressure, the lattice responded with a further collapse of the lattice by 15-18% and a transformation to a hcp structure. The in-situ measurements are discussed and results summarized.

  11. Interdomain region in single-crystal lithium niobate bimorph actuators produced by light annealing

    SciTech Connect (OSTI)

    Kubasov, I. V. Timshina, M. S.; Kiselev, D. A.; Malinkovich, M. D.; Bykov, A. S.; Parkhomenko, Yu. N.

    2015-09-15

    The interdomain region of a bidomain strucrture formed in 127°-cut lithium niobate single crystals using light annealing has been studied by optical and scanning probe microscopies. A periodic subdomain structure on the 180° macrodomain wall is visualized by piezoresponse force microscopy. The piezoresponse signal (polarization) is shown to be a power-law function of the domain width with an exponent n = 0.53.

  12. Giant increase in critical current density of KxFe2-ySe₂ single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lei, Hechang; Petrovic, C.

    2011-12-28

    The critical current density Jabc of KxFe2-ySe₂ single crystals can be enhanced by more than one order of magnitude, up to ~2.1×10⁴ A/cm² by the post annealing and quenching technique. A scaling analysis reveals the universal behavior of the normalized pinning force as a function of the reduced field for all temperatures, indicating the presence of a single vortex pinning mechanism. The main pinning sources are three-dimensional (3D) point-like normal cores. The dominant vortex interaction with pinning centers is via spatial variations in critical temperature Tc (“δTc pinning”).

  13. The effect of interelement dipole coupling in patterned ultrathin single crystal Fe square arrays

    SciTech Connect (OSTI)

    Sun Li; Zhai Ya; Wong Pingkwanj; Zhang Wen; Xu Yongbing; Zou Xiao; Wu Jing; Luo Linqiang; Zhai Hongru

    2011-02-01

    The correlation between the magnetic properties and the interelement separation in patterned arrays of ultrathin single crystal Fe films of 12 monolayers (ML) grown on GaAs(100) has been studied. The critical condition to form single domain remanent states in the square elements was found to be 10 {mu}m in size and 20 {mu}m for the interelement separation. The coercivity was also found to increase with the increasing interelement separation in the patterned arrays. These results are attributed to the competition between the large in-plane uniaxial anisotropy, the demagnetizing field, and interelement dipole coupling as determined semiqualitatively by the ferromagnetic resonance measurements.

  14. Thin Single Crystal Silicon Solar Cells on Ceramic Substrates: November 2009 - November 2010

    SciTech Connect (OSTI)

    Kumar, A.; Ravi, K. V.

    2011-06-01

    In this program we have been developing a technology for fabricating thin (< 50 micrometres) single crystal silicon wafers on foreign substrates. We reverse the conventional approach of depositing or forming silicon on foreign substrates by depositing or forming thick (200 to 400 micrometres) ceramic materials on high quality single crystal silicon films ~ 50 micrometres thick. Our key innovation is the fabrication of thin, refractory, and self-adhering 'handling layers or substrates' on thin epitaxial silicon films in-situ, from powder precursors obtained from low cost raw materials. This 'handling layer' has sufficient strength for device and module processing and fabrication. Successful production of full sized (125 mm X 125 mm) silicon on ceramic wafers with 50 micrometre thick single crystal silicon has been achieved and device process flow developed for solar cell fabrication. Impurity transfer from the ceramic to the silicon during the elevated temperature consolidation process has resulted in very low minority carrier lifetimes and resulting low cell efficiencies. Detailed analysis of minority carrier lifetime, metals analysis and device characterization have been done. A full sized solar cell efficiency of 8% has been demonstrated.

  15. Defect Engineering in SrI2:Eu2+ Single Crystal Scintillators

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wu, Yuntao; Boatner, Lynn A.; Lindsey, Adam C.; Zhuravleva, Mariya; Jones, Steven; Auxier, John D.; Hall, Howard L.; Melcher, Charles L.

    2015-06-23

    Eu2+-activated strontium iodide is an excellent single crystal scintillator used for gamma-ray detection and significant effort is currently focused on the development of large-scale crystal growth techniques. A new approach of molten-salt pumping or so-called melt aging was recently applied to optimize the crystal quality and scintillation performance. Nevertheless, a detailed understanding of the underlying mechanism of this technique is still lacking. The main purpose of this paper is to conduct an in-depth study of the interplay between microstructure, trap centers and scintillation efficiency after melt aging treatment. Three SrI2:2 mol% Eu2+ single crystals with 16 mm diameter were grownmore » using the Bridgman method under identical growth conditions with the exception of the melt aging time (e.g. 0, 24 and 72 hours). Using energy-dispersive X-ray spectroscopy, it is found that the matrix composition of the finished crystal after melt aging treatment approaches the stoichiometric composition. The mechanism responsible for the formation of secondary phase inclusions in melt-aged SrI2:Eu2+ is discussed. Simultaneous improvement in light yield, energy resolution, scintillation decay-time and afterglow is achieved in melt-aged SrI2:Eu2+. The correlation between performance improvement and defect structure is addressed. The results of this paper lead to a better understanding of the effects of defect engineering in control and optimization of metal halide scintillators using the melt aging technique.« less

  16. Calculations of single crystal elastic constants for yttria partially stabilised zirconia from powder diffraction data

    SciTech Connect (OSTI)

    Lunt, A. J. G. Xie, M. Y.; Baimpas, N.; Korsunsky, A. M.; Zhang, S. Y.; Kabra, S.; Kelleher, J.; Neo, T. K.

    2014-08-07

    Yttria Stabilised Zirconia (YSZ) is a tough, phase-transforming ceramic that finds use in a wide range of commercial applications from dental prostheses to thermal barrier coatings. Micromechanical modelling of phase transformation can deliver reliable predictions in terms of the influence of temperature and stress. However, models must rely on the accurate knowledge of single crystal elastic stiffness constants. Some techniques for elastic stiffness determination are well-established. The most popular of these involve exploiting frequency shifts and phase velocities of acoustic waves. However, the application of these techniques to YSZ can be problematic due to the micro-twinning observed in larger crystals. Here, we propose an alternative approach based on selective elastic strain sampling (e.g., by diffraction) of grain ensembles sharing certain orientation, and the prediction of the same quantities by polycrystalline modelling, for example, the Reuss or Voigt average. The inverse problem arises consisting of adjusting the single crystal stiffness matrix to match the polycrystal predictions to observations. In the present model-matching study, we sought to determine the single crystal stiffness matrix of tetragonal YSZ using the results of time-of-flight neutron diffraction obtained from an in situ compression experiment and Finite Element modelling of the deformation of polycrystalline tetragonal YSZ. The best match between the model predictions and observations was obtained for the optimized stiffness values of C11 = 451, C33 = 302, C44 = 39, C66 = 82, C12 = 240, and C13 = 50 (units: GPa). Considering the significant amount of scatter in the published literature data, our result appears reasonably consistent.

  17. Controlling single and few-layer graphene crystals growth in a solid carbon source based chemical vapor deposition

    SciTech Connect (OSTI)

    Papon, Remi; Sharma, Subash; Shinde, Sachin M.; Vishwakarma, Riteshkumar; Tanemura, Masaki [Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Kalita, Golap, E-mail: kalita.golap@nitech.ac.jp [Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Center for Fostering Young and Innovative Researchers, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, 466-8555 (Japan)

    2014-09-29

    Here, we reveal the growth process of single and few-layer graphene crystals in the solid carbon source based chemical vapor deposition (CVD) technique. Nucleation and growth of graphene crystals on a polycrystalline Cu foil are significantly affected by the injection of carbon atoms with pyrolysis rate of the carbon source. We observe micron length ribbons like growth front as well as saturated growth edges of graphene crystals depending on growth conditions. Controlling the pyrolysis rate of carbon source, monolayer and few-layer crystals and corresponding continuous films are obtained. In a controlled process, we observed growth of large monolayer graphene crystals, which interconnect and merge together to form a continuous film. On the other hand, adlayer growth is observed with an increased pyrolysis rate, resulting few-layer graphene crystal structure and merged continuous film. The understanding of monolayer and few-layer crystals growth in the developed CVD process can be significant to grow graphene with controlled layer numbers.

  18. Millimeter size single crystals of superconducting YBa.sub.2 Cu.sub.3 O.sub .

    DOE Patents [OSTI]

    Damento, Michael A.; Gschneidner, Jr., Karl A.

    1989-04-25

    A method of growing large, up to 1 mm size single crystals of superconducting YBa.sub.2 Cu.sub.3 O.sub.x, wherein x equals from 6.5 to 7.2.

  19. Millimeter size single crystals of superconducting YBa[sub 2]Cu[sub 3]O[sub x

    DOE Patents [OSTI]

    Damento, M.A.; Gschneidner, K.A. Jr.

    1989-04-25

    A method of growing large, up to 1 mm size single crystals of superconducting YBa[sub 2]Cu[sub 3]O[sub x], wherein x equals from 6.5 to 7.2 is disclosed.

  20. Time-dependent Protein-directed Growth of Gold Nanoparticles within a Single Crystal of Lysozyme

    SciTech Connect (OSTI)

    H Wei; Z Wang; J Zhang; S House; Y Gao; L Yang; H Robinson; L Tan; H Xing; C Hou

    2011-12-31

    Gold nanoparticles are useful in biomedical applications due to their distinct optical properties and high chemical stability. Reports of the biogenic formation of gold colloids from gold complexes has also led to an increased level of interest in the biomineralization of gold. However, the mechanism responsible for biomolecule-directed gold nanoparticle formation remains unclear due to the lack of structural information about biological systems and the fast kinetics of biomimetic chemical systems in solution. Here we show that intact single crystals of lysozyme can be used to study the time-dependent, protein-directed growth of gold nanoparticles. The protein crystals slow down the growth of the gold nanoparticles, allowing detailed kinetic studies to be carried out, and permit a three-dimensional structural characterization that would be difficult to achieve in solution. Furthermore, we show that additional chemical species can be used to fine-tune the growth rate of the gold nanoparticles.

  1. Detailed Surface Analysis Of Incremental Centrifugal Barrel Polishing (CBP) Of Single-Crystal Niobium Samples

    SciTech Connect (OSTI)

    Palczewski, Ari D.; Hui Tian; Trofimova, Olga; Reece, Charles E.

    2011-07-01

    We performed Centrifugal Barrel Polishing (CBP) on single crystal niobium samples/coupons housed in a stainless steel sample holder following the polishing recipe developed at Fermi Lab (FNAL) in 2011 \\cite{C. A. Cooper 2011}. Post CBP, the sample coupons were analyzed for surface roughness, crystal composition and structure, and particle contamination. Following the initial analysis each coupon was high pressure rinsed (HRP) and analyzed for the effectiveness of contamination removal. We were able to obtain the mirror like surface finish after the final stage of tumbling, although some defects and embedded particles remained. In addition, standard HPR appears to have little effect on removing embedded particles which remain after each tumbling step, although final polishing media removal was partially affected by standard/extended HPR.

  2. Millimeter-Wave Dielectric Properties of Single Crystal Ferroelectric and Dielectric Materials

    SciTech Connect (OSTI)

    McCloy, John S.; Korolev, Konstantin A.; Li, Zijing; Afsar, Mohammed N.; Sundaram, S. K.

    2011-01-03

    Transmittance measurements on various single crystal ferroelectric materials over a broad millimeter-wave frequency range have been performed. Frequency dependence of the complex dielectric permittivity has been determined in the millimeter wave region for the first time. The measurements have been employed using a free-space quasi-optical millimeter-wave spectrometer equipped with a set of high power backward wave oscillators (BWOs) as sources of coherent radiation, tunable in the range from 30 - 120 GHz. The uncertainties and possible sources of instrumentation and measurement errors related to the free-space millimeter-wave technique are discussed. This work has demonstrated that precise MMW permittivities can be obtained even on small thin crystals using the BWO quasi-optical approach.

  3. One-dimensional SANS employing bent-single crystal optics: Theory and demonstration

    SciTech Connect (OSTI)

    Heuser, B.J.; Popovici, M.; Berliner, R.

    1995-12-31

    A recent small-angle neutron scattering (SANS) instrumentation development at the University of Missouri Research Reactor Center (MURR) using bent, double Si crystal diffraction is presented. Neutron rocking curves of flat single crystals are only a few seconds of arc with correspondingly low integrated intensities. The rocking curve can be significantly broadened if the crystals are bent. However, the phase-space acceptance and emergence windows of two bent crystals in parallel can be matched only if the reflecting planes have different d-spacing. The authors have used a combination of the Si(111) and (220) reflections in the work presented here. The peak intensity of the rocking curve with this configuration was approximately 2.5 {times} 10{sup 5} neutrons per second over a 5 cm{sup 2} area of sample at 1.5 {angstrom}. The rocking curve wings fell sharply (approximately as Q{sup {minus}11}), permitting accurate scattered intensity measurements down to a minimum Q value of 0.005 1/{angstrom} at a Q resolution of 0.003 1/{angstrom}. The technique also offers the possibility of variable resolution without too much difficulty; changes up to a factor of 2 can be made by adjusting the sample-to-analyzer crystal distance, while changes of a factor of 10 can be made by using different Si reflections. Since the incident neutron wavelength can be tuned to the peak of the leakage spectrum, this technique is ideal for low-flux reactors, which otherwise cannot be used for SANS research. The usefulness of one-dimensional SANS is demonstrated by measurements of Portland cement.

  4. Demonstration of a Single-Crystal Reflector-Filter for Enhancing Slow Neutron Beams

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Muhrer, Guenter; Schönfeldt, Troels; Iverson, Erik B.; Mocko, Michal; Baxter, David V.; Hügle, Thomas; Gallmeier, Franz X.; Klinkby, Esben

    2016-06-14

    The cold polycrystalline beryllium reflector-filter concept has been used to enhance the cold neutron emission of cryogenic hydrogen moderators, while suppressing the intermediate wavelength and fast neutron emission at the same time. While suppressing the fast neutron emission is often desired, the suppression of intermediate wavelength neutrons is often unwelcome. It has been hypothesized that replacing the polycrystalline reflector-filter concept with a single-crystal reflector-filter concept would overcome the suppression of intermediate wavelength neutrons and thereby extend the usability of the reflector-filter concept to shorter but still important wavelengths. In this paper we present the first experimental data on a single-crystalmore » reflector-filter and compare experimental results with hypothesized performance. We find that a single-crystal reflector-filter retains the long-wavelength benefit of the polycrystalline reflector-filter, without suffering the same loss of important intermediate wavelength neutrons. Ultimately, this finding extends the applicability of the reflector-filter concept to intermediate wavelengths, and furthermore indicates that the reflector-filter benefits arise from its interaction with fast (background) neutrons, not with intermediate wavelength neutrons of potential interest in many types of neutron scattering.« less

  5. Shock compression modeling of metallic single crystals: comparison of finite difference, steady wave, and analytical solutions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lloyd, Jeffrey T.; Clayton, John D.; Austin, Ryan A.; McDowell, David L.

    2015-07-10

    Background: The shock response of metallic single crystals can be captured using a micro-mechanical description of the thermoelastic-viscoplastic material response; however, using a such a description within the context of traditional numerical methods may introduce a physical artifacts. Advantages and disadvantages of complex material descriptions, in particular the viscoplastic response, must be framed within approximations introduced by numerical methods. Methods: Three methods of modeling the shock response of metallic single crystals are summarized: finite difference simulations, steady wave simulations, and algebraic solutions of the Rankine-Hugoniot jump conditions. For the former two numerical techniques, a dislocation density based framework describes themore » rate- and temperature-dependent shear strength on each slip system. For the latter analytical technique, a simple (two-parameter) rate- and temperature-independent linear hardening description is necessarily invoked to enable simultaneous solution of the governing equations. For all models, the same nonlinear thermoelastic energy potential incorporating elastic constants of up to order 3 is applied. Results: Solutions are compared for plate impact of highly symmetric orientations (all three methods) and low symmetry orientations (numerical methods only) of aluminum single crystals shocked to 5 GPa (weak shock regime) and 25 GPa (overdriven regime). Conclusions: For weak shocks, results of the two numerical methods are very similar, regardless of crystallographic orientation. For strong shocks, artificial viscosity affects the finite difference solution, and effects of transverse waves for the lower symmetry orientations not captured by the steady wave method become important. The analytical solution, which can only be applied to highly symmetric orientations, provides reasonable accuracy with regards to prediction of most variables in the final shocked state but, by construction, does not provide

  6. Electronic band structure imaging of three layer twisted graphene on single crystal Cu(111)

    SciTech Connect (OSTI)

    Marquez Velasco, J.; Department of Physics, National Technical University of Athens, Athens ; Kelaidis, N.; Xenogiannopoulou, E.; Tsoutsou, D.; Tsipas, P.; Speliotis, Th.; Pilatos, G.; Likodimos, V.; Falaras, P.; Dimoulas, A.; Raptis, Y. S.

    2013-11-18

    Few layer graphene (FLG) is grown on single crystal Cu(111) by Chemical Vapor Deposition, and the electronic valence band structure is imaged by Angle-Resolved Photo-Emission Spectroscopy. It is found that graphene essentially grows polycrystalline. Three nearly ideal Dirac cones are observed along the Cu ?{sup }K{sup } direction in k-space, attributed to the presence of ?4 twisted three layer graphene with negligible interlayer coupling. The number of layers and the stacking order are compatible with Raman data analysis demonstrating the complementarity of the two techniques for a more accurate characterization of FLG.

  7. Magnetization Reversal Process of Single Crystal α-Fe Containing a Nonmagnetic Particle

    SciTech Connect (OSTI)

    Li, Yi; Xu, Ben; Hu, Shenyang Y.; Li, Yulan; Li, Qiu-Lin; Liu, Wei

    2015-09-25

    The magnetization reversal process and hysteresis loops in a single crystal α-iron with nonmagnetic particles are simulated in this work based on the Landau-Lifshitz–Gilbert equation. The evolutions of the magnetic domain morphology are studied, and our analyses show that the magnetization reversal process is affected by the interaction between the moving domain wall and the existing nonmagnetic particles. This interaction strongly depends on the size of the particles, and it is found that particles with a particular size contribute the most to magnetic hardening.

  8. Thin films of metal oxides on metal single crystals: Structure and growth by scanning tunneling microscopy

    SciTech Connect (OSTI)

    Galloway, H.C.

    1995-12-01

    Detailed studies of the growth and structure of thin films of metal oxides grown on metal single crystal surfaces using Scanning Tunneling Microscopy (STM) are presented. The oxide overlayer systems studied are iron oxide and titanium oxide on the Pt(III) surface. The complexity of the metal oxides and large lattice mismatches often lead to surface structures with large unit cells. These are particularly suited to a local real space technique such as scanning tunneling microscopy. In particular, the symmetry that is directly observed with the STM elucidates the relationship of the oxide overlayers to the substrate as well as distinguishing, the structures of different oxides.

  9. Comparative study of broadband electrodynamic properties of single-crystal and thin-film strontium titanate

    SciTech Connect (OSTI)

    Findikoglu, A. T.; Jia, Q. X.; Kwon, C.; Reagor, D. W.; Kaduchak, G.; Rasmussen, K. Oe.; Bishop, A. R.

    1999-12-27

    We have used a coplanar waveguide structure to study broadband electrodynamic properties of single-crystal and thin-film strontium titanate. We have incorporated both time- and frequency-domain measurements to determine small-signal effective refractive index and loss tangent as functions of frequency (up to 4 GHz), dc bias (up to 10{sup 6} V/m), and cryogenic temperature (17 and 60 K). The large-signal impulse response of the devices and the associated phenomenological nonlinear wave equation illustrate how dissipation and nonlinearity combine to produce the overall response in the large-signal regime. (c) 1999 American Institute of Physics.

  10. Far off-resonant coupling between photonic crystal microcavity and single quantum dot with resonant excitation

    SciTech Connect (OSTI)

    Banihashemi, Mehdi; Ahmadi, Vahid, E-mail: v-ahmadi@modares.ac.ir [Department of Electrical and Computer Engineering, Tarbiat Modares University, Tehran, P.O. Box 14115-194 (Iran, Islamic Republic of)] [Department of Electrical and Computer Engineering, Tarbiat Modares University, Tehran, P.O. Box 14115-194 (Iran, Islamic Republic of); Nakamura, Tatsuya; Kojima, Takanori; Kojima, Kazunobu; Noda, Susumu [Department of Electronic Science and Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)] [Department of Electronic Science and Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)

    2013-12-16

    In this paper, we experimentally demonstrate that with sub-nanowatt coherent s-shell excitation of a single InAs quantum dot, off-resonant coupling of 4.1?nm is possible between L3 photonic crystal microcavity and the quantum dot at 50?K. This resonant excitation reduces strongly the effect of surrounding charges to quantum dot, multiexciton complexes and pure dephasing. It seems that this far off-resonant coupling is the result of increased number of acoustical phonons due to high operating temperature of 50?K. The 4.1?nm detuning is the largest amount for this kind of coupling.

  11. Dielectric and magnetic investigations of GaFeO{sub 3} single crystals

    SciTech Connect (OSTI)

    Srimathy, B. Bhaumik, Indranil Ganesamoorthy, S. Karnal, A. K. Kumar, J.

    2014-04-24

    Structural, dielectric and magnetic properties have been investigated for the polar ferrimagnet, GaFeO{sub 3} single crystals grown by optical floating zone technique. Phase formation was confirmed from X-ray diffraction. Hopping conduction mechanism of Fe{sup 2+} ions and oxygen vacancies contribute to the electric polarization and dielectric constant of the material. Disorderness in the cation site gives rise to the magnetic ordering and the splitting in the zero field cooled (ZFC) and field cooled (FC) magnetization curves reveals the movement of the domain walls.

  12. Improved crystal orientation and physical properties from single-shot XFEL stills

    SciTech Connect (OSTI)

    Sauter, Nicholas K., E-mail: nksauter@lbl.gov; Hattne, Johan; Brewster, Aaron S.; Echols, Nathaniel; Zwart, Petrus H.; Adams, Paul D. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2014-12-01

    X-ray free-electron laser crystallography relies on the collection of still-shot diffraction patterns. New methods are developed for optimal modeling of the crystals orientations and mosaic block properties. X-ray diffraction patterns from still crystals are inherently difficult to process because the crystal orientation is not uniquely determined by measuring the Bragg spot positions. Only one of the three rotational degrees of freedom is directly coupled to spot positions; the other two rotations move Bragg spots in and out of the reflecting condition but do not change the direction of the diffracted rays. This hinders the ability to recover accurate structure factors from experiments that are dependent on single-shot exposures, such as femtosecond diffract-and-destroy protocols at X-ray free-electron lasers (XFELs). Here, additional methods are introduced to optimally model the diffraction. The best orientation is obtained by requiring, for the brightest observed spots, that each reciprocal-lattice point be placed into the exact reflecting condition implied by Braggs law with a minimal rotation. This approach reduces the experimental uncertainties in noisy XFEL data, improving the crystallographic R factors and sharpening anomalous differences that are near the level of the noise.

  13. Monolithic single GaN nanowire laser with photonic crystal microcavity on silicon

    SciTech Connect (OSTI)

    Heo, Junseok; Guo Wei; Bhattacharya, Pallab

    2011-01-10

    Optically pumped lasing at room temperature in a silicon based monolithic single GaN nanowire with a two-dimensional photonic crystal microcavity is demonstrated. Catalyst-free nanowires with low density ({approx}10{sup 8} cm{sup -2}) are grown on Si by plasma-assisted molecular beam epitaxy. High resolution transmission electron microscopy images reveal that the nanowires are of wurtzite structure and they have no observable defects. A single nanowire laser fabricated on Si is characterized by a lasing transition at {lambda}=371.3 nm with a linewidth of 0.55 nm. The threshold is observed at a pump power density of {approx}120 kW/cm{sup 2} and the spontaneous emission factor {beta} is estimated to be 0.08.

  14. High Efficiency Single Crystal CdTe Solar Cells: November 19, 2009 - January 31, 2011

    SciTech Connect (OSTI)

    Carmody, M.; Gilmore, A.

    2011-05-01

    The goal of the program was to develop single crystal CdTe-based top cells grown on Si solar cells as a platform for the subsequent manufacture of high efficiency tandem cells for CPV applications. The keys to both the single junction and the tandem junction cell architectures are the ability to grow high quality single-crystal CdTe and CdZnTe layers on p-type Si substrates, to dope the CdTe and CdZnTe controllably, both n and p-type, and to make low resistance ohmic front and back contacts. EPIR demonstrated the consistent MBE growth of CdTe/Si and CdZnTe/Si having high crystalline quality despite very large lattice mismatches; epitaxial CdTe/Si and CdZnTe/Si consistently showed state-of-the-art electron mobilities and good hole mobilities; bulk minority carrier recombination lifetimes of unintentionally p-doped CdTe and CdZnTe grown by MBE on Si were demonstrated to be consistently of order 100 ns or longer; desired n- and p-doping levels were achieved; solar cell series specific resistances <10 ?-cm2 were achieved; A single-junction solar cell having a state-of-the-art value of Voc and a unverified 16.4% efficiency was fabricated from CdZnTe having a 1.80 eV bandgap, ideal for the top junction in a tandem cell with a Si bottom junction.

  15. The local structure and ferromagnetism in Fe-implanted SrTiO? single crystals

    SciTech Connect (OSTI)

    Lobacheva, O. Chavarha, M.; Yiu, Y. M.; Sham, T. K.; Goncharova, L. V.

    2014-07-07

    We report a connection between the local structure of low-level Fe impurities and vacancies as the cause of ferromagnetic behavior observed in strontium titanate single crystals (STO), which were implanted with Fe and Si ions at different doses then annealed in oxygen. The effects of Fe doping and post-implantation annealing of STO were studied by X-ray Absorption Near Edge Structure (XANES) spectroscopy and Superconducting Quantum Interference Device magnetometry. XANES spectra for Fe and Ti K- and L-edge reveal the changes in the local environment of Fe and Ti following the implantation and annealing steps. The annealing in oxygen atmosphere partially healed implantation damages and changed the oxidation state of the implanted iron from metallic Fe? to Fe?/Fe? oxide. The STO single crystals were weak ferromagnets prior to implantation. The maximum saturation moment was obtained after our highest implantation dose of 210? Fe atom/cm, which could be correlated with the metallic Fe? phases in addition to the presence of O/Ti vacancies. After recrystallization annealing, the ferromagnetic response disappears. Iron oxide phases with Fe? and Fe? corresponding to this regime were identified and confirmed by calculations using Real Space Multiple Scattering program (FEFF9).

  16. Precision control of thermal transport in cryogenic single-crystal silicon devices

    SciTech Connect (OSTI)

    Rostem, K.; Chuss, D. T.; Colazo, F. A.; Crowe, E. J.; Denis, K. L.; Lourie, N. P.; Moseley, S. H.; Stevenson, T. R.; Wollack, E. J.

    2014-03-28

    We report on the diffusive-ballistic thermal conductance of multi-moded single-crystal silicon beams measured below 1?K. It is shown that the phonon mean-free-path ? is a strong function of the surface roughness characteristics of the beams. This effect is enhanced in diffuse beams with lengths much larger than ?, even when the surface is fairly smooth, 510?nm rms, and the peak thermal wavelength is 0.6??m. Resonant phonon scattering has been observed in beams with a pitted surface morphology and characteristic pit depth of 30?nm. Hence, if the surface roughness is not adequately controlled, the thermal conductance can vary significantly for diffuse beams fabricated across a wafer. In contrast, when the beam length is of order ?, the conductance is dominated by ballistic transport and is effectively set by the beam cross-sectional area. We have demonstrated a uniformity of 8% in fractional deviation for ballistic beams, and this deviation is largely set by the thermal conductance of diffuse beams that support the micro-electro-mechanical device and electrical leads. In addition, we have found no evidence for excess specific heat in single-crystal silicon membranes. This allows for the precise control of the device heat capacity with normal metal films. We discuss the results in the context of the design and fabrication of large-format arrays of far-infrared and millimeter wavelength cryogenic detectors.

  17. Optical emission diagnostics of plasmas in chemical vapor deposition of single-crystal diamond

    SciTech Connect (OSTI)

    Hemawan, Kadek W. Hemley, Russell J.

    2015-11-15

    A key aspect of single crystal diamond growth via microwave plasma chemical vapor deposition is in-process control of the local plasma–substrate environment, that is, plasma gas phase concentrations of activated species at the plasma boundary layer near the substrate surface. Emission spectra of the plasma relative to the diamond substrate inside the microwave plasma reactor chamber have been analyzed via optical emission spectroscopy. The spectra of radical species such as CH, C{sub 2}, and H (Balmer series) important for diamond growth were identified and analyzed. The emission intensities of these electronically excited species were found to be more dependent on operating pressure than on microwave power. Plasma gas temperatures were calculated from measurements of the C{sub 2} Swan band (d{sup 3}Π → a{sup 3}Π transition) system. The plasma gas temperature ranges from 2800 to 3400 K depending on the spatial location of the plasma ball, microwave power and operating pressure. Addition of Ar into CH{sub 4}+H{sub 2} plasma input gas mixture has little influence on the Hα, Hβ, and Hγ intensities and single-crystal diamond growth rates.

  18. Temperature and field induced strain measurements in single crystal Gd5Si2Ge2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    McCall, S. K.; Nersessian, N.; Carman, G. P.; Pecharsky, V. K.; Schlagel, D. L.; Radousky, H. B.

    2016-03-29

    The first-order magneto-structural transformation that occurs in Gd5Si2Ge2 near room temperature makes it a strong candidate for many energy harvesting applications. Understanding the single crystal properties is crucial for allowing simulations of device performance. In this study, magnetically and thermally induced transformation strains were measured in a single crystal of Gd5Si2.05Ge1.95 as it transforms from a high-temperature monoclinic paramagnet to a lower-temperature orthorhombic ferromagnet. Thermally induced transformation strains of –8500 ppm, +960 ppm and +1800 ppm, and magnetically induced transformation strains of –8500 ppm, +900 ppm and +2300 ppm were measured along the a, b and c axes, respectively. Furthermore,more » using experimental data coupled with general thermodynamic considerations, a universal phase diagram was constructed showing the transition from the monoclinic to the orthorhombic phase as a function of temperature and magnetic field.« less

  19. Cooperative Island Growth of Large Area Single-Crystal Graphene by Chemical Vapor Deposition on Cu

    SciTech Connect (OSTI)

    Regmi, Murari [Oak Ridge National Laboratory (ORNL); Rouleau, Christopher [Oak Ridge National Laboratory (ORNL); Puretzky, Alexander A [ORNL; Ivanov, Ilia N [ORNL; Geohegan, David B [ORNL; Chen, Jihua [ORNL; Eastman, Jeffrey [Argonne National Laboratory (ANL); Eres, Gyula [ORNL

    2014-01-01

    We describe a two-step approach for suppressing nucleation of graphene on Cu using chemical vapor deposition. In the first step, as received Cu foils are oxidized in air at temperatures up to 500 C to remove surface impurities and to induce the regrowth of Cu grains during subsequent annealing in H2 flow at 1040 C prior to graphene growth. In the second step, transient reactant cooling is performed by using a brief Ar pulse at the onset of growth to induce collisional deactivation of the carbon growth species. The combination of these two steps results in a three orders of magnitude reduction in the graphene nucleation density, enabling the growth of millimeter-size single crystal graphene grains. A kinetic model shows that suppressing nucleation promotes a cooperative island growth mode that favors the formation of large area single crystal graphene, and it is accompanied by a roughly 3 orders of magnitude increase in the reactive sticking probability of methane compared to that in random nucleation growth.

  20. Diffraction Profiles of Elasticity Bent Single Crystals with Constant Strain Gradients

    SciTech Connect (OSTI)

    Yan,H.; Kalenci, O.; Noyan, I.

    2007-01-01

    This work presents a set of equations that can be used to predict the dynamical diffraction profile from a non-transparent single crystal with a constant strain gradient examined in Bragg reflection geometry with a spherical incident X-ray beam. In agreement with previous work, the present analysis predicts two peaks: a primary diffraction peak, which would have still been observed in the absence of the strain gradient and which exits the specimen surface at the intersection point of the incident beam with the sample surface, and a secondary (mirage) peak, caused by the deflection of the wavefield within the material, which exits the specimen surface further from this intersection point. The integrated intensity of the mirage peak increases with increasing strain gradient, while its separation from the primary reflection peak decreases. The directions of the rays forming the mirage peak are parallel to those forming the primary diffraction peak. However, their spatial displacement might cause (fictitious) angular shifts in diffractometers equipped with area detectors or slit optics. The analysis results are compared with experimental data from an Si single-crystal strip bent in cantilever configuration, and the implications of the mirage peak for Laue analysis and high-precision diffraction measurements are discussed.

  1. XRD micro-XANES EMPA and SIMS investigation on phlogopite single crystals from Mt. Vulture (Italy)

    SciTech Connect (OSTI)

    F Scordari; M Dyar; E Schingaro; M Lacalamita; L Ottolini

    2011-12-31

    Selected phlogopite flakes from Mt. Vulture in southern Italy were studied using a combination of single-crystal techniques: electron microprobe analysis (EMPA), secondary ion mass spectrometry (SIMS), single-crystal X-ray diffraction (SCXRD), and micro-X-ray absorption near-edge spectroscopy (XANES). The latter technique was employed to analyze the structure of the Fe-K absorption edge over the region from 7080-8100 eV and to determine Fe{sup 3+}/{Sigma}Fe at a micrometer scale, albeit with large error bars due to known effects of orientation on pre-edge energy. The annite component, Fe/(Mg+Fe), of the samples studied ranged from 0.16 to 0.31, the Ti content from 0.11 to 0.27 atoms per formula unit (apfu) and the Ba content from 0.03 to 0.09 apfu. SIMS analysis showed H{sub 2}O (wt%) = 1.81-3.30, F (wt%) = 0.44-1.29, and Li{sub 2}O (wt%) = 0.001-0.027. The intra single-crystal chemical variability for major/minor elements (Mg, Fe, Al, Ba, Ti, and K) was found particularly significant for samples VUT191{_}11 and PG5{_}1, less significant for the other samples of the set. SIMS data relative to crystals VUT187{_}24, VUT191{_}10, VUT191{_}11, and VUT187{_}28 showed a noteworthy variation in the concentrations of some light elements (H, Li, and F) with coefficient of variation CV (as 1{sigma}%) up to {approx}18% for H{sub 2}O. The analyzed micas belong to the 1M polytype. Structure refinements using anisotropic displacement parameters were performed in space group C2/m and converged at 3.08 {<=} R {<=} 3.63, 3.32 {<=} R{sub w} {<=} 3.98%. Micro-XANES results yielded Fe{sup 3+}/{Sigma}Fe from 51-93%. Previous Moessbauer data from powdered samples suggested Fe{sup 3+}/{Sigma}Fe values ranging from 49-87%. However, the Fe{sup 3+} content determined by both techniques is sometimes remarkably different, in part because of the large errors ({+-}10-15%) presently associated with the micro-XANES technique and in part because the Fe{sup 3+} content of a single crystal may

  2. Growth, structural and optical characterization of L-histidine 4-nitrophenolate (LHPNP) single crystals for NLO applications

    SciTech Connect (OSTI)

    Mahadevan, M.; Ramachandran, K.; Anandan, P.; Arivanandhan, M. E-mail: royhaya@ipc.shizuoka.ac.jp; Hayakawa, Y. E-mail: royhaya@ipc.shizuoka.ac.jp

    2014-10-15

    Using slow evaporation solution growth technique, single crystals of L-histidine-4-nitro phenolate has been grown from the solution. Structural analyses were carried out by powder x-ray diffraction, FT-Raman, Fourier Transform Infrared and Nuclear Magnetic Resonance spectral methods to conform the grown crystals. Thermal stability of the grown crystals was studied by thermo-gravimetric (TG) and differential thermal analyses (DTA). UV-Vis spectral analysis has been carried out to find the transparency of the grown crystal. Nonlinear optical property has been confirmed by Kurtz powder technique. The PL measurements were carried out in Perkin Elmer LS 55 Luminescence spectrometer using 410 nm as excitation wavelength. The observed properties have confirmed that the grown crystal is suitable for nonlinear optical applications.

  3. Elastic properties of Pd-hydrogen, Pd-deuterium, and Pd-tritium single crystals

    SciTech Connect (OSTI)

    Schwarz, R.B. . E-mail: rxzs@lanl.gov; Bach, H.T.; Harms, U.; Tuggle, D.

    2005-02-01

    We used a resonant-ultrasound-spectroscopy technique to measure the three independent elastic constants of PdH{sub x}, PdD{sub x}, and PdT{sub x} single crystals at 300 K. For 0.1x0.62 our PdH{sub x} crystals are two-phase mixtures of coherent {alpha} and {beta} hydride phases. For increasing x in this range, C{sub 44} decreases monotonically whereas C'=12(C11-C12) has a concave parabolic dependence. This difference is because C' is softened by an anelastic relaxation resulting from acoustic-stress-induced changes in the shape of the coherent lenticular-shape precipitates ({beta}-hydride precipitates in {alpha}-hydride matrix and {alpha}-hydride precipitates in {beta}-hydride matrix). In the {beta}-phase C' and C{sub 44} decrease with increasing hydrogen (or deuterium or tritium) content. Furthermore, C' exhibits a strong isotope effect whereas C{sub 44} does not. This effect is attributed to differences in the excitation of optical phonons in Pd-H, Pd-D and Pd-T.

  4. FRACTIONAL CRYSTALLIZATION OF HANFORD SINGLE SHELL TANK (SST) WASTES A MODELING APPROACH

    SciTech Connect (OSTI)

    HAMILTON, D.W.

    2006-12-21

    The Hanford site has 149 underground single-shell tanks (SST) storing mostly soluble, multi-salt, mixed wastes resulting from Cold War era weapons material production. These wastes must be retrieved and the salts immobilized before the tanks can be closed to comply with an overall site closure consent order entered into by the U.S. Department of Energy (DOE), the Environmental Protection Agency, and Washington State. Water will be used to retrieve the wastes and the resulting solution will be pumped to the proposed treatment process where a high curie (primarily {sup 137}Cs) waste fraction will be separated from the other waste constituents. The separated waste streams will then be vitrified to allow for safe storage as an immobilized high level waste, or low level waste, borosilicate glass. Fractional crystallization, a common unit operation for production of industrial chemicals and pharmaceuticals, was proposed as the method to separate the salt wastes; it works by evaporating excess water until the solubilities of various species in the solution are exceeded (the solubility of a particular species depends on its concentration, temperature of the solution, and the presence of other ionic species in the solution). By establishing the proper conditions, selected pure salts can be crystallized and separated from the radioactive liquid phase.

  5. Atomistic simulations of nanowelding of single-crystal and amorphous gold nanowires

    SciTech Connect (OSTI)

    Wu, Cheng-Da; Fang, Te-Hua Wu, Chung-Chin

    2015-01-07

    The mechanism and quality of the welding of single-crystal (SC) and amorphous gold nanowires (NWs) with head-to-head contact are studied using molecular dynamics simulations based on the second-moment approximation of the many-body tight-binding potential. The results are discussed in terms of atomic trajectories, slip vectors, stress, and radial distribution function. Simulation results show that the alignment for the amorphous NWs during welding is easier than that for the SC NWs due to the former's relatively stable geometry. A few dislocations nucleate and propagate on the (111) close-packed plane (slip plane) inside the SC NWs during the welding and stretching processes. During welding, an incomplete jointing area first forms through the interactions of the van der Waals attractive force, and the jointing area increases with increasing extent of contact between the two NWs. A crystallization transition region forms in the jointing area for the welding of SC-amorphous or amorphous-SC NWs. With increasing interference, an amorphous gold NW shortens more than does a SC gold NW due to the former's relatively poor strength. The pressure required for welding decreases with increasing temperature.

  6. Improved crystal orientation and physical properties from single-shot XFEL stills

    SciTech Connect (OSTI)

    Sauter, Nicholas K.; Hattne, Johan; Brewster, Aaron S.; Echols, Nathaniel; Zwart, Petrus H.; Adams, Paul D.

    2014-11-28

    X-ray diffraction patterns from still crystals are inherently difficult to process because the crystal orientation is not uniquely determined by measuring the Bragg spot positions. Only one of the three rotational degrees of freedom is directly coupled to spot positions; the other two rotations move Bragg spots in and out of the reflecting condition but do not change the direction of the diffracted rays. This hinders the ability to recover accurate structure factors from experiments that are dependent on single-shot exposures, such as femtosecond diffract-and-destroy protocols at X-ray free-electron lasers (XFELs). Here, additional methods are introduced to optimally model the diffraction. The best orientation is obtained by requiring, for the brightest observed spots, that each reciprocal-lattice point be placed into the exact reflecting condition implied by Bragg's law with a minimal rotation. This approach reduces the experimental uncertainties in noisy XFEL data, improving the crystallographic R factors and sharpening anomalous differences that are near the level of the noise.

  7. Improved crystal orientation and physical properties from single-shot XFEL stills

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sauter, Nicholas K.; Hattne, Johan; Brewster, Aaron S.; Echols, Nathaniel; Zwart, Petrus H.; Adams, Paul D.

    2014-11-28

    X-ray diffraction patterns from still crystals are inherently difficult to process because the crystal orientation is not uniquely determined by measuring the Bragg spot positions. Only one of the three rotational degrees of freedom is directly coupled to spot positions; the other two rotations move Bragg spots in and out of the reflecting condition but do not change the direction of the diffracted rays. This hinders the ability to recover accurate structure factors from experiments that are dependent on single-shot exposures, such as femtosecond diffract-and-destroy protocols at X-ray free-electron lasers (XFELs). Here, additional methods are introduced to optimally model themore » diffraction. The best orientation is obtained by requiring, for the brightest observed spots, that each reciprocal-lattice point be placed into the exact reflecting condition implied by Bragg's law with a minimal rotation. This approach reduces the experimental uncertainties in noisy XFEL data, improving the crystallographic R factors and sharpening anomalous differences that are near the level of the noise.« less

  8. Development of Single Crystal Chemical Vapor Deposition Diamonds for Detector Applications

    SciTech Connect (OSTI)

    Rainer Wallny

    2012-10-15

    Diamond was studied as a possible radiation hard technology for use in future high radiation environments. With the commissioning of the LHC expected in 2010, and the LHC upgrades expected in 2015, all LHC experiments are planning for detector upgrades which require radiation hard technologies. Chemical Vapor Deposition (CVD) diamond has now been used extensively in beam conditions monitors as the innermost detectors in the highest radiation areas of BaBar, Belle and CDF and is installed and operational in all LHC experiments. As a result, this material is now being discussed as an alternative sensor material for tracking very close to the interaction region of the super-LHC where the most extreme radiation conditions will exist. Our work addressed the further development of the new material, single-crystal Chemical Vapor Deposition diamond, towards reliable industrial production of large pieces and new geometries needed for detector applications.

  9. Effect of nitrogen on the growth of boron doped single crystal diamond

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Karna, Sunil; Vohra, Yogesh

    2013-11-18

    Boron-doped single crystal diamond films were grown homoepitaxially on synthetic (100) Type Ib diamond substrates using microwave plasma assisted chemical vapor deposition. A modification in surface morphology of the film with increasing boron concentration in the plasma has been observed using atomic force microscopy. Use of nitrogen during boron doping has been found to improve the surface morphology and the growth rate of films but it lowers the electrical conductivity of the film. The Raman spectra indicated a zone center optical phonon mode along with a few additional bands at the lower wavenumber regions. The change in the peak profilemore » of the zone center optical phonon mode and its downshift were observed with the increasing boron content in the film. Furthermore, sharpening and upshift of Raman line was observed in the film that was grown in presence of nitrogen along with diborane in process gas.« less

  10. Optical properties of Eu{sup 2+} doped antipervoskite fluoride single crystals

    SciTech Connect (OSTI)

    Daniel, D. Joseph; Ramasamy, P.; Nithya, R.; Madhusoodanan, U.

    2013-02-05

    Single crystals of pure and Eu{sup 2+} doped LiBaF{sub 3} have been grown from melt by using a vertical Bridgman-Stockbarger method. Absorption and luminescence spectra for pure and rare-earth-doped LiBaF{sub 3} were studied. At ambient conditions the photoluminescence spectra consisted of sharp lines peaked at {approx}359 nm attributed to the {sup 6}P7/2{yields}{sup 8}S7/2 transitions in the 4f{sub 7} electronic configuration of Eu{sup 2+} and a broad band extending between 370 and 450 nm attributed to Eu{sup 2+} trapped exciton recombination. The effect of {sup 60}Co gamma irradiation has also been investigated.

  11. Development of Single Crystal Chemical Vapor Deposition Diamonds for Detector Applications

    SciTech Connect (OSTI)

    Harris Kagan; K.K. Gan; Richard Kass

    2009-03-31

    Diamond was studied as a possible radiation hard technology for use in future high radiation environments. With the commissioning of the LHC expected in 2009, and the LHC upgrades expected in 2013, all LHC experiments are planning for detector upgrades which require radiation hard technologies. Chemical Vapor Deposition (CVD) diamond has now been used extensively in beam conditions monitors as the innermost detectors in the highest radiation areas of BaBar, Belle and CDF and is installed in all LHC experiments. As a result, this material is now being discussed as an alternative sensor material for tracking very close to the interaction region of the super-LHC where the most extreme radiation conditions will exist. Our work addressed the further development of the new material, single-crystal Chemical Vapor Deposition diamond, towards reliable industrial production of large pieces and new geometries needed for detector applications.

  12. Single crystal growth and characterization of the large-unit-cell compound Cu13Ba

    SciTech Connect (OSTI)

    Jesche, Anton; Budko, Serguei L.; Canfield, Paul C.

    2013-10-31

    Single crystals of Cu13Ba were successfully grown out of BaCu self flux. Temperature dependent magnetization, M (T ), electrical resistivity, ?(T)?(T), and specific heat, Cp(T)Cp(T), data are reported. Isothermal magnetization measurements, M(H)M(H), show clear de Haas-van Alphen oscillations at T = 2 K for applied fields as low as View the MathML source?0H=1T. An anomalous behavior of the magnetic susceptibility is observed up to T ? 50 K reflecting the effect of de Haas-van Alphen oscillations at fairly high temperatures. The field- and temperature-dependencies of the magnetization indicate the presence of diluted magnetic impurities with a concentration of the order of 0.01 at.%. Accordingly, the minimum and lower temperature rise observed in the electrical resistivity at and below T = 15 K is attributed to the Kondo-impurity effect.

  13. A photoemission study of the diamond and the single crystal C{sub 60}

    SciTech Connect (OSTI)

    Wu, Jin

    1994-03-01

    This report studied the elctronic structure of diamond (100) and diamond/metal interface and C{sub 60}, using angle-resolved and core level photoemission. The C(100)-(2X1) surface electronic structure was studied using both core level and angle resolved valence band photoemission spectroscopy. The surface component of the C 1s core level spectrum agrees with theoretical existence of only symmetrical dimers. In the case of metal/diamond interfaces, core level and valence photoelectron spectroscopy and LEED studies WERE MADE OF B and Sb on diamond (100) and (111) surfaces. In the case of single-crystal C{sub 60}, photoemission spectra show sharp molecular features, indicating that the molecular orbitals are relatively undisturbed in solid C{sub 60}.

  14. Photoresponsive Release from Azobenzene-Modified Single Cubic Crystal NaCl/Silica Particles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jiang, Xingmao; Liu, Nanguo; Assink, Roger A.; Jiang, Yingbing; Brinker, C. Jeffrey

    2011-01-01

    Azobenzene ligands were uniformly anchored to the pore surfaces of nanoporous silica particles with single crystal NaCl using 4-(3-triethoxysilylpropylureido)azobenzene (TSUA). The functionalization delayed the release of NaCl significantly. The modified particles demonstrated a photocontrolled release by trans/cis isomerization of azobenzene moieties. The addition of amphiphilic solvents, propylene glycol (PG), propylene glycol propyl ether (PGPE), and dipropylene glycol propyl ether (DPGPE) delayed the release in water, although the wetting behavior was improved and the delay is the most for the block molecules with the longest carbon chain. The speedup by UV irradiation suggests a strong dependence of diffusion on the switchablemore » pore size. TGA, XRD, FTIR, and NMR techniques were used to characterize the structures.« less

  15. Photo-transport properties of Pb{sub 2}CrO{sub 5} single crystals

    SciTech Connect (OSTI)

    Mondal, P. S.; Okazaki, R. Taniguchi, H.; Terasaki, I.

    2014-11-21

    We report photo-thermoelectric transport phenomena in Pb{sub 2}CrO{sub 5} single crystals. Without illumination, this material exhibits an insulating behavior characterized by an activation-type temperature variation of the electrical conductivity. The Seebeck coefficient contrastingly shows a crossover from high-temperature insulating to low-temperature metallic behavior, which is attributed to degenerate carriers in a donor level. We have found that under illumination, both the conductivity and the Seebeck coefficient increase in magnitude with increasing photon flux density in the degenerate-conduction regime. This result is difficult to understand within a simple photo-doping effect, which usually leads to a decrease in the Seebeck coefficient under illumination. The observed phenomenon is discussed in terms of a two-carrier contribution to the transport properties.

  16. Rear surface spallation on single-crystal silicon in nanosecond laser micromachining

    SciTech Connect (OSTI)

    Ren, Jun; Orlov, Sergei S.; Hesselink, Lambertus

    2005-05-15

    Rear surface spallation of single-crystal silicon under 5-ns laser pulse ablation at intensities of 0.6-60 GW/cm{sup 2} is studied through postablation examination of the ablated samples. The spallation threshold energy and the spallation depth's dependences on the energy and target thickness are measured. From the linear relation between the spallation threshold energy and the target thickness, an estimation of the material spall strength around 1.4 GPa is obtained, in reasonable agreement with the spall strength estimation of 0.8-1.2 GPa at a strain rate of 10{sup 7} s{sup -1} using Grady's model for brittle materials. The experiment reveals the internal fracturing process over an extended zone in silicon, which is controlled by the competition between the shock pressure load and the laser ablation rate. The qualities of the laser microstructuring and micromachining results are greatly improved by using an acoustic impedance matching approach.

  17. Single-crystal diamond refractive lens for focusing X-rays in two dimensions

    SciTech Connect (OSTI)

    Antipov, S.; Baryshev, Sergey; Butler, J. E.; Antipova, O.; Liu, Zunping; Stoupin, S.

    2016-01-01

    The fabrication and performance evaluation of single-crystal diamond refractive X-ray lenses of which the surfaces are paraboloids of revolution for focusing X-rays in two dimensions simultaneously are reported. The lenses were manufactured using a femtosecond laser micromachining process and tested using X-ray synchrotron radiation. Such lenses were stacked together to form a standard compound refractive lens (CRL). Owing to the superior physical properties of the material, diamond CRLs could become indispensable wavefront-preserving primary focusing optics for X-ray free-electron lasers and the next-generation synchrotron storage rings. They can be used for highly efficient refocusing of the extremely bright X-ray sources for secondary optical schemes with limited aperture such as nanofocusing Fresnel zone plates and multilayer Laue lenses.

  18. Summary Report of Summer Work: High Purity Single Crystal Growth & Microstructure of Ferritic-Martensitic Steels

    SciTech Connect (OSTI)

    Pestovich, Kimberly Shay

    2015-08-18

    Harnessing the power of the nuclear sciences for national security and to benefit others is one of Los Alamos National Laboratory’s missions. MST-8 focuses on manipulating and studying how the structure, processing, properties, and performance of materials interact at the atomic level under nuclear conditions. Within this group, single crystal scintillators contribute to the safety and reliability of weapons, provide global security safeguards, and build on scientific principles that carry over to medical fields for cancer detection. Improved cladding materials made of ferritic-martensitic alloys support the mission of DOE-NE’s Fuel Cycle Research and Development program to close the nuclear fuel cycle, aiming to solve nuclear waste management challenges and thereby increase the performance and safety of current and future reactors.

  19. Fabrication of Fe nanowires on yittrium-stabilized zirconia single crystal substrates by thermal CVD methods

    SciTech Connect (OSTI)

    Kawahito, A.; Yanase, T.; Endo, T.; Nagahama, T.; Shimada, T.

    2015-05-07

    Magnetic nanowires (NWs) are promising as material for use in spintronics and as the precursor of permanent magnets because they have unique properties due to their high aspect ratio. The growth of magnetic Fe whiskers was reported in the 1960s, but the diameter was not on a nanoscale level and the growth mechanism was not fully elucidated. In the present paper, we report the almost vertical growth of Fe NWs on a single crystal yttrium-stabilized zirconia (Y{sub 0.15}Zr{sub 0.85}O{sub 2}) by a thermal CVD method. The NWs show a characteristic taper part on the bottom growing from a trigonal pyramidal nucleus. The taper angle and length can be controlled by changing the growth condition in two steps, which will lead to obtaining uniformly distributed thin Fe NWs for applications.

  20. Nanosecond pump and probe observation of bimolecular exciton effects in rubrene single crystals

    SciTech Connect (OSTI)

    Ward, Kebra A.; Richman, Brittany R.; Biaggio, Ivan

    2015-06-01

    Transient grating pump and probe experiments are used to investigate excitonic processes on the nanosecond time scale in rubrene single crystals. We find that bimolecular interactions cause a photoinduced excited state density on the order of 0.5 × 10{sup 20 }cm{sup −3}—corresponding to an average distance of ∼3 nm between individual states—to decrease by a factor of 2 after 2 ns, following a typical power-law decay. We assign the observed power-law decays to high-density interactions between excited states. Because of the high efficiency singlet exciton fission observed in rubrene, these bimolecular interactions are likely those between triplet excitons or between coherent quantum superpositions of a singlet and a pair of triplet-excitons.

  1. A study of the structure and scattering mechanisms of subterahertz phonons in lithium fluoride single crystals and optical ceramics

    SciTech Connect (OSTI)

    Khazanov, E. N. Taranov, A. V.; Gainutdinov, R. V.; Akchurin, M. Sh.; Basiev, T. T.; Konyushkin, V. A.; Fedorov, P. P.; Kuznetsov, S. V.; Osiko, V. V.

    2010-06-15

    The methods of optical, electron, and atomic force microscopy (AFM) are applied to the study of the real structure of optical lithium fluoride ceramic obtained by hot deformation of single crystals. A comparative analysis is carried out of the scattering mechanisms of weakly nonequilibrium thermal phonons at liquid helium temperatures in LiF single crystals and ceramics. It is demonstrated that the phonon scattering in the original single crystals is determined by the forced vibrations of dislocations in the stress field of an elastic plane wave (a phonon), i.e., by the flutter mechanism. As the degree of deformation of the original material increases, the ceramics exhibit a change in the plastic deformation mechanisms, which leads to a decrease in the average size of grains and to an ordered structure. In this case, the dominant scattering is that by intergrain boundaries. The thickness and the acoustic impedance of these boundaries are evaluated.

  2. Enhanced magnetic hysteresis in Ni-Mn-Ga single crystal and its influence on magnetic shape memory effect

    SciTech Connect (OSTI)

    Heczko, O. Drahokoupil, J.; Straka, L.

    2015-05-07

    Enhanced magnetic hysteresis due to boron doping in combination with magnetic shape memory effect in Ni-Mn-Ga single crystal results in new interesting functionality of magnetic shape memory (MSM) alloys such as mechanical demagnetization. In Ni{sub 50.0}Mn{sub 28.5}Ga{sub 21.5} single crystal, the boron doping increased magnetic coercivity from few Oe to 270?Oe while not affecting the transformation behavior and 10?M martensite structure. However, the magnetic field needed for MSM effect also increased in doped sample. The magnetic behavior is compared to undoped single crystal of similar composition. The evidence from the X-ray diffraction, magnetic domain structure, magnetization loops, and temperature evolution of the magnetic coercivity points out that the enhanced hysteresis is caused by stress-induced anisotropy.

  3. A tale of two mechanisms. Strain-softening versus strain-hardening in single crystals under small stressed volumes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bei, Hongbin; Xia, Yuzhi; Barabash, Rozaliya; Gao, Y. F.

    2015-08-10

    Pre-straining defect-free single crystals will introduce heterogeneous dislocation nucleation sources that reduce the measured strength from the theoretical value, while pre-straining bulk samples will lead to strain hardening. Their competition is investigated by nanoindentation pop-in tests on variously pre-strained Mo single crystals with several indenter radii (~micrometer). Pre-straining primarily shifts deformation mechanism from homogeneous dislocation nucleation to a stochastic behavior, while strain hardening plays a secondary role, as summarized in a master plot of pop-in strength versus normalized indenter radius.

  4. High-resolution photoluminescence spectroscopy of Sn-doped ZnO single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kumar, E. Senthil; Mohammadbeigi, F.; Boatner, Lynn A.; Watkins, S. P.

    2016-03-18

    Here, Group IV donors in ZnO are poorly understood, despite evidence that they are effective n-dopants. We present high-resolution photoluminescence spectroscopy studies of unintentionally doped and Sn doped ZnO single crystals grown by the chemical vapor transport method. Doped samples showed greatly increased emission from the I10 bound exciton transition which was recently proven to be related to the incorporation of Sn impurities based on radio-isotope studies. PL linewidths are exceptionally sharp for these samples, enabling clear identification of several donor species. Temperature dependent PL measurements of the I10 line emission energy and intensity dependence reveal a behavior similar tomore » other shallow donors in ZnO. Ionized donor bound exciton and two electron satellite transitions of the I10 transition are unambiguously identified and yield a donor binding energy of 71 meV. In contrast to recent reports of Ge-related donors in ZnO, the spectroscopic binding energy for the Sn-related donor bound exciton follows a linear relationship with donor binding energy (Haynes rule), confirming the shallow nature of this defect center, which we attribute to a SnZn double donor compensated by an unknown single acceptor.« less

  5. Superconductivity and Physical Properties of CaPd2Ge2 Single Crystals

    SciTech Connect (OSTI)

    Anand, V K; Kim, Hyunsoo; Tanatar, Makariy A; Prozorov, Ruslan; Johnston, David C

    2014-10-08

    We present the superconducting and normal state properties of CaPd2Ge2 single crystals investigated by magnetic susceptibility ?, isothermal magnetization M, heat capacity Cp, in-plane electrical resistivity ? and London penetration depth ? versus temperature T and magnetic field H measurements. Bulk superconductivity is inferred from the ?(T) and Cp(T) data. The ?(T) data exhibit metallic behavior and a superconducting transition with Tc onset = 1.98 K and zero resistivity at Tc 0 = 1.67 K. The ?(T) reveals the onset of superconductivity at 2.0 K. For T > 2.0 K, the ?(T) and M(H) are weakly anisotropic paramagnetic with ?ab > ?c. The Cp(T) data confirm the bulk superconductivity below Tc = 1.69(3) K. The superconducting state electronic heat capacity is analyzed within the framework of a single-band ?-model of BCS superconductivity and various normal and superconducting state parameters are estimated. Within the ?-model, the Cp(T) data and the ab plane ?(T) data consistently indicate a moderately anisotropic s-wave gap with ?(0)/kBTc ? 1.6, somewhat smaller than the BCS value of 1.764. The relationship of the heat capacity jump at Tc and the penetration depth measurement to the anisotropy in the s-wave gap is discussed.

  6. Synthesis and single crystal x-ray diffraction study of a Schiff base derived from 4-acylpyrazolone and 2-aminophenol

    SciTech Connect (OSTI)

    Sharma, Naresh; Kant, Rajni Gupta, Vivek K.; Jadeja, R. N.

    2014-04-24

    The title compound, (Z)-1-(3-chlorophenyl)-4[1((2hydroxyphenyl)amino)propylidene] -3-methyl-1H-pyrazol-5(4H)-one was synthesized by refluxing compound 1-(m-chlorophenyl)-3-methyl-4-propionyl-5-pyrazolone, with 2-aminophenol in ethanol. The compound crystallizes in the orthorhombic crystal system with space group Pca2{sub 1} having unit cell parameters: a = 26.2993(8), b = 7.0724(2) and c = 18.7170(5)Å. The structure contains two crystallographically independent molecules, A, and, B, in the asymmetric unit cell. The crystal structure was solved by direct method using single crystal X-ray diffraction data collected at room temperature and refined by full-matrix least-squares procedures to a final R- value of 0.049 for 5207 observed reflections.

  7. Spectroscopy of Charge Carriers and Traps in Field-Doped Single Crystal Organic Semiconductors

    SciTech Connect (OSTI)

    Zhu, Xiaoyang

    2014-12-10

    The proposed research aims to achieve quantitative, molecular level understanding of charge carriers and traps in field-doped crystalline organic semiconductors via in situ linear and nonlinear optical spectroscopy, in conjunction with transport measurements and molecular/crystal engineering. Organic semiconductors are emerging as viable materials for low-cost electronics and optoelectronics, such as organic photovoltaics (OPV), organic field effect transistors (OFETs), and organic light emitting diodes (OLEDs). Despite extensive studies spanning many decades, a clear understanding of the nature of charge carriers in organic semiconductors is still lacking. It is generally appreciated that polaron formation and charge carrier trapping are two hallmarks associated with electrical transport in organic semiconductors; the former results from the low dielectric constants and weak intermolecular electronic overlap while the latter can be attributed to the prevalence of structural disorder. These properties have lead to the common observation of low charge carrier mobilities, e.g., in the range of 10-5 - 10-3 cm2/Vs, particularly at low carrier concentrations. However, there is also growing evidence that charge carrier mobility approaching those of inorganic semiconductors and metals can exist in some crystalline organic semiconductors, such as pentacene, tetracene and rubrene. A particularly striking example is single crystal rubrene (Figure 1), in which hole mobilities well above 10 cm2/Vs have been observed in OFETs operating at room temperature. Temperature dependent transport and spectroscopic measurements both revealed evidence of free carriers in rubrene. Outstanding questions are: what are the structural features and physical properties that make rubrene so unique? How do we establish fundamental design principles for the development of other organic semiconductors of high mobility? These questions are critically important but not comprehensive, as the nature of

  8. Development of Single Crystal Chemical Vapor Deposition Diamonds for Detector Applications

    SciTech Connect (OSTI)

    Kagan, Harris; Kass, Richard; Gan, K.K.

    2014-01-23

    With the LHC upgrades in 2013, and further LHC upgrades scheduled in 2018, most LHC experiments are planning for detector upgrades which require more radiation hard technologies than presently available. At present all LHC experiments now have some form of diamond detector. As a result Chemical Vapor Deposition (CVD) diamond has now been used extensively in beam conditions monitors as the innermost detectors in the highest radiation areas of all LHC experiments. Moreover CVD diamond is now being discussed as an alternative sensor material for tracking very close to the interaction region of the HL-LHC where the most extreme radiation conditions will exist. Our work addressed the further development of the new material, single-crystal Chemical Vapor Deposition diamond, towards reliable industrial production of large pieces and new geometries needed for detector applications. Our accomplishments include: Developed a two U.S.companies to produce electronic grade diamond, Worked with companies and acquired large area diamond pieces, Performed radiation hardness tests using various proton energies: 70 MeV (Cyric, Japan), 800 MeV (Los Alamos), and 24 GeV (CERN).

  9. Effect of dislocation trapping on deuterium diffusion in deformed, single-crystal Pd

    SciTech Connect (OSTI)

    Heuser, B.J.; King, J.S.

    1998-06-01

    Small-angle neutron scattering (SANS) has been used to characterize deuterium trapping at dislocations in deformed, single-crystal Pd during in situ gas evolution experiments. Two methods of deformation were employed--cold rolling and hydride cycling--which create different dislocation arrangements or substructures in Pd. The reduction of the trapped deuterium concentration at dislocations during evolution was directly monitored with SANS. Exponential decay rates of the trapped concentration were observed for both sample types, as is expected in a bulk diffusion process modified by the dislocation trapping interaction. The deuterium concentration reduction proceeded 1.2 to 1.4 times faster in the cold-rolled sample material than in the cycled material. This is attributed to the presence of a smaller number of dislocation trapping sites in the cold-rolled material. The binding energy of deuterium at dislocations was determined by applying a diffusion-based model. A binding energy of 0.20 eV was found to characterize the trapping interaction in both cold-rolled and hydride-cycled Pd.

  10. Welding and weldability of directionally solidified single crystal nickel-base super-alloys

    SciTech Connect (OSTI)

    vitek, j.m.

    1996-09-01

    The objective of this CRADA project was to investigate the weldability of polycrystalline, directionally-solidified, and single-crystal, nickel-base super-alloys. These materials are used extensively in turbine engine components. The ability to weld these materials is highly desirable in that it would greatly facilitate component fabrication. Welding of these materials would also have the potential benefit of allowing for the repair of cracked or worn components. Specifically, the program had four objectives: (1) to evaluate the weldability of nickel-base super-alloys; (2) to characterize the solidification microstructure of the welds; (3) to evaluate the phase stability of the weldments during exposure to service conditions; and (4) to determine the mechanical properties of the welds. Westinghouse Electric Corporation was to supply material for the program, in both as-case and heat-treated form. This was to include commercially available as well as experimental alloys developed at Westinghouse. ORNL was to perform weldability tests on the materials using a variety of welding procedures.

  11. Creep of CMSX-4 superalloy single crystals: Effects of rafting at high temperature

    SciTech Connect (OSTI)

    Reed, R.C.; Matan, N.; Cox, D.C.; Rist, M.A.; Rae, C.M.F.

    1999-09-29

    The creep performance of (001)-orientated CMSX-4 superalloy single crystals at temperatures beyond 1000 C is analyzed. Rafting of the {gamma}{prime} structure occurs rapidly, e.g., for the 1150 C/100 MPa tests rafting is completed within the first 10 h. At this stage and for a considerable time thereafter the creep strain rate decreases with increasing strain, implying a creep hardening effect which is absent at lower temperatures when the kinetics of rafting is less rapid. Once a critical strain {epsilon}* of (0.7 {+-} 0.3)% is reached, the creep strain increases dramatically and failure occurs within a few tens of hours. It is demonstrated that methods of interpretation which, assume a proportionality between the creep strain rate and creep strain, are unable to account for creep hardening which occurs as a consequence of rafting. A modification is proposed which accounts for the blocking of the glide/climb of {l{underscore}brace}111{r{underscore}brace}{l{underscore}angle}1{bar 1}0{r{underscore}angle} creep dislocations which occurs as the number of vertical {gamma} channels is reduced and cellular dislocation networks become stabilized. Consequently, failure must be taken to be associated with creep cavitation, which occurs predominantly around casting porosity. It is emphasized that more work is required to quantify the interaction between the various creep damage mechanisms.

  12. Kelvin probe characterization of buried graphitic microchannels in single-crystal diamond

    SciTech Connect (OSTI)

    Bernardi, E. Battiato, A.; Olivero, P.; Vittone, E.; Picollo, F.

    2015-01-14

    In this work, we present an investigation by Kelvin Probe Microscopy (KPM) of buried graphitic microchannels fabricated in single-crystal diamond by direct MeV ion microbeam writing. Metal deposition of variable-thickness masks was adopted to implant channels with emerging endpoints and high temperature annealing was performed in order to induce the graphitization of the highly-damaged buried region. When an electrical current was flowing through the biased buried channel, the structure was clearly evidenced by KPM maps of the electrical potential of the surface region overlying the channel at increasing distances from the grounded electrode. The KPM profiling shows regions of opposite contrast located at different distances from the endpoints of the channel. This effect is attributed to the different electrical conduction properties of the surface and of the buried graphitic layer. The model adopted to interpret these KPM maps and profiles proved to be suitable for the electronic characterization of buried conductive channels, providing a non-invasive method to measure the local resistivity with a micrometer resolution. The results demonstrate the potential of the technique as a powerful diagnostic tool to monitor the functionality of all-carbon graphite/diamond devices to be fabricated by MeV ion beam lithography.

  13. Oxidation of methanol on single crystal platinum electrodes in alkaline solution

    SciTech Connect (OSTI)

    Tripkovic, A.V.; Marinkovic, N.; Adzic, R.R.

    1995-10-01

    Methanol oxidation has been studied on three low-index single crystal Pt electrodes and four stepped surfaces, vicinal to the (111) and (100) orientations in alkaline solutions. Considering the onset of the reaction, it appears that the activity decreases in the sequence Pt(100), Pt(110) and Pt(111). This can also be inferred from the quasi-steady-state measurements. The current peaks, observed at different potentials, show the highest activity of Pt(111). The steps cause increase of the surface activity, but are prone to a fast poisoning. The reaction involves a formation of a small amount of CO on Pt(100) but a negligible amount on Pt(111). This was inferred from the in situ FTIR measurements. Two different reaction mechanisms were identified for the Pt(111) and Pt(100). The data clearly show that a large difference of the activity of Pt for methanol oxidation in acid and alkaline solutions originates in a smaller or negligible poisoning effects in alkaline solutions.

  14. Strength statistics of single crystals and metallic glasses under small stressed volumes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gao, Yanfei; Bei, Hongbin

    2016-05-13

    It has been well documented that plastic deformation of crystalline and amorphous metals/alloys shows a general trend of “smaller is stronger”. The majority of the experimental and modeling studies along this line have been focused on finding and reasoning the scaling slope or exponent in the logarithmic plot of strength versus size. In contrast to this view, here we show that the universal picture should be the thermally activated nucleation mechanisms in small stressed volume, the stochastic behavior as to find the weakest links in intermediate sizes of the stressed volume, and the convolution of these two mechanisms with respectmore » to variables such as indenter radius in nanoindentation pop-in, crystallographic orientation, pre-strain level, sample length as in uniaxial tests, and others. Furthermore, experiments that cover the entire spectrum of length scales and a unified model that treats both thermal activation and spatial stochasticity have discovered new perspectives in understanding and correlating the strength statistics in a vast of observations in nanoindentation, micro-pillar compression, and fiber/whisker tension tests of single crystals and metallic glasses.« less

  15. Evaluation of scuffing behavior of single-crystal zirconia ceramic materials.

    SciTech Connect (OSTI)

    Lorenzo-Martin, C.; Ajayi, O. O.; Singh, D.; Routbort, J. L.; Energy Systems

    2007-09-10

    Scuffing, described as sudden catastrophic failure of lubricated sliding surfaces, is usually characterized by a sudden rapid increase in friction, temperature, and noise, and is an important failure mode on sliding surfaces. In metallic materials, scuffing results in severe plastic deformation of surfaces in contact. This study evaluated the scuffing behavior of two variants of zirconia (ZrO{sub 2}) ceramic. Using a block-on-ring contact configuration and unformulated polyalphaolefin (PAO) lubricant, step-load-increase scuffing tests were conducted with single crystals of cubic ZrO{sub 2}-9.5% Y{sub 2}O{sub 3} and tetragonal ZrO{sub 2}-3% Y{sub 2}O{sub 3}. Phenomenological 'scuffing', characterized by a sudden rise in friction coefficient and noise, was observed in the cubic material. For this material, 'scuffing' occurred by sudden fracture at the end of test. The tetragonal material underwent no sudden failure (scuffing). This lack of scuffing is attributed to the sequential operation of three plastic deformation mechanisms: ferroelastic domain switching, tetragonal-to-monoclinic phase transformation, and dislocation slip as the frictional stress and energy dissipation pathway.

  16. Elastic-plastic and phase transition of zinc oxide single crystal under shock compression

    SciTech Connect (OSTI)

    Liu, Xun; Mashimo, Tsutomu Li, Wei; Zhou, Xianming; Sekine, Toshimori

    2015-03-07

    The Hugoniot data for zinc oxide (ZnO) single crystals were measured up to 80 GPa along both the 〈112{sup ¯}0〉 (a-axis) and 〈0001〉 (c-axis) directions using a velocity interferometer system for any reflector and inclined-mirror method combined with a powder gun and two-stage light gas gun. The Hugoniot-elastic limits of ZnO were determined to be 10.5 and 11.5 GPa along the a- and c-axes, respectively. The wurtzite (B4) to rocksalt (B1) phase transition pressures along the a- and c-axes are 12.3 and 14.4 GPa, respectively. Shock velocity (U{sub s}) versus particle velocity (U{sub p}) relation of the final phase is given by the following relationship: U{sub s} (km/s) = 2.76 + 1.51U{sub p} (km/s). Based on the Debye-Grüneisen model and Birch-Murnaghan equation of state (EOS), we discuss the EOS of the B1 phase ZnO. The bulk modulus (K{sub 0}) and its pressure derivative (K{sub 0}′) are estimated to be K{sub 0} = 174 GPa and K{sub 0}′ = 3.9, respectively.

  17. Terahertz probes of magnetic field induced spin reorientation in YFeO{sub 3} single crystal

    SciTech Connect (OSTI)

    Lin, Xian; Jiang, Junjie; Ma, Guohong; Jin, Zuanming; Wang, Dongyang; Tian, Zhen; Han, Jiaguang; Cheng, Zhenxiang

    2015-03-02

    Using the terahertz time-domain spectroscopy, we demonstrate the spin reorientation of a canted antiferromagnetic YFeO{sub 3} single crystal, by evaluating the temperature and magnetic field dependence of resonant frequency and amplitude for the quasi-ferromagnetic (FM) and quasi-antiferromagnetic modes (AFM), a deeper insight into the dynamics of spin reorientation in rare-earth orthoferrites is established. Due to the absence of 4f-electrons in Y ion, the spin reorientation of Fe sublattices can only be induced by the applied magnetic field, rather than temperature. In agreement with the theoretical predication, the frequency of FM mode decreases with magnetic field. In addition, an obvious step of spin reorientation phase transition occurs with a relatively large applied magnetic field of 4 T. By comparison with the family members of RFeO{sub 3} (R = Y{sup 3+} or rare-earth ions), our results suggest that the chosen of R would tailor the dynamical rotation properties of Fe ions, leading to the designable spin switching in the orthoferrite antiferromagnetic systems.

  18. Anisotropic small-polaron hopping in W:BiVO{sub 4} single crystals

    SciTech Connect (OSTI)

    Rettie, Alexander J. E.; Chemelewski, William D.; Zhou, Jianshi; Lindemuth, Jeffrey; McCloy, John S.; Marshall, Luke G.; Emin, David; Mullins, C. Buddie

    2015-01-12

    DC electrical conductivity, Seebeck and Hall coefficients are measured between 300 and 450 K on single crystals of monoclinic bismuth vanadate that are doped n-type with 0.3% tungsten donors (W:BiVO{sub 4}). Strongly activated small-polaron hopping is implied by the activation energies of the Arrhenius conductivities (about 300 meV) greatly exceeding the energies characterizing the falls of the Seebeck coefficients' magnitudes with increasing temperature (about 50 meV). Small-polaron hopping is further evidenced by the measured Hall mobility in the ab-plane (10{sup −1 }cm{sup 2 }V{sup −1 }s{sup −1} at 300 K) being larger and much less strongly activated than the deduced drift mobility (about 5 × 10{sup −5 }cm{sup 2 }V{sup −1 }s{sup −1} at 300 K). The conductivity and n-type Seebeck coefficient is found to be anisotropic with the conductivity larger and the Seebeck coefficient's magnitude smaller and less temperature dependent for motion within the ab-plane than that in the c-direction. These anisotropies are addressed by considering highly anisotropic next-nearest-neighbor (≈5 Å) transfers in addition to the somewhat shorter (≈4 Å), nearly isotropic nearest-neighbor transfers.

  19. Application of ITO/Al reflectors for increasing the efficiency of single-crystal silicon solar cells

    SciTech Connect (OSTI)

    Kopach, V. R.; Kirichenko, M. V. Khrypunov, G. S.; Zaitsev, R. V.

    2010-06-15

    It is shown that an increase in the efficiency and manufacturability of single-junction single-crystal silicon photoelectric converters of solar energy requires the use of a back-surface reflector based on conductive transparent indium-tin oxide (ITO) 0.25-2 {mu}m thick. To increase the efficiency and reduce the sensitivity to the angle of light incidence on the photoreceiving surface of multijunction photoelectric converters with vertical diode cells based on single-crystal silicon, ITO/Al reflectors with an ITO layer >1 {mu}m thick along vertical boundaries of diode cells should be fabricated. The experimental study of multijunction photoelectric converters with ITO/Al reflectors at diode cell boundaries shows the necessity of modernizing the used technology of ITO layers to achieve their theoretically calculated thickness.

  20. Preparation and structural characterization of FeCo epitaxial thin films on insulating single-crystal substrates

    SciTech Connect (OSTI)

    Nishiyama, Tsutomu; Ohtake, Mitsuru; Futamoto, Masaaki; Kirino, Fumiyoshi

    2010-05-15

    FeCo epitaxial films were prepared on MgO(111), SrTiO{sub 3}(111), and Al{sub 2}O{sub 3}(0001) single-crystal substrates by ultrahigh vacuum molecular beam epitaxy. The effects of insulating substrate material on the film growth process and the structures were investigated. FeCo(110){sub bcc} films grow on MgO substrates with two type domains, Nishiyama-Wassermann (NW) and Kurdjumov-Sachs (KS) relationships. On the contrary, FeCo films grown on SrTiO{sub 3} and Al{sub 2}O{sub 3} substrates include FeCo(111){sub bcc} crystal in addition to the FeCo(110){sub bcc} crystals with NW and KS relationships. The FeCo(111){sub bcc} crystal consists of two type domains whose orientations are rotated around the film normal by 180 deg. each other. The out-of-plane and the in-plane lattice spacings of FeCo(110){sub bcc} and FeCo(111){sub bcc} crystals formed on the insulating substrates are in agreement with those of the bulk Fe{sub 50}Co{sub 50} (at. %) crystal with small errors ranging between +0.2% and +0.4%, showing that the strains in the epitaxial films are very small.

  1. The polarization trajectory of terahertz magnetic dipole radiation in (110)-oriented PrFeO{sub 3} single crystal

    SciTech Connect (OSTI)

    Song, Gaibei; Jin, Zuanming; Lin, Xian; Jiang, Junjie; Wang, Xinyan; Wu, Hailong; Ma, Guohong E-mail: sxcao@shu.edu.cn; Cao, Shixun E-mail: sxcao@shu.edu.cn

    2014-04-28

    By using the polarized terahertz (THz) time-domain spectroscopy, the macro-magnetization motion in (110)-oriented PrFeO{sub 3} single crystal was constructed. We emphasize that the trajectory of the emitted THz waveforms relies on not only the motion of macroscopic magnetization vector, but also the spin configuration in the ground state and the propagation of THz pulse. The azimuthal angle (the incident THz pulse polarization with respect to the crystal axes) enables us to control the polarization trajectories of the quasiferromagnetic and quasiantiferromagnetic mode radiations that can lead to further applications on multiple information storing and quantum processing.

  2. Method of bonding single crystal quartz by field-assisted bonding

    DOE Patents [OSTI]

    Curlee, Richard M.; Tuthill, Clinton D.; Watkins, Randall D.

    1991-01-01

    The method of producing a hermetic stable structural bond between quartz crystals includes providing first and second quartz crystals and depositing thin films of borosilicate glass and silicon on portions of the first and second crystals, respectively. The portions of the first and second crystals are then juxtaposed in a surface contact relationship and heated to a temperature for a period sufficient to cause the glass and silicon films to become electrically conductive. An electrical potential is then applied across the first and second crystals for creating an electrostatic field between the adjoining surfaces and causing the juxtaposed portions to be attracted into an intimate contact and form a bond for joining the adjoining surfaces of the crystals.

  3. Method of bonding single crystal quartz by field-assisted bonding

    DOE Patents [OSTI]

    Curlee, R.M.; Tuthill, C.D.; Watkins, R.D.

    1991-04-23

    The method of producing a hermetic stable structural bond between quartz crystals includes providing first and second quartz crystals and depositing thin films of borosilicate glass and silicon on portions of the first and second crystals, respectively. The portions of the first and second crystals are then juxtaposed in a surface contact relationship and heated to a temperature for a period sufficient to cause the glass and silicon films to become electrically conductive. An electrical potential is then applied across the first and second crystals for creating an electrostatic field between the adjoining surfaces and causing the juxtaposed portions to be attracted into an intimate contact and form a bond for joining the adjoining surfaces of the crystals. 2 figures.

  4. Intercalation of organic molecules into SnS{sub 2} single crystals

    SciTech Connect (OSTI)

    Toh, M.L.; Tan, K.J.; Wei, F.X.; Zhang, K.K.; Jiang, H.; Kloc, C.

    2013-02-15

    SnS{sub 2} is a layered semiconductor with a van der Waals gap separating the covalently bonded layers. In this study, post-synthesis intercalation of donor organic amine molecules, such as ethylenediamine (en), into tin disulfide and secondary intercalation of p-phenylenediamine (PPD) and 1, 5-naphthalenediamine (NDA) into SnS{sub 2e}n have been verified with X-ray diffraction. PPD and NDA did not intercalate directly even during prolonged annealing but replaced en readily if en was already present in the van der Waals gap. The c-lattice dilation is proportional to the intercalant size. Unit cell lattices of intercalated products were determined from the positions of the X-ray diffraction peaks. Optical images taken during the intercalation showed that intercalation progressed from the periphery towards the interior of the crystal. TEM diffraction patterns in the [0 0 1] direction of SnS{sub 2} after intercalation revealed defects and stacking mismatches among the SnS{sub 2} layers caused by the intercalation. UV-Vis absorption studies showed a red shift in the band edge of the SnS{sub 2} material after intercalation. The band edge was 2.2 eV for pristine SnS{sub 2}; after intercalation with en or PPD, the absorbance spectra band edges shifted to approximately 0.7 eV or 0.5 eV, respectively. - Graphical Abstract: SnS{sub 2} single crystals were intercalated with organic amine molecules such as ethylenediamine, phenylenediamine and naphthalenediamine. Absorption studies showed red shift of band edge after intercalation, which was consistent with optical observations. X-ray diffraction indicated lattice dilation in the c-lattice of SnS{sub 2} after intercalation. Highlights: Black-Right-Pointing-Pointer Organic molecules intercalated inhomogenously between covalently bonded SnS{sub 2} layers. Black-Right-Pointing-Pointer Ethylenediamine (en) intercalate directly into SnS{sub 2}. Black-Right-Pointing-Pointer Phenylenediamine (PPD) and naphthalenediamine (NDA) can be

  5. Crystallographic, electronic, thermal, and magnetic properties of single-crystal SrCo2As2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Pandey, Abhishek; Quirinale, D. G.; Jayasekara, W.; Sapkota, A.; Kim, M. G.; Dhaka, R. S.; Lee, Y.; Heitmann, T. W.; Stephens, P. W.; Ogloblichev, V.; et al

    2013-07-01

    In tetragonal SrCo2As2 single crystals, inelastic neutron scattering measurements demonstrated that strong stripe-type antiferromagnetic (AFM) correlations occur at a temperature T = 5 K [W. Jayasekara et al., arXiv:1306.5174] that are the same as in the isostructural AFe2As2 (A = Ca, Sr, Ba) parent compounds of high-Tc superconductors. This surprising discovery suggests that SrCo2As2 may also be a good parent compound for high-Tc superconductivity. Here, structural and thermal expansion, electrical resistivity ρ, angle-resolved photoemission spectroscopy (ARPES), heat capacity Cp, magnetic susceptibility χ, 75As NMR and neutron diffraction measurements of SrCo2As2 crystals are reported together with LDA band structure calculations thatmore » shed further light on this fascinating material. The c-axis thermal expansion coefficient αc is negative from 7 to 300 K, whereas αa is positive over this T range. The ρ(T) shows metallic character. The ARPES measurements and band theory confirm the metallic character and in addition show the presence of a flat band near the Fermi energy EF. The band calculations exhibit an extremely sharp peak in the density of states D(EF) arising from a flat dx2-y2 band. A comparison of the Sommerfeld coefficient of the electronic specific heat with χ(T → 0) suggests the presence of strong ferromagnetic itinerant spin correlations which on the basis of the Stoner criterion predicts that SrCo2As2 should be an itinerant ferromagnet, in conflict with the magnetization data. The χ(T) does have a large magnitude, but also exhibits a broad maximum at 115 K suggestive of dynamic short-range AFM spin correlations, in agreement with the neutron scattering data. The measurements show no evidence for any type of phase transition between 1.3 and 300 K and we propose that metallic SrCo2As2 has a gapless quantum spin-liquid ground state.« less

  6. Thermal oxidation of single crystal aluminum antimonide and materials having the same

    DOE Patents [OSTI]

    Sherohman, John William; Yee, Jick Hong; Coombs, III, Arthur William; Wu, Kuang Jen J.

    2012-12-25

    In one embodiment, a method for forming a non-conductive crystalline oxide layer on an AlSb crystal includes heat treating an AlSb crystal in a partial vacuum atmosphere at a temperature conducive for air adsorbed molecules to desorb, surface molecule groups to decompose, and elemental Sb to evaporate from a surface of the AlSb crystal and exposing the AlSb crystal to an atmosphere comprising oxygen to form a crystalline oxide layer on the surface of the AlSb crystal. In another embodiment, a method for forming a non-conductive crystalline oxide layer on an AlSb crystal includes heat treating an AlSb crystal in a non-oxidizing atmosphere at a temperature conducive for decomposition of an amorphous oxidized surface layer and evaporation of elemental Sb from the AlSb crystal surface and forming stable oxides of Al and Sb from residual surface oxygen to form a crystalline oxide layer on the surface of the AlSb crystal.

  7. Investigation on growth and laser properties of GGG:(Nd,Cr) single crystals

    SciTech Connect (OSTI)

    Zhang; Lin; Liu; Liu; Zhu

    1986-04-04

    Investigation on the growth and laser properties of gadolinium gallium garnet crystal doped with neodymium and chromium is reported. As the segregation coefficient of Nd in GGG is less than 1 and that of Cr is greater than 1, a modified Czochralski method for growth is adopted in order to keep the dopants being uniform in the grown crystal.

  8. Possible applications of the steering of charged particles by bent single crystals

    SciTech Connect (OSTI)

    Carrigan, R.A. Jr.; Gibson, W.M.; Sun, C.R.; Tsyganov, E.N.

    1981-01-01

    This article reviews some aspects of the steering of charged particles using channeling in bent crystals. Crystal angular and spatial acceptance, deflection dechanneling, and radiation damage are discussed. Examples of possible bent transport, focusing, the possibility of charm particle separated beams, and magnetic moment determination.

  9. Experimental and theoretical investigations of non-centrosymmetric 8-hydroxyquinolinium dibenzoyl-(L)-tartrate methanol monohydrate single crystal

    SciTech Connect (OSTI)

    Sudharsana, N.; Krishnakumar, V.; Nagalakshmi, R.

    2015-01-15

    Graphical abstract: ORTEP diagram of HQDBT. - Highlights: • Single crystal XRD and NMR studies confirm the formation of the title compound. • SHG efficiency was found to be 0.6 times that of KDP. • First-order hyperpolarizability (β) was calculated using HF and B3LYP methods. - Abstract: A novel 8-hydroxyquinolinium dibenzoyl-(L)-tartrate methanol monohydrate crystal has been grown by slow evaporation technique. The single crystal X-ray diffraction analysis has been done for the title compound and is found to crystallize in orthorhombic space group P2{sub 1}2{sub 1}2{sub 1}. The optical absorption cut-off wavelength is found to be 440 nm. The vibrational analysis has been carried out to assess the functional groups present in the title compound. The molecular structure of the title compound has been confirmed by nuclear magnetic resonance spectroscopy. Thermogravimetric, differential scanning calorimetric and differential thermal analyses reveal the melting point and thermal stability of the title compound. The second harmonic generation efficiency is confirmed by Kurtz–Perry powder technique. Further quantum chemical calculations are performed using Gaussian 03 software.

  10. Large single crystal quaternary alloys of IB-IIIA-SE.sub.2 and methods of synthesizing the same

    DOE Patents [OSTI]

    Ciszek, Theodore F.

    1988-01-01

    New alloys of Cu.sub.x Ag.sub.(1-x) InSe.sub.2 (where x ranges between 0 and 1 and preferably has a value of about 0.75) and CuIn.sub.y Ga.sub.(1-y) Se.sub.2 (where y ranges between 0 and 1 and preferably has a value of about 0.90) in the form of single crystals with enhanced structure perfection, which crystals are substantially free of fissures are disclosed. Processes are disclosed for preparing the new alloys of Cu.sub.x Ag.sub.(1-x) InSe.sub.2. The process includes placing stoichiometric quantities of a Cu, Ag, In, and Se reaction mixture or stoichiometric quantities of a Cu, In, Ga, and Se reaction mixture in a refractory crucible in such a manner that the reaction mixture is surrounded by B.sub.2 O.sub.3, placing the thus loaded crucible in a chamber under a high pressure atmosphere of inert gas to confine the volatile Se to the crucible, and heating the reaction mixture to its melting point. The melt can then be cooled slowly to form, by direct solidification, a single crystal with enhanced structure perfection, which crystal is substantially free of fissures.

  11. Large single crystal quaternary alloys of IB-IIIA-Se/sub 2/ and methods of synthesizing the same

    DOE Patents [OSTI]

    Ciszek, T.F.

    1986-07-15

    New alloys of Cu/sub x/Ag/sub (1-x)/InSe/sub 2/ (where x ranges between 0 and 1 and preferably has a value of about 0.75) and CuIn/sub y/Ga/sub (1-y)/Se/sub 2/ (where y ranges between 0 and 1 and preferably has a value of about 0.90) in the form of single crystals with enhanced structure perfection, which crystals are substantially free of fissures, are disclosed. Processes are disclosed for preparing the new alloys of Cu/sub x/Ag/sub (1-x)/InSe/sub 2/. The process includes placing stoichiometric quantities of a Cu, Ag, In, and Se reaction mixture or stoichiometric quantities of a Cu, In, Ga, and Se reaction mixture in a refractory crucible in such a manner that the reaction mixture is surrounded by B/sub 2/O/sub 3/, placing the thus loaded crucible in a chamber under a high pressure atmosphere of inert gas to confine the volatile Se to the crucible, and heating the reaction mixture to its melting point. The melt can then be cooled slowly to form, by direct solidification, a single crystal with enhanced structure perfection, which crystal is substantially free of fissures.

  12. Optimization of Weld Conditions and Alloy Composition for Welding of Single-Crystal Nickel-Based Superalloys

    SciTech Connect (OSTI)

    Vitek, John Michael; David, Stan A; Babu, Sudarsanam S

    2007-01-01

    Calculations were carried out to identify optimum welding conditions and weld alloy compositions to avoid stray grain formation during welding of single-crystal nickel-based superalloys. The calculations were performed using a combination of three models: a thermal model to describe the weld pool shape and the local thermal gradient and solidification front velocity; a geometric model to identify the local active dendrite growth variant, and a nucleation and growth model to describe the extent of stray grain formation ahead of the advancing solidification front. Optimum welding conditions (low weld power, high weld speed) were identified from the model calculations. Additional calculations were made to determine potential alloy modifications that reduce the solidification temperature range while maintaining high gamma prime content. The combination of optimum weld conditions and alloy compositions should allow for weld repair of single-crystal nickel-based superalloys without sacrificing properties or performance.

  13. Growth of single-crystal {alpha}-MnO{sub 2} nanorods on multi-walled carbon nanotubes

    SciTech Connect (OSTI)

    Chen Yong; Liu Chenguang; Liu Chang; Lu Gaoqing; Cheng Huiming

    2007-11-06

    Single-crystal {alpha}-MnO{sub 2} nanorods were grown on multi-walled carbon nanotubes (MWNTs) in H{sub 2}SO{sub 4} aqueous solution. The morphology and microstructure of the composites were examined by transmission electron microscopy, high-resolution transmission electron microscopy (HRTEM), X-ray diffractometry and energy dispersive spectroscopy (EDS). The results show that {alpha}-MnO{sub 2} single-crystal nanorods with a mean diameter of 15 nm were densely grown on the surface of MWNTs. Those MWNTs/MnO{sub 2} composites were used as an electrode material for supercapacitors, and it was found that the supercapacitor performance using MWNTs/MnO{sub 2} composites was improved largely compared to that using pure MWNTs and {alpha}-MnO{sub 2} nanorod mechanically mixed with MWNTs.

  14. On the Chemistry and Physical Properties of Flux and Floating Zone Grown SmB6 Single Crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Phelan, W. A.; Koohpayeh, S. M.; Cottingham, P.; Tutmaher, J. A.; Leiner, J. C.; Lumsden, M. D.; Lavelle, C. M.; Wang, X. P.; Hoffmann, C.; Siegler, M. A.; et al

    2016-02-19

    Recent theoretical and experimental findings suggest the long-known but not well understood low temperature resistance plateau of SmB6 may originate from protected surface states arising from a topologically non-trivial bulk band structure having strong Kondo hybridization. Yet others have ascribed this feature to impurities, vacancies, and surface reconstructions. Given the typical methods used to prepare SmB6 single crystals, flux and floating-zone procedures, such ascriptions should not be taken lightly. We demonstrate how compositional variations and/or observable amounts of impurities in SmB6 crystals grown using both procedures affect the physical properties. From X-ray diffraction, neutron diffraction, and X-ray computed tomography experimentsmore » we observe that natural isotope containing (SmB6) and doubly isotope enriched (154Sm11B6) crystals prepared using aluminum flux contain co-crystallized, epitaxial aluminum. Further, a large, nearly stoichiometric crystal of SmB6 was successfully grown using the float-zone technique; upon continuing the zone melting, samarium vacancies were introduced. These samarium vacancies drastically alter the resistance and plateauing magnitude of the low temperature resistance compared to stoichiometric SmB6. Finally, these results highlight that impurities and compositional variations, even at low concentrations, must be considered when collecting/analyzing physical property data of SmB6. Finally, a more accurate samarium-154 coherent neutron scattering length, 8.9(1) fm, is reported.« less

  15. Evidence for graphite-like hexagonal AlN nanosheets epitaxially grown on single crystal Ag(111)

    SciTech Connect (OSTI)

    Tsipas, P.; Kassavetis, S.; Tsoutsou, D.; Xenogiannopoulou, E.; Golias, E.; Giamini, S. A.; Dimoulas, A.; Grazianetti, C.; Fanciulli, M.; Dipartimento di Scienza dei Materiali, Universit degli Studi di Milano Bicocca, I-20126, Milano ; Chiappe, D.; Molle, A.

    2013-12-16

    Ultrathin (sub-monolayer to 12 monolayers) AlN nanosheets are grown epitaxially by plasma assisted molecular beam epitaxy on Ag(111) single crystals. Electron diffraction and scanning tunneling microscopy provide evidence that AlN on Ag adopts a graphite-like hexagonal structure with a larger lattice constant compared to bulk-like wurtzite AlN. This claim is further supported by ultraviolet photoelectron spectroscopy indicating a reduced energy bandgap as expected for hexagonal AlN.

  16. Thermal-mechanical stability of single crystal oxide refractive concentrators for high-temperature solar thermal propulsion

    SciTech Connect (OSTI)

    Zhu, D.; Jacobson, S.; Miller, R.A.

    1999-07-01

    Single crystal oxides such as yttria-stabilized zirconia (Y{sub 2}O{sub 3}-ZrO{sub 2}), yttrium aluminum garnet (Y{sub 3}Al{sub 5}O{sub 12}, or YAG), magnesium oxide (MgO) and sapphire (Al{sub 2}O{sub 3}) are candidate refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermo-mechanical reliability of these components in severe thermal environments during the space mission sun/shade transition is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions, and thus provide vital information for the component design. In this paper, a controlled heat flux thermal shock test approach is established for the single crystal oxide materials using a 3.0 kW continuous wave CO{sub 2} laser, with a wavelength 10.6 micron. Thermal fracture behavior and failure mechanisms of these oxide materials are investigated and critical temperature gradients are determined under various temperature and heating conditions. The test results show that single crystal sapphire is able to sustain the highest temperature gradient and heating-cooling rate, and thus exhibit the best thermal shock resistance, as compared to the yttria-stabilized zirconia, yttrium aluminum garnet and magnesium oxide.

  17. Investigations on spectral and dielectric properties of semi-organic single crystal – morpholinium nitrate

    SciTech Connect (OSTI)

    Arul, H.; Babu, D. Rajan Vizhi, R. Ezhil

    2015-06-24

    Semi organic nonlinear optical crystal Morpholinium nitrate (MN) was synthesized and subsequently grown from the solution by slow evaporation method. The sample has been subjected to powder X-ray diffraction to identify the crystalline nature and the prominent peaks were indexed. The crystal belongs to the monoclinic system with a space group P2{sub 1}/C. Carbon NMR analysis confirms the presence of carbon in the structure of the title compound. Dielectric studies have been carried out on the grown crystal as a function of frequencies at different temperatures. Dielectric constant, dielectric loss and AC conductivity were also calculated.

  18. Effect of ultrasound on the growth striation and electrical properties of Ga{sub 0.03}In{sub 0.97}Sb single crystals

    SciTech Connect (OSTI)

    Kozhemyakin, G. N. Zolkina, L. V.; Rom, M. A.

    2008-12-15

    The growth striation of impurity segregation and electrical properties of Ga{sub 0.03}In{sub 0.97}Sb single crystals grown by the Czochralski method in an ultrasonic field have been investigated. It is established that ultrasonic irradiation of the melt during growth significantly decreases the growth striation (in particular, it eliminates striations spaced at a distance of more than 14 {mu}m). The Ga{sub 0.03}In{sub 0.97}Sb single crystals grown in an ultrasonic field had a higher charge-carrier mobility and thermoelectric power in comparison with the single crystals grown without ultrasound.

  19. TH-C-19A-06: Measurements with a New Commercial Synthetic Single Crystal Diamond Detector

    SciTech Connect (OSTI)

    Laub, W; Crilly, R

    2014-06-15

    Purpose: A commercial version of a synthetic single crystal diamond detector in a Scottky diode configuration was recently released as the new type 60019 microDiamond detector (PTW-Freiburg). In this study we investigate the dosimetric properties of this detector and explore if the use of the microDiamond detector can be expanded to high energy photon beams of up to 15MV and to large field measurements. Methods: Energy dependency was investigated. Photon and electron depth-dose curves were measured. Photon PDDs were measured with the Semiflex type 31010, microLion type 31018, P-Diode type 60016, SRS Diode type 60018, and the microDiamond type 60019 detector. Electron depth-dose curves were measured with a Markus chamber type 23343, an E Diode type 60017 and the microDiamond type 60019 detector (all PTW-Freiburg). Profiles were measured with the E-Diode and microDiamond at dose maximum depths. Results: The microDiamond detector shows no energy dependence in high energy photon or electron dosimetry. Electron PDD measurements with the E-Diode and microDiamond are in good agreement except for the bremsstrahlungs region, where values are about 0.5 % lower with the microDiamond detector. Markus detector measurements agree with E-Diode measurements in this region. For depths larger than dmax, depth-dose curves of photon beams measured with the microDiamond detector are in close agreement to those measured with the microLion detector for small fields and with those measured with a Semiflex 0.125cc ionization chamber for large fields. For profile measurements, microDiamond detector measurements agree well with microLion and P-Diode measurements in the high-dose region and the penumbra region. For areas outside the open field, P-Diode measurements are about 0.5–1.0% higher than microDiamond and microLion measurements. Conclusion: The investigated diamond detector is suitable for a wide range of applications in high energy photon and electron dosimetry and is interesting

  20. Electrical properties of In{sub 2}Se{sub 3} single crystals and photosensitivity of Al/In{sub 2}Se{sub 3} Schottky barriers

    SciTech Connect (OSTI)

    Bodnar, I. V.; Ilchuk, G. A.; Petrus', R. Yu.; Rud', V. Yu.; Rud', Yu. V.; Serginov, M.

    2009-09-15

    In{sub 2}Se{sub 3} single crystals {approx}40 mm long and 14 mm in diameter were grown by the Bridgman method. The composition of grown single crystals and their crystal structure were determined. The conductivity ({sigma}) and Hall constant (R) of grown single crystals were measured and the first Schottky barriers Al/n-In{sub 2}Se{sub 3} were fabricated. Rectification and photovoltaic effect were detected in the new structures. Based on the study of the photosensitivity spectra of Al/n-In{sub 2}Se{sub 3} structures, the nature of the interband transitions and band gap of In{sub 2}Se{sub 3} crystals were determined. It was concluded that the new structures can be applied to develop broadband photoconverters of optical radiation.

  1. Orientation epitaxy of Ge1–xSnx films grown on single crystal CaF2 substrates

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    A. J. Littlejohn; Zhang, L. H.; Lu, T. -M.; Kisslinger, K.; and Wang, G. -C.

    2016-03-15

    Ge1–xSnx films were grown via physical vapor deposition below the crystallization temperature of Ge on single crystal (111) and (100) CaF2 substrates to assess the role of Sn alloying in Ge crystallization. By studying samples grown at several growth temperatures ranging from 250 °C to 400 °C we report temperature-dependent trends in several of the films' properties. X-ray diffraction theta vs. two-theta (θ/2θ) scans indicate single orientation Ge1–xSnx(111) films are grown on CaF2(111) substrates at each temperature, while a temperature-dependent superposition of (111) and (100) orientations are exhibited in films grown on CaF2(100) above 250 °C. This is the firstmore » report of (111) oriented Ge1–xSnx grown on a (100) oriented CaF2 substrate, which is successfully predicted by a superlattice area matching model. These results are confirmed by X-ray diffraction pole figure analysis. θ/2θ results indicate substitutional Sn alloying in each film of about 5%, corroborated by energy dispersive spectroscopy. In addition, morphological and electrical properties are measured by scanning electron microscopy, atomic force microscopy and Hall mobility measurements and are also shown to be dependent upon growth temperature.« less

  2. Insulating and metallic spin glass in Ni-doped KxFe2-ySe₂ single crystals

    SciTech Connect (OSTI)

    Ryu, H.; Abeykoon, M.; Wang, K.; Lei, H.; Lazarevic, N.; Warren, J.; Bozin, E.; Popovic, Z.; Petrovic, C.

    2015-05-04

    Electron doping effects by Ni in KxFe2-δ-yNiySe₂ (0.06 ≤ y ≤ 1.44) single-crystal alloys are reported.

  3. Insulating and metallic spin glass in Ni-doped KxFe2-ySe? single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ryu, Hyejin; Abeykoon, Milinda; Wang, Kefeng; Lei, Hechang; Lazarevic, N.; Warren, J. B.; Bozin, E. S.; Popovic, Z. V.; Petrovic, C.

    2015-05-04

    We report electron doping effects by Ni in KxFe2-?-yNiySe? (0.06 ? y ? 1.44) single crystal alloys. A rich ground state phase diagram is observed. A small amount of Ni (~ 4%) suppressed superconductivity below 1.8 K, inducing insulating spin glass magnetic ground state for higher Ni content. With further Ni substitution, metallic resistivity is restored. For high Ni concentration in the lattice the unit cell symmetry is high symmetry I4/mmm with no phase separation whereas both I4/m + I4/mmm space groups were detected in the phase separated crystals when concentration of Ni morewith the absence of crystalline Fe vacancy order.less

  4. Insulating and metallic spin glass in Ni-doped K x Fe 2 - y Se 2 single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ryu, Hyejin; Abeykoon, Milinda; Wang, Kefeng; Lei, Hechang; Lazarevic, N.; Warren, J. B.; Bozin, E. S.; Popovic, Z. V.; Petrovic, C.

    2015-05-04

    We report electron doping effects by Ni in KxFe2-δ-yNiySe₂(0.06≤y≤1.44) single-crystal alloys. A rich ground-state phase diagram is observed. A small amount of Ni (~4%) suppressed superconductivity below 1.8 K, inducing insulating spin-glass magnetic ground state for higher Ni content. With further Ni substitution, metallic resistivity is restored. For high Ni concentration in the lattice the unit cell symmetry is high symmetry I4/mmm with no phase separation whereas both I4/m+I4/mmm space groups were detected in the phase separated crystals when concentration of Ni < Fe. The absence of superconductivity coincides with the absence of crystalline Fe vacancy order.

  5. Growth of large aluminum nitride single crystals with thermal-gradient control

    DOE Patents [OSTI]

    Bondokov, Robert T; Rao, Shailaja P; Gibb, Shawn Robert; Schowalter, Leo J

    2015-05-12

    In various embodiments, non-zero thermal gradients are formed within a growth chamber both substantially parallel and substantially perpendicular to the growth direction during formation of semiconductor crystals, where the ratio of the two thermal gradients (parallel to perpendicular) is less than 10, by, e.g., arrangement of thermal shields outside of the growth chamber.

  6. Structural characterization of metastable hcp-Ni thin films epitaxially grown on Au(100) single-crystal underlayers

    SciTech Connect (OSTI)

    Ohtake, Mitsuru; Tanaka, Takahiro; Futamoto, Masaaki; Kirino, Fumiyoshi

    2010-05-15

    Ni(1120) epitaxial thin films with hcp structure were prepared on Au(100) single-crystal underlayers at 100 deg. C by ultra high vacuum molecular beam epitaxy. The detailed film structure is studied by in situ reflection high energy electron diffraction, x-ray diffraction, and transmission electron microscopy. The hcp-Ni film consists of two types of variants whose c-axes are rotated around the film normal by 90 deg. each other. An atomically sharp boundary is recognized between the film and the underlayer, where misfit dislocations are introduced. Presence of such dislocations seems to relieve the strain caused by the lattice mismatch between the film and the underlayer.

  7. Surface structure determinations of crystalline ionic thin films grown on transition metal single crystal surfaces by low energy electron diffraction

    SciTech Connect (OSTI)

    Roberts, J.G.

    2000-05-01

    The surface structures of NaCl(100), LiF(100) and alpha-MgCl2(0001) adsorbed on various metal single crystals have been determined by low energy electron diffraction (LEED). Thin films of these salts were grown on metal substrates by exposing the heated metal surface to a molecular flux of salt emitted from a Knudsen cell. This method of investigating thin films of insulators (ionic salts) on a conducting substrate (metal) circumvents surface charging problems that plagued bulk studies, thereby allowing the use of electron-based techniques to characterize the surface.

  8. An electron microscopy study of dislocation structures in Mg single crystals compressed along [0 0 0 1] at room temperature

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kumar, K. S.; Chisholm, Matthew F.; Geng, J.; Mishra, R. K.

    2016-01-09

    We compressed Mg single crystals along [0 0 0 1] at room temperature to various stress levels (40, 80, 120, 160 and 320 MPa) and the evolution of dislocation structure with stress increment was investigated by TEM slip is confirmed to be the dominant deformation mode; the predominance of edge dislocation debris lying along the <1 0more » $$\\bar{1}$$ 0> implies that screw dislocations are more mobile than their edge counterpart. The edge dislocation may dissociate into and dislocations, and the latter can extend further on the basal plane and bound a basal-stacking fault.« less

  9. FRACTIONAL CRYSTALLIZATION OF HANFORD SINGLE SHELL TANK (SST) WASTES LABORATORY DEVELOPMENT

    SciTech Connect (OSTI)

    HERTING, D.L.

    2006-12-05

    Laboratory studies demonstrate that fractional crystallization is a viable process for separating Hanford medium-curie waste into high-curie and low-curie fractions. The product salt from the crystallization process qualifies as low-curie feed to a supplemental treatment system (e.g., bulk vitrification). The high-curie raffinate is returned to the double-shell tank system, eventually to be sent as feed to the Waste Treatment and Immobilization Plant. Process flowsheet tests were designed with the aid of thermodynamic chemical modeling. Laboratory equipment design and test procedures were developed using simulated tank waste samples. Proof-of-concept flowsheet tests were carried out in a shielded hot cell using actual tank waste samples. Data from both simulated waste tests and actual tank waste tests demonstrate that the process exceeded all of the separation criteria established for the program.

  10. Electron Transfer between Cytochrome C and Cytochome C Peroxidase in Single Crystals

    SciTech Connect (OSTI)

    Kang, Seong A.; Marjavaara, Pieti J.; Crane, Brian R.

    2010-11-10

    Cytochrome c (Cc) and cytochrome c peroxidase (CcP) form an important redox pair for understanding interprotein electron transfer (ET). Measurements of ET rates from photoexcited CcP substituted with Zn porphyrin to either yeast Fe(III)Cc or horse Fe(III)Cc in crystals reveal that the molecular associations found in the respective crystal structures determine solution reactivity. Similar forward rates for yeast isozyme-1 Cc (yCc) and yCc homologue horse Cc (hCc), despite different orientations relative to CcP, suggest small-amplitude conformational gating of ET even in the crystalline state; faster back ET in the yCc compared to the hCc complex agrees with the relative coupling between redox sites predicted by the structures.

  11. High Field Magnetization measurements of uranium dioxide single crystals (P08358- E003-PF)

    SciTech Connect (OSTI)

    Gofryk, K.; Harrison, N.; Jaime, M.

    2014-12-01

    Our preliminary high field magnetic measurements of UO2 are consistent with a complex nature of the magnetic ordering in this material, compatible with the previously proposed non-collinear 3-k magnetic structure. Further extensive magnetic studies on well-oriented (<100 > and <111>) UO2 crystals are planned to address the puzzling behavior of UO2 in both antiferromagnetic and paramagnetic states at high fields.

  12. Nanowire photonic crystal waveguides for single-atom trapping and strong light-matter interactions

    SciTech Connect (OSTI)

    Yu, S.-P.; Hood, J. D.; Muniz, J. A.; Martin, M. J.; Hung, C.-L.; Kimble, H. J.; Norte, Richard; Meenehan, Sen M.; Cohen, Justin D.; Painter, Oskar

    2014-03-17

    We present a comprehensive study of dispersion-engineered nanowire photonic crystal waveguides suitable for experiments in quantum optics and atomic physics with optically trapped atoms. Detailed design methodology and specifications are provided, as are the processing steps used to create silicon nitride waveguides of low optical loss in the near-IR. Measurements of the waveguide optical properties and power-handling capability are also presented.

  13. Characterization and modeling of mechanical behavior of single crystal titanium deformed by split-Hopkinson pressure bar

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Morrow, B. M.; Lebensohn, R. A.; Trujillo, C. P.; Martinez, D. T.; Addessio, F. L.; Bronkhorst, C. A.; Lookman, T.; Cerreta, E. K.

    2016-03-28

    Single crystal titanium samples were dynamically loaded using split-Hopkinson pressure bar (SHPB) and the resulting microstructures were examined. Characterization of the twins and dislocations present in the microstructure was conducted to understand the pathway for observed mechanical behavior. Electron backscatter diffraction (EBSD) was used to measure textures and quantify twinning. Microstructures were profusely twinned after loading, and twin variants and corresponding textures were different as a function of initial orientation. Focused ion beam (FIB) foils were created to analyze dislocation content using transmission electron microscopy (TEM). Large amounts of dislocations were present, indicating that plasticity was achieved through slip andmore » twinning together. Viscoplastic self-consistent (VPSC) modeling was used to confirm the complex order of operations during deformation. The activation of different mechanisms was highly dependent upon crystal orientation. For [0001] and View the MathML source[101¯1]-oriented crystals, compressive twinning was observed, followed by secondary tensile twinning. Furthermore, dislocations though prevalent in the microstructure, contributed to final texture far less than twinning.« less

  14. Effect of Fe-doping on nonlinear optical responses and carrier trapping dynamics in GaN single crystals

    SciTech Connect (OSTI)

    Fang, Yu; Yang, Junyi; Yang, Yong; Zhou, Feng; Wu, Xingzhi; Xiao, Zhengguo; Song, Yinglin

    2015-08-03

    We presented a quantitative study on the Fe-doping concentration dependence of optical nonlinearities and ultrafast carrier dynamics in Fe-doped GaN (GaN:Fe) single crystals using picosecond Z-scan and femtosecond pump-probe with phase object techniques under two-photon excitation. In contrast to the two-photon absorption that was found to be independent on the Fe-doping, the nonlinear refraction decreased with the Fe concentration due to the fast carrier trapping effect of Fe{sup 3+}/Fe{sup 2+} deep acceptors, which simultaneously acted as an efficient non-radiative recombination channels for excess carriers. Remarkably, compared to that of Si-doped GaN bulk crystal, the free-carrier refraction effect in GaN:Fe crystals was found to be enhanced considerably since Fe-doping and the effective carrier lifetime (∼10 ps) could be tuned over three orders of magnitude at high Fe-doping level of 1 × 10{sup 19 }cm{sup −3}.

  15. Microstructure and magnetic properties of FeCo epitaxial thin films grown on MgO single-crystal substrates

    SciTech Connect (OSTI)

    Shikada, Kouhei; Ohtake, Mitsuru; Futamoto, Masaaki; Kirino, Fumiyoshi

    2009-04-01

    FeCo epitaxial films were prepared on MgO(100), MgO(110), and MgO(111) substrates by ultrahigh vacuum molecular beam epitaxy. FeCo thin films with (100), (211), and (110) planes parallel to the substrate surface grow on respective MgO substrates. FeCo/MgO interface structures are studied by high-resolution cross-sectional transmission electron microscopy and the epitaxial growth mechanism is discussed. Atomically sharp boundaries are recognized between the FeCo thin films and the MgO substrates where misfit dislocations are introduced in the FeCo thin films presumably to decrease the lattice misfits. Misfit dislocations are observed approximately every 9 and 1.4 nm in FeCo thin film at the FeCo/MgO(100) and the FeCo/MgO(110) interfaces, respectively. X-ray diffraction analysis indicates that the lattice spacing measured parallel to the single-crystal substrate surfaces are in agreement within 0.1% with those of the respective bulk values of Fe{sub 50}Co{sub 50} alloy crystal, showing that the FeCo film strain is very small. The magnetic anisotropies of these epitaxial films basically reflect the magnetocrystalline anisotropy of bulk FeCo alloy crystal.

  16. Phosphate single mode large mode area all-solid photonic crystal fiber with multi-watt output power

    SciTech Connect (OSTI)

    Wang, Longfei; He, Dongbing; Yu, Chunlei; Hu, Lili; Chen, Danping; Liu, Hui; Qiu, Jianrong

    2014-03-31

    An index-depressed active core, single-mode phosphate all-solid large-mode-area photonic crystal fiber (PCF) is theoretically investigated using full-vectorial finite difference approach and experimentally realized. The PCF has a maximum output power of 5.4 W and 31% slope efficiency. Single-mode operation is realized through PCFs with core diameters of 30, 35, and 40 μm, respectively. The beam quality is not degraded even at maximum output power. Our simulations and experiments reveal that the laser performance is significantly affected by the center-to-center distance between the two nearest rods Λ, the rod diameter d, and their ratio d/Λ, implying that much attention should be given in employing optimal parameters to achieve excellent laser performance.

  17. Antiferromagnetism in EuCu2As2 and EuCu1.82Sb2 single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Anand, V. K.; Johnston, D. C.

    2015-05-07

    Single crystals of EuCu2As2 and EuCu2Sb2 were grown from CuAs and CuSb self-flux, respectively. The crystallographic, magnetic, thermal, and electronic transport properties of the single crystals were investigated by room-temperature x-ray diffraction (XRD), magnetic susceptibility χ versus temperature T, isothermal magnetization M versus magnetic field H, specific heat Cp(T), and electrical resistivity ρ(T) measurements. EuCu2As2 crystallizes in the body-centered tetragonal ThCr2Si2-type structure (space group I4/mmm), whereas EuCu2Sb2 crystallizes in the related primitive tetragonal CaBe2Ge2-type structure (space group P4/nmm). The energy-dispersive x-ray spectroscopy and XRD data for the EuCu2Sb2 crystals showed the presence of vacancies on the Cu sites, yielding themore » actual composition EuCu1.82Sb2. The ρ(T) and Cp(T) data reveal metallic character for both EuCu2As2 and EuCu1.82Sb2. Antiferromagnetic (AFM) ordering is indicated from the χ(T),Cp(T), and ρ(T) data for both EuCu2As2 (TN = 17.5 K) and EuCu1.82Sb2 (TN = 5.1 K). In EuCu1.82Sb2, the ordered-state χ(T) and M(H) data suggest either a collinear A-type AFM ordering of Eu+2 spins S = 7/2 or a planar noncollinear AFM structure, with the ordered moments oriented in the tetragonal ab plane in either case. This ordered-moment orientation for the A-type AFM is consistent with calculations with magnetic dipole interactions. As a result, the anisotropic χ(T) and isothermal M(H) data for EuCu2As2, also containing Eu+2 spins S = 7/2, strongly deviate from the predictions of molecular field theory for collinear AFM ordering and the AFM structure appears to be both noncollinear and noncoplanar.« less

  18. Synthesis, structure, growth and characterization of a novel organic NLO single crystal: Morpholin-4-ium p-aminobenzoate

    SciTech Connect (OSTI)

    Shanmugam, G.; Ravi Kumar, K.; Sridhar, B.; Brahadeeswaran, S.

    2012-09-15

    Highlights: ► A new organic NLO crystal morpholin-4-ium p-aminobenzoate has been grown for the first time. ► The structure is reported for the first time in the literature. ► Thermal, optical and SHG studies suggest its suitability for various NLO applications. -- Abstract: The title compound, morpholin-4-ium p-aminobenzoate (MPABA)(C{sub 4}H{sub 10}NO{sup +},C{sub 7}H{sub 6}NO{sub 2}{sup −}), has been synthesized for the first time by the addition of morpholine with 4-aminobenzoic acid in equi-molar ratio and good quality single crystals have been grown by solution growth technique using methanol as a solvent. The molecular structure of the compound was solved and refined by Direct Methods using SHELXS97 and full-matrix least-squares technique using SHELXL97, respectively. MPABA crystallizes in a monoclinic system with unit cell parameters, a = 5.948(5) Å, b = 18.033(4) Å, c = 10.577(5) Å, β = 90.40(1)° and non-centrosymmetric space group Cc. The experimentally measured density and chemical compositions were found to be in good agreement with the theoretical values. The phases and functional groups of MPABA have been identified and confirmed through powder X-ray diffraction and Fourier transform infrared (FTIR) studies, respectively. The thermal stability and decomposition details were studied through TG/DTA thermograms. The UV–visible transmission spectra were recorded for the grown crystal and its NLO characteristic was explored by powder second harmonic generation (SHG) studies.

  19. Single crystal plastic behavior of a single-phase, face-center-cubic-structured, equiatomic FeNiCrCo alloy

    SciTech Connect (OSTI)

    Wu, Zhenggang; Gao, Y. F.; Bei, Hongbin

    2015-07-25

    To understand the fundamental deformation mechanisms of compositionally complex alloys, single crystals of a multi-component equiatomic FeNiCoCr alloy with face-centered cubic (FCC) structure were grown for mechanical studies. Similarly to typical FCC pure metals, slip trace analyses indicate that dislocation slips take place on (1 1 1) planes along [110] directions. The critical resolved shear stress (CRSS) obeys the Schmid law at both 77 and 293 K, and tensioncompression asymmetry is not observed. Although this material slips in a normal FCC manner both at 293 and 77 K, compared to typical FCC metals the CRSSs strong temperature dependence is abnormal.

  20. Single crystal plastic behavior of a single-phase, face-center-cubic-structured, equiatomic FeNiCrCo alloy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wu, Zhenggang; Gao, Y. F.; Bei, Hongbin

    2015-07-25

    To understand the fundamental deformation mechanisms of compositionally complex alloys, single crystals of a multi-component equiatomic FeNiCoCr alloy with face-centered cubic (FCC) structure were grown for mechanical studies. Similarly to typical FCC pure metals, slip trace analyses indicate that dislocation slips take place on (1 1 1) planes along [11¯0] directions. The critical resolved shear stress (CRSS) obeys the Schmid law at both 77 and 293 K, and tension–compression asymmetry is not observed. Although this material slips in a normal FCC manner both at 293 and 77 K, compared to typical FCC metals the CRSS’s strong temperature dependence is abnormal.

  1. On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement

    SciTech Connect (OSTI)

    Kristie Cooper; Gary Pickrell; Anbo Wang

    2005-11-01

    This report summarizes technical progress April-September 2005 on the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Due to the difficulties described on the last report, field testing of the BPDI system has not continued to date. However, we have developed an alternative high temperature sensing solution, which is described in this report. The sensing system will be installed and tested at TECO's Polk Power Station. Following a site visit in June 2005, our efforts have been focused on preparing for that field test, including he design of the sensor mechanical packaging, sensor electronics, the data transfer module, and the necessary software codes to accommodate this application.. We are currently ready to start sensor fabrication.

  2. Heteroepitaxial growth of Pt and Au thin films on MgO single crystals by bias-assisted sputtering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tolstova, Yulia; Omelchenko, Stefan T.; Shing, Amanda M.; Atwater, Harry A.

    2016-03-17

    The crystallographic orientation of a metal affects its surface energy and structure, and has profound implications for surface chemical reactions and interface engineering, which are important in areas ranging from optoelectronic device fabrication to catalysis. However, it can be very difficult and expensive to manufacture, orient, and cut single crystal metals along different crystallographic orientations, especially in the case of precious metals. One approach is to grow thin metal films epitaxially on dielectric substrates. In this work, we report on growth of Pt and Au films on MgO single crystal substrates of (100) and (110) surface orientation for use asmore » epitaxial templates for thin film photovoltaic devices. We develop bias-assisted sputtering for deposition of oriented Pt and Au films with sub-nanometer roughness. We show that biasing the substrate decreases the substrate temperature necessary to achieve epitaxial orientation, with temperature reduction from 600 to 350 °C for Au, and from 750 to 550 °C for Pt, without use of transition metal seed layers. Additionally, this temperature can be further reduced by reducing the growth rate. Biased deposition with varying substrate bias power and working pressure also enables control of the film morphology and surface roughness.« less

  3. On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement

    SciTech Connect (OSTI)

    Kristie Cooper; Anbo Wang

    2007-03-31

    This report summarizes technical progress October 2006 - March 2007 on the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. During the second phase, an alternative high temperature sensing system based on Fabry-Perot interferometry was developed that offers a number of advantages over the BPDI solution. The objective of this program is to bring the sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. The sapphire wafer-based interferometric sensing system that was installed at TECO's Polk Power Station remained in operation for seven months. Our efforts have been focused on monitoring and analyzing the real-time data collected, and preparing for a second field test.

  4. Molecular dynamics simulation of self-rotation effects on ultra-precision polishing of single-crystal copper

    SciTech Connect (OSTI)

    Yang, Yihan; Zhao, Hongwei; Zhang, Lin; Shao, Mingkun; Liu, Hongda; Huang, Hu

    2013-10-15

    Understanding the behaviors of the material removal mechanism of ultra-precision polishing process has been a critical issue of generating well-formed surface. In order to make clear the abrasive self-rotation effects on material removal at the atomic level, a three-dimensional molecular dynamics (MD) model is conducted to study the mechanics of ultra-precision polishing on single-crystal copper with a diamond abrasive and the effects of abrasive self-rotation velocity and direction. Morse potential energy function and EAM potential energy function are applied to model the copper/diamond and copper/copper interactions, respectively. The simulation results show that the deformation mechanism of single-crystal copper is due to the formation and movement of dislocations in the specimen. In addition, with the increasing of abrasive self-rotation velocity, the deformation mechanism falls from cutting to plowing regimes. The abrasive self-rotation velocity and direction have effects on the morphology and quality of the specimen surface, distribution and evolution of defects under the surface of the specimen. Also, the interatomic force between abrasive and specimen is studied to account for the effects of different polishing conditions.

  5. Giant magnetocaloric effect and temperature induced magnetization jump in GdCrO{sub 3} single crystal

    SciTech Connect (OSTI)

    Yin, L. H.; Yang, J.; Kan, X. C.; Song, W. H.; Dai, J. M.; Sun, Y. P.

    2015-04-07

    We report on a systematic study of the single-crystal GdCrO{sub 3}, which shows various novel magnetic features, such as temperature-induced magnetization reversal (TMR), temperature-induced magnetization jump (TMJ), spin reorientation, and giant magnetocaloric effect (MCE). In the field-cooled cooling process with modest magnetic field along the c axis, GdCrO{sub 3} first shows a TMR at T{sub comp}∼120−130 K and then an abrupt TMJ with a sign change of magnetization at T{sub jump}∼52−120 K, and finally a spin reorientation at T{sub SR}∼4−7 K. Interestingly, the remarkable TMJ behavior, which was not reported ever before, persists at higher fields up to 10 kOe even when TMR disappears. In addition, giant MCE with the maximum value of magnetic entropy change reaching ∼31.6 J/kg K for a field change of 44 kOe was also observed in GdCrO{sub 3} single crystal, suggesting it could be a potential material for low-T magnetic refrigeration. A possible mechanism for these peculiar magnetic behaviors is discussed based on the various competing magnetic interactions between the 3d electrons of Cr{sup 3+} ions and 4f electrons of Gd{sup 3+} ions.

  6. Van der Waals Epitaxial Growth of Single-Crystal Two-Dimensional GaSe on Graphene

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, Xufan; Basile, Leonardo; Huang, Bing; Ma, Cheng; Lee, Jaekwang; Vlassiouk, Ivan V.; Puretzky, Alexander A.; Lin, Ming-Wei; Chi, Miaofang; Idrobo Tapia, Juan Carlos; et al

    2015-07-22

    Two-dimensional (2D) van der Waals (vdW) heterostructures are a family of artificially-structured materials that promise tunable optoelectronic properties for devices with enhanced functionalities. Compared to stamping, direct epitaxy of vdW heterostructures is ideal for clean interlayer interfaces and scalable device fabrication. Here, we explore the synthesis and preferred orientations of 2D GaSe atomic layers on graphene (Gr) by vdW epitaxy. Guided by the wrinkles on graphene, GaSe nuclei form that share a predominant lattice orientation. Due to vdW epitaxial growth many nuclei grow as perfectly aligned crystals and coalesce to form large (tens of microns), single-crystal flakes. Through theoretical investigationsmoreof interlayer energetics, and measurements of preferred orientations by atomic-resolution STEM and electron diffraction, a 10.9 interlayer rotation of the GaSe lattice with respect to the underlying graphene is found to be the most energetically preferred vdW heterostructure with the largest binding energy and the longest-range ordering. These GaSe/Gr vdW heterostructures exhibit an enhanced Raman E21g band of monolayer GaSe along with highly-quenched photoluminescence due to strong charge transfer. Despite the very large lattice mismatch of GaSe/Gr through vdW epitaxy, the predominant orientation control and convergent formation of large single-crystal flakes demonstrated here is promising for the scalable synthesis of large-area vdW heterostructures for the development of new optical and optoelectronic devices.less

  7. Investigations of Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal as a scintillator

    SciTech Connect (OSTI)

    Zhang, Zhi-Jun; Hu, Guan-Qin; Wang, Hong; Zhu, Lin-Lin; Zhao, Jing-Tai

    2014-04-01

    Highlights: • Eu{sup 2+}-activated Ba{sub 3}BP{sub 3}O{sub 12} single crystals have been grown by the top-seeded solution growth method (TSSG) for the first time. • Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal exhibits wide transparency in the wavelength range from 250 to 700 nm. • Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal shows high overall scintillation efficiency (1.8 times of BGO) and moderate decay time (860 ns). - Abstract: Single crystals of Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} with high optical quality have been grown by the top-seeded solution growth (TSSG) method using BPO{sub 4}–NaF mixture as the flux. Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal exhibits wide transparency in the wavelength range from 250 to 700 nm, and shows a broad emission band in the wavelength range of 350–650 nm when excited by X-ray radiation. The overall scintillation efficiency is about 1.8 times of that of BGO crystal under the same conditions. Its room temperature fluorescence decay curve exhibits a single-exponent shape with decay time of about 860 ns. It is worth noting that Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal may be of great interest for applications in the field of scintillation materials considering its scintillation properties, as well as the good chemical stability.

  8. Photo-Seebeck effect in tetragonal PbO single crystals

    SciTech Connect (OSTI)

    Mondal, P. S.; Okazaki, R.; Taniguchi, H.; Terasaki, I.

    2013-11-07

    We report the observation of photo-Seebeck effect in tetragonal PbO crystals. The photo-induced carriers contribute to the transport phenomena, and consequently the electrical conductivity increases and the Seebeck coefficient decreases with increasing photon flux density. A parallel-circuit model is used to evaluate the actual contributions of photo-excited carriers from the measured transport data. The photo-induced carrier concentration estimated from the Seebeck coefficient increases almost linearly with increasing photon flux density, indicating a successful photo-doping effect on the thermoelectric property. The mobility decreases by illumination but the reduction rate strongly depends on the illuminated photon energy. Possible mechanisms of such photon-energy-dependent mobility are discussed.

  9. Structural state of a radiation-modified Ti{sub 50}Ni{sub 47}Fe{sub 3} single crystal

    SciTech Connect (OSTI)

    Parkhomenko, V. D. Dubinin, S. F.; Maksimov, V. I.

    2011-12-15

    The structural state of a Ti{sub 50}Ni{sub 47}Fe{sub 3} single crystal irradiated by fast neutrons (F = 2.5 Multiplication-Sign 10{sup 20} cm{sup -2}) at 340 K was studied by thermal neutron diffraction at 78 and 295 K. The melt of this composition was chosen with the purpose of designing a radiation-resistant material exhibiting a shape-memory effect. It was found that the melt remains crystalline after irradiation, whereas the Ti{sub 49}Ni{sub 51} crystal studied earlier becomes amorphous after an analogous irradiation. In spite of the fact that the main structural motif of the crystal remains unchanged after irradiation, martensitic transformations in the crystal do not occur and, consequently, the shape-memory effect is not retained. The radiation resistance of this class of crystals was estimated.

  10. Shock wave compression of hexagonal-close-packed metal single crystals: Time-dependent, anisotropic elastic-plastic response of beryllium

    SciTech Connect (OSTI)

    Winey, J. M.; Gupta, Y. M.

    2014-07-21

    Understanding and modeling the response of hcp metals to high stress impulsive loading is challenging because the lower crystal symmetry, compared to cubic metals, results in a significantly more complex material response. To gain insight into the inelastic deformation of hcp metals subjected to high dynamic stresses, shock wave compression of single crystals provides a useful approach because different inelastic deformation mechanisms can be examined selectively by shock compression along different crystal orientations. As a representative example, we report, here, on wave propagation simulations for beryllium (Be) single crystals shocked along the c-axis, a-axis, and several low-symmetry directions to peak stresses reaching 7?GPa. The simulations utilized a time-dependent, anisotropic material model that incorporated dislocation dynamics, deformation twinning, and shear cracking based descriptions of inelastic deformation. The simulation results showed good overall agreement with measured wave profiles for all the different crystal orientations examined [Pope and Johnson, J. Appl. Phys. 46, 720 (1975)], including features arising from wave mode coupling due to the highly anisotropic inelastic response of Be. This good agreement demonstrates that the measured profiles can be understood in terms of dislocation slip along basal, prismatic, and pyramidal planes, together with deformation twinning along (101{sup }2) planes. Our results show that the response of shocked Be single crystals involves the simultaneous operation of multiple, distinct inelastic deformation mechanisms for all orientations except the c-axis. For shocked c-axis Be, the measured wave profiles do not provide good discrimination between pyramidal slip and other inelastic deformation mechanisms, such as shear cracking. The findings presented here provide insight into the complex inelastic deformation response of shocked Be single crystals and are expected to be useful for other hcp crystals. More

  11. Photochemical Grafting of Organic Alkenes to Single-Crystal TiO2 Surfaces: A Mechanistic Study

    SciTech Connect (OSTI)

    Franking, Ryan A.; Kim, Heesuk; Chambers, Scott A.; Mangham, Andrew N.; Hamers, Robert J.

    2012-08-21

    The UV-induced photochemical grafting of terminal alkenes has emerged as a versatile way to form molecular layers on semiconductor surfaces. Recent studies have shown that grafting reactions can be initiated by photoelectron emission into the reactant liquid as well as by excitation across the semiconductor bandgap, but the relative importance of these two processes is expected to depend on the nature of the semiconductor and the reactant alkene and the excitation wavelength. Here we report a study of the wavelength-dependent photochemical grafting of alkenes onto single-crystal TiO2 samples. Trifluoroacetamide-protected 10-aminododec-1-ene (TFAAD), 10-N-BOC-aminodec-1-ene (t-BOC) and 1-dodecene were used as model alkenes. On rutile(110), photons with energy above the bandgap but below the expected work function are not effective at inducing grafting, while photons with energy sufficient to induce electronic transitions from the TiO2 Fermi level to electronic acceptor states of the reactant molecules induce grafting. A comparison of rutile (110), rutile(001), anatase (001), and anatase(101) samples shows slightly enhanced grafting for rutile but no difference between crystal faces for a given crystal phase. Hydroxylation of the surface increases the reaction rate by lowering the work function and thereby facilitating photoelectron ejection into the adjacent alkene. These results demonstrate that photoelectron emission is the dominant mechanism responsible for grafting when using short-wavelength (~254 nm) light and suggest that photoemission events beginning on mid-gap states may play a crucial role.

  12. Boost the electron mobility of solution-grown organic single crystals via reducing the amount of polar solvent residues

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Xue, Guobiao; Xin, Huolin L.; Wu, Jiake; Fan, Congcheng; Liu, Shuang; Huang, Zhuoting; Liu, Yujing; Shan, Bowen; Miao, Qian; Chen, Hongzheng; et al

    2015-10-29

    Enhancing electron transport to match with the development in hole transport is critical for organic electronics in the future. As electron motion is susceptible to extrinsic factors, seeking these factors and avoiding their negative effects have become the central challenge. Here, the existence of polar solvent residues in solution-grown single-crystals of 6,13-bis(triisopropylsilylethynyl)-5,7,12,14-tetraazapentacene is identified as a factor detrimental to electron motion. Field-effect transistors of the crystals exhibit electron mobility boosted by about 60% after the residues are removed. The average electron mobility reaches up to 8.0 ± 2.2 cm2 V–1 s–1 with a highest value of 13.3 cm2 V–1 s–1;more » these results are significantly higher than those obtained previously for the same molecule (1.0–5.0 cm2 V–1 s–1). Furthermore, the achieved mobility is also higher than the maximum reported electron mobility for organic materials (11 cm2 V–1 s–1). As a result, this work should greatly accelerate the advancement of organic electron-transporting materials.« less

  13. Charge transfer of single laser crystallized intrinsic and phosphorus-doped Si-nanocrystals visualized by Kelvin probe force microscopy

    SciTech Connect (OSTI)

    Xu, Jie; Xu, Jun Lu, Peng; Shan, Dan; Li, Wei; Chen, Kunji

    2014-10-07

    Isolated intrinsic and phosphorus doped (P-doped) Si-nanocrystals (Si-NCs) on n- and p-Si substrates are fabricated by excimer laser crystallization techniques. The formation of Si-NCs is confirmed by atomic force microscopy (AFM) and conductive AFM measurements. Kelvin probe force microscopy (KPFM) is then carried out to visualize the trapped charges in a single Si-NC dot which derives from the charge transfer between Si-NCs and Si substrates due to their different Fermi levels. The laser crystallized P-doped Si-NCs have a similar Fermi level around the mid-gap to the intrinsic counterparts, which might be caused by the inactivated impurity atoms or the surface states-related Fermi level pinning. A clear rise of the Fermi level in P-doped Si-NCs is observed after a short time thermal annealing treatment, indicating the activation of dopants in Si-NCs. Moreover, the surface charge quantity can be estimated using a simple parallel plate capacitor model for a quantitative understanding of the KPFM results at the nanoscale.

  14. Effects of composition and temperature on the large field behavior of [011]{sub C} relaxor ferroelectric single crystals

    SciTech Connect (OSTI)

    Gallagher, John A.; Lynch, Christopher S.; Tian, Jian

    2014-08-04

    The large field behavior of [011]{sub C} cut relaxor ferroelectric lead indium niobate–lead magnesium niobate–lead titanate, xPb(In{sub 1/2}Nb{sub 1/2})O{sub 3}-(1-x-y)Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-yPbTiO{sub 3}, single crystals was experimentally characterized in the piezoelectric d{sub 322}-mode configuration under combined mechanical, electrical, and thermal loading. Increasing the concentration of lead indium niobate and decreasing the concentration of lead titanate in compositions near the morphotropic phase boundary resulted in a decrease of mechanical compliance, dielectric permittivity, and piezoelectric coefficients as well as a shift from a continuous to a discontinuous transformation.

  15. Catalytic hydrodechlorination of CFC-114a (CF{sub 3}-CFCl{sub 2}) over palladium single crystals

    SciTech Connect (OSTI)

    Gerken, C.A.; Rupprechter, G.; Ribeiro, F.H.; Somorjai, G.A.

    1997-12-31

    As the chlorofluorocarbons (CFC`s) are being phased out, their most promising replacements are the hydrofluorocarbons (HFC`s). In particular, CFC-12 (CF{sub 2}Cl{sub 2}), widely used as a refrigerant, for example, is being replaced by HFC-134a CF{sub 3}-CFH{sub 2}. One possible route to HFC-134a is the hydrodechlorination of CFC-114a (CF{sub 3}CFCl{sub 2}) over palladium catalysts. We report results using single crystal palladium catalysts and compare the reactivity of the low Miller index planes and a polycrystalline foil. We correlate these results with parallel UHV surface science experiments. Deuterium isotope studies (D{sub 2} rather than H{sub 2}) will also be presented and discussed. Of particular interest is an observed sample history-dependent inverse isotope effect.

  16. Phase transition in bulk single crystals and thin films of VO2 by nanoscale infrared spectroscopy and imaging

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Mengkun; Sternbach, Aaron J.; Wagner, Martin; Slusar, Tetiana V.; Kong, Tai; Bud'ko, Sergey L.; Kittiwatanakul, Salinporn; Qazilbash, M. M.; McLeod, Alexander; Fei, Zhe; et al

    2015-06-29

    We have systematically studied a variety of vanadium dioxide (VO2) crystalline forms, including bulk single crystals and oriented thin films, using infrared (IR) near-field spectroscopic imaging techniques. By measuring the IR spectroscopic responses of electrons and phonons in VO2 with sub-grain-size spatial resolution (~20nm), we show that epitaxial strain in VO2 thin films not only triggers spontaneous local phase separations, but leads to intermediate electronic and lattice states that are intrinsically different from those found in bulk. Generalized rules of strain- and symmetry-dependent mesoscopic phase inhomogeneity are also discussed. Furthermore, these results set the stage for a comprehensive understanding ofmore » complex energy landscapes that may not be readily determined by macroscopic approaches.« less

  17. A 31?T split-pair pulsed magnet for single crystal x-ray diffraction at low temperature

    SciTech Connect (OSTI)

    Duc, F.; Frings, P.; Nardone, M.; Billette, J.; Zitouni, A.; Delescluse, P.; Bard, J.; Nicolin, J. P.; Rikken, G. L. J. A.; Fabrges, X.; Roth, T.; Detlefs, C.; Lesourd, M.; Zhang, L.

    2014-05-15

    We have developed a pulsed magnet system with panoramic access for synchrotron x-ray diffraction in magnetic fields up to 31?T and at low temperature down to 1.5?K. The apparatus consists of a split-pair magnet, a liquid nitrogen bath to cool the pulsed coil, and a helium cryostat allowing sample temperatures from 1.5 up to 250?K. Using a 1.15?MJ mobile generator, magnetic field pulses of 60?ms length were generated in the magnet, with a rise time of 16.5?ms and a repetition rate of 2 pulses/h at 31?T. The setup was validated for single crystal diffraction on the ESRF beamline ID06.

  18. Ellipsometric characterization and density-functional theory analysis of anisotropic optical properties of single-crystal ?-SnS

    SciTech Connect (OSTI)

    Banai, R. E.; Brownson, J. R. S.; Burton, L. A.; Walsh, A.; Choi, S. G. To, B.; Hofherr, F.; Sorgenfrei, T.; Crll, A.

    2014-07-07

    We report on the anisotropic optical properties of single-crystal tin monosulfide (SnS). The components ?{sub a}, ?{sub b}, and ?{sub c} of the pseudodielectric-function tensor (?)=(??)+i(??) spectra are taken from 0.73 to 6.45 eV by spectroscopic ellipsometry. The measured (?) spectra are in a good agreement with the results of the calculated dielectric response from hybrid density functional theory. The (?) spectra show the direct band-gap onset and a total of eight above-band-gap optical structures that are associated with the interband-transition critical points (CPs). We obtain accurate CP energies by fitting analytic CP expressions to second-energy-derivatives of the (?) data. Their probable electronic origins and implications for photovoltaic applications are discussed.

  19. Low Surface Recombination Velocity in Solution-Grown CH3NH3PbBr3 Perovskite Single Crystal

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yang, Ye; Yan, Yong; Yang, Mengjin; Choi, Sukgeun; Zhu, Kai; Luter, Joseph M.; Beard, Matthew C.

    2015-08-06

    Organic-inorganic hybrid perovskites are attracting intense research effort due to their impressive performance in solar cells. While the carrier transport parameters such as mobility and bulk carrier lifetime shows sufficient characteristics, the surface recombination, which can have major impact on the solar cell performance, has not been studied. Here we measure surface recombination dynamics in CH3NH3PbBr3 perovskite single crystals using broadband transient reflectance spectroscopy. The surface recombination velocity is found to be 3.4±0.1 103 cm s-1, B2–3 orders of magnitude lower than that in many important unpassivated semiconductors employed in solar cells. Our result suggests that the planar grain sizemore » for the perovskite thin films should be larger thanB30 mm to avoid the influence of surface recombination on the effective carrier lifetime.« less

  20. Sustained phase separation and spin glass in Co-doped KxFe2-ySe2 single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ryu, Hyejin; Wang, Kefeng; Opacic, M.; Lazarevic, N.; Warren, J. B.; Popovic, Z. V.; Bozin, Emil S.; Petrovic, C.

    2015-11-19

    We describe Co substitution effects in KxFe2-y-zCozSe2 (0.06 ≤ z ≤ 1.73) single crystal alloys. By 3.5% of Co doping superconductivity is suppressed whereas phase separation of semiconducting K2Fe4Se5 and superconducting/metallic KxFe2Se2 is still present. We show that the arrangement and distribution of superconducting phase (stripe phase) is connected with the arrangement of K, Fe and Co atoms. Semiconducting spin glass is found in proximity to superconducting state, persisting for large Co concentrations. At high Co concentrations ferromagnetic metallic state emerges above the spin glass. This is coincident with changes of the unit cell, arrangement and connectivity of stripemore » conducting phase.« less

  1. Sustained phase separation and spin glass in Co-doped KxFe2?ySe2 single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ryu, Hyejin; Wang, Kefeng; Opacic, M.; Lazarevic, N.; Warren, J. B.; Popovic, Z. V.; Bozin, Emil S.; Petrovic, C.

    2015-11-19

    We describe Co substitution effects in KxFe2-y-zCozSe2 (0.06 ? z ? 1.73) single crystal alloys. By 3.5% of Co doping superconductivity is suppressed whereas phase separation of semiconducting K2Fe4Se5 and superconducting/metallic KxFe2Se2 is still present. We show that the arrangement and distribution of superconducting phase (stripe phase) is connected with the arrangement of K, Fe and Co atoms. Semiconducting spin glass is found in proximity to superconducting state, persisting for large Co concentrations. At high Co concentrations ferromagnetic metallic state emerges above the spin glass. This is coincident with changes of the unit cell, arrangement and connectivity of stripemoreconducting phase.less

  2. First order magnetic transition in single crystal CaFe2As2 detected by 75As NMR

    SciTech Connect (OSTI)

    Baek, Seung Ho; Curro, Nicholas J

    2008-01-01

    We report {sup 75}As Nuclear Magnetic Resonance data in a single crystal of CaFe{sub 2}As{sub 2}. The Knight shift, the electric field gradient, and the spin lattice relaxation rate are strongly temperature dependent in the paramagnetic state, and change discontinuously at the structural transition temperature, T{sub S} = T{sub N} = 167 K. Immediately below, the NMR spectra reveal an internal field at the As site associated with the presence of a commensurate magnetic order. These results indicate that the structural and magnetic transitions in CaFe{sub 2}As{sub 2} are first order and strongly coupled, and that the electron density in the FeAs plane is highly sensitive to the out-of-plane structure.

  3. In-Plane Electronic Anisotropy of Underdoped ___122___ Fe-Arsenide Superconductors Revealed by Measurements of Detwinned Single Crystals

    SciTech Connect (OSTI)

    Fisher, Ian Randal

    2012-05-08

    The parent phases of the Fe-arsenide superconductors harbor an antiferromagnetic ground state. Significantly, the Neel transition is either preceded or accompanied by a structural transition that breaks the four fold symmetry of the high-temperature lattice. Borrowing language from the field of soft condensed matter physics, this broken discrete rotational symmetry is widely referred to as an Ising nematic phase transition. Understanding the origin of this effect is a key component of a complete theoretical description of the occurrence of superconductivity in this family of compounds, motivating both theoretical and experimental investigation of the nematic transition and the associated in-plane anisotropy. Here we review recent experimental progress in determining the intrinsic in-plane electronic anisotropy as revealed by resistivity, reflectivity and ARPES measurements of detwinned single crystals of underdoped Fe arsenide superconductors in the '122' family of compounds.

  4. High-pressure single-crystal elasticity study of CO{sub 2} across phase I-III transition

    SciTech Connect (OSTI)

    Zhang, Jin S. Bass, Jay D.; Shieh, Sean R.; Dera, Przemyslaw; Prakapenka, Vitali

    2014-04-07

    Sound velocities and elastic moduli of solid single-crystal CO{sub 2} were measured at pressures up to 11.7(3) GPa by Brillouin spectroscopy. The aggregate adiabatic bulk modulus (K{sub S}), shear modulus (G), and their pressure derivatives for CO{sub 2} Phase I are K{sub S0}?=?3.4(6) GPa, G{sub 0}?=?1.8(2) GPa, (dK{sub S}/dP){sub 0}?=?7.8(3), (dG/dP){sub 0}?=?2.5(1), (d{sup 2}K{sub S}/dP{sup 2}){sub 0}?=??0.23(3) GPa{sup ?1}, and (d{sup 2}G/dP{sup 2}){sub 0}?=??0.10(1) GPa{sup ?1}. A small increase of elastic properties was observed between 9.8(1) and 10.5(3) GPa, in agreement with the CO{sub 2} I-III transition pressure determined from previous x-ray diffraction experiments. Above the transition pressure P{sub T}, we observed a mixture dominated by CO{sub 2}-I, with minor CO{sub 2}-III. The CO{sub 2}-I + III mixture shows slightly increased sound velocities compared to pure CO{sub 2}-I. Elastic anisotropy calculated from the single-crystal elasticity tensor exhibits a decrease with pressure beginning at 7.9(1) GPa, which is lower than P{sub T}. Our results coincide with recent X-ray Raman observations, suggesting that a pressure-induced electronic transition is related to local structural and optical changes.

  5. Octahedral distortion induced magnetic anomalies in LaMn{sub 0.5}Co{sub 0.5}O{sub 3} single crystals

    SciTech Connect (OSTI)

    Manna, Kaustuv Elizabeth, Suja; Anil Kumar, P. S.; Bhadram, Venkata Srinu; Narayana, Chandrabhas

    2014-07-28

    Single crystals of LaMn{sub 0.5}Co{sub 0.5}O{sub 3} belonging to the ferromagnetic-insulator and distorted perovskite class were grown using a four-mirror optical float zone furnace. The as-grown crystal crystallizes into an orthorhombic Pbnm structure. The spatially resolved 2D Raman scan reveals a strain-induced distribution of transition metal (TM)oxygen (O) octahedral deformation in the as-grown crystal. A rigorous annealing process releases the strain, thereby generating homogeneous octahedral distortion. The octahedra tilt by reducing the bond angle TM-O-TM, resulting in a decline of the exchange energy in the annealed crystal. The critical behavior is investigated from the bulk magnetization. It is found that the ground state magnetic behavior assigned to the strain-free LaMn{sub 0.5}Co{sub 0.5}O{sub 3} crystal is of the 3D Heisenberg kind. Strain induces mean field-like interaction in some sites, and consequently, the critical exponents deviate from the 3D Heisenberg class in the as-grown crystal. The temperature-dependent Raman scattering study reveals strong spin-phonon coupling and the existence of two magnetic ground states in the same crystal.

  6. Single-crystal epitaxial thin films of SrFeO{sub 2} with FeO{sub 2} 'infinite layers'

    SciTech Connect (OSTI)

    Inoue, Satoru; Kawai, Masanori; Shimakawa, Yuichi [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Mizumaki, Masaichiro; Kawamura, Naomi [Japan Synchrotron Radiation Research Institute/SPring-8, Sayo, Hyogo 679-5198 (Japan); Watanabe, Takashi; Tsujimoto, Yoshihiro; Kageyama, Hiroshi; Yoshimura, Kazuyoshi [Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502 (Japan)

    2008-04-21

    Single-crystal thin films of SrFeO{sub 2}, which is an oxygen-deficient perovskite with ''infinite layers'' of Fe{sup 2+}O{sub 2}, were prepared by using CaH{sub 2} for low-temperature reduction of epitaxial SrFeO{sub 2.5} single-crystal films deposited on KTaO{sub 3} substrates. This reduction process, removing oxygen ions from the perovskite structure framework and causing rearrangements of oxygen ions, topotactically transforms the brownmillerite SrFeO{sub 2.5} to the c-axis oriented SrFeO{sub 2}.

  7. Superconducting properties of Rh9In4S4 single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kaluarachchi, Udhara S.; Lin, Qisheng; Xie, Weiwei; Taufour, Valentin; Bud'ko, Sergey L.; Miller, Gordon J.; Canfield, Paul C.

    2016-03-28

    The synthesis and crystallographic, thermodynamic, and transport properties of single crystalline Rh9In4S4 were studied. The resistivity, magnetization, and specific heat measurements all clearly indicate bulk superconductivity with a critical temperature, Tc~2.25 K. The Sommerfeld coefficient γ and the Debye temperature (ΘD) were found to be 34 mJ mol–1 K–2 and 217 K, respectively. The observed specific heat jump, ΔC/γTc=1.66, is larger than the expected BCS weak coupling value of 1.43. Ginzburg-Landau (GL) ratio of the low-temperature GL-penetration depth, λGL≈5750 Å, to the GL-coherence length, ξGL≈94 Å, is large: κ ~60. However, we observed a peak effect in the resistivity measurementmore » as a function of both temperature and magnetic field.« less

  8. Preparation and supercapacitor application of the single crystal nickel hydroxide and oxide nanosheets

    SciTech Connect (OSTI)

    Li, Qing; Ni, Haifang; Cai, Yun; Cai, Xiaoyan; Liu, Yongjun; Chen, Gang; Fan, Li-Zhen; Wang, Yude

    2013-09-01

    Graphical abstract: The nickel hydroxide and nickel oxide nanosheets prepared using CTAB at room temperature exhibit a high specific capacitance, prompt charge/discharge rate. - Highlights: The nickel hydroxide nanosheets were prepared using CTAB at room temperature. Ni(OH){sub 2} nanosheet can be successfully converted to NiO nanosheet via calcination. The NiO nanosheet has a specific capacitance of 388 F g{sup ?1} at 5 A g{sup ?1} in KOH solution. Anneal temperature impacts capacitive properties as electrode. - Abstract: The single crystalline Ni(OH){sub 2} nanosheets were synthesized by a simple chemical precipitation method using nickel chloride as precursors and ammonia as precipitating agent. The Ni(OH){sub 2} nanosheets were successfully converted to NiO nanosheets via calcination under appropriate conditions. Analytical methods such as X-ray diffraction (XRD) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and Fourier transformed infrared (FTIR) spectra were employed to characterize the morphology and microstructure of the final products. The experimental results revealed that Ni(OH){sub 2} nanosheets were shape-preserved transformed to NiO nanosheets at 250 C for 24 h. Ni(OH){sub 2} and NiO nanosheets were directly functionalized as supercapacitor electrodes for potential energy storage applications, whose chargedischarge properties, electrochemical impedance spectra, cyclic voltammetry, and cycle performance were examined. The experimental results show that the single-crystalline NiO nanosheets are a promising candidate for the supercapacitor electrode. They exhibit a high specific capacitance, prompt charge/discharge rate.

  9. Superconducting gap evolution in overdoped BaFe₂(As1-xPx)₂ single crystals through nanocalorimetry

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Campanini, D.; Diao, Z.; Fang, L.; Kwok, W.-K.; Welp, U.; Rydh, A.

    2015-06-18

    We report on specific heat measurements on clean overdoped BaFe₂(As1-xPx)₂ single crystals performed with a high resolution membrane-based nanocalorimeter. A nonzero residual electronic specific heat coefficient at zero temperature γr=C/T|T→0 is seen for all doping compositions, indicating a considerable fraction of the Fermi surface ungapped or having very deep minima. The remaining superconducting electronic specific heat is analyzed through a two-band s-wave α model in order to investigate the gap structure. Close to optimal doping we detect a single zero-temperature gap of Δ₀~5.3 me V, corresponding to Δ₀/kBTc ~ 2.2. Increasing the phosphorus concentration x, the main gap reduces tillmore » a value of Δ₀ ~ 1.9 meV for x = 0.55 and a second weaker gap becomes evident. From the magnetic field effect on γr, all samples however show similar behavior [γr(H) - γr (H = 0)∝ Hn, with n between 0.6 and 0.7]. This indicates that, despite a considerable redistribution of the gap weights, the total degree of gap anisotropy does not change drastically with doping.« less

  10. Tightly integrated single- and multi-crystal data collection strategy calculation and parallelized data processing in JBluIce beamline control system

    SciTech Connect (OSTI)

    Pothineni, Sudhir Babu; Venugopalan, Nagarajan; Ogata, Craig M.; Hilgart, Mark C.; Stepanov, Sergey; Sanishvili, Ruslan; Becker, Michael; Winter, Graeme; Sauter, Nicholas K.; Smith, Janet L.; Fischetti, Robert F.

    2014-11-18

    The calculation of single- and multi-crystal data collection strategies and a data processing pipeline have been tightly integrated into the macromolecular crystallographic data acquisition and beamline control software JBluIce. Both tasks employ wrapper scripts around existing crystallographic software. JBluIce executes scripts through a distributed resource management system to make efficient use of all available computing resources through parallel processing. The JBluIce single-crystal data collection strategy feature uses a choice of strategy programs to help users rank sample crystals and collect data. The strategy results can be conveniently exported to a data collection run. The JBluIce multi-crystal strategy feature calculates a collection strategy to optimize coverage of reciprocal space in cases where incomplete data are available from previous samples. The JBluIce data processing runs simultaneously with data collection using a choice of data reduction wrappers for integration and scaling of newly collected data, with an option for merging with pre-existing data. Data are processed separately if collected from multiple sites on a crystal or from multiple crystals, then scaled and merged. Results from all strategy and processing calculations are displayed in relevant tabs of JBluIce.

  11. Tightly integrated single- and multi-crystal data collection strategy calculation and parallelized data processing in JBluIce beamline control system

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Pothineni, Sudhir Babu; Venugopalan, Nagarajan; Ogata, Craig M.; Hilgart, Mark C.; Stepanov, Sergey; Sanishvili, Ruslan; Becker, Michael; Winter, Graeme; Sauter, Nicholas K.; Smith, Janet L.; et al

    2014-11-18

    The calculation of single- and multi-crystal data collection strategies and a data processing pipeline have been tightly integrated into the macromolecular crystallographic data acquisition and beamline control software JBluIce. Both tasks employ wrapper scripts around existing crystallographic software. JBluIce executes scripts through a distributed resource management system to make efficient use of all available computing resources through parallel processing. The JBluIce single-crystal data collection strategy feature uses a choice of strategy programs to help users rank sample crystals and collect data. The strategy results can be conveniently exported to a data collection run. The JBluIce multi-crystal strategy feature calculates amore » collection strategy to optimize coverage of reciprocal space in cases where incomplete data are available from previous samples. The JBluIce data processing runs simultaneously with data collection using a choice of data reduction wrappers for integration and scaling of newly collected data, with an option for merging with pre-existing data. Data are processed separately if collected from multiple sites on a crystal or from multiple crystals, then scaled and merged. Results from all strategy and processing calculations are displayed in relevant tabs of JBluIce.« less

  12. A Successful Synthesis of the CoCrFeNiAl{sub 0.3} Single-Crystal, High-Entropy Alloy by Bridgman Solidification

    SciTech Connect (OSTI)

    Ma, S. G.; Zhang, S. F.; Gao, M. C.; Liaw, P. K.; Zhang, Y.

    2013-12-01

    For the first time, a face-centered-cubic, single-crystal CoCrFeNiAl{sub 0.3} (designated as Al0.3), high-entropy alloy (HEA) was successfully synthesized by the Bridgman solidification (BS) method, at an extremely low withdrawal velocity through a constant temperature gradient, for which it underwent two BS steps. Specially, at the first BS step, the alloy sample underwent several morphological transitions accompanying the crystal growth from the melt. This microstructure evolves from as-cast dendrites, to equiaxed grains, and then to columnar crystals, and last to the single crystal. In particular, at the equiaxed-grain region, some visible annealing twins were observed, which indicates a low stacking fault energy of the Al0.3 alloy. Although a body-centered- cubic CoCrFeNiAl (Al1) HEA was also prepared under the same conditions, only a single columnar-crystal structure with instinctively preferential crystallographic orientations was obtained by the same procedure. A similar morphological transition from dendrites to equiaxed grains occurred at the equiaxed-grain region in Al1 alloy, but the annealing twins were not observed probably because a higher Al addition leads to a higher stacking fault energy for this alloy.

  13. Time-Resolved Femtosecond Laser-Induced Desorption from Magnesium Oxide and Lithium Fluoride Single Crystals

    SciTech Connect (OSTI)

    Beck, Kenneth M. ); Joly, Alan G. ); Hess, Wayne P. )

    1999-12-01

    We have used the pump-probe technique to measure the photostimulated positive ion yield, as a function of time-delay between two sub-threshold femtosecond laser pulses. We find the ion yield, from 265 nm femtosecond irradiated MgO and LiF, depends critically on the laser pulse delay two-pulse experiments. For example, single pulse excitation of MgO produces a variety of ions including Mg+, MgO+, and H+. If the femtosecond laser pulse is split into two sub-threshold beams and then re-combined with a variable time delay, the Mg+ desorption yield displays three distinct lifetimes and persists for laser delays of over 100 picoseconds. A pulse delay of only 500 femtoseconds nearly eliminates ion desorption except for Mg+. In contrast, for LiF the majority of Li+ yields decays rapidly, largely within the femtosecond pulse duration. However, a weak but measurable decay component of approximately 2 picoseconds is indicated. We hypothesize the nonresonant two-photon excitation contributes to the ultrafast desorption mechanism through the creation of electron/hole pairs and allows direct observation of the surface electron/hole pair trapping dynamics and measurement of the surface free carrier lifetime.

  14. Station for X-ray structural analysis of materials and single crystals (including nanocrystals) on a synchrotron radiation beam from the wiggler at the Siberia-2 storage ring

    SciTech Connect (OSTI)

    Kheiker, D. M. Kovalchuk, M. V.; Korchuganov, V. N.; Shilin, Yu. N.; Shishkov, V. A.; Sulyanov, S. N.; Dorovatovskii, P. V.; Rubinsky, S. V.; Rusakov, A. A.

    2007-11-15

    The design of the station for structural analysis of polycrystalline materials and single crystals (including nanoobjects and macromolecular crystals) on a synchrotron radiation beam from the superconducting wiggler of the Siberia-2 storage ring is described. The wiggler is constructed at the Budker Institute of Nuclear Physics of the Siberian Division of the Russian Academy of Sciences. The X-ray optical scheme of the station involves a (1, -1) double-crystal monochromator with a fixed position of the monochromatic beam and a sagittal bending of the second crystal, segmented mirrors bent by piezoelectric motors, and a (2{theta}, {omega}, {phi}) three-circle goniometer with a fixed tilt angle. Almost all devices of the station are designed and fabricated at the Shubnikov Institute of Crystallography of the Russian Academy of Sciences. The Bruker APEX11 two-dimensional CCD detector will serve as a detector in the station.

  15. Ferroelectric domain structures in <001>-oriented K{sub 0.15}Na{sub 0.85}NbO{sub 3} lead-free single crystal

    SciTech Connect (OSTI)

    Chen, Yan; Wong, Chi-Man; Yau, Hei-Man; Dai, Jiyan; Deng, Hao; Luo, Haosu; Wang, Danyang; Yan, Zhibo; Chan, Helen L. W.

    2015-03-15

    In this work, ferroelectric domain structures of <001 >-oriented K{sub 0.15}Na{sub 0.85}NbO{sub 3} single crystal are characterized. Transmission electron microscopy (TEM) observation revealed high-density of laminate domain structures in the crystal and the lattices of the neighboring domains are found to be twisted in a small angle. Superlattice diffraction spots of 1/2 (eeo) and 1/2 (ooe) in electron diffraction patterns are observed in the crystal, revealing the a{sup +}a{sup +}c{sup −} tilting of oxygen octahedral in the perovskite structure. The piezoresponse of domains and in-situ poling responses of K{sub 0.15}Na{sub 0.85}NbO{sub 3} crystal are observed by piezoresponse force microscopy (PFM), and the results assure its good ferroelectric properties.

  16. Resolution of the discrepancy between the variation of the physical properties of Ce1-xYbxCoIn5 single crystals and thin films with Yb composition

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jang, S.; White, B. D.; Lum, I. K.; Kim, H.; Tanatar, M. A.; Straszheim, W. E.; Prozorov, R.; Keiber, T.; Bridges, F.; Shu, L.; et al

    2014-11-18

    The extraordinary electronic phenomena including an Yb valence transition, a change in Fermi surface topology, and suppression of the heavy fermion quantum critical field at a nominal concentration x≈0.2 have been found in the Ce1-xYbxCoIn5 system. These phenomena have no discernable effect on the unconventional superconductivity and normal-state non-Fermi liquid behaviour that occur over a broad range of x up to ~0.8. However, the variation of the coherence temperature T* and the superconducting critical temperature Tc with nominal Yb concentration x for bulk single crystals is much weaker than that of thin films. To determine whether differences in the actualmore » Yb concentration of bulk single crystals and thin film samples might be responsible for these discrepancies, we employed Vegard’s law and the spectroscopically determined values of the valences of Ce and Yb as a function of x to determine the actual composition xact of bulk single crystals. This analysis is supported by energy-dispersive X-ray spectroscopy, wavelength-dispersive X-ray spectroscopy, and transmission X-ray absorption edge spectroscopy measurements. The actual composition xact is found to be about one-third of the nominal concentration x up to x~0.5, and resolves the discrepancy between the variation of the physical properties of Ce1-xYbxCoIn5 single crystals and thin films with Yb concentration.« less

  17. Development and turbine engine performance of three advanced rhenium containing superalloys for single crystal and directionally solidified blades and vanes

    SciTech Connect (OSTI)

    Broomfield, R.W.; Ford, D.A.; Bhangu, J.K.; Thomas, M.C.; Frasier, D.J.; Burkholder, P.S.; Harris, K.; Erickson, G.L.; Wahl, J.B.

    1998-07-01

    Turbine inlet temperatures over the next few years will approach 1,650 C (3,000 F) at maximum power for the latest large commercial turbofan engines, resulting in high fuel efficiency and thrust levels approaching 445 kN (100,000 lbs). High reliability and durability must be intrinsically designed into these turbine engines to meet operating economic targets and ETOPS certification requirements. This level of performance has been brought about by a combination of advances in air cooling for turbine blades and vanes, design technology for stresses and airflow, single crystal and directionally solidified casting process improvements, and the development and use of rhenium (Re) containing high {gamma}{prime} volume fraction nickel-base superalloys with advanced coatings, including full-airfoil ceramic thermal barrier coatings. Re additions to cast airfoil superalloys not only improves creep and thermo-mechanical fatigue strength, but also environmental properties including coating performance. Re dramatically slows down diffusion in these alloys at high operating temperatures. A team approach has been used to develop a family of two nickel-base single crystal alloys (CMSX-4 containing 3% Re and CMSX-10 containing 6% Re) and a directionally solidified, columnar grain nickel-base alloy (CM 186 LC containing 3% Re) for a variety of turbine engine applications. A range of critical properties of these alloys is reviewed in relation to turbine component engineering performance through engine certification testing and service experience. Industrial turbines are now commencing to use this aero developed turbine technology in both small and large frame units in addition to aero-derivative industrial engines. These applications are demanding, with high reliability required for turbine airfoils out to 25,000 hours, with perhaps greater than 50% of the time spent at maximum power. Combined cycle efficiencies of large frame industrial engines are scheduled to reach 60% in the US

  18. Synthesis, spectral characterization, and single crystal structure studies of (2-nitro-ethene-1,1-diyl)-bis-((4-isopropyl-benzyl)sulfane)

    SciTech Connect (OSTI)

    Sakthikumar, L.; Mahalakshmy, R.; Bhargavi, G.; Srinivasan, N.

    2015-12-15

    The title compound (2-nitro-ethene-1,1-diyl)-bis-(4-isopropylbenzyl)sulfane) (5), was synthesised using a two step process. The structure of the product (5) was established by UV, FT-IR, {sup 1}H NMR, {sup 13}C NMR, C,H,N analysis, LC-MS and single crystal X-ray diffraction analysis. The single crystal of the title compound (5) was crystallized in Monoclinic with the space group of P21/c. The crystal exhibit the following unit cell parameters a = 12.8165(18), b = 6.1878(6), c = 27.082(4) Å, β = 90.705(17)°, V = 2147.6(5) A{sup 3}, Z = 4, D{sub x} = 1.242 Mg/m{sup 3} and the molecular formula of C{sub 22}H{sub 27}N{sub 1}O{sub 2}S{sub 2} was found. The final R value was 0.0776. The crystal structure is stabilized by an interesting intramolecular push and pull five membered electrocyclic interaction between the O1–N1–C2–C1–S1- and via the intermolecular H-bonding interaction between C2–H2···O2.

  19. Phase coexistence and transformations in field-cooled ternary piezoelectric single crystals near the morphotropic phase boundary

    SciTech Connect (OSTI)

    Luo, Chengtao; Wang, Yaojin Wang, Zhiguang; Ge, Wenwei; Li, Jiefang; Viehland, D.; Luo, Haosu

    2014-12-08

    Structural phase transformations in (100)-oriented Pb(In{sub 1/2}Nb{sub 1/2})O{sub 3}-Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} single crystals have been investigated by X-ray diffraction. A cubic (C) → tetragonal (T) → monoclinic-C (M{sub C}) transformation sequence was observed in the field-cooled condition. Two phase coexistence regions of C + T and T + M{sub C} were found. In addition to an increase in the C → T phase transition temperature and a decrease of the T → M{sub C} one, a broadening of the coexistence regions was also found with increasing field. This broadening can be explained by the presence of polar nano regions within the C, T, and M{sub C} phase regions.

  20. AN INVESTIGATION INTO THE MECHANICS OF SINGLE CRYSTAL TURBINE BLADES WITH A VIEW TOWARDS ENHANCING GAS TURBINE EFFICIENCY

    SciTech Connect (OSTI)

    K.R. Rajagopal; I.J. Rao

    2006-05-05

    The demand for increased efficiency of gas turbines used in power generation and aircraft applications has fueled research into advanced materials for gas turbine blades that can withstand higher temperatures in that they have excellent resistance to creep. The term ''Superalloys'' describes a group of alloys developed for applications that require high performance at elevated temperatures. Superalloys have a load bearing capacity up to 0.9 times their melting temperature. The objective of the investigation was to develop a thermodynamic model that can be used to describe the response of single crystal superalloys that takes into account the microstructure of the alloy within the context of a continuum model. Having developed the model, its efficacy was to be tested by corroborating the predictions of the model with available experimental data. Such a model was developed and it is implemented in the finite element software ABAQUS/STANDARD through a user subroutine (UMAT) so that the model can be used in realistic geometries that correspond to turbine blades.

  1. Thermal chemistry of copper(I)-N,N '-di-sec-butylacetamidinate on Cu(110) single-crystal surfaces

    SciTech Connect (OSTI)

    Ma Qiang; Zaera, Francisco; Gordon, Roy G.

    2012-01-15

    The surface chemistry of copper(I)-N,N'-di-sec-butylacetamidinate on Cu(110) single-crystal surfaces has been characterized under ultrahigh vacuum by temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy. A series of thermal stepwise conversions were identified, starting with the partial dissociative adsorption of the copper acetamidinate dimers into a mixture of monomers and dimers on the surface. An early dissociation of a C-N bond leads to the production of N-sec-butylacetamidine, which is detected in TPD experiments in three temperature regimes, the last one centered around 480 K. Butene, and a small amount of butane, is also detected above approximately 500 K, and hydrogen production, an indication of dehydrogenation of surface fragments, is observed at 460, 550 and 670 K. In total, only about 10% of the initial copper(I)-N,N'-di-sec-butylacetamidinate adsorbed monolayer decomposes, and only about {approx}3% of carbon is left behind on the surface after heating to high temperatures. The implications of this surface chemistry to the design of chemical film growth processes using copper acetamidinates as precursors are discussed.

  2. Single crystal neutron diffraction study of the magnetic structure of TmNi{sub 2}B{sub 2}C

    SciTech Connect (OSTI)

    Sternlieb, B.; Shapiro, S.; Stassis, C.; Goldman, A.I.; Canfield, P.

    1997-02-01

    Neutron diffraction techniques have been used to study the magnetic structure of single crystals of the magnetic superconductor (T{sub c} {congruent} 11K) TmNi{sub 2}B{sub 2}C. We find that below approximately 1.5K the magnetic moments order in an incommensurate spin wave with propagation vector q{sub m} = q{sub m} (a* +b*) (or q{sub m} = q{sub m} (a* + b*)) with q{sub m} = 0.094 {+-} 0.001. The spin wave is transverse with the moments aligned along the c-axis, and the observation of relatively intense higher order harmonics shows that the modulation is not purely sinusoidal but considerably squared. This incommensurate magnetic structure, which coexists with superconductivity below T{sub N} {congruent} 1.5K, is quite different from those observed in the magnetic superconductors HoNi{sub 2}B{sub 2}C and ErNi{sub 2}B{sub 2}C. The origin of diffraction peaks observed in scans parallel to a* is briefly discussed.

  3. Dentritic morphology and microsegregation in directionally solidified superalloy, PWA-1480, single crystal: Effect of gravity; center director's discretionary fund report

    SciTech Connect (OSTI)

    Tewari, S.N.; Kumar, M.V.; Lee, J.E.; Curreri, P.A.

    1990-11-01

    Primary dendrite spacings, secondary dendrite spacings, and microsegregation have been examined in PWA-1480 single crystal specimens which were directionally solidified during parabolic maneuvers on the KC-135 aircraft. Experimentally observed growth rate and thermal gradient dependence of primary dendrite spacings are in good agreement with predictions from dendrite growth models for binary alloys. Secondary dendrite coarsening kinetics show a reasonable fit with the predictions from an analytical model proposed by Kirkwood for a binary alloy. The partition coefficients of tantalum, titanium, and aluminum are observed to be less than unity, while that for tungsten and cobalt are greater than unity. This is qualitatively similar to the nickel base binaries. Microsegregation profiles experimentally observed for PWA-1480 superalloy show a good fit with Bower, Brody, and Flemings model developed for binary alloys. Transitions in gravity levels do not appear to affect primary dendrite spacings. A trend of decreased secondary arm spacings with transition from high gravity to the low gravity period was observed at a growth speed of 0.023 cm s(exp -1). However, definite conclusions can only be drawn by experiments at lower growth speeds which make it possible to examine the side-branch coarsening kinetics over a longer duration. Such experiments, not possible due to the insufficient low-gravity time of the KC-135, may be carried out in the low-gravity environment of space.

  4. SU-F-BRE-02: Characterization of a New Commercial Single Crystal Diamond Detector in Photon, Electron and Proton Beams

    SciTech Connect (OSTI)

    Akino, Y; Das, I

    2014-06-15

    Purpose: Diamond detectors even with superior characteristics have become obsolete due to poor design, selection of crystal and cost. Recently, microDiamond using synthetic single crystal diamond detector (SCDD) is commercially available which is characterized in various radiation beams in this study. Methods: The characteristics of a commercial SCDD model 60019 (PTW) to a 6- and 15-MV photon beams, 6- and 20-MeV electron beams, and 208 MeV proton beams were investigated and compared to the pre-characterized detectors: TN31010 (0.125 cm{sup 3}) and TN30006 (pinpoint) ionization chambers (PTW), EDGE detector (Sun Nuclear Corp), and SFD Stereotactic Dosimetry Diode Detector (IBA). The depth-dose and profiles data were collected for various field sizes and depths. The dose linearity and dose rate dependency were also evaluated. To evaluate the effects of the preirradiation, the diamond detector which had not been irradiated on the day was set up in the water tank and the response to 100 MU was measured every 20 s. The temperature dependency was tested for the range of 4–60 °C. Angular dependency was evaluated in water phantom by rotating the SCDD. Results: For all radiation types and field sizes, the depth-dose data of the diamond chamber showed identical curve to those of ionization chambers. The profile of the diamond detector was very similar to those of the Edge and SFD detectors, although the 0.125 cm{sup 3} and pinpoint chambers showed averaging effects in the penumbrae region. The temperature dependency was within 0.7% in the range of 4–41°C. A dose of 900 cGy and 1200 cGy were needed to stabilize the chamber to the level within 0.5% and 0.2%, respectively. Conclusion: The type 60019 SCDD detector showed suitable characteristics for depth-dose and profile measurements for wide range of field sizes. However, at least 1000 cGy of pre-irradiation is needed for accurate measurements.

  5. Bridgman Growth of Large SrI2:Eu2+ Single Crystals: A High-performance Scintillator for Radiation Detection Applications

    SciTech Connect (OSTI)

    Boatner, Lynn A; Ramey, Joanne Oxendine; Kolopus, James A; Hawrami, Rastgo; Higgins, William; Van Loef, Edgar; Glodo, J.; Shah, Kanai; Bhattacharya, P.; Tupitsyn, E; Groza, Michael; Burger, Arnold

    2013-01-01

    Single-crystal strontium iodide (SrI2) doped with relatively high levels (e.g., 3 - 6 %) of Eu2+ exhibits characteristics that make this material superior, in a number of respects, to other scintillators that are currently used for radiation detection. Specifically, SrI2:Eu2+ has a light yield that is significantly higher than LaBr3:Ce3+ -a currently employed commercial high-performance scintillator. Additionally, SrI2:Eu2+ is characterized by an energy resolution as high as 2.6% at the 137Cs gamma-ray energy of 662 keV, and there is no radioactive component in SrI2:Eu2+ - unlike LaBr3:Ce3+ that contains 138La. The Ce3+-doped LaBr3 decay time is, however, faster (30 nsec) than the 1.2 sec decay time of SrI2:Eu2+. Due to the relatively low melting point of strontium iodide (~515 oC), crystal growth can be carried out in quartz crucibles by the vertical Bridgman technique. Materials-processing and crystal-growth techniques that are specific to the Bridgman growth of europium-doped strontium iodide scintillators are described here. These techniques include the use of a porous quartz frit to physically filter the molten salt from a quartz antechamber into the Bridgman growth crucible and the use of a bent or bulb grain selector design to suppress multiple grain growth. Single crystals of SrI2:Eu2+ scintillators with good optical quality and scintillation characteristics have been grown in sizes up to 5.0 cm in diameter by applying these techniques. Other aspects of the SrI2:Eu2+ crystal-growth methods and of the still unresolved crystal-growth issues are described here.

  6. Radiation damage by light- and heavy-ion bombardment of single-crystal LiNbO?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Huang, Hsu-Cheng; Zhang, Lihua; Malladi, Girish; Dadap, Jerry I.; Manandhar, Sandeep; Kisslinger, Kim; Vemuri, Rama Sesha R.; Shutthanandan, Vaithiyalingam; Bakhru, Hassaram; Osgood, Jr., Richard M.

    2015-04-14

    In this work, a battery of analytical methods including in situ RBS/C, confocal micro-Raman, TEM/STEM, EDS, AFM, and optical microscopy were used to provide a comparative investigation of light- and heavy-ion radiation damage in single-crystal LiNbO?. High (~MeV) and low (~100s keV) ion energies, corresponding to different stopping power mechanisms, were used and their associated damage events were observed. In addition, sequential irradiation of both ion species was also performed and their cumulative depth-dependent damage was determined. It was found that the contribution from electronic stopping by high-energy heavy ions gave rise to a lower critical fluence for damage formationmorethan for the case of low-energy irradiation. Such energy-dependent critical fluence of heavy-ion irradiation is two to three orders of magnitude smaller than that for the case of light-ion damage. In addition, materials amorphization and collision cascades were seen for heavy-ion irradiation, while for light ion, crystallinity remained at the highest fluence used in the experiment. The irradiation-induced damage is characterized by the formation of defect clusters, elastic strain, surface deformation, as well as change in elemental composition. In particular, the presence of nanometric-scale damage pockets results in increased RBS/C backscattered signal and the appearance of normally forbidden Raman phonon modes. The location of the highest density of damage is in good agreement with SRIM calculations. (author)less

  7. From micro- to nano-scale molding of metals : size effect during molding of single crystal Al with rectangular strip punches.

    SciTech Connect (OSTI)

    Chen, K.; Meng, W. J.; Mei, F.; Hiller, J.; Miller, D. J. (Materials Science Division); (Louisiana State Univ.); (Enervana Tech. LLC)

    2011-02-01

    A single crystal Al specimen was molded at room temperature with long, rectangular, strip diamond punches. Quantitative molding response curves were obtained at a series of punch widths, ranging from 5 {micro}m to 550 nm. A significant size effect was observed, manifesting itself in terms of significantly increasing characteristic molding pressure as the punch width decreases to 1.5 {micro}m and below. A detailed comparison of the present strip punch molding results was made with Berkovich pyramidal indentation on the same single crystal Al specimen. The comparison reveals distinctly different dependence of the characteristic pressure on corresponding characteristic length. The present results show the feasibility of micro-/nano-scale compression molding as a micro-/nano-fabrication technique, and offer an experimental test case for size-dependent plasticity theories.

  8. A nitrogen doped low-dislocation density free-standing single crystal diamond plate fabricated by a lift-off process

    SciTech Connect (OSTI)

    Mokuno, Yoshiaki Kato, Yukako; Tsubouchi, Nobuteru; Chayahara, Akiyoshi; Yamada, Hideaki; Shikata, Shinichi

    2014-06-23

    A nitrogen-doped single crystal diamond plate with a low dislocation density is fabricated by chemical vapor deposition (CVD) from a high pressure high temperature synthetic type IIa seed substrate by ion implantation and lift-off processes. To avoid sub-surface damage, the seed surface was subjected to deep ion beam etching. In addition, we introduced a nitrogen flow during the CVD step to grow low-strain diamond at a relatively high growth rate. This resulted in a plate with low birefringence and a dislocation density as low as 400?cm{sup ?2}, which is the lowest reported value for a lift-off plate. Reproducing this lift-off process may allow mass-production of single crystal CVD diamond plates with low dislocation density and consistent quality.

  9. Ultrafast free-carrier dynamics in Cu{sub 2}ZnSnS{sub 4} single crystals studied using femtosecond time-resolved optical spectroscopy

    SciTech Connect (OSTI)

    Phuong, L. Q.; Kanemitsu, Y.; Okano, M.; Yamada, Y.; Yamashita, G.; Morimoto, T.; Nagai, M.; Ashida, M.; Nagaoka, A.; Yoshino, K.

    2014-12-08

    We studied the dynamics of photogenerated carriers in Cu{sub 2}ZnSnS{sub 4} (CZTS) single crystals using femtosecond transient reflectivity (TR) and optical pump-THz probe transient absorption (THz-TA) spectroscopy. The TR and THz-TA decay dynamics consistently showed that free carriers have long lifetimes of up to a few nanoseconds. The excitation-photon-energy-dependent TR measurements revealed a slow picosecond energy relaxation of free carriers to the band edge in CZTS. The relaxation and recombination dynamics of free carriers were affected by nonradiative recombinations at the surface. Our results revealed a global feature of energy relaxation and recombination processes of free carriers in CZTS single crystals.

  10. A 350 mK, 9 T scanning tunneling microscope for the study of superconducting thin films on insulating substrates and single crystals

    SciTech Connect (OSTI)

    Kamlapure, Anand; Saraswat, Garima; Ganguli, Somesh Chandra; Bagwe, Vivas; Raychaudhuri, Pratap; Pai, Subash P.

    2013-12-15

    We report the construction and performance of a low temperature, high field scanning tunneling microscope (STM) operating down to 350 mK and in magnetic fields up to 9 T, with thin film deposition and in situ single crystal cleaving capabilities. The main focus lies on the simple design of STM head and a sample holder design that allows us to get spectroscopic data on superconducting thin films grown in situ on insulating substrates. Other design details on sample transport, sample preparation chamber, and vibration isolation schemes are also described. We demonstrate the capability of our instrument through the atomic resolution imaging and spectroscopy on NbSe{sub 2} single crystal and spectroscopic maps obtained on homogeneously disordered NbN thin film.

  11. Giant room-temperature barocaloric effect and pressure-mediated electrocaloric effect in BaTiO{sub 3} single crystal

    SciTech Connect (OSTI)

    Liu, Yang; Wei, Jie; Janolin, Pierre-Eymeric; Infante, Ingrid C.; Dkhil, Brahim E-mail: xlou03@mail.xjtu.edu.cn; Lou, Xiaojie E-mail: xlou03@mail.xjtu.edu.cn

    2014-04-21

    Barocaloric effect in BaTiO{sub 3} single crystal is studied by a thermodynamic phenomenological model. It is demonstrated that a giant barocaloric effect can be achieved near room temperature with an adiabatic temperature change of more than 3 K and a temperature span about 50 K. As expected, the electrocaloric peak can be shifted towards room temperature by pressure. However, a slight reduction of the electrocaloric peak is found in contrast to relaxor ferroelectrics and LiNbO{sub 3}. We believe that our findings could open a potential route by combining the barocaloric effect and pressure-mediated electrocaloric effect in BaTiO{sub 3} single crystal for cooling devices.

  12. Anisotropic superconducting and normal state magnetic properties of single crystals of RNi*2*B*2*C compounds (R = Y, Gd, Dy, Ho, Er, and Tm)

    SciTech Connect (OSTI)

    Cho, B.

    1995-11-01

    The interaction of superconductivity with magnetism has been one of the most interesting and important phenomena in solid state physics since the 1950`s when small amounts of magnetic impurities were incorporated in superconductors. The discovery of the magnetic superconductors RNi{sub 2}B{sub 2}C (R = rare earth, Y) offers a new system to study this interaction. The wide ranges of superconducting transition (T{sub c}) and antiferromagnetic (AF) ordering temperatures (T{sub N}) (0 K {le} T{sub c} {le} 16 K, 0 K {le} T{sub N} {le} 20 K) give a good opportunity to observe a variety of interesting phenomena. Single crystals of high quality with appropriate size and mass are crucial in examining the anisotropic intrinsic properties. Single crystals have been grown successfully by an unusual high temperature flux method and characterized thoroughly by X-ray, electrical transport, magnetization, neutron scattering, scanning electron microscopy, and other measurements.

  13. Pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} on amorphous dielectric layers towards monolithic 3D photonic integration

    SciTech Connect (OSTI)

    Li, Haofeng; Brouillet, Jeremy; Wang, Xiaoxin; Liu, Jifeng

    2014-11-17

    We demonstrate pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} crystallized on amorphous layers at <450 °C towards 3D Si photonic integration. We developed two approaches to seed the lateral single crystal growth: (1) utilize the Gibbs-Thomson eutectic temperature depression at the tip of an amorphous GeSn nanotaper for selective nucleation; (2) laser-induced nucleation at one end of a GeSn strip. Either way, the crystallized Ge{sub 0.89}Sn{sub 0.11} is dominated by a single grain >18 μm long that forms optoelectronically benign twin boundaries with others grains. These pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} patterns are suitable for monolithic 3D integration of active photonic devices on Si.

  14. Electron-hole diffusion lengths >175 μm in solution-grown CH3NH3PbI3 single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dong, Qingfeng; Fang, Yanjun; Shao, Yuchuan; Mulligan, Padhraic; Qiu, Jie; Cao, Lei; Huang, Jinsong

    2015-02-27

    Long, balanced electron and hole diffusion lengths greater than 100 nanometers in the polycrystalline organolead trihalide compound CH3NH3PbI3 are critical for highly efficient perovskite solar cells. We found that the diffusion lengths in CH3NH3PbI3 single crystals grown by a solution-growth method can exceed 175 micrometers under 1 sun (100 mW cm–2) illumination and exceed 3 millimeters under weak light for both electrons and holes. The internal quantum efficiencies approach 100% in 3-millimeter-thick single-crystal perovskite solar cells under weak light. These long diffusion lengths result from greater carrier mobility, longer lifetime, and much smaller trap densities in the single crystals thanmore » in polycrystalline thin films. As a result, the long carrier diffusion lengths enabled the use of CH3NH3PbI3 in radiation sensing and energy harvesting through the gammavoltaic effect, with an efficiency of 3.9% measured with an intense cesium-137 source.« less

  15. Electron-hole diffusion lengths >175 μm in solution-grown CH3NH3PbI3 single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dong, Qingfeng; Fang, Yanjun; Shao, Yuchuan; Mulligan, Padhraic; Qiu, Jie; Cao, Lei; Huang, Jinsong

    2015-02-27

    Long, balanced electron and hole diffusion lengths greater than 100 nanometers in the polycrystalline organolead trihalide compound CH3NH3PbI3 are critical for highly efficient perovskite solar cells. We found that the diffusion lengths in CH3NH3PbI3 single crystals grown by a solution-growth method can exceed 175 micrometers under 1 sun (100 mW cm–2) illumination and exceed 3 millimeters under weak light for both electrons and holes. The internal quantum efficiencies approach 100% in 3-millimeter-thick single-crystal perovskite solar cells under weak light. These long diffusion lengths result from greater carrier mobility, longer lifetime, and much smaller trap densities in the single crystals thanmore »in polycrystalline thin films. As a result, the long carrier diffusion lengths enabled the use of CH3NH3PbI3 in radiation sensing and energy harvesting through the gammavoltaic effect, with an efficiency of 3.9% measured with an intense cesium-137 source.« less

  16. Study of the internal structure of lithium fluoride single crystal by laboratory X-ray topo-tomography

    SciTech Connect (OSTI)

    Zolotov, D. A. Buzmakov, A. V.; Asadchikov, V. E.; Voloshin, A. E.; Shkurko, V. N.; Smirnov, I. S.

    2011-05-15

    Defects in a synthetic LiF crystal have been studied by X-ray topo-tomography on laboratory X-ray sources with a spatial resolution of {approx}10 {mu}m. An algebraic reconstruction method was applied to reconstruct the defect 3D structure of the crystal based on the diffraction data. The results presented in this study are in good agreement with the topographic data obtained by the Lang method.

  17. Intermolecular effects on the radiogenic formation of electron-capture phosphorus-centered radicals. A single-crystal ESR study of diastereoisomeric precursors

    SciTech Connect (OSTI)

    Aagaard, O.M.; Janssen, R.A.J.; de Waal, B.F.M.; Buck, H.M. )

    1990-01-31

    ESR experiments on X-irradiated single crystals of the 2R,4S,5R and 2S,4S,5R diastereoisomers of 2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine 2-sulfide reveal that the yield of radiogenic electron-capture reactions in the solid state strongly depends on intermolecular interactions in the crystal. In the present case a high yield of P-Cl three-electron-bond phosphoranyl radical anions is found in crystals of the 2R,4S,5R isomer, whereas no radical formation can be detected for the 2S,4S,5R isomer. An analysis of nonbonded interactions with neighboring molecules reveals that the geometry relaxation necessary for the radical stabilization is easily accommodated in crystals of the 2R,4S,SR isomer but not in the 2S,4S,5R isomer, explaining the observed difference in electron-capture efficiency. Experiments on radical formation in a MeTHF host matrix give further insight into the importance of the environment on radiogenic radical formation. The possible concurrent effect of the matrix on the electronic configuration and spin density distribution of the resulting phosphoranyl radical is discussed.

  18. Preparation and properties of evaporated CdTe films compared with single crystal CdTe. Progress report No. 2, February 1-April 30, 1981

    SciTech Connect (OSTI)

    Bube, R H

    1981-01-01

    The design, construction and testing of the hot-wall vacuum evaporation system is proceeding on schedule. The vacuum system, a Varian 3118 diffusion pump system, has been installed and tested. A calculation of the optimum possible efficiency for an n-p CdTe homojunction indicates a value of 14%. A complete background is given on the growth of over fifty CdTe single crystals at Stanford, the last four of which were grown as part of this program. Use of crystal regrowth and vibration during growth both increase crystal quality. Higher electrical activity of phosphorus acceptors in CdTe is achieved when 0.1% excess Te is used in place of 0.5% excess Te. Careful characterization of boules grown for this program are underway, using Hall effect or capacitance-voltage data on selected samples. Initial investigation of the properties of grain boundaries in p-type CdTe : P crystals indicates a grain boundary height of 0.44 eV unaffected by illumination. These results suggest that grain boundaries are more strongly pinned in p-type than in n-type CdTe.

  19. Epitaxial growth of fcc-Co{sub x}Ni{sub 100-x} thin films on MgO(110) single-crystal substrates

    SciTech Connect (OSTI)

    Ohtake, Mitsuru; Nukaga, Yuri; Sato, Yoichi; Futamoto, Masaaki; Kirino, Fumiyoshi

    2009-12-15

    Co{sub x}Ni{sub 100-x} (x=100, 80, 20, 0 at. %) epitaxial thin films were prepared on MgO(110) single-crystal substrates heated at 300 deg. C by ultrahigh vacuum molecular beam epitaxy. The growth mechanism is discussed based on lattice strain and crystallographic defects. CoNi(110) single-crystal films with a fcc structure are obtained for all compositions. Co{sub x}Ni{sub 100-x} film growth follows the Volmer-Weber mode. X-ray diffraction analysis indicates that the out-of-plane and the in-plane lattice spacings of the Co{sub x}Ni{sub 100-x} films are in agreement within +-0.5% with the values of the respective bulk Co{sub x}Ni{sub 100-x} crystals, suggesting that the strain in the film is very small. High-resolution cross-sectional transmission microscopy shows that an atomically sharp boundary is formed between a Co(110){sub fcc} film and a MgO(110) substrate, where periodical misfit dislocations are preferentially introduced in the film at the Co/MgO interface. The presence of such periodical misfit dislocations relieves the strain caused by the lattice mismatch between the film and the substrate.

  20. Atomic layer deposition of epitaxial layers of anatase on strontium titanate single crystals: Morphological and photoelectrochemical characterization

    SciTech Connect (OSTI)

    Kraus, Theodore J.; Nepomnyashchii, Alexander B.; Parkinson, B. A.

    2015-01-15

    Atomic layer deposition was used to grow epitaxial layers of anatase (001) TiO{sub 2} on the surface of SrTiO{sub 3} (100) crystals with a 3% lattice mismatch. The epilayers grow as anatase (001) as confirmed by x-ray diffraction. Atomic force microscope images of deposited films showed epitaxial layer-by-layer growth up to about 10 nm, whereas thicker films, of up to 32 nm, revealed the formation of 2–5 nm anatase nanocrystallites oriented in the (001) direction. The anatase epilayers were used as substrates for dye sensitization. The as received strontium titanate crystal was not sensitized with a ruthenium-based dye (N3) or a thiacyanine dye (G15); however, photocurrent from excited state electron injection from these dyes was observed when adsorbed on the anatase epilayers. These results show that highly ordered anatase surfaces can be grown on an easily obtained substrate crystal.

  1. Raman spectroscopic studies of Nd{sub 0.75}Sm{sub 0.25}GaO{sub 3} single crystals

    SciTech Connect (OSTI)

    Nithya, R. Ravindran, T. R.; Daniel, D. J.

    2015-06-24

    Single crystals of Nd{sub 1-x}Sm{sub x}GaO{sub 3} (x= 0 and 0.25) were grown by a four mirror IR image furnace using floating zone technique. The crystals are characterized by X-ray diffraction and Raman spectroscopic measurements. NGO adopts orthorhombic structure with Pbnm symmetry and samarium substituted compound also exhibited the same structure as that of the pristine compound without secondary phases. Polarized Raman spectra are measured at ambient temperature in a back scattering geometry. Spectra exhibit low intensity first-order Raman bands. In addition, several high intensity second-order Raman bands have been observed in the frequency range 2000 to 4000 cm{sup −1}.

  2. Effect of proton irradiation on superconductivity in optimally doped BaFe2(As1-xPx)2 single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Smylie, M. P.; Leroux, M.; Fang, L.; Chmaissem, Omar H.; Claus, H.; Kayani, A.; Snezhko, A.; Welp, U.; Kwok, W. -K.; Mishra, V.; et al

    2016-03-10

    Irradiation with 4 MeV protons was used to systematically introduce defects in single crystals of the iron-arsenide superconductor BaFe2(As1-xPx)2, x = 0.33. The effect of disorder on the low-temperature behavior of the London penetration depth λ(T) and transition temperature Tc was investigated. In nearly optimally doped samples with Tc ~ 29 K, signatures of a superconducting gap with nodes were observed. Contrary to previous reports on electron-irradiated crystals, we do not see a disorder-driven lifting of accidental nodes, and we observe that proton-induced defects are weaker pair breakers than electron-induced defects. Lastly, we attribute our findings to anisotropic electron scatteringmore » caused by proton irradiation defects.« less

  3. Insulating and metallic spin glass in KxFe2-δ-yNiySe2 (0.06 ≤ y ≤ 1.44 ) single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ryu, Hyejin; Abeykoon, Milinda; Wang, Kefeng; Lei, Hechang; Lazarevic, N.; Warren, J. B.; Bozin, E. S.; Popovic, Z. V.; Petrovic, C.

    2015-05-04

    We report electron doping effects by Ni in KxFe2-δ-yNiySe₂ (0.06 ≤ y ≤ 1.44) single crystal alloys. A rich ground state phase diagram is observed. Thus, a small amount of Ni (~ 4%) suppressed superconductivity below 1.8 K, inducing insulating spin glass magnetic ground state for higher Ni content. With further Ni substitution, metallic resistivity is restored. For high Ni concentration in the lattice the unit cell symmetry is high symmetry I4/mmm with no phase separation whereas both I4/m + I4/mmm space groups were detected in the phase separated crystals when concentration of Ni < Fe. The absence of superconductivitymore » coincides with the absence of crystalline Fe vacancy order.« less

  4. In situ dehydration behavior of zeolite-like pentagonite: A single-crystal X-ray study

    SciTech Connect (OSTI)

    Danisi, Rosa Micaela; Armbruster, Thomas; Lazic, Biljana

    2013-01-15

    The structural modifications upon heating of pentagonite, Ca(VO)(Si{sub 4}O{sub 10}){center_dot}4H{sub 2}O (space group Ccm2{sub 1}, a=10.3708(2), b=14.0643(2), c=8.97810(10) A, V=1309.53(3) A{sup 3}) were investigated by in situ temperature dependent single-crystal X-ray structure refinements. Diffraction data of a sample from Poona district (India) have been measured in steps of 25 up to 250 Degree-Sign C and in steps of 50 Degree-Sign C between 250 and 400 Degree-Sign C. Pentagonite has a porous framework structure made up by layers of silicate tetrahedra connected by V{sup 4+}O{sub 5} square pyramids. Ca and H{sub 2}O molecules are extraframework occupants. Room temperature diffraction data allowed refinement of H positions. The hydrogen-bond system links the extraframework occupants to the silicate layers and also interconnects the H{sub 2}O molecules located inside the channels. Ca is seven-fold coordinated forming four bonds to O of the tetrahedral framework and three bonds to extraframework H{sub 2}O. The H{sub 2}O molecule at O9 showing a high displacement parameter is not bonded to Ca. The dehydration in pentagonite proceeds in three steps. At 100 Degree-Sign C the H{sub 2}O molecule at O8 was released while O9 moved towards Ca. As a consequence the displacement parameter of H{sub 2}O at O9 halved compared to that at room temperature. The unit-cell volume decreased to 1287.33(3) A{sup 3} leading to a formula with 3H{sub 2}O per formula unit (pfu). Ca remained seven-fold coordinated. At 175 Degree-Sign C Ca(VO)(Si{sub 4}O{sub 10}){center_dot}3H{sub 2}O transformed into a new phase with 1H{sub 2}O molecule pfu characterized by doubling of the c axis and the monoclinic space group Pn. Severe bending of specific T--O--T angles led to contraction of the porous three-dimensional framework. In addition, H{sub 2}O at O9 was expelled while H{sub 2}O at O7 approached a position in the center of the channel. The normalized volume decreased to 1069.44(9) A{sup 3

  5. Spin glass in semiconducting KFe1.05Ag0.88Te2 single crystals

    SciTech Connect (OSTI)

    Ryu, H.; Lei, H.; Klobes, B.; Warren, J. B.; Hermann, R. P.; Petrovic, C.

    2015-05-26

    We report discovery of KFe1.05Ag0.88Te2 single crystals with semiconducting spin glass ground state. Composition and structure analysis suggest nearly stoichiometric I4/mmm space group but allow for the existence of vacancies, absent in long range semiconducting antiferromagnet KFe1.05Ag0.88Te2. The subtle change in stoichometry in Fe/Ag sublattice changes magnetic ground state but not conductivity, giving further insight into the semiconducting gap mechanism.

  6. Giant increase in critical current density of KxFe2-ySe? single crystals

    SciTech Connect (OSTI)

    Lei, Hechang; Petrovic, C.

    2011-12-28

    The critical current density Jabc of KxFe2-ySe? single crystals can be enhanced by more than one order of magnitude, up to ~2.110? A/cm by the post annealing and quenching technique. A scaling analysis reveals the universal behavior of the normalized pinning force as a function of the reduced field for all temperatures, indicating the presence of a single vortex pinning mechanism. The main pinning sources are three-dimensional (3D) point-like normal cores. The dominant vortex interaction with pinning centers is via spatial variations in critical temperature Tc (?Tc pinning).

  7. Influence of Sn on the thermoelectric properties of (Bi{sub x}Sb{sub 1-x}){sub 2}Te{sub 3} single crystals

    SciTech Connect (OSTI)

    Kulbachinskii, V.A.; Kytin, V.G.; Kudryashov, A.A.; Lunin, R.A.

    2012-09-15

    The influence of tin on the thermoelectric properties of p-(Bi{sub x}Sb{sub 1-x}){sub 2}Te{sub 3} single crystals (x=0; 0.25; 0.5) has been investigated. The temperature dependence of the Seebeck coefficient S, the electrical conductivity {sigma}, the heat conductivity k and the thermoelectric figure of merit of p-(Bi{sub x}Sb{sub 1-x}){sub 2}Te{sub 3} single crystals were measured in the temperature range 7-300 K. By an increase the Sn content, the hole concentration increases in p-(Bi{sub x}Sb{sub 1-x}){sub 2-y}Sn{sub y}Te{sub 3}. The heat conductivity k of the p-(Bi{sub x}Sb{sub 1-x}){sub 2-y}Sn{sub y}Te{sub 3} crystals decreases due to the Sn doping, while the electrical conductivity {sigma} increases in the temperature interval about 200single crystals (x=0; 0.25; 0.5) has been investigated. Temperature dependence of Seebeck coefficient S, electrical conductivity {sigma}, thermal conductivity k and figure of merit of p-(Bi{sub x}Sb{sub 1-x}){sub 2}Te{sub 3} single crystals were measured in the temperature range 7-300 K. Electrical conductivity increases in the temperature interval 150Kcrystals decreases due to Sn doping. The Seebeck coefficient S for all compositions is positive and decreases due

  8. Growth of c-axis oriented YBaCuO films on oxidized textured Ni sheets and on (100) and (110) oriented NiO single crystals

    SciTech Connect (OSTI)

    Ginsbach, A.; Schneider, R.; Grueninger, H.W.; Grabe, G. )

    1991-03-01

    This paper reports on YBaCuO films grown on oxidized textured Ni sheets and on (100) and (110) oriented NiO single crystals by magnetron sputter deposition from a stoichiometric tubular target. The properties of the YBaCuO films are investigated as function of various preparation parameters (oxidation procedure of the sheets, substrate temperature T{sub s}, HTSC film thickness). At T{sub s} = 780{degrees} C and for film thickness larger than 200 nm, the films have T{sub c} values around 80K. The textures of the Ni sheets, NiO layers and YBaCuO films are determined using X-ray diffraction in Bragg-Brentano geometry and scanning electron microscopy. It is remarkable, that on textured oxidized Ni the YBaCuO films grow c-axis oriented. For comparison the properties of films on differently oriented NiO single crystals are investigated. It is found that the film properties are better on (100) than on (110) surfaces.

  9. Microstructure of (110)-Oriented Epitaxial SrRuO3 Thin Films Grown on Off-Cut Single Crystal YSZ(100) Substrates

    SciTech Connect (OSTI)

    Zhu, Xinhua; Lee, Sung Kyun; Lee, Ho Nyung; Hesse, Dietrich

    2005-01-01

    The microstructure of (1 1 0){sup pc}-oriented epitaxial SrRuO{sub 3} (SRO) thin films grown by pulsed laser deposition on (1 0 0)YSZ (YSZ: yttria-stabilized zirconia) single crystal substrates with a miscut angle of 5{sup o} has been investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The films grow epitaxially with their pseudocubic (1 1 0) plane parallel to the (1 0 0) surface of the YSZ single crystal substrate, and with an in-plane orientation relationship of [{ovr 1} 1 1]{sub SRO}//[0 1 1]{sub YSZ}. Cross-sectional TEM investigations show that the films have a rough, facetted surface. Generally, four different azimuthal domains are present in (1 1 0)SRO films on (1 0 0)YSZ. Their number can be significantly reduced using annealed offcut YSZ substrates before SRO deposition, and this reduction effect is shown to be much stronger on [0 1 1]-miscut (1 0 0)YSZ than on [0 0 1]-miscut ones. Size and morphology of the azimuthal pseudocubic domains and their domain boundaries, as well as of anti-phase domains and their domain boundaries are studied by plan-view and cross-section TEM.

  10. Adsorption calorimetry during metal vapor deposition on single crystal surfaces: Increased flux, reduced optical radiation, and real-time flux and reflectivity measurements

    SciTech Connect (OSTI)

    Sellers, Jason R. V.; James, Trevor E.; Hemmingson, Stephanie L.; Farmer, Jason A.; Campbell, Charles T.

    2013-12-15

    Thin films of metals and other materials are often grown by physical vapor deposition. To understand such processes, it is desirable to measure the adsorption energy of the deposited species as the film grows, especially when grown on single crystal substrates where the structure of the adsorbed species, evolving interface, and thin film are more homogeneous and well-defined in structure. Our group previously described in this journal an adsorption calorimeter capable of such measurements on single-crystal surfaces under the clean conditions of ultrahigh vacuum [J. T. Stuckless, N. A. Frei, and C. T. Campbell, Rev. Sci. Instrum. 69, 2427 (1998)]. Here we describe several improvements to that original design that allow for heat measurements with ∼18-fold smaller standard deviation, greater absolute accuracy in energy calibration, and, most importantly, measurements of the adsorption of lower vapor-pressure materials which would have previously been impossible. These improvements are accomplished by: (1) using an electron beam evaporator instead of a Knudsen cell to generate the metal vapor at the source of the pulsed atomic beam, (2) changing the atomic beam design to decrease the relative amount of optical radiation that accompanies evaporation, (3) adding an off-axis quartz crystal microbalance for real-time measurement of the flux of the atomic beam during calorimetry experiments, and (4) adding capabilities for in situ relative diffuse optical reflectivity determinations (necessary for heat signal calibration). These improvements are not limited to adsorption calorimetry during metal deposition, but also could be applied to better study film growth of other elements and even molecular adsorbates.

  11. High field electron paramagnetic resonance spectroscopy under ultrahigh vacuum conditionsA multipurpose machine to study paramagnetic species on well defined single crystal surfaces

    SciTech Connect (OSTI)

    Rocker, J.; Cornu, D.; Kieseritzky, E.; Hnsel-Ziegler, W.; Freund, H.-J.; Seiler, A.; Bondarchuk, O.

    2014-08-01

    A new ultrahigh vacuum (UHV) electron paramagnetic resonance (EPR) spectrometer operating at 94 GHz to investigate paramagnetic centers on single crystal surfaces is described. It is particularly designed to study paramagnetic centers on well-defined model catalysts using epitaxial thin oxide films grown on metal single crystals. The EPR setup is based on a commercial Bruker E600 spectrometer, which is adapted to ultrahigh vacuum conditions using a home made Fabry Perot resonator. The key idea of the resonator is to use the planar metal single crystal required to grow the single crystalline oxide films as one of the mirrors of the resonator. EPR spectroscopy is solely sensitive to paramagnetic species, which are typically minority species in such a system. Hence, additional experimental characterization tools are required to allow for a comprehensive investigation of the surface. The apparatus includes a preparation chamber hosting equipment, which is required to prepare supported model catalysts. In addition, surface characterization tools such as low energy electron diffraction (LEED)/Auger spectroscopy, temperature programmed desorption (TPD), and infrared reflection absorption spectroscopy (IRAS) are available to characterize the surfaces. A second chamber used to perform EPR spectroscopy at 94 GHz has a room temperature scanning tunneling microscope attached to it, which allows for real space structural characterization. The heart of the UHV adaptation of the EPR experiment is the sealing of the Fabry-Perot resonator against atmosphere. To this end it is possible to use a thin sapphire window glued to the backside of the coupling orifice of the Fabry Perot resonator. With the help of a variety of stabilization measures reducing vibrations as well as thermal drift it is possible to accumulate data for a time span, which is for low temperature measurements only limited by the amount of liquid helium. Test measurements show that the system can detect paramagnetic

  12. Mixed crystal organic scintillators

    DOE Patents [OSTI]

    Zaitseva, Natalia P; Carman, M Leslie; Glenn, Andrew M; Hamel, Sebastien; Hatarik, Robert; Payne, Stephen A; Stoeffl, Wolfgang

    2014-09-16

    A mixed organic crystal according to one embodiment includes a single mixed crystal having two compounds with different bandgap energies, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source, wherein the signal response signature does not include a significantly-delayed luminescence characteristic of neutrons interacting with the organic crystal relative to a luminescence characteristic of gamma rays interacting with the organic crystal. According to one embodiment, an organic crystal includes bibenzyl and stilbene or a stilbene derivative, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source.

  13. 4D STUDY OF STRAIN GRADIENTS EVOLUTION IN TWINNED NiMnGa SINGLE CRYSTALS UNDER MAGNETIC FIELD

    SciTech Connect (OSTI)

    Barabash, Rozaliya; Xu, Ruqing; Barabash, Oleg M; Sozinov, Alexei

    2014-01-01

    Time-resolved 3D X-ray microscopy with a submicron beam size was used to follow the evolution of strains in off-stoichiometric NiMnGa twinned crystals near type I (hard) twin boundary under magnetic field. Laminate A/B microstructure was revealed near the twin boundaries in A variant. Large strain gradients are observed in the C variant in the immediate vicinity of the type I twin boundary: the lattice is under large tensile strains ~0.4% along the c- axes within first micron. Distinct a and b lattice parameter evolution with temperature and magnetic field is demonstrated. In an applied magnetic field the strain field was observed at larger distances from the twin boundary and becomes more complex. Stochastic twin boundary motion was observed after the magnetic field reaches a certain critical value.

  14. CRYSTAL COLLIMATION AT RHIC.

    SciTech Connect (OSTI)

    FLILLER,R.P.,III.DREES,A.GASSNER,D.HAMMONS,L.MCINTYRE,G.PEGGS,S.TRBOJEVIC,D.BIRYUKOV,V.CHESNOKOV,Y.TEREKHOV,V.

    2003-06-19

    Crystal Channeling occurs when an ion enters a crystal with a small angle with respect to the crystal planes. The electrostatic interaction between the incoming ion and the lattice causes the ion to follow the crystal planes. By mechanically bending a crystal, it is possible to use a crystal to deflect ions. One novel use of a bent crystal is to use it to channel beam halo particles into a collimator downstream. By deflecting the halo particles into a collimator with a crystal it may be possible to improve collimation efficiency as compared to a single collimator. A bent crystal is installed in the yellow ring of the Relativistic Heavy Ion Collider (RHIC). In this paper we discuss our experience with the crystal collimator, and compare our results to previous data, simulation, and theoretical prediction.

  15. Boost the electron mobility of solution-grown organic single crystals via reducing the amount of polar solvent residues

    SciTech Connect (OSTI)

    Xue, Guobiao; Xin, Huolin L.; Wu, Jiake; Fan, Congcheng; Liu, Shuang; Huang, Zhuoting; Liu, Yujing; Shan, Bowen; Miao, Qian; Chen, Hongzheng; Li, Hanying

    2015-10-29

    Enhancing electron transport to match with the development in hole transport is critical for organic electronics in the future. As electron motion is susceptible to extrinsic factors, seeking these factors and avoiding their negative effects have become the central challenge. Here, the existence of polar solvent residues in solution-grown single-crystals of 6,13-bis(triisopropylsilylethynyl)-5,7,12,14-tetraazapentacene is identified as a factor detrimental to electron motion. Field-effect transistors of the crystals exhibit electron mobility boosted by about 60% after the residues are removed. The average electron mobility reaches up to 8.0 ± 2.2 cm2 V–1 s–1 with a highest value of 13.3 cm2 V–1 s–1; these results are significantly higher than those obtained previously for the same molecule (1.0–5.0 cm2 V–1 s–1). Furthermore, the achieved mobility is also higher than the maximum reported electron mobility for organic materials (11 cm2 V–1 s–1). As a result, this work should greatly accelerate the advancement of organic electron-transporting materials.

  16. Transition to collapsed tetragonal phase in CaFe2As2 single crystals as seen by 57Fe Mössbauer spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bud'ko, Sergey L.; Ma, Xiaoming; Tomić, Milan; Ran, Sheng; Valentí, Roser; Canfield, Paul C.

    2016-01-21

    Temperature dependent measurements of 57Fe Mössbauer spectra on CaFe2As2 single crystals in the tetragonal and collapsed tetragonal phases are reported. Clear features in the temperature dependencies of the isomer shift, relative spectra area, and quadrupole splitting are observed at the transition from the tetragonal to the collapsed tetragonal phase. From the temperature dependent isomer shift and spectral area data, an average stiffening of the phonon modes in the collapsed tetragonal phase is inferred. The quadrupole splitting increases by ~25% on cooling from room temperature to ~100 K in the tetragonal phase and is only weakly temperature dependent at low temperaturesmore » in the collapsed tetragonal phase, in agreement with the anisotropic thermal expansion in this material. In order to gain microscopic insight about these measurements, we perform ab initio density functional theory calculations of the electric field gradient and the electron density of CaFe2As2 in both phases. By comparing the experimental data with the calculations we are able to fully characterize the crystal structure of the samples in the collapsed-tetragonal phase through determination of the As z coordinate. Furthermore, based on the obtained temperature dependent structural data we are able to propose charge saturation of the Fe-As bond region as the mechanism behind the stabilization of the collapsed-tetragonal phase at ambient pressure.« less

  17. Single crystal neutron diffraction study of lattice and magnetic structures of 5M modulated Ni2Mn1.14Ga0.86

    SciTech Connect (OSTI)

    Pramanick, Abhijit; Wang, Xiaoping; An, Ke; Stoica, Alexandru Dan; Hoffmann, Christina; Wang, Xun-Li

    2012-01-01

    A comprehensive description of the crystal and magnetic structures of Ni-Mn-Ga magnetic shape memory alloys is important to understand the physical origins of their magnetoelastic properties. These structural details for an off-stoichiometric Ni2Mn1.14Ga0.86 alloy have been obtained from refinement of high-resolution single crystal neutron diffraction data following a (3+1)-dimensional superspace formalism. In particular, the structure adopts a P2/m( 0 )00 (3+1)-D superspace symmetry with the following fundamental lattice parameters: a=4.255(4) , b=5.613(4) , c=4.216(3) , a commensurate periodicity of 5M and a modulation wave vector of . The magnetic moments are aligned along the b-axis. The modulations for atomic site displacements, site occupancies and magnetic moments are elucidated from a (3+1)-D refinement of the neutron diffraction data. In addition to atomic displacements corresponding to shear waves along <110>, distortions of Ni-centric tetrahedra are also evident. Physical interpretations for the different structural distortions and their relationship with magnetic properties are discussed.

  18. Low Surface Recombination Velocity in Solution-Grown CH3NH3PbBr3 Perovskite Single Crystal

    SciTech Connect (OSTI)

    Yang, Ye; Yan, Yong; Yang, Mengjin; Choi, Sukgeun; Zhu, Kai; Luter, Joseph M.; Beard, Matthew C.

    2015-08-06

    Organic-inorganic hybrid perovskites are attracting intense research effort due to their impressive performance in solar cells. While the carrier transport parameters such as mobility and bulk carrier lifetime shows sufficient characteristics, the surface recombination, which can have major impact on the solar cell performance, has not been studied. Here we measure surface recombination dynamics in CH3NH3PbBr3 perovskite single crystals using broadband transient reflectance spectroscopy. The surface recombination velocity is found to be 3.4±0.1 103 cm s-1, B2–3 orders of magnitude lower than that in many important unpassivated semiconductors employed in solar cells. Our result suggests that the planar grain size for the perovskite thin films should be larger thanB30 mm to avoid the influence of surface recombination on the effective carrier lifetime.

  19. Suppression of the Critical Temperature of Superconducting NdFeAs(OF) Single Crystals by Kondo-Like Defect Sites Induced by {alpha}-Particle Irradiation

    SciTech Connect (OSTI)

    Tarantini, C.; Gurevich, A.; Larbalestier, D. C.; Putti, M.; Shen, Y.; Singh, R. K.; Rowell, J. M.; Newman, N.; Cheng Peng; Jia Ying; Wen Haihu

    2010-02-26

    We report the effect of {alpha}-particle irradiation on the reduction of the critical temperature T{sub c} of a NdFeAs(OF) single crystal. Our data indicate that irradiation defects cause both nonmagnetic and magnetic scattering, resulting in the Kondo-like excess resistance {Delta}{rho}(T)propor tolnT over 2 decades in temperatures above T{sub c}. The critical density of magnetic irradiation defects which suppresses T{sub c} is found to be much higher than those for cuprates and multiband BCS superconductors. We suggest that such anomalously weak pair breaking by irradiation defects indicates that magnetic scattering in pnictides is coupled with pairing interactions mediated by spin fluctuations.

  20. A study of the phase transition and magnetocaloric effect in multiferroic La{sub 2}MnNiO{sub 6} single crystals

    SciTech Connect (OSTI)

    Balli, M. Jandl, S.; Fournier, P.; Gospodinov, M. M.

    2014-05-07

    Magnetic and magnetocaloric properties of single crystal double perovskite La{sub 2}MnNiO{sub 6} have been investigated in details. Its ordered phase with a high Curie temperature (T{sub C} = 280 K) exhibits a significant refrigerant capacity around room temperature. A model based on the mean field theory approximation has been used in order to quantify the magnetic and magnetocaloric properties in the ordered La{sub 2}MnNiO{sub 6}. The magnetization and entropy changes were satisfactorily simulated as a function of temperature and magnetic field. On the other hand, the presence of cationic disorder in La{sub 2}MnNiO{sub 6} phases allows to shift the Curie point to low temperature without a significant change in the magnetocaloric performance.

  1. Fast ion energy distribution from third harmonic radio frequency heating measured with a single crystal diamond detector at the Joint European Torus

    SciTech Connect (OSTI)

    Nocente, M.; Rebai, M.; Gorini, G.; Cazzaniga, C.; Tardocchi, M.; Giacomelli, L.; Muraro, A.; Binda, F.; Eriksson, J.; Sharapov, S.; Collaboration:

    2015-10-15

    Neutron spectroscopy measurements with a single crystal diamond detector have been carried out at JET, for the first time in an experiment aimed at accelerating deuterons to MeV energies with radio frequency heating at the third harmonic. Data are interpreted by means of the expected response function of the detector and are used to extract parameters of the highly non-Maxwellian distribution function generated in this scenario. A comparison with observations using a time of flight and liquid scintillator neutron spectrometers is also presented. The results demonstrate the capability of diamond detectors to contribute to fast ion physics studies at JET and are of more general relevance in view of the application of such detectors for spectroscopy measurements in the neutron camera of next step tokamak devices.

  2. Formation mechanism of superconducting phase and its three-dimensional architecture in pseudo-single-crystal KxFe2-ySe2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Yong; Xing, Qingfeng; Straszheim, Warren E.; Marshman, Jeff; Pedersen, Pal; McLaughlin, Richard; Lograsso, Thomas A.

    2016-02-11

    Here, we report how the superconducting phase forms in pseudo-single-crystal KxFe2-ySe2. In situ scanning electron microscopy (SEM) observation reveals that, as an order-disorder transition occurs, on cooling, most of the high-temperature iron-vacancy-disordered phase gradually changes into the iron-vacancy-ordered phase whereas a small quantity of the high-temperature phase retains its structure and aggregates to the stripes with more iron concentration but less potassium concentration compared to the iron-vacancy-ordered phase. The stripes that are generally recognized as the superconducting phase are actually formed as a remnant of the high-temperature phase with a compositional change after an “imperfect” order-disorder transition. It should bemore » emphasized that the phase separation in pseudo-single-crystal KxFe2-ySe2 is caused by the iron-vacancy order-disorder transition. The shrinkage of the high-temperature phase and the expansion of the newly created iron-vacancy-ordered phase during the phase separation rule out the mechanism of spinodal decomposition proposed in an early report [Wang et al, Phys. Rev. B 91, 064513 (2015)]. Since the formation of the superconducting phase relies on the occurrence of the iron-vacancy order-disorder transition, it is impossible to synthesize a pure superconducting phase by a conventional solid state reaction or melt growth. By focused ion beam-scanning electron microscopy, we further demonstrate that the superconducting phase forms a contiguous three-dimensional architecture composed of parallelepipeds that have a coherent orientation relationship with the iron-vacancy-ordered phase.« less

  3. Kondo lattice and antiferromagnetic behavior in quaternary CeTAl4Si2 (T = Rh, Ir) single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Maurya, Arvind; Kulkarni, Ruta; Thamizhavel, Arumugam; Paudyal, Durga; Dhar, Sudesh Kumar

    2016-02-26

    Here, we have explored in detail the anisotropic magnetic properties of CeRhAl4Si2 and CeIrAl4Si2, which undergo two antiferromagnetic transitions, at TN1 = 12.6 and 15.5 K, followed by a second transition at TN2 = 9.4 and 13.8 K, respectively, with the [001]-axis as the relatively easy axis of magnetization. The electrical resistivity at ambient and applied pressure provides evidence of Kondo interaction in both compounds, further supported by a reduced value of the entropy associated with the magnetic ordering. The Sommerfeld coefficient γ is inferred to be 195.6 and 49.4 mJ/(mol K2) for CeRhAl4Si2 and CeIrAl4Si2, respectively, classifying these materialsmore » as moderate heavy-fermion compounds. The crystal electric field energy levels are derived from the peak seen in the Schottky heat capacity. Furthermore, we have also performed electronic structure calculations by using the local spin density approximation + U [LSDA+U] approach, which provide physical insights on the observed magnetic behavior of these two compounds.« less

  4. Single-Crystal Raman Spectroscopy and X-ray Crystallography at Beamline X26-C of the NSLS

    SciTech Connect (OSTI)

    D Stoner-Ma; J Skinner; D Schneider; M Cowan; R Sweet; A Orville

    2011-12-31

    Three-dimensional structures derived from X-ray diffraction of protein crystals provide a wealth of information. Features and interactions important for the function of macromolecules can be deduced and catalytic mechanisms postulated. Still, many questions can remain, for example regarding metal oxidation states and the interpretation of 'mystery density', i.e. ambiguous or unknown features within the electron density maps, especially at {approx}2 {angstrom} resolutions typical of most macromolecular structures. Beamline X26-C at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory (BNL), provides researchers with the opportunity to not only determine the atomic structure of their samples but also to explore the electronic and vibrational characteristics of the sample before, during and after X-ray diffraction data collection. When samples are maintained under cryo-conditions, an opportunity to promote and follow photochemical reactions in situ as a function of X-ray exposure is also provided. Plans are in place to further expand the capabilities at beamline X26-C and to develop beamlines at NSLS-II, currently under construction at BNL, which will provide users access to a wide array of complementary spectroscopic methods in addition to high-quality X-ray diffraction data.

  5. Multiphoton photoluminescence contrast in switched Mg:LiNbO{sub 3} and Mg:LiTaO{sub 3} single crystals

    SciTech Connect (OSTI)

    Reichenbach, P., E-mail: philipp.reichenbach@iapp.de; Kmpfe, T.; Thiessen, A.; Haumann, A.; Eng, L. M. [Institut fr Angewandte Photophysik, Technische Universitt Dresden, George-Bhr-Str. 1, 01069 Dresden (Germany); Woike, T. [Institut fr Strukturphysik, Technische Universitt Dresden, Zellescher Weg 16, 01069 Dresden (Germany)

    2014-09-22

    We observed a multiphoton luminescence contrast between virgin and single-switched domains in Mg-doped LiNbO{sub 3} (LNO) and LiTaO{sub 3} (LTO) single crystals with different doping levels of 07?mol. % and 08?mol. %, respectively. A luminescence contrast in the range of 3% was measured between as-grown and electrically inverted domain areas in Mg:LNO samples, while the contrast reaches values of up to 30% for the Mg:LTO case. Under annealing, an exponential decay of the domain contrast was observed. The activation energy of about 1?eV being determined for the decay allowed a comparison with reported activation energies of associated defects, clearly illustrating a strong connection between thermal contrast decay and the H{sup +} and Li{sup +}-ion mobility. Finally, performing similar experiments on oxidized samples undoubtedly demonstrated that the origin of the reported luminescence contrast is strongly connected with lithium ions.

  6. Catalyzed hydrogenation of nitrogen and ethylene on metal (Fe, Pt) single crystal surfaces and effects of coadsorption: A sum frequency generation vibrational spectroscopy study

    SciTech Connect (OSTI)

    Westerberg, Staffan Per Gustav

    2004-12-15

    High-pressure catalytic reactions and associated processes, such as adsorption have been studied on a molecular level on single crystal surfaces. Sum Frequency Generation (SFG) vibrational spectroscopy together with Auger Electron Spectroscopy (AES), Temperature Programmed Desorption (TPD) and Gas Chromatography (GC) were used to investigate the nature of species on catalytic surfaces and to measure the catalytic reaction rates. Special attention has been directed at studying high-pressure reactions and in particular, ammonia synthesis in order to identify reaction intermediates and the influence of adsorbates on the surface during reaction conditions. The adsorption of gases N{sub 2}, H{sub 2}, O{sub 2} and NH{sub 3} that play a role in ammonia synthesis have been studied on the Fe(111) crystal surface by sum frequency generation vibrational spectroscopy using an integrated Ultra-High Vacuum (UHV)/high-pressure system. SFG spectra are presented for the dissociation intermediates, NH{sub 2} ({approx}3325 cm{sup -1}) and NH ({approx}3235 cm{sup -1}) under high pressure of ammonia (200 Torr) on the clean Fe(111) surface. Addition of 0.5 Torr of oxygen to 200 Torr of ammonia does not significantly change the bonding of dissociation intermediates to the surface. However, it leads to a phase change of nearly 180{sup o} between the resonant and non-resonant second order non-linear susceptibility of the surface, demonstrated by the reversal of the SFG spectral features. Heating the surface in the presence of 200 Torr ammonia and 0.5 Torr oxygen reduces the oxygen coverage, which can be seen from the SFG spectra as another relative phase change of 180{sup o}. The reduction of the oxide is also supported by Auger electron spectroscopy. The result suggests that the phase change of the spectral features could serve as a sensitive indicator of the chemical environment of the adsorbates.

  7. Structurally-driven metal-insulator transition in Ca{sub 2}Ru{sub 1-x}Cr{sub x}O{sub 4} (0{<=}x<0.14): A single crystal X-ray diffraction study

    SciTech Connect (OSTI)

    Qi, T.F.; Ge, M.; Korneta, O.B.; Parkin, S.; De Long, L.E.; Cao, G.

    2011-04-15

    Correlation between structure and transport properties are investigated in high-quality single-crystals of Ca{sub 2}Ru{sub 1-x}Cr{sub x}O{sub 4} with 0single crystal X-ray diffraction and by electronic studies. The parent compound was known to exhibit an intriguing first-order structurally driven metal-insulator (MI) transition at 357 K. Upon chromium doping on the ruthenium site, the metal-insulator transition temperature (T{sub MI}) was drastically reduced, and is related to the competition between structural changes that occur upon Cr doping and with decreasing temperature. A strong suppression of structural distortions with increasing Cr substitution was identified. No clear T{sub MI} can be observed when x>13.5% and the system behaves as an insulator. Such a large, sharp metal-insulator transition and tuneable transition temperature may have potential applications in electronic devices. -- Graphical abstract: The metal-insulator transition temperature (T{sub MI}) was drastically reduced by Cr doping, and is closely related to the distortion of structure. Display Omitted Research highlights: {yields} The metal-insulator transition temperature (T{sub MI}) was drastically reduced by doping Cr into Ca{sub 2}RuO{sub 4} single crystal. {yields} Detailed single crystal structural analysis provided important insight into this structurally-driven metal-insulator transition. {yields} Negative Volume Thermal Expansion (NVTE) was observed with increasing temperature.

  8. Experimental determination of single-crystal halite thermal conductivity, diffusivity and specific heat from -75°C to 300°C

    SciTech Connect (OSTI)

    Urquhart, Alexander; Bauer, Stephen

    2015-05-19

    The thermal properties of halite have broad practical importance, from design and long-term modeling of nuclear waste repositories to analysis and performance assessment of underground natural gas, petroleum and air storage facilities. Using a computer-controlled transient plane source method, single-crystal halite thermal conductivity, thermal diffusivity and specific heat were measured from -75°C to 300°C. These measurements reproduce historical high-temperature experiments and extend the lower temperature extreme into cryogenic conditions. Measurements were taken in 25-degree increments from -75°C to 300°C. Over this temperature range, thermal conductivity decreases by a factor of 3.7, from 9.975 to 2.699 W/mK , and thermal diffusivity decreases by a factor of 3.6, from 5.032 to 1.396 mm²/s. Specific heat does not appear to be temperature dependent, remaining near 2.0 MJ/m³K at all temperatures. This work is intended to develop and expand the existing dataset of halite thermal properties, which are of particular value in defining the parameters of salt storage thermophysical models. The work was motivated by a need for thermal conductivity values in a mixture theory model used to determine bulk thermal conductivity of reconsolidating crushed salt.

  9. Interfacial dislocations in (111) oriented (Ba0.7Sr0.3)TiO3 films on SrTiO3 single crystal

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Shen, Xuan; Yamada, Tomoaki; Lin, Ruoqian; Kamo, Takafumi; Funakubo, Hiroshi; Wu, Di; Xin, Huolin L.; Su, Dong

    2015-10-08

    In this study, we have investigated the interfacial structure of epitaxial (Ba,Sr)TiO3 films grown on (111)-oriented SrTiO3 single-crystal substrates using transmission electron microscopy (TEM) techniques. Compared with the (100) epitaxial perovskite films, we observe dominant dislocation half-loop with Burgers vectors of a<110> comprised of a misfit dislocation along <112>, and threading dislocations along <110> or <100>. The misfit dislocation with Burgers vector of a <110> can dissociate into two ½ a <110> partial dislocations and one stacking fault. We found the dislocation reactions occur not only between misfit dislocations, but also between threading dislocations. Via three-dimensional electron tomography, we retrievedmore » the configurations of the threading dislocation reactions. The reactions between threading dislocations lead to a more efficient strain relaxation than do the misfit dislocations alone in the near-interface region of the (111)-oriented (Ba0.7Sr0.3)TiO3 films.« less

  10. Nature of red luminescence band in research-grade ZnO single crystals: A “self-activated” configurational transition

    SciTech Connect (OSTI)

    Chen, Y. N.; Xu, S. J. Zheng, C. C.; Ning, J. Q.; Ling, F. C. C.; Anwand, W.; Brauer, G.; Skorupa, W.

    2014-07-28

    By implanting Zn{sup +} ions into research-grade intentionally undoped ZnO single crystal for facilitating Zn interstitials (Zn{sub i}) and O vacancies (V{sub O}) which is revealed by precise X-Ray diffraction rocking curves, we observe an apparent broad red luminescence band with a nearly perfect Gaussian lineshape. This red luminescence band has the zero phonon line at ∼2.4 eV and shows distinctive lattice temperature dependence which is well interpreted with the configurational coordinate model. It also shows a low “kick out” thermal energy and small thermal quenching energy. A “self-activated” optical transition between a shallow donor and the defect center of Zn{sub i}-V{sub O} complex or V{sub Zn}V{sub O} di-vacancies is proposed to be responsible for the red luminescence band. Accompanied with the optical transition, large lattice relaxation simultaneously occurs around the center, as indicated by the generation of multiphonons.

  11. Experimental determination of single-crystal halite thermal conductivity, diffusivity and specific heat from -75°C to 300°C

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Urquhart, Alexander; Bauer, Stephen

    2015-05-19

    The thermal properties of halite have broad practical importance, from design and long-term modeling of nuclear waste repositories to analysis and performance assessment of underground natural gas, petroleum and air storage facilities. Using a computer-controlled transient plane source method, single-crystal halite thermal conductivity, thermal diffusivity and specific heat were measured from -75°C to 300°C. These measurements reproduce historical high-temperature experiments and extend the lower temperature extreme into cryogenic conditions. Measurements were taken in 25-degree increments from -75°C to 300°C. Over this temperature range, thermal conductivity decreases by a factor of 3.7, from 9.975 to 2.699 W/mK , and thermal diffusivitymore » decreases by a factor of 3.6, from 5.032 to 1.396 mm²/s. Specific heat does not appear to be temperature dependent, remaining near 2.0 MJ/m³K at all temperatures. This work is intended to develop and expand the existing dataset of halite thermal properties, which are of particular value in defining the parameters of salt storage thermophysical models. The work was motivated by a need for thermal conductivity values in a mixture theory model used to determine bulk thermal conductivity of reconsolidating crushed salt.« less

  12. Optical and magneto-optical properties of single crystals of RFe{sub 2} (R = Gd, Tb, Ho, and Lu) and GdCo{sub 2} intermetallic compounds

    SciTech Connect (OSTI)

    Lee, S.J.

    1999-02-12

    The author has studied the diagonal and off-diagonal optical conductivity of RFe{sub 2}(R = Gd, Tb, Ho, Lu) and GdCo{sub 2} single crystals grown by the flux method. Using spectroscopic ellipsometry the author has measured the dielectric function from 1.5 to 5.5 eV. The magneto-optical Kerr spectrometer at temperatures between 7 and 295 K and applied magnetic fields between 0.5 to 1.6 T. The apparatus and calibration method are described in detail. Using magneto-optical data and optical constants he derives the experimental value of the off-diagonal conductivity components. Theoretical calculations of optical conductivities and magneto-optical parameters were performed using the tight binding-linear muffin tin orbitals method within the local spin density approximation. He applied this TB-LMTO method to LuFe{sub 2}. The theoretical results obtained agree well with the experimental data. The oxidation effects on the diagonal part of the optical conductivity were considered using a three-phase model. The oxidation effects on the magneto-optical parameters were also considered by treating the oxide layer as a nonmagnetic thin transparent layer. These corrections change not only the magnitude but also the shape of the optical conductivity and the magneto-optical parameters.

  13. Anisotropic Hc2 , thermodynamic and transport measurements, and pressure dependence of Tc in K2Cr3As3 single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kong, Tai; Bud'ko, Sergey L.; Canfield, Paul C.

    2015-01-30

    We present a detailed study of single crystalline K2Cr3As3 and analyze its thermodynamic and transport properties, anisotropic Hc2(T), and initial pressure dependence of Tc. In zero field, the temperature-dependent resistivity is metallic. Deviation from a linear temperature dependence is evident below 100 K and a T3 dependence is roughly followed from just above Tc (~10K) to ~40K. Anisotropic Hc2(T) data were measured up to 140 kOe with field applied along and perpendicular to the rodlike crystals. For the applied field perpendicular to the rod, Hc2(T) is linear with a slope ~–70 kOe/K. For field applied along the rod, the slopemore » is about –120 kOe/K below 70 kOe. Above 70 kOe, the magnitude of the slope decreases to ~–70 kOe/K. The electronic specific heat coefficient γ, just above Tc, is 73 mJ/mol K2; the Debye temperature ΘD is 220 K. As a result, the specific heat jump at the superconducting transition ΔC~2.2γTc. Finally, for hydrostatic pressures up to ~7 kbar, Tc decreases under pressure linearly at a rate of –0.034K/kbar.« less

  14. Hydrogenation of the alpha,beta-Unsaturated Aldehydes Acrolein, Crotonaldehyde, and Prenal over Pt Single Crystals: A Kinetic and Sum-Frequency Generation Vibrational Spectroscopy Study

    SciTech Connect (OSTI)

    Kliewer, C.J.; Somorjai, G.A.

    2008-11-26

    Sum-frequency generation vibrational spectroscopy (SFG-VS) and kinetic measurements using gas chromatography have been used to study the surface reaction intermediates during the hydrogenation of three {alpha},{beta}-unsaturated aldehydes, acrolein, crotonaldehyde, and prenal, over Pt(111) at Torr pressures (1 Torr aldehyde, 100 Torr hydrogen) in the temperature range of 295K to 415K. SFG-VS data showed that acrolein has mixed adsorption species of {eta}{sub 2}-di-{sigma}(CC)-trans, {eta}{sub 2}-di-{sigma}(CC)-cis as well as highly coordinated {eta}{sub 3} or {eta}{sub 4} species. Crotonaldehyde adsorbed to Pt(111) as {eta}{sub 2} surface intermediates. SFG-VS during prenal hydrogenation also suggested the presence of the {eta}{sub 2} adsorption species, and became more highly coordinated as the temperature was raised to 415K, in agreement with its enhanced C=O hydrogenation. The effect of catalyst surface structure was clarified by carrying out the hydrogenation of crotonaldehyde over both Pt(111) and Pt(100) single crystals while acquiring the SFG-VS spectra in situ. Both the kinetics and SFG-VS showed little structure sensitivity. Pt(100) generated more decarbonylation 'cracking' product while Pt(111) had a higher selectivity for the formation of the desired unsaturated alcohol, crotylalcohol.

  15. Crystallographic, electronic, thermal, and magnetic properties of single-crystal SrCo2As2

    SciTech Connect (OSTI)

    Pandey, Abhishek; Quirinale, D. G.; Jayasekara, W.; Sapkota, A.; Kim, M. G.; Dhaka, R. S.; Lee, Y.; Heitmann, T. W.; Stephens, P. W.; Ogloblichev, V.; Kreyssig, A.; McQueeney, R. J.; Goldman, A. I.; Kaminski, Adam; Harmon, B. N.; Furukawa, Y.; Johnston, D. C.

    2013-07-01

    In tetragonal SrCo2As2 single crystals, inelastic neutron scattering measurements demonstrated that strong stripe-type antiferromagnetic (AFM) correlations occur at a temperature T = 5 K [W. Jayasekara et al., arXiv:1306.5174] that are the same as in the isostructural AFe2As2 (A = Ca, Sr, Ba) parent compounds of high-Tc superconductors. This surprising discovery suggests that SrCo2As2 may also be a good parent compound for high-Tc superconductivity. Here, structural and thermal expansion, electrical resistivity ?, angle-resolved photoemission spectroscopy (ARPES), heat capacity Cp, magnetic susceptibility ?, 75As NMR and neutron diffraction measurements of SrCo2As2 crystals are reported together with LDA band structure calculations that shed further light on this fascinating material. The c-axis thermal expansion coefficient ?c is negative from 7 to 300 K, whereas ?a is positive over this T range. The ?(T) shows metallic character. The ARPES measurements and band theory confirm the metallic character and in addition show the presence of a flat band near the Fermi energy EF. The band calculations exhibit an extremely sharp peak in the density of states D(EF) arising from a flat dx2-y2 band. A comparison of the Sommerfeld coefficient of the electronic specific heat with ?(T ? 0) suggests the presence of strong ferromagnetic itinerant spin correlations which on the basis of the Stoner criterion predicts that SrCo2As2 should be an itinerant ferromagnet, in conflict with the magnetization data. The ?(T) does have a large magnitude, but also exhibits a broad maximum at 115 K suggestive of dynamic short-range AFM spin correlations, in agreement with the neutron scattering data. The measurements show no evidence for any type of phase transition

  16. Single Cystal Services | The Ames Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Single Cystal Services We are a leader in the preparation of high-quality single crystals of rare earth and refractory metals and their alloys. High-purity single crystals of rare...

  17. X-ray diffraction on the X-cut of a Ca{sub 3}TaGa{sub 3}Si{sub 2}O{sub 14} single crystal modulated by a surface acoustic wave

    SciTech Connect (OSTI)

    Irzhak, D. Roshchupkin, D.

    2014-06-28

    The result of X-ray diffraction study on a single crystal of the calcium-gallogermanate family Ca{sub 3}TaGa{sub 3}Si{sub 2}O{sub 14} (CTGS) modulated by a surface acoustic wave (SAW) is presented. The power flow angle for SAW propagating along the X{sub 2} axis of the X-cut in CTGS was measured. The rocking curves for the CTGS crystal were recorded at different amplitudes of an input high frequency electric signal on interdigital transducer used to excite a SAW. Based on the data obtained, intensity dependence of diffraction satellites on the amplitude of electric signal exciting a SAW was built. Numerical simulation of the crystal rocking curves and dependence of diffraction satellite intensities on the SAW amplitude enabled the selection of a set of material constants at which the most complete coincidence of experimental and calculated results is observed.

  18. Upper critical fields and thermally-activated transport of Nd(0.7Fe0.3) FeAs single crystal

    SciTech Connect (OSTI)

    Balakirev, Fedor F; Jaroszynski, J; Hunte, F; Balicas, L; Jo, Youn - Jung; Raicevic, I; Gurevich, A; Larbalestier, D C; Fang, L; Cheng, P; Jia, Y; Wen, H H

    2008-01-01

    We present measurements of the resistivity and the upper critical field H{sub c2} of Nd(O{sub 0.7}F{sub 0.3})FeAs single crystals in strong DC and pulsed magnetic fields up to 45 T and 60 T, respectively. We found that the field scale of H{sub c2} is comparable to {approx}100 T of high T{sub c} cuprates. H{sub c2}(T) parallel to the c-axis exhibits a pronounced upward curvature similar to what was extracted from earlier measurements on polycrystalline samples. Thus this behavior is indeed an intrinsic feature of oxypnictides, rather than manifestation of vortex lattice melting or granularity. The orientational dependence of H{sub c2} shows deviations from the one-band Ginzburg-Landau scaling. The mass anisotropy decreases as T decreases, from 9.2 at 44K to 5 at 34K. Spin dependent magnetoresistance and nonlinearities in the Hall coefficient suggest contribution to the conductivity from electron-electron interactions modified by disorder reminiscent that of diluted magnetic semiconductors. The Ohmic resistivity measured below T{sub c} but above the irreversibility field exhibits a clear Arrhenius thermally activated behavior over 4--5 decades. The activation energy has very different field dependencies for H{parallel}ab and H{perpendicular}ab. We discuss to what extent different pairing scenarios can manifest themselves in the observed behavior of H{sub c2}, using the two-band model of superconductivity. The results indicate the importance of paramagnetic effects on H{sub c2}(T), which may significantly reduce H{sub c2}(0) as compared to H{sub c2}(0) {approx}200--300 T based on extrapolations of H{sub c2}(T) near T{sub c} down to low temperatures.

  19. Quantum Critical Behavior in the Heavy Fermion Single Crystal Ce(Ni0.935Pd0.065)2Ge2

    SciTech Connect (OSTI)

    Wang, Cuihuan [ORNL; Lawrence, J M [University of California, Irvine; Christianson, Andrew D [ORNL; Chang, S [NIST Center for Neutron Research (NCRN), Gaithersburg, MD; Bauer, E D [Los Alamos National Laboratory (LANL); Gofryk, K [Los Alamos National Laboratory (LANL); Ronning, F [Los Alamos National Laboratory (LANL); Thompson, J D [Los Alamos National Laboratory (LANL); McClellan, K J [Los Alamos National Laboratory (LANL); Rodriguez-Rivera, J A [NCNR and University of Maryland; Lynn, J W [NIST Center for Neutron Research (NCRN), Gaithersburg, MD

    2011-01-01

    We have performed magnetic susceptibility, specific heat, resistivity, and inelastic neutron scattering measurements on a single crystal of the heavy Fermion compound Ce(Ni{sub 0.935}Pd{sup 0.065}){sub 2}Ge{sub 2}, which is believed to be close to a quantum critical point (QCP) at T = 0. At lowest temperature (1.8--3.5 K), the magnetic susceptibility behaves as {chi}(T)-{chi} (0) {proportional_to} T{sup -1/6} with {chi} (0) = 0.032 x 10{sup -6} m{sup 3}/mole (0.0025 emu/mole). For T < 1 K, the specific heat can be fit to the formula {Delta} C/T = {gamma}{sub 0} - T{sup 1/2} with {gamma}{sub 0} of order 700 mJ/mole-K{sup 2}. The resistivity behaves as {rho} = {rho}{sub 0} + AT{sup 3/2} for temperatures below 2 K. This low temperature behavior for {gamma} (T) and {rho} (T) is in accord with the SCR theory of Moriya and Takimoto. The inelastic neutron scattering spectra show a broad peak near 1.5 meV that appears to be independent of Q; we interpret this as Kondo scattering with T{sub K} = 17 K. In addition, the scattering is enhanced near Q=(1/2, 1/2, 0) with maximum scattering at {Delta} E = 0.45 meV{sup -}; we interpret this as scattering from antiferromagnetic fluctuations near the antiferromagnetic QCP.

  20. Symmetry of piezoelectric (1–x)Pb(Mg1/3Nb2/3)O₃-xPbTiO₃ (x=0.31) single crystal at different length scales in the morphotropic phase boundary region

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kim, Kyou-Hyun; Payne, David A.; Zuo, Jian-Min

    2012-11-29

    We use probes of three different length scales to examine symmetry of (1–x)Pb(Mg1/3Nb2/3)O₃-xPbTiO₃ (PMN-xPT) single crystals in the morphotropic phase boundary (MPB) region at composition x = 0.31 (PMN-31% PT). On the macroscopic scale, x-ray diffraction (XRD) shows a mixture of strong and weak diffraction peaks of different widths. The closest match to XRD peak data is made with monoclinic Pm (MC) symmetry. On the local scale of a few nanometers, convergent beam electron diffraction (CBED) studies, with a 1.6-nm electron probe, reveal no obvious symmetry. These CBED experimental patterns can be approximately matched with simulations based on monoclinic symmetry,more » which suggests locally distorted monoclinic structure. A monoclinic Cm (MA or MB)-like symmetry could also be obtained from certain regions of the crystal by using a larger electron probe size of several tens of nanometers in diameter. Thus the monoclinic symmetry of single crystal PMN-31%PT is developed only in parts of the crystal by averaging over locally distorted structure on the scale of few tens of nanometers. The macroscopic symmetry observed by XRD is a result of averaging from the local structure in PMN-31%PT single crystal. The lack of local symmetry at a few nanometers scale suggests that the polarization switching results from a change in local displacements, which are not restricted to specific symmetry planes or directions.« less

  1. Resolution of the discrepancy between the variation of the physical properties of Ce1-xYbxCoIn5 single crystals and thin films with Yb composition

    SciTech Connect (OSTI)

    Jang, S.; White, B. D.; Lum, I. K.; Kim, H.; Tanatar, M. A.; Straszheim, W. E.; Prozorov, R.; Keiber, T.; Bridges, F.; Shu, L.; Baumbach, R. E.; Janoschek, M.; Maple, M. B.

    2014-11-18

    The extraordinary electronic phenomena including an Yb valence transition, a change in Fermi surface topology, and suppression of the heavy fermion quantum critical field at a nominal concentration x≈0.2 have been found in the Ce1-xYbxCoIn5 system. These phenomena have no discernable effect on the unconventional superconductivity and normal-state non-Fermi liquid behaviour that occur over a broad range of x up to ~0.8. However, the variation of the coherence temperature T* and the superconducting critical temperature Tc with nominal Yb concentration x for bulk single crystals is much weaker than that of thin films. To determine whether differences in the actual Yb concentration of bulk single crystals and thin film samples might be responsible for these discrepancies, we employed Vegard’s law and the spectroscopically determined values of the valences of Ce and Yb as a function of x to determine the actual composition xact of bulk single crystals. This analysis is supported by energy-dispersive X-ray spectroscopy, wavelength-dispersive X-ray spectroscopy, and transmission X-ray absorption edge spectroscopy measurements. The actual composition xact is found to be about one-third of the nominal concentration x up to x~0.5, and resolves the discrepancy between the variation of the physical properties of Ce1-xYbxCoIn5 single crystals and thin films with Yb concentration.

  2. Erratum: Evolution of precipitate morphology during heat treatment and its implications for the superconductivity in KxFe1.6+ySe2 single crystals [Phys. Rev. B 86 , 144507 (2012)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Y.; Xing, Q.; Dennis, K. W.; McCallum, R. W.; Lograsso, T. A.

    2015-08-14

    In this article, we study the relationship between precipitate morphology and superconductivity in KxFe1.6+ySe2 single crystals grown by self-flux method. Scanning electron microscopy (SEM) measurements revealed that the superconducting phase forms a network in the samples quenched above iron vacancy order-disorder transition temperature Ts, whereas it aggregates into micrometer-sized rectangular bars and aligns as disconnected chains in the furnace-cooled samples.

  3. Electron-hole diffusion lengths >175 μm in solution-grown CH3NH3PbI3 single crystals

    SciTech Connect (OSTI)

    Dong, Qingfeng; Fang, Yanjun; Shao, Yuchuan; Mulligan, Padhraic; Qiu, Jie; Cao, Lei; Huang, Jinsong

    2015-02-27

    Long, balanced electron and hole diffusion lengths greater than 100 nanometers in the polycrystalline organolead trihalide compound CH3NH3PbI3 are critical for highly efficient perovskite solar cells. We found that the diffusion lengths in CH3NH3PbI3 single crystals grown by a solution-growth method can exceed 175 micrometers under 1 sun (100 mW cm–2) illumination and exceed 3 millimeters under weak light for both electrons and holes. The internal quantum efficiencies approach 100% in 3-millimeter-thick single-crystal perovskite solar cells under weak light. These long diffusion lengths result from greater carrier mobility, longer lifetime, and much smaller trap densities in the single crystals than in polycrystalline thin films. As a result, the long carrier diffusion lengths enabled the use of CH3NH3PbI3 in radiation sensing and energy harvesting through the gammavoltaic effect, with an efficiency of 3.9% measured with an intense cesium-137 source.

  4. Insulating and metallic spin glass in KxFe2-δ-yNiySe2 (0.06 ≤ y ≤ 1.44 ) single crystals

    SciTech Connect (OSTI)

    Ryu, Hyejin; Abeykoon, Milinda; Wang, Kefeng; Lei, Hechang; Lazarevic, N.; Warren, J. B.; Bozin, E. S.; Popovic, Z. V.; Petrovic, C.

    2015-05-04

    We report electron doping effects by Ni in KxFe2-δ-yNiySe₂ (0.06 ≤ y ≤ 1.44) single crystal alloys. A rich ground state phase diagram is observed. Thus, a small amount of Ni (~ 4%) suppressed superconductivity below 1.8 K, inducing insulating spin glass magnetic ground state for higher Ni content. With further Ni substitution, metallic resistivity is restored. For high Ni concentration in the lattice the unit cell symmetry is high symmetry I4/mmm with no phase separation whereas both I4/m + I4/mmm space groups were detected in the phase separated crystals when concentration of Ni < Fe. The absence of superconductivity coincides with the absence of crystalline Fe vacancy order.

  5. Insulating and metallic spin glass in KxFe2-?-yNiySe2 (0.06 ? y ? 1.44 ) single crystals

    SciTech Connect (OSTI)

    Ryu, Hyejin; Abeykoon, Milinda; Wang, Kefeng; Lei, Hechang; Lazarevic, N.; Warren, J. B.; Bozin, E. S.; Popovic, Z. V.; Petrovic, C.

    2015-05-04

    We report electron doping effects by Ni in KxFe2-?-yNiySe? (0.06 ? y ? 1.44) single crystal alloys. A rich ground state phase diagram is observed. Thus, a small amount of Ni (~ 4%) suppressed superconductivity below 1.8 K, inducing insulating spin glass magnetic ground state for higher Ni content. With further Ni substitution, metallic resistivity is restored. For high Ni concentration in the lattice the unit cell symmetry is high symmetry I4/mmm with no phase separation whereas both I4/m + I4/mmm space groups were detected in the phase separated crystals when concentration of Ni < Fe. The absence of superconductivity coincides with the absence of crystalline Fe vacancy order.

  6. High field magnetotransport and point contact Andreev reflection measurements on CuCr{sub 2}Se{sub 4} and CuCr{sub 2}Se{sub 3}BrDegenerate magnetic semiconductor single crystals

    SciTech Connect (OSTI)

    Borisov, K. Coey, J. M. D.; Stamenov, P.; Alaria, J.

    2014-05-07

    Single crystals of the metallically degenerate fully magnetic semiconductors CuCr{sub 2}Se{sub 4} and CuCr{sub 2}Se{sub 3}Br have been prepared by the Chemical Vapour Transport method, using either Se or Br as transport agents. The high-quality, millimetre-sized, octahedrally faceted, needle- and platelet-shaped crystals are characterised by means of high field magnetotransport (?{sub 0}H? 14?T) and Point Contact Andreev Reflection. The relatively high spin polarisation observed |P|>0.56, together with the relatively low minority carrier effective mass of 0.25 m{sub e}, and long scattering time 10{sup ?13}?s, could poise these materials for integration in low- and close-to-room temperature minority injection bipolar heterojunction transistor demonstrations.

  7. Technology Development for High-Efficiency Solar Cells and Modules Using Thin (<80 um) Single-Crystal Silicon Wafers Produced by Epitaxy: June 11, 2011 - April 30, 2013

    SciTech Connect (OSTI)

    Ravi, T. S.

    2013-05-01

    Final technical progress report of Crystal Solar subcontract NEU-31-40054-01. The objective of this 18-month program was to demonstrate the viability of high-efficiency thin (less than 80 um) monocrystalline silicon (Si) solar cells and modules with a low-cost epitaxial growth process.

  8. Continuous cross-over from ferroelectric to relaxor state and piezoelectric properties of BaTiO{sub 3}-BaZrO{sub 3}-CaTiO{sub 3} single crystals

    SciTech Connect (OSTI)

    Benabdallah, F.; Veber, P. Prakasam, M.; Viraphong, O.; Maglione, M.; Shimamura, K.

    2014-04-14

    Optimal properties like piezoelectricity can be found in polarizable materials for which the structure changes sharply under small composition variations in the vicinity of their morphotropic phase boundary or the triple point in their isobaric temperature-composition phase diagram. In the latter, lead-free (Ba{sub 0.850}Ca{sub 0.150})(Ti{sub 0.900}Zr{sub 0.100})O{sub 3} ceramics exhibit outstanding piezoelectric coefficients. For the first time, we report the growth of piezoelectric lead-free single crystals in the BaTiO{sub 3}-BaZrO{sub 3}-CaTiO{sub 3} pseudo-ternary system. The stoichiometry control in the CaO-BaO-TiO{sub 2}-ZrO{sub 2} solid solution led to single crystals with various compositions ranging from (Ba{sub 0.857}Ca{sub 0.143})(Ti{sub 0.928}Zr{sub 0.072})O{sub 3} to (Ba{sub 0.953}Ca{sub 0.047})(Ti{sub 0.427}Zr{sub 0.573})O{sub 3}. We evidenced a continuous cross-over from a ferroelectric state at high titanium content to a relaxor one on increasing the zirconium content. Such a property tuning is rather seldom observed in lead-free ferroelectrics and confirms what was already reported for ceramics. Single crystal with (Ba{sub 0.838}Ca{sub 0.162})(Ti{sub 0.854}Zr{sub 0.146})O{sub 3} composition, which has been grown and oriented along [001] crystallographic direction, displayed electromechanical coefficients d{sub 31} and k{sub 31} of 93 pC.N{sup −1} and 0.18, respectively, near the room temperature (T = 305 K)

  9. Investigation into the evolution of the structure of K{sub 1-x}Li{sub x}Ta{sub 1-y}Nb{sub y}O{sub 3} single crystals under variations in temperature

    SciTech Connect (OSTI)

    Borisov, S. A.; Vakhrushev, S. B.; Koroleva, E. Yu.; Naberezhnov, A. A. Syrnikov, P. P.; Simkin, V. G.; Kutnjak, Z.; Egami, T.; Dmowski, W.; Piekarz, P.

    2007-05-15

    The evolution of the structure of K{sub 1-x}Li{sub x}Ta{sub 1-y}Nb{sub y}O{sub 3} single crystals with x = 0.001, y = 0.026, and 1900 ppm Cu (KLTN277) and with x = 0.0014 and y = 0.024 (KLTN123), which exhibit an extremely high permittivity (up to 4 x 10{sup 5} in the quasi-static regime for the KLTN277 crystal), is investigated in the range from room temperature to 20 K. It is demonstrated that, upon cooling to the lowest temperatures, both crystals retain their cubic structure, but the lattice parameters pass through a minimum at the temperature of the observed anomalies of the dielectric response ({approx}50 K). In the neutron diffraction pattern of the KLTN123 sample, satellites appear in the vicinity of the (hhh) reflections at temperatures below {approx}50 K. These satellites can be associated with the nucleation of the rhombohedral phase.

  10. Quartz crystal growth

    DOE Patents [OSTI]

    Baughman, Richard J.

    1992-01-01

    A process for growing single crystals from an amorphous substance that can undergo phase transformation to the crystalline state in an appropriate solvent. The process is carried out in an autoclave having a lower dissolution zone and an upper crystallization zone between which a temperature differential (.DELTA.T) is maintained at all times. The apparatus loaded with the substance, solvent, and seed crystals is heated slowly maintaining a very low .DELTA.T between the warmer lower zone and cooler upper zone until the amorphous substance is transformed to the crystalline state in the lower zone. The heating rate is then increased to maintain a large .DELTA.T sufficient to increase material transport between the zones and rapid crystallization. .alpha.-Quartz single crystal can thus be made from fused quartz in caustic solvent by heating to 350.degree. C. stepwise with a .DELTA.T of 0.25.degree.-3.degree. C., increasing the .DELTA.T to about 50.degree. C. after the fused quartz has crystallized, and maintaining these conditions until crystal growth in the upper zone is completed.

  11. Epitaxial single-crystal thin films of MnxTi1-xO2-? grown on (rutile)TiO2 substrates with pulsed laser deposition: Experiment and theory

    SciTech Connect (OSTI)

    Ilton, Eugene S.; Droubay, Timothy C.; Chaka, Anne M.; Kovarik, Libor; Varga, Tamas; Arey, Bruce W.; Kerisit, Sebastien N.

    2015-02-01

    Epitaxial rutile-structured single-crystal MnxTi1-xO2-? films were synthesized on rutile- (110) and -(001) substrates using pulsed laser deposition. The films were characterized by reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and aberration-corrected transmission electron microscopy (ACTEM). Under the present conditions, 400oC and PO2 = 20 mTorr, single crystal epitaxial thin films were grown for x = 0.13, where x is the nominal average mole fraction of Mn. In fact, arbitrarily thick films could be grown with near invariant Mn/Ti concentration profiles from the substrate/film interface to the film surface. In contrast, at x = 0.25, Mn became enriched towards the surface and a secondary nano-scale phase formed which appeared to maintain the basic rutile structure but with enhanced z-contrast in the tunnels, or tetrahedral interstitial sites. Ab initio thermodynamic calculations provided quantitative estimates for the destabilizing effect of expanding the ?-MnO2 lattice parameters to those of TiO2-rutile, the stabilizing effect of diluting Mn with increasing Ti concentration, and competing reaction pathways.

  12. Response measurement of single-crystal chemical vapor deposition diamond radiation detector for intense X-rays aiming at neutron bang-time and neutron burn-history measurement on an inertial confinement fusion with fast ignition

    SciTech Connect (OSTI)

    Shimaoka, T. Kaneko, J. H.; Tsubota, M.; Arikawa, Y.; Nagai, T.; Kojima, S.; Abe, Y.; Sakata, S.; Fujioka, S.; Nakai, M.; Shiraga, H.; Azechi, H.; Isobe, M.; Sato, Y.; Chayahara, A.; Umezawa, H.; Shikata, S.

    2015-05-15

    A neutron bang time and burn history monitor in inertial confinement fusion with fast ignition are necessary for plasma diagnostics. In the FIREX project, however, no detector attained those capabilities because high-intensity X-rays accompanied fast electrons used for plasma heating. To solve this problem, single-crystal CVD diamond was grown and fabricated into a radiation detector. The detector, which had excellent charge transportation property, was tested to obtain a response function for intense X-rays. The applicability for neutron bang time and burn history monitor was verified experimentally. Charge collection efficiency of 99.5% 0.8% and 97.1% 1.4% for holes and electrons were obtained using 5.486 MeV alpha particles. The drift velocity at electric field which saturates charge collection efficiency was 1.1 0.4 10{sup 7} cm/s and 1.0 0.3 10{sup 7} cm/s for holes and electrons. Fast response of several ns pulse width for intense X-ray was obtained at the GEKKO XII experiment, which is sufficiently fast for ToF measurements to obtain a neutron signal separately from X-rays. Based on these results, we confirmed that the single-crystal CVD diamond detector obtained neutron signal with good S/N under ion temperature 0.51 keV and neutron yield of more than 10{sup 9} neutrons/shot.

  13. Integrated quasi-phase-matched second-harmonic generator and electrooptic scanner on LiTaO{sub 3} single crystals

    SciTech Connect (OSTI)

    Gopalan, V.; Kawas, M.J.; Schlesinger, T.E.; Stancil, D.D.; Gupta, M.C.

    1996-12-01

    The authors report the first integrated quasi-phase-matched second-harmonic generator and electrooptic scanner on ferroelectric Z-cut LiTaO{sub 3}. The quasi-phase-matched second-harmonic generation device frequency doubles the infrared light at 829.7 nm into blue at 414.85 nm with a bulk conversion efficiency of 0.52%/W-cm. The blue light generated in the bulk then passes through an electrooptic scanner, consisting of a series of lithographically defined triangular-shaped domain-inverted regions extending through the thickness of the crystal. A deflection of 12 mrad/kv for the output blue light and 7.4 mrad/kv for the infrared light was observed at the scanner output.

  14. Low temperature structural variations of Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}-7%BaTiO{sub 3} single crystal: Evidences from optical ellipsometry and Raman scattering

    SciTech Connect (OSTI)

    Huang, T.; Guo, S.; Xu, L. P.; Hu, Z. G. Chu, J. H.; Chen, C.; Luo, H. S.

    2015-06-14

    Optical properties and structural variations of Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}-7%BaTiO{sub 3} (NBT-7%BT) single crystal have been studied by temperature-dependent optical ellipsometry and Raman spectroscopy from 4.2 to 300 K. The second derivative of the complex dielectric functions reveals two interband transitions (E{sub cp1} and E{sub cp2}) located at about 3.49 and 4.25 eV, respectively. Depending on the temperature evolution of electronic transitions, structural variations appear near 60, 150, and 240 K, respectively. These anomalies are also well illustrated from the low-frequency phonon modes involving vibrations of Bi. The low-temperature structural variations of NBT-7%BT crystal can be associated with instability of the crystalline lattice driven by off-centered Bi ions, followed by the variations of polarizability of the unit cells.

  15. Hydrogen in polar intermetallics: Syntheses and structures of the ternary Ca5Bi3D0.93, Yb5Bi3Hx, and Sm5Bi3H~1 by powder neutron or single crystal X-ray diffraction

    SciTech Connect (OSTI)

    Leon-Escamilla, E. Alejandro; Dervenagas, Panagiotis; Stasis, Constantine; Corbett, John D.

    2010-01-01

    The syntheses of the title compounds are described in detail. Structural characterizations from refinements of single crystal X-ray diffraction data for Yb{sub 5}Bi{sub 3}H{sub x} and Sm{sub 5}Bi{sub 3}H{sub 1} and of powder neutron diffraction data for Ca{sub 5}Bi{sub 3}D{sub 0.93(3)} are reported. These confirm that all three crystallize with the heavy atom structure type of {beta}-Yb{sub 5}Sb{sub 3}, and the third gives the first proof that the deuterium lies in the center of nominal calcium tetrahedra, isostructural with the Ca{sub 5}Sb{sub 3}F-type structure. These Ca and Yb phases are particularly stable with respect to dissociation to Mn{sub 5}Si{sub 3}-type product plus H{sub 2}. Some contradictions in the literature regarding Yb{sub 5}Sb{sub 3} and Yb{sub 5}Sb{sub 3}H{sub x} phases are considered in terms of adventitious hydrogen impurities that are generated during reactions in fused silica containers at elevated temperatures.

  16. High-Pressure Single-Crystal Neutron Scattering Study of Magnetic and Fe Vacancy Orders in (Tl,Rb)2 Fe4 Se5 Superconductor

    SciTech Connect (OSTI)

    Ye, Feng; Bao, Wei; Chi, Song-Xue; Santos, Antonio M. dos; Molaison, Jamie J.; Fang, Ming-Hu; Wang, Hang-Dong; Mao, Qian-Hui; Wang, Jin-Chen; Liu, Juan-Juan; Sheng, Jie-Ming

    2014-12-01

    We investigate the magnetic and iron vacancy orders in superconducting (Tl,Rb)2Fe4Se5 single-crystals by using a high-pressure neutron diffraction technique. Similar to the temperature effect, the block antiferromagnetic order gradually decreases upon increasing pressure while the Fe vacancy superstructural order remains intact before its precipitous disappearance at the critical pressure Pc = 8.3 GPa. Combined with previously determined Pc for superconductivity, our phase diagram under pressure reveals the concurrence of the block AFM order, the √5 × √5 iron vacancy order and superconductivity for the 245 superconductor. Lastly, a synthesis of current experimental data in a coherent physical picture is attempted.

  17. Phase transition in bulk single crystals and thin films of VO2 by nanoscale infrared spectroscopy and imaging

    SciTech Connect (OSTI)

    Liu, Mengkun; Sternbach, Aaron J.; Wagner, Martin; Slusar, Tetiana V.; Kong, Tai; Bud'ko, Sergey L.; Kittiwatanakul, Salinporn; Qazilbash, M. M.; McLeod, Alexander; Fei, Zhe; Abreu, Elsa; Zhang, Jingdi; Goldflam, Michael; Dai, Siyuan; Ni, Guang -Xin; Lu, Jiwei; Bechtel, Hans A.; Martin, Michael C.; Raschke, Markus B.; Averitt, Richard D.; Wolf, Stuart A.; Kim, Hyun -Tak; Canfield, Paul C.; Basov, D. N.

    2015-06-29

    We have systematically studied a variety of vanadium dioxide (VO2) crystalline forms, including bulk single crystals and oriented thin films, using infrared (IR) near-field spectroscopic imaging techniques. By measuring the IR spectroscopic responses of electrons and phonons in VO2 with sub-grain-size spatial resolution (~20nm), we show that epitaxial strain in VO2 thin films not only triggers spontaneous local phase separations, but leads to intermediate electronic and lattice states that are intrinsically different from those found in bulk. Generalized rules of strain- and symmetry-dependent mesoscopic phase inhomogeneity are also discussed. Furthermore, these results set the stage for a comprehensive understanding of complex energy landscapes that may not be readily determined by macroscopic approaches.

  18. Intermediate valence in single crystals of (Lu{sub 1?x}Y b{sub x}){sub 3}Rh{sub 4}Ge{sub 13} (0 ? x ? 1)

    SciTech Connect (OSTI)

    Rai, Binod K.; Morosan, E.

    2015-04-01

    Single crystals of (Lu{sub 1?x}Y b{sub x}){sub 3}Rh{sub 4}Ge{sub 13} were characterized by magnetization, specific heat, and electrical resistivity measurements. Doping Yb into the non-magnetic Lu{sub 3}Rh{sub 4}Ge{sub 13} compound tunes this cubic systems properties from a superconductor with disordered metal normal state (x < 0.05) to a Kondo for 0.05 ? x ?0.2 and intermediate valence at the highest Yb concentrations. The evidence for intermediate Yb valence comes from a broad maximum in the magnetic susceptibility and X-ray photoelectron spectroscopy. Furthermore, the resistivity displays a local maximum at finite temperatures at intermediate compositions x, followed by apparent metallic behavior closest to the Yb end compound in the series.

  19. Second order phase transition temperature of single crystals of Gd5Si1.3Ge2.7 and Gd5Si1.4Ge2.6

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hadimani, R. L.; Melikhov, Y.; Schlagel, D. L.; Lograsso, T. A.; Dennis, K. W.; McCallum, R. W.; Jiles, D. C.

    2015-01-30

    Gd5(SixGe1–x)4 has mixed phases in the composition range 0.32 < x < 0.41, which have not been widely studied. In this paper, we have synthesized and indexed single crystal samples of Gd5Si1.3Ge2.7 and Gd5Si1.4Ge2.6. In this study, we have investigated the first order and second order phase transition temperatures of these samples using magnetic moment vs. temperature and magnetic moment vs. magnetic field at different temperatures. We have used a modified Arrott plot technique that was developed and reported by us previously to determine the “hidden” second order phase transition temperature of the orthorhombic II phase.

  20. Toward epitaxially grown two-dimensional crystal hetero-structures: Single and double MoS{sub 2}/graphene hetero-structures by chemical vapor depositions

    SciTech Connect (OSTI)

    Lin, Meng-Yu [Graduate Institute of Electronics Engineering, National Taiwan University, Taipei, Taiwan (China); Research Center for Applied Sciences, Academia Sinica, Nankang, Taipei, Taiwan (China); Chang, Chung-En [Department of Photonics, National Chiao-Tung University, Hsinchu, Taiwan (China); Wang, Cheng-Hung [Institute of Display, National Chiao-Tung University, Hsinchu, Taiwan (China); Su, Chen-Fung; Chen, Chi [Research Center for Applied Sciences, Academia Sinica, Nankang, Taipei, Taiwan (China); Lee, Si-Chen [Graduate Institute of Electronics Engineering, National Taiwan University, Taipei, Taiwan (China); Lin, Shih-Yen, E-mail: shihyen@gate.sinica.edu.tw [Graduate Institute of Electronics Engineering, National Taiwan University, Taipei, Taiwan (China); Research Center for Applied Sciences, Academia Sinica, Nankang, Taipei, Taiwan (China); Department of Photonics, National Chiao-Tung University, Hsinchu, Taiwan (China)

    2014-08-18

    Uniform large-size MoS{sub 2}/graphene hetero-structures fabricated directly on sapphire substrates are demonstrated with layer-number controllability by chemical vapor deposition (CVD). The cross-sectional high-resolution transmission electron microscopy (HRTEM) images provide the direct evidences of layer numbers of MoS{sub 2}/graphene hetero-structures. Photo-excited electron induced Fermi level shift of the graphene channel are observed on the single MoS{sub 2}/graphene hetero-structure transistors. Furthermore, double hetero-structures of graphene/MoS{sub 2}/graphene are achieved by CVD fabrication of graphene layers on top of the MoS{sub 2}, as confirmed by the cross-sectional HRTEM. These results have paved the possibility of epitaxially grown multi-hetero-structures for practical applications.

  1. Expanding Lorentz and spectrum corrections to large volumes of reciprocal space for single-crystal time-of-flight neutron diffraction

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Michels-Clark, Tara M.; Savici, Andrei T.; Lynch, Vickie E.; Wang, Xiaoping; Hoffmann, Christina M.

    2016-03-01

    Evidence is mounting that potentially exploitable properties of technologically and chemically interesting crystalline materials are often attributable to local structure effects, which can be observed as modulated diffuse scattering (mDS) next to Bragg diffraction (BD). BD forms a regular sparse grid of intense discrete points in reciprocal space. Traditionally, the intensity of each Bragg peak is extracted by integration of each individual reflection first, followed by application of the required corrections. In contrast, mDS is weak and covers expansive volumes of reciprocal space close to, or between, Bragg reflections. For a representative measurement of the diffuse scattering, multiple sample orientationsmore » are generally required, where many points in reciprocal space are measured multiple times and the resulting data are combined. The common post-integration data reduction method is not optimal with regard to counting statistics. A general and inclusive data processing method is needed. In this contribution, a comprehensive data analysis approach is introduced to correct and merge the full volume of scattering data in a single step, while correctly accounting for the statistical weight of the individual measurements. Lastly, development of this new approach required the exploration of a data treatment and correction protocol that includes the entire collected reciprocal space volume, using neutron time-of-flight or wavelength-resolved data collected at TOPAZ at the Spallation Neutron Source at Oak Ridge National Laboratory.« less

  2. Interfacial dislocations in (111) oriented (Ba0.7Sr0.3)TiO3 films on SrTiO3 single crystal

    SciTech Connect (OSTI)

    Shen, Xuan; Yamada, Tomoaki; Lin, Ruoqian; Kamo, Takafumi; Funakubo, Hiroshi; Wu, Di; Xin, Huolin L.; Su, Dong

    2015-10-08

    In this study, we have investigated the interfacial structure of epitaxial (Ba,Sr)TiO3 films grown on (111)-oriented SrTiO3 single-crystal substrates using transmission electron microscopy (TEM) techniques. Compared with the (100) epitaxial perovskite films, we observe dominant dislocation half-loop with Burgers vectors of a<110> comprised of a misfit dislocation along <112>, and threading dislocations along <110> or <100>. The misfit dislocation with Burgers vector of a <110> can dissociate into two ½ a <110> partial dislocations and one stacking fault. We found the dislocation reactions occur not only between misfit dislocations, but also between threading dislocations. Via three-dimensional electron tomography, we retrieved the configurations of the threading dislocation reactions. The reactions between threading dislocations lead to a more efficient strain relaxation than do the misfit dislocations alone in the near-interface region of the (111)-oriented (Ba0.7Sr0.3)TiO3 films.

  3. Incommensurate magnetic ordering in Cu{sub 2}Te{sub 2}O{sub 5}X{sub 2} (X=Cl,Br) studied by single crystal neutron diffraction

    SciTech Connect (OSTI)

    Zaharko, O.; Roennow, H.; Mesot, J.; Crowe, S. J.; Paul, D. McK.; Brown, P. J.; Daoud-Aladine, A.; Meents, A.; Wagner, A.; Prester, M.; Berger, H.

    2006-02-01

    Polarized and unpolarized neutron-diffraction studies have been carried out on single crystals of the coupled spin tetrahedra systems Cu{sub 2}Te{sub 2}O{sub 5}X{sub 2} (X=Cl,Br). A model of the magnetic structure associated with the propagation vectors k{sup '}{sub Cl}{approx_equal}(-0.150,0.422,(1/2)) and k{sup '}{sub Br}{approx_equal}(-0.172,0.356,(1/2)) and stable below T{sub N}=18 K for X=Cl and T{sub N}=11 K for X=Br is proposed. A feature of the model, common to both the bromide and chloride, is a canted coplanar motif for the four Cu{sup 2+} spins on each tetrahedron which rotates on a helix from cell to cell following the propagation vector. The Cu{sup 2+} magnetic moment determined for X=Br,0.395(5){mu}{sub B}, is significantly less than for X=Cl,0.88(1){mu}{sub B} at 2 K. The magnetic structure of the chloride associated with the wave vector k{sup '} differs from that determined previously for the wave vector k{approx_equal}(0.150,0.422,(1/2)) [O. Zaharko et al., Phys. Rev. Lett. 93, 217206(E) (2004)].

  4. Temperature dependence of structural parameters in oxide-ion-conducting Nd{sub 9.33}(SiO{sub 4}){sub 6}O{sub 2}: single crystal X-ray studies from 295 to 900K

    SciTech Connect (OSTI)

    Okudera, Hiroki . E-mail: h.okudera@fkf.mpg.de; Yoshiasa, Akira; Masubuchi, Yuuji; Higuchi, Mikio; Kikkawa, Shinichi

    2004-12-01

    Crystallographic space group, structural parameters and their thermal changes in oxide-ion-conducting Nd{sub 9.33}(SiO{sub 4}){sub 6}O{sub 2} were investigated using high-temperature single-crystal X-ray diffraction experiments in the temperature range of 295=

  5. Nitrogen termination of single crystal (100) diamond surface by radio frequency N{sub 2} plasma process: An in-situ x-ray photoemission spectroscopy and secondary electron emission studies

    SciTech Connect (OSTI)

    Chandran, Maneesh E-mail: choffman@tx.technion.ac.il; Shasha, Michal; Michaelson, Shaul; Hoffman, Alon E-mail: choffman@tx.technion.ac.il

    2015-09-14

    In this letter, we report the electronic and chemical properties of nitrogen terminated (N-terminated) single crystal (100) diamond surface, which is a promising candidate for shallow NV{sup −} centers. N-termination is realized by an indirect RF nitrogen plasma process without inducing a large density of surface defects. Thermal stability and electronic property of N-terminated diamond surface are systematically investigated under well-controlled conditions by in-situ x-ray photoelectron spectroscopy and secondary electron emission. An increase in the low energy cut-off of the secondary electron energy distribution curve (EDC), with respect to a bare diamond surface, indicates a positive electron affinity of the N-terminated diamond. Exposure to atomic hydrogen results in reorganization of N-terminated diamond to H-terminated diamond, which exhibited a negative electron affinity surface. The change in intensity and spectral features of the secondary electron EDC of the N-terminated diamond is discussed.

  6. Pyrrole Hydrogenation over Rh(111) and Pt(111) Single-Crystal Surfaces and Hydrogenation Promotion Mediated by 1-Methylpyrrole: A Kinetic and Sum-Frequency Generation Vibrational Spectroscopy Study

    SciTech Connect (OSTI)

    Kliewer, Christopher J.; Bieri, Marco; Somorjai, Gabor A.

    2008-03-04

    Sum-frequency generation (SFG) surface vibrational spectroscopy and kinetic measurements using gas chromatography have been used to study the adsorption and hydrogenation of pyrrole over both Pt(111) and Rh(111) single-crystal surfaces at Torr pressures (3 Torr pyrrole, 30 Torr H{sub 2}) to form pyrrolidine and the minor product butylamine. Over Pt(111) at 298 K it was found that pyrrole adsorbs in an upright geometry cleaving the N-H bond to bind through the nitrogen evidenced by SFG data. Over Rh(111) at 298 K pyrrole adsorbs in a tilted geometry relative to the surface through the p-aromatic system. A pyrroline surface reaction intermediate, which was not detected in the gas phase, was seen by SFG during the hydrogenation over both surfaces. Significant enhancement of the reaction rate was achieved over both metal surfaces by adsorbing 1-methylpyrrole before reaction. SFG vibrational spectroscopic results indicate that reaction promotion is achieved by weakening the bonding between the N-containing products and the metal surface because of lateral interactions on the surface between 1-methylpyrrole and the reaction species, reducing the desorption energy of the products. It was found that the ring-opening product butylamine was a reaction poison over both surfaces, but this effect can be minimized by treating the catalyst surfaces with 1-methylpyrrole before reaction. The reaction rate was not enhanced with elevated temperatures, and SFG suggests desorption of pyrrole at elevated temperatures.

  7. Multicolor photonic crystal laser array

    DOE Patents [OSTI]

    Wright, Jeremy B; Brener, Igal; Subramania, Ganapathi S; Wang, George T; Li, Qiming

    2015-04-28

    A multicolor photonic crystal laser array comprises pixels of monolithically grown gain sections each with a different emission center wavelength. As an example, two-dimensional surface-emitting photonic crystal lasers comprising broad gain-bandwidth III-nitride multiple quantum well axial heterostructures were fabricated using a novel top-down nanowire fabrication method. Single-mode lasing was obtained in the blue-violet spectral region with 60 nm of tuning (or 16% of the nominal center wavelength) that was determined purely by the photonic crystal geometry. This approach can be extended to cover the entire visible spectrum.

  8. Photonic crystal surface-emitting lasers

    DOE Patents [OSTI]

    Chua, Song Liang; Lu, Ling; Soljacic, Marin

    2015-06-23

    A photonic-crystal surface-emitting laser (PCSEL) includes a gain medium electromagnetically coupled to a photonic crystal whose energy band structure exhibits a Dirac cone of linear dispersion at the center of the photonic crystal's Brillouin zone. This Dirac cone's vertex is called a Dirac point; because it is at the Brillouin zone center, it is called an accidental Dirac point. Tuning the photonic crystal's band structure (e.g., by changing the photonic crystal's dimensions or refractive index) to exhibit an accidental Dirac point increases the photonic crystal's mode spacing by orders of magnitudes and reduces or eliminates the photonic crystal's distributed in-plane feedback. Thus, the photonic crystal can act as a resonator that supports single-mode output from the PCSEL over a larger area than is possible with conventional PCSELs, which have quadratic band edge dispersion. Because output power generally scales with output area, this increase in output area results in higher possible output powers.

  9. Synthesis and crystal structure studies of ethyl 5-methyl-1,...

    Office of Scientific and Technical Information (OSTI)

    investigated by single crystal X-ray diffraction method. It crystallizes in monoclinic class under the space group P2sub 1c with cell parameters a 8.4593(4) , b15.6284(6)...

  10. In-situ Studies of the Reactions of Bifunctional and Heterocyclic Molecules over Noble Metal Single Crystal and Nanoparticle Catalysts Studied with Kinetics and Sum-Frequency Generation Vibrational Spectroscopy

    SciTech Connect (OSTI)

    Kliewer, Christopher J.

    2009-06-30

    Sum frequency generation surface vibrational spectroscopy (SFG-VS) in combination with gas chromatography (GC) was used in-situ to monitor surface bound reaction intermediates and reaction selectivities for the hydrogenation reactions of pyrrole, furan, pyridine, acrolein, crotonaldehyde, and prenal over Pt(111), Pt(100), Rh(111), and platinum nanoparticles under Torr reactant pressures and temperatures of 300K to 450K. The focus of this work is the correlation between the SFG-VS observed surface bound reaction intermediates and adsorption modes with the reaction selectivity, and how this is affected by catalyst structure and temperature. Pyrrole hydrogenation was investigated over Pt(111) and Rh(111) single crystals at Torr pressures. It was found that pyrrole adsorbs to Pt(111) perpendicularly by cleaving the N-H bond and binding through the nitrogen. However, over Rh(111) pyrrole adsorbs in a tilted geometry binding through the {pi}-aromatic orbitals. A surface-bound pyrroline reaction intermediate was detected over both surfaces with SFG-VS. It was found that the ring-cracking product butylamine is a reaction poison over both surfaces studied. Furan hydrogenation was studied over Pt(111), Pt(100), 10 nm cubic platinum nanoparticles and 1 nm platinum nanoparticles. The product distribution was observed to be highly structure sensitive and the acquired SFG-VS spectra reflected this sensitivity. Pt(100) exhibited more ring-cracking to form butanol than Pt(111), while the nanoparticles yielded higher selectivities for the partially saturated ring dihydrofuran. Pyridine hydrogenation was investigated over Pt(111) and Pt(100). The {alpha}-pyridyl surface adsorption mode was observed with SFG-VS over both surfaces. 1,4-dihydropyridine was seen as a surface intermediate over Pt(100) but not Pt(111). Upon heating the surfaces to 350K, the adsorbed pyridine changes to a flat-lying adsorption mode. No evidence was found for the pyridinium cation. The hydrogenation of the

  11. Shock compression of [001] single crystal silicon

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhao, S.; Remington, B.; Hahn, E. N.; Kad, B.; Bringa, E. M.; Meyers, M. A.

    2016-03-14

    Silicon is ubiquitous in our advanced technological society, yet our current understanding of change to its mechanical response at extreme pressures and strain-rates is far from complete. This is due to its brittleness, making recovery experiments difficult. High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon (using impedance-matched momentum traps) unveiled remarkable structural changes observed by transmission electron microscopy. As laser energy increases, corresponding to an increase in peak shock pressure, the following plastic responses are are observed: surface cleavage along {111} planes, dislocations and stacking faults; bands of amorphized material initially forming on crystallographic orientations consistent withmore » dislocation slip; and coarse regions of amorphized material. Molecular dynamics simulations approach equivalent length and time scales to laser experiments and reveal the evolution of shock-induced partial dislocations and their crucial role in the preliminary stages of amorphization. Furthermore, application of coupled hydrostatic and shear stresses produce amorphization below the hydrostatically determined critical melting pressure under dynamic shock compression.« less

  12. Synthesis, spectral characterization, and single crystal structure...

    Office of Scientific and Technical Information (OSTI)

    Citation Details In-Document Search Title: Synthesis, spectral ... Resource Type: Journal Article Resource Relation: Journal Name: Crystallography Reports; Journal Volume: ...

  13. Nonequilibrium quasiparticle relaxation dynamics in single crystals...

    Office of Scientific and Technical Information (OSTI)

    Publication Date: 2011-09-13 OSTI Identifier: 1100755 Type: Publisher's Accepted Manuscript Journal Name: Physical Review. B. Condensed Matter and Materials Physics Additional ...

  14. Synthesis, spectral characterization, and single crystal structure...

    Office of Scientific and Technical Information (OSTI)

    Inc.; Country of input: International Atomic Energy Agency (IAEA) Country of ... MONOCRYSTALS; NMR SPECTRA; SYNTHESIS; X-RAY DIFFRACTION Word Cloud More Like This Full ...

  15. Optics of globular photonic crystals

    SciTech Connect (OSTI)

    Gorelik, V S

    2007-05-31

    The results of experimental and theoretical studies of the optical properties of globular photonic crystals - new physical objects having a crystal structure with the lattice period exceeding considerably the atomic size, are presented. As globular photonic crystals, artificial opal matrices consisting of close-packed silica globules of diameter {approx}200 nm were used. The reflection spectra of these objects characterising the parameters of photonic bands existing in these crystals in the visible spectral region are presented. The idealised models of the energy band structure of photonic crystals investigated in the review give analytic dispersion dependences for the group velocity and the effective photon mass in a globular photonic crystal. The characteristics of secondary emission excited in globular photonic crystals by monochromatic and broadband radiation are presented. The results of investigations of single-photon-excited delayed scattering of light observed in globular photonic crystals exposed to cw UV radiation and radiation from a repetitively pulsed copper vapour laser are presented. The possibilities of using globular photonic crystals as active media for lasing in different spectral regions are considered. It is proposed to use globular photonic crystals as sensitive sensors in optoelectronic devices for molecular analysis of organic and inorganic materials by the modern methods of laser spectroscopy. The results of experimental studies of spontaneous and stimulated globular scattering of light are discussed. The conditions for observing resonance and two-photon-excited delayed scattering of light are found. The possibility of accumulation and localisation of the laser radiation energy inside a globular photonic crystal is reported. (review)

  16. Jefferson Lab Builds First Single Crystal Single Cell Accelerating...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... After a brief, low-temperature bake, the cavity achieved an accelerating gradient of 45 MVm, ... surfaces after only chemical surface treatment, better mechanical performance and ...

  17. Structure and physical properties of single crystal PrCr{sub 2}Al{sub 20} and CeM{sub 2}Al{sub 20} (M=V, Cr): A comparison of compounds adopting the CeCr{sub 2}Al{sub 20} structure type

    SciTech Connect (OSTI)

    Kangas, Michael J.; Schmitt, Devin C.; Sakai, Akito; Nakatsuji, Satoru; Institute of Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 ; Chan, Julia Y.

    2012-12-15

    Crystal growth and full structure determination of compounds adopting the CeCr{sub 2}Al{sub 20} structure type, LnTi{sub 2}Al{sub 20} (Ln=La-Pr, Sm, and Yb), LnV{sub 2}Al{sub 20} (Ln=La-Pr, and Sm), and LnCr{sub 2}Al{sub 20} (Ln=La-Pr, Sm, and Yb), are reported. Resistivity, magnetic susceptibility, and heat capacity of flux grown single crystals of the nonmagnetic CeM{sub 2}Al{sub 20} (Ln=Ce, Yb; M=Ti, V) compounds are compared to PrCr{sub 2}Al{sub 20}. Of particular interest is PrCr{sub 2}Al{sub 20} which does not show any phase transition down to the lowest temperature of the measurement (400 mK in resistivity measurement and 1.8 K for magnetic susceptibility measurements) and exhibits Kondo behavior at low temperatures. - Graphical abstract: Crystal structure of SmV{sub 2}Al{sub 20} showing the interpenetrating diamond-like samarium network and pyrochlore-like vanadium network. Highlights: Black-Right-Pointing-Pointer Single crystals of LnM{sub 2}Al{sub 20} were grown from a molten aluminum flux. Black-Right-Pointing-Pointer Magnetic, electrical, and specific heat of single crystal LnM{sub 2}Al{sub 20} are presented. Black-Right-Pointing-Pointer PrCr{sub 2}Al{sub 20} exhibits evidence of Kondo effect.

  18. Enhanced ferroelectric properties and thermal stability of nonstoichiometric 0.92(Na{sub 0.5}Bi{sub 0.5})TiO{sub 3}-0.08(K{sub 0.5}Bi{sub 0.5})TiO{sub 3} single crystals

    SciTech Connect (OSTI)

    Zhang, Haiwu E-mail: hsluo@mail.sic.ac.cn; Chen, Chao; Deng, Hao; Li, Long; Graduate University of Chinese Academy of Sciences, Beijing 100049 ; Zhao, Xiangyong; Lin, Di; Li, Xiaobing; Ren, Bo; Luo, Haosu E-mail: hsluo@mail.sic.ac.cn; Yan, Jun

    2013-11-18

    Bi deficient, Mn doped 0.92(Na{sub 0.5}Bi{sub 0.5})TiO{sub 3}-0.08(K{sub 0.5}Bi{sub 0.5})TiO{sub 3} single crystals were grown by carefully controlled top-seeded solution growth method. Local structures were investigated by transmission electron microscopy. The site occupation and valence state of manganese were characterized by electron paramagnetic resonance spectrum. The leakage current density in the as-grown single crystals is effectively depressed. The introduced defect complexes suppress the temperature induced phase transformation, increasing the depolarization temperature (165?C) and thermal stability of ferroelectric properties.

  19. Coherent multilayer crystals and method of making

    DOE Patents [OSTI]

    Schuller, I.K.; Falco, C.M.

    1980-10-30

    A new material is described consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 A to 2500 A. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

  20. Method of making coherent multilayer crystals

    DOE Patents [OSTI]

    Schuller, Ivan K. (Woodridge, IL); Falco, Charles M. (Woodridge, IL)

    1984-01-01

    A new material consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 .ANG. to 2500 .ANG.. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

  1. Crystallization and functionality of inorganic materials

    SciTech Connect (OSTI)

    Xue, Dongfeng, E-mail: dongfeng@ciac.jl.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China) [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Li, Keyan [School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China)] [School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Liu, Jun [Key Laboratory of Low Dimensional Materials and Application Technology, Ministry of Education, Faculty of Materials, Optoelectronics and Physics, Xiangtan University, 411105 (China)] [Key Laboratory of Low Dimensional Materials and Application Technology, Ministry of Education, Faculty of Materials, Optoelectronics and Physics, Xiangtan University, 411105 (China); Sun, Congting; Chen, Kunfeng [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China) [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China)

    2012-10-15

    In this article, we briefly summarized our recent work on the studies of crystallization and functionality of inorganic materials. On the basis of the chemical bonding theory of single crystal growth, we can quantitatively simulate Cu{sub 2}O crystallization processes in solution system. We also kinetically controlled Cu{sub 2}O crystallization process in the reduction solution route. Lithium ion battery and supercapacitor performances of some oxides such as Co{sub 3}O{sub 4} and MnO{sub 2} were shown to elucidate the important effect of crystallization on functionality of inorganic materials. This work encourages us to create novel functionalities through the study of crystallization of inorganic materials, which warrants more chances in the field of functional materials.

  2. Crystallization process

    SciTech Connect (OSTI)

    Adler, Robert J.; Brown, William R.; Auyang, Lun; Liu, Yin-Chang; Cook, W. Jeffrey

    1986-01-01

    An improved crystallization process is disclosed for separating a crystallizable material and an excluded material which is at least partially excluded from the solid phase of the crystallizable material obtained upon freezing a liquid phase of the materials. The solid phase is more dense than the liquid phase, and it is separated therefrom by relative movement with the formation of a packed bed of solid phase. The packed bed is continuously formed adjacent its lower end and passed from the liquid phase into a countercurrent flow of backwash liquid. The packed bed extends through the level of the backwash liquid to provide a drained bed of solid phase adjacent its upper end which is melted by a condensing vapor.

  3. Epitaxial strengthening of crystals

    DOE Patents [OSTI]

    Morris, Robert C.; Marion II, Ohn E.; Gaultieri, Devlin M.

    1988-12-06

    An epitaxial layer is used to place the surface of a crystal in compression o as to greatly increase the durability of the crystal such as a laser medium crystal.

  4. Epitaxial strengthening of crystals

    DOE Patents [OSTI]

    Morris, Robert C.; Marion, II, John E.; Gaultieri, Devlin M.

    1988-01-01

    An epitaxial layer is used to place the surface of a crystal in compression o as to greatly increase the durability of the crystal such as a laser medium crystal.

  5. Crystal structure determination of Efavirenz

    SciTech Connect (OSTI)

    Popeneciu, Horea Dumitru, Ristoiu; Tripon, Carmen Borodi, Gheorghe Pop, Mihaela Maria

    2015-12-23

    Needle-shaped single crystals of the title compound, C{sub 14}H{sub 9}ClF{sub 3}NO{sub 2}, were obtained from a co-crystallization experiment of Efavirenz with maleic acid in a (1:1) ratio, using methanol as solvent. Crystal structure determination at room temperature revealed a significant anisotropy of the lattice expansion compared to the previously reported low-temperature structure. In both low- and room temperature structures the cyclopropylethynyl fragment in one of the asymmetric unit molecules is disordered. While at low-temperature only one C atom exhibits positional disorder, at room temperature the disorder is present for two C atoms of the cyclopropane ring.

  6. Monochromator Crystal Glitch Library

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    SSRL's Monochromator Crystal Glitch Library allows users to view glitch spectra online, list specific crystal orientations, and download PDF files of the glitch spectra. (Specialized Interface)

  7. Magnetotransport of single crystalline NbAs (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    We report transport measurement in zero and applied magnetic field on a single crystal of NbAs. Transverse and longitudinal magnetoresistance in the plane of this tetragonal ...

  8. Exciton-Exciton Annihilation in Copper-Phthalocyanine Single...

    Office of Scientific and Technical Information (OSTI)

    Annihilation in Copper-Phthalocyanine Single-Crystal Nanowires Citation Details In-Document Search Title: Exciton-Exciton Annihilation in Copper-Phthalocyanine ...

  9. High energy resolution, high angular acceptance crystal monochromator

    DOE Patents [OSTI]

    Alp, Ercan E.; Mooney, Timothy M.; Toellner, Thomas

    1996-06-04

    A 4-bounce dispersive crystal monochromator reduces the bandpass of synchrotron radiation to a 10-50 meV range without sacrificing angular acceptance. The monochromator includes the combination of an asymmetrical channel-cut single crystal of lower order reflection and a symmetrical channel-cut single crystal of higher order reflection in a nested geometric configuration. In the disclosed embodiment, a highly asymmetrically cut (.alpha.=20) outer silicon crystal (4 2 2) with low order reflection is combined with a symmetrically cut inner silicon crystal (10 6 4) with high order reflection to condition a hard x-ray component (5-30 keV) of synchrotron radiation down to the .mu.eV-neV level. Each of the crystals is coupled to the combination of a positioning inchworm and angle encoder via a respective rotation stage for accurate relative positioning of the crystals and precise energy tuning of the monochromator.

  10. High energy resolution, high angular acceptance crystal monochromator

    DOE Patents [OSTI]

    Alp, E.E.; Mooney, T.M.; Toellner, T.

    1996-06-04

    A 4-bounce dispersive crystal monochromator reduces the bandpass of synchrotron radiation to a 10-50 meV range without sacrificing angular acceptance. The monochromator includes the combination of an asymmetrical channel-cut single crystal of lower order reflection and a symmetrical channel-cut single crystal of higher order reflection in a nested geometric configuration. In the disclosed embodiment, a highly asymmetrically cut ({alpha}=20) outer silicon crystal (4 2 2) with low order reflection is combined with a symmetrically cut inner silicon crystal (10 6 4) with high order reflection to condition a hard x-ray component (5--30 keV) of synchrotron radiation down to the {micro}eV-neV level. Each of the crystals is coupled to the combination of a positioning inchworm and angle encoder via a respective rotation stage for accurate relative positioning of the crystals and precise energy tuning of the monochromator. 7 figs.

  11. Single-crystal structure refinement of four compounds in the Y{sub 1{minus}{ital x}}Pr{sub {ital x}}Ba{sub 2}Cu{sub 3{minus}{ital y}}Al{sub {ital y}}O{sub 7{minus}{delta}} system

    SciTech Connect (OSTI)

    Meden, A.; Holzinger-Schweiger, E.; Leising, G.; Pejovnik, S.; Golic, L.

    1996-12-01

    X-ray single crystal diffraction data were used for structural refinement of the title compounds with different {ital x} (0.15, 0.27, 0.49 and 0.89). Crystals were grown in alumina crucibles using self-flux method. Aluminum, which originates from the crucibles, substitutes only Cu(1), and thus induces tetragonal symmetry which was observed in all four crystals. The main structural effect of praseodymium is an increased separation of superconducting layers. Substituent concentrations ({ital x} and {ital y} in the formula) have been refined and compared with the values obtained by EDX (energy dispersive x-ray analysis) in an electron microscope. It was indicated that the refined values of Y:Pr ratio and the oxygen content are more reliable than those obtained by EDX while the refinement is less sensitive for Cu(1):Al ratio and this value is more uncertain. This is in accordance with the result of wet chemical analysis. {copyright} {ital 1996 Materials Research Society.}

  12. Method for solid state crystal growth

    DOE Patents [OSTI]

    Nolas, George S.; Beekman, Matthew K.

    2013-04-09

    A novel method for high quality crystal growth of intermetallic clathrates is presented. The synthesis of high quality pure phase crystals has been complicated by the simultaneous formation of both clathrate type-I and clathrate type-II structures. It was found that selective, phase pure, single-crystal growth of type-I and type-II clathrates can be achieved by maintaining sufficient partial pressure of a chemical constituent during slow, controlled deprivation of the chemical constituent from the primary reactant. The chemical constituent is slowly removed from the primary reactant by the reaction of the chemical constituent vapor with a secondary reactant, spatially separated from the primary reactant, in a closed volume under uniaxial pressure and heat to form the single phase pure crystals.

  13. Growth and defect structure of CdF{sub 2} crystal and nonstoichiometric Cd{sub 1-x}R{sub x}F{sub 2+x} phases (R are rare earth elements and in): 6. Growth and ionic conductivity of Cd{sub 0.904}In{sub 0.096}F{sub 2.096} single crystal

    SciTech Connect (OSTI)

    Sorokin, N. I. Sul'yanova, E. A.; Buchinskaya, I. I.; Artyukhov, A. A.; Sobolev, B. P.

    2013-07-15

    Cd{sub 0.904}In{sub 0.096}F{sub 2.096} crystals with fluorite-type defect structures have been grown from melt in a fluorinating atmosphere by the Bridgman method, and their ionic conductivity is investigated. The fluorine-ion transport activation enthalpy in Cd{sub 0.904}In{sub 0.096}F{sub 2.096} ({Delta}H = 0.68 eV) is much smaller than the corresponding characteristic of the crystals belonging to the isoconcentration series Cd{sub 0.9}R{sub 0.1}F{sub 2.1}, R = La-Lu, Y ({Delta}H = 0.8-0.9 eV). The ionic conductivity of Cd{sub 0.904}In{sub 0.096}F{sub 2.096} is {sigma} = 2 Multiplication-Sign 10{sup -4} S/cm (at 467 K); this value exceeds the conductivity of the CdF{sub 2} crystal matrix and the highest conductivity Cd{sub 0.9}R{sub 0.1}F{sub 2.1} crystals with rare earth elements by factors of 3 Multiplication-Sign 10{sup 3} and {approx}10, respectively. Nonstoichiometric crystals of solid electrolyte Cd{sub 1-x}In{sub x}F{sub 2+x} have the highest conductivity out of all studied electrolytes based on the CdF{sub 2} matrix.

  14. Pressure cryocooling protein crystals

    DOE Patents [OSTI]

    Kim, Chae Un; Gruner, Sol M.

    2011-10-04

    Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

  15. Spectroscopic, thermal and structural studies on manganous malate crystals

    SciTech Connect (OSTI)

    Thomas, J. Lincy, A. Mahalakshmi, V.; Saban, K. V.

    2013-01-15

    Prismatic crystals of manganous malate have been prepared by controlled ionic diffusion in hydrosilica gel. The structure was elucidated using single crystal X-ray diffraction. The crystals are orthorhombic with space group Pbca. Vibrations of the functional groups were identified by the FTIR spectrum. Thermogravimetric and differential thermal analyses (TG-DTA) were carried out to explore the thermal decomposition pattern of the material. Structural information derived from FTIR and TG-DTA studies is in conformity with the single crystal XRD data.

  16. Magnetotransport of single crystalline NbAs (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    Citation Details In-Document Search Title: Magnetotransport of single crystalline NbAs We report transport measurement in zero and applied magnetic field on a single crystal of ...

  17. Evolution of structure in Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} single crystals with BaTiO{sub 3}

    SciTech Connect (OSTI)

    Ge, Wenwei Luo, Chengtao; Li, Jiefang; Viehland, D.; Zhang, Qinhui; Luo, Haosu; Ren, Yang

    2014-10-20

    The structural, dielectric, and piezoelectric properties of Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}-x mol. %BaTiO{sub 3} (NBT-x%BT) crystals have been investigated. The dielectric and piezoelectric properties of NBT-x%BT were enhanced near x = 5–7. High resolution synchrotron x-ray powder diffraction studies revealed the presence of a phase boundary between monoclinic (Cc) and tetragonal (P4bm) phases near x = 5–7, where the dielectric and piezoelectric properties were enhanced.

  18. Growth of <001> TGCC crystals by Sankaranarayanan–Ramasamy (SR) method and its characterization

    SciTech Connect (OSTI)

    Boopathi, K.; Ramasamy, P.

    2015-06-24

    Single crystals of tris (glycine) Calcium (II) dichloride (TGCC) were successfully grown by Sankaranarayanan-Ramasamy (SR) method and conventional slow evaporation solution technique which have the sizes of 40 mm in length, 20 mm in diameter and 10×10×3 mm{sup 3} respectively. The grown TGCC crystals have been subjected to single crystal X-ray diffraction, UV-Vis NIR studies, Vickers micro hardness analysis, laser damage and SHG analysis. The transmittance of the grown crystal was analyzed by recording UV-Vis-NIR analysis. Mechanical strength of the SR method grown crystals was higher than the conventional method grown crystal.

  19. Growing Giant Crystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    crystals Growing Giant Crystals A new process similar to making rock candy was developed at NIF to rapidly grow very large crystals that are about 2 cubic feet in size and weigh up to 800 pounds-about the weight of a large grizzly bear! The crystals are made of potassium dihydrogen phosphate (or KDP), a naturally occurring chemical. In crystal form, KDP has good optical properties. Crystal plates have special optical properties, like prisms, that transmit, bend, and break light up into the

  20. CRYSTAL COLLIMATION AT RHIC.

    SciTech Connect (OSTI)

    FLILLER,III, R.P.; DREES,A.; GASSNER,D.; HAMMONS,L.; MCINTYRE,G.; PEGGS,S.; TRBOJEVIC,D.; BIRYUKOV,V.; CHESNKOV,Y.; TEREKHOV,V.

    2002-06-02

    For the year 2001 run, a bent crystal was installed in the yellow ring of the Relativistic Heavy Ion Collider (RHIC). The crystal forms the first stage of a two stage collimation system. By aligning the crystal to the beam, halo particles are channeled through the crystal and deflected into a copper scraper. The purpose is to reduce beam halo with greater efficiency than with a scraper alone. In this paper we present the first results from the use of the crystal collimator. We compare the crystal performance under various conditions, such as different particle species, and beta functions.

  1. Crystal Systems | Open Energy Information

    Open Energy Info (EERE)

    is located in Salem, Massachusetts. Crystal Systems produces sapphire crystals for optics and electronics, and silicon for photovoltaics. References Crystal Systems...

  2. Spectrometry of the Rutherford backscattering of ions and the Raman scattering of light in GaS single crystals irradiated with 140-keV H{sub 2}{sup +} ions

    SciTech Connect (OSTI)

    Garibov, A. A.; Madatov, R. S.; Komarov, F. F.; Pilko, V. V.; Mustafayev, Yu. M.; Akhmedov, F. I.; Jakhangirov, M. M.

    2015-05-15

    The methods of the Raman scattering of light and Rutherford backscattering are used to study the degree of structural disorder in layered GaS crystals before and after irradiation with 140-keV H{sub 2}{sup +} ions. It is shown that the distribution of the crystal’s components over depth is homogeneous; for doses as high as 5 × 10{sup 15} cm{sup −2}, the stoichiometric composition of the compound’s components is retained. The experimental value of the critical dose for the beginning of amorphization amounts to about 5 × 10{sup 15} cm{sup −2} and is in accordance with the calculated value. The results obtained by the method of the Raman scattering of light confirm conservation of crystalline structure and the start of the amorphization process.

  3. Apparatus for mounting crystal

    DOE Patents [OSTI]

    Longeway, Paul A.

    1985-01-01

    A thickness monitor useful in deposition or etching reactor systems comprising a crystal-controlled oscillator in which the crystal is deposited or etched to change the frequency of the oscillator. The crystal rests within a thermally conductive metallic housing and arranged to be temperature controlled. Electrode contacts are made to the surface primarily by gravity force such that the crystal is substantially free of stress otherwise induced by high temperature.

  4. Second order phase transition temperature of single crystals of Gd5Si1.3Ge2.7 and Gd5Si1.4Ge2.6

    SciTech Connect (OSTI)

    Hadimani, R. L.; Melikhov, Y.; Schlagel, D. L.; Lograsso, T. A.; Dennis, K. W.; McCallum, R. W.; Jiles, D. C.

    2015-01-30

    Gd5(SixGe1–x)4 has mixed phases in the composition range 0.32 < x < 0.41, which have not been widely studied. In this paper, we have synthesized and indexed single crystal samples of Gd5Si1.3Ge2.7 and Gd5Si1.4Ge2.6. In this study, we have investigated the first order and second order phase transition temperatures of these samples using magnetic moment vs. temperature and magnetic moment vs. magnetic field at different temperatures. We have used a modified Arrott plot technique that was developed and reported by us previously to determine the “hidden” second order phase transition temperature of the orthorhombic II phase.

  5. Sustained phase separation and spin glass in Co-doped KxFe2-ySe2 single crystals

    SciTech Connect (OSTI)

    Ryu, Hyejin; Wang, Kefeng; Opacic, M.; Lazarevic, N.; Warren, J. B.; Popovic, Z. V.; Bozin, Emil S.; Petrovic, C.

    2015-11-19

    We describe Co substitution effects in KxFe2-y-zCozSe2 (0.06 ≤ z ≤ 1.73) single crystal alloys. By 3.5% of Co doping superconductivity is suppressed whereas phase separation of semiconducting K2Fe4Se5 and superconducting/metallic KxFe2Se2 is still present. We show that the arrangement and distribution of superconducting phase (stripe phase) is connected with the arrangement of K, Fe and Co atoms. Semiconducting spin glass is found in proximity to superconducting state, persisting for large Co concentrations. At high Co concentrations ferromagnetic metallic state emerges above the spin glass. This is coincident with changes of the unit cell, arrangement and connectivity of stripe conducting phase.

  6. Neutron scattering study of underdoped Ba1-xKxFe₂As₂ (x=0.09 and 0.17) self-flux-grown single crystals and the universality of the tricritical point

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rotundu, C. R.; Tian, W.; Rule, K. C.; Forrest, T. R.; Zhao, J.; Zarestky, J. L.; Birgeneau, R. J.

    2012-04-04

    We present a combination of elastic neutron scattering measurements in zero and 14.5 T and magnetization measurements in zero and 14 T on underdoped superconducting Ba1-xKxFe₂As₂ (x=0.17), and the same measurements in zero field on a nonsuperconducting crystal with x=0.09. The data suggest that the underdoped materials may not be electronic phase separated but rather have slightly inhomogeneous potassium doping. The temperature dependence of the magnetic order parameter below the transition of the sample with x=0.09 is more gradual than that for the case of the undoped BaFe₂As₂, suggesting that this doping may be in the vicinity of a tricriticalmore » point. We advance therefore the hypothesis that the tricritical point is a common feature of all superconducting 122s. For the x=0.17 sample, while Tc is suppressed from ≈17 to ≈8 K by a magnetic field of 14 T, the intensity of the magnetic Bragg peaks (1 0 3) at 1.2 K is enhanced by 10%, showing competition of superconductivity and antiferromagnetism. The intensity of the magnetic Bragg peaks (1 0 3) in the (Tc, TN) temperature interval remain practically unchanged in 14.5 T within a 10% statistical error. The present results are discussed in the context of the existing literature.« less

  7. Neutron scattering study of underdoped Ba1-xKxFe₂As₂ (x=0.09 and 0.17) self-flux-grown single crystals and the universality of the tricritical point

    SciTech Connect (OSTI)

    Rotundu, C. R.; Tian, W.; Rule, K. C.; Forrest, T. R.; Zhao, J.; Zarestky, J. L.; Birgeneau, R. J.

    2012-04-04

    We present a combination of elastic neutron scattering measurements in zero and 14.5 T and magnetization measurements in zero and 14 T on underdoped superconducting Ba1-xKxFe₂As₂ (x=0.17), and the same measurements in zero field on a nonsuperconducting crystal with x=0.09. The data suggest that the underdoped materials may not be electronic phase separated but rather have slightly inhomogeneous potassium doping. The temperature dependence of the magnetic order parameter below the transition of the sample with x=0.09 is more gradual than that for the case of the undoped BaFe₂As₂, suggesting that this doping may be in the vicinity of a tricritical point. We advance therefore the hypothesis that the tricritical point is a common feature of all superconducting 122s. For the x=0.17 sample, while Tc is suppressed from ≈17 to ≈8 K by a magnetic field of 14 T, the intensity of the magnetic Bragg peaks (1 0 3) at 1.2 K is enhanced by 10%, showing competition of superconductivity and antiferromagnetism. The intensity of the magnetic Bragg peaks (1 0 3) in the (Tc, TN) temperature interval remain practically unchanged in 14.5 T within a 10% statistical error. The present results are discussed in the context of the existing literature.

  8. Photonic crystal light source

    DOE Patents [OSTI]

    Fleming, James G.; Lin, Shawn-Yu; Bur, James A.

    2004-07-27

    A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

  9. Method for the preparation of photochromic insulating crystals

    DOE Patents [OSTI]

    Abraham, M.M.; Boldu, J.L.; Chen, Y.; Orera, V.M.

    1984-09-28

    A method for preparing reversible-photochromic magnesium oxide (MgO) crystals is disclosed. Single crystals of MgO doped with both lithium (Li) and nickel (Ni) are grown by a conventional arc fusion method. The as-grown crystals are characterized by an amber coloration. The crystals lose the amber coloration and become photochromic when they are thermochemically reduced by heating at temperatures greater then 1000/sup 0/K in a hydrogen atmosphere. Alternate irradiation with uv and visible light result in rejuvenation and bleaching of the amber coloration, respectively.

  10. Method for the preparation of photochromic insulating crystals

    DOE Patents [OSTI]

    Abraham, Marvin M.; Boldu, Jose L.; Chen, Yok; Orera, Victor M.

    1986-01-01

    A method for preparing reversible-photochromic magnesium oxide (MgO) crystals. Single crystals of MgO doped with both lithium (Li) and nickel (Ni) are grown by a conventional arc fusion method. The as-grown crystals are characterized by an amber coloration. The crystals lose the amber coloration and become photochromic when they are thermochemically reduced by heating at temperatures greater than 1000.degree. K. in a hydrogen atmosphere. Alternate irradiation with UV and visible light result in rejuvenation and bleaching of the amber coloration, respectively.

  11. HANFORD MEDIUM-LOW CURIE WASTE PRETREATMENT ALTERNATIVES PROJECT FRACTIONAL CRYSTALLIZATION PILOT SCALE TESTING FINAL REPORT

    SciTech Connect (OSTI)

    HERTING DL

    2008-09-16

    The Fractional Crystallization Pilot Plant was designed and constructed to demonstrate that fractional crystallization is a viable way to separate the high-level and low-activity radioactive waste streams from retrieved Hanford single-shell tank saltcake. The focus of this report is to review the design, construction, and testing details of the fractional crystallization pilot plant not previously disseminated.

  12. Resonance electronic Raman scattering in rare earth crystals

    SciTech Connect (OSTI)

    Williams, G.M.

    1988-11-10

    The intensities of Raman scattering transitions between electronic energy levels of trivalent rare earth ions doped into transparent crystals were measured and compared to theory. A particle emphasis was placed on the examination of the effect of intermediate state resonances on the Raman scattering intensities. Two specific systems were studied: Ce/sup 3 +/(4f/sup 1/) in single crystals of LuPO/sub 4/ and Er/sup 3 +/(4f/sup 11/) in single crystals of ErPO/sub 4/. 134 refs., 92 figs., 33 tabs.

  13. Phase equilibria in the quasiternary system Ag{sub 2}S–Ga{sub 2}S{sub 3}–In{sub 2}S{sub 3} and optical properties of (Ga{sub 55}In{sub 45}){sub 2}S{sub 300}, (Ga{sub 54.59}In{sub 44.66}Er{sub 0.75}){sub 2}S{sub 300} single crystals

    SciTech Connect (OSTI)

    Ivashchenko, I.A.; Danyliuk, I.V.; Olekseyuk, I.D.; Pankevych, V.Z.; Halyan, V.V.

    2015-07-15

    The quasiternary system Ag{sub 2}S–Ga{sub 2}S{sub 3}–In{sub 2}S{sub 3} was investigated by differential thermal, X-ray diffraction analyses. The phase diagram of the Ga{sub 2}S{sub 3}–In{sub 2}S{sub 3} system and nine polythermal sections, isothermal section at 820 K and the liquidus surface projection were constructed. The existence of the large solid solutions ranges of binary and ternary compounds was established. The range of the existence of the quaternary phase AgGa{sub x}In{sub 5−x}S{sub 8} (2.25≤x≤2.85) at 820 K was determined. The single crystals (Ga{sub 55}In{sub 45}){sub 2}S{sub 300} and (Ga{sub 54.59}In{sub 44.66}Er{sub 0.75}){sub 2}S{sub 300} were grown by a directional crystallization method from solution-melt. Optical absorption spectra in the 500–1600 nm range were recorded. The luminescence of the (Ga{sub 54.59}In{sub 44.66}Er{sub 0.75}){sub 2}S{sub 300} single crystal shows a maximum at 1530 nm for the excitation wavelengths of 532 and 980 nm at 80 and 300 K. - Graphical abstract: Isothermal section of the quasiternary system Ag{sub 2}S–Ga{sub 2}S{sub 3}–In{sub 2}S{sub 3} at 820 K and normalized photoluminescence spectra of the single crystal (Ga{sub 54.59}In{sub 44.66}Er{sub 0.75}){sub 2}S{sub 300} at 300 K. - Highlights: • Isothermal section at 820 K, liquidus surface projection were built for Ag{sub 2}S–Ga{sub 2}S{sub 3}–In{sub 2}S{sub 3}. • Optical properties of single crystals were studied.

  14. Automated macromolecular crystallization screening

    DOE Patents [OSTI]

    Segelke, Brent W.; Rupp, Bernhard; Krupka, Heike I.

    2005-03-01

    An automated macromolecular crystallization screening system wherein a multiplicity of reagent mixes are produced. A multiplicity of analysis plates is produced utilizing the reagent mixes combined with a sample. The analysis plates are incubated to promote growth of crystals. Images of the crystals are made. The images are analyzed with regard to suitability of the crystals for analysis by x-ray crystallography. A design of reagent mixes is produced based upon the expected suitability of the crystals for analysis by x-ray crystallography. A second multiplicity of mixes of the reagent components is produced utilizing the design and a second multiplicity of reagent mixes is used for a second round of automated macromolecular crystallization screening. In one embodiment the multiplicity of reagent mixes are produced by a random selection of reagent components.

  15. A novel organic nonlinear optical crystal: Creatininium succinate

    SciTech Connect (OSTI)

    Thirumurugan, R.; Anitha, K.

    2015-06-24

    A novel organic material complex of creatininium succinate (CS) has been synthesized and single crystals were grown by the reaction of creatinine and succinic acid from aqueous solution by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated using single crystal X-ray diffraction analysis and the structure was refined by least-squares method to R = 0.027 for 1840 reflections. FT-IR spectral investigation has been carried out to identify the various functional groups in the title compound. UV–Vis transmission was carried out which shows the crystal has a good optical transmittance in the visible region with lower cutoff wavelength around 220 nm. Nonlinear optical property of the crystal was confirmed by Kurtz-Perry powder technique.

  16. Shallow melt apparatus for semicontinuous czochralski crystal growth

    DOE Patents [OSTI]

    Wang, Tihu; Ciszek, Theodore F.

    2006-01-10

    In a single crystal pulling apparatus for providing a Czochralski crystal growth process, the improvement of a shallow melt In a single crystal pulling apparatus for providing a Czochralski crystal growth process, the improvement of a shallow melt crucible (20) to eliminate the necessity supplying a large quantity of feed stock materials that had to be preloaded in a deep crucible to grow a large ingot, comprising a gas tight container a crucible with a deepened periphery (25) to prevent snapping of a shallow melt and reduce turbulent melt convection; source supply means for adding source material to the semiconductor melt; a double barrier (23) to minimize heat transfer between the deepened periphery (25) and the shallow melt in the growth compartment; offset holes (24) in the double barrier (23) to increase melt travel length between the deepened periphery (25) and the shallow growth compartment; and the interface heater/heat sink (22) to control the interface shape and crystal growth rate.

  17. Liquid Crystal Optofluidics

    SciTech Connect (OSTI)

    Vasdekis, Andreas E.; Cuennet, J. G.; Psaltis, D.

    2012-10-11

    By employing anisotropic fluids and namely liquid crystals, fluid flow becomes an additional degree of freedom in designing optofluidic devices. In this paper, we demonstrate optofluidic liquid crystal devices based on the direct flow of nematic liquid crystals in microfluidic channels. Contrary to previous reports, in the present embodiment we employ the effective phase delay acquired by light travelling through flowing liquid crystal, without analysing the polarisation state of the transmitted light. With this method, we demonstrate the variation in the diffraction pattern of an array of microfluidic channels acting as a grating. We also discuss our recent activities in integrating mechanical oscillators for on-chip peristaltic pumping.

  18. Phononic crystal devices

    SciTech Connect (OSTI)

    El-Kady, Ihab F.; Olsson, Roy H.

    2012-01-10

    Phononic crystals that have the ability to modify and control the thermal black body phonon distribution and the phonon component of heat transport in a solid. In particular, the thermal conductivity and heat capacity can be modified by altering the phonon density of states in a phononic crystal. The present invention is directed to phononic crystal devices and materials such as radio frequency (RF) tags powered from ambient heat, dielectrics with extremely low thermal conductivity, thermoelectric materials with a higher ratio of electrical-to-thermal conductivity, materials with phononically engineered heat capacity, phononic crystal waveguides that enable accelerated cooling, and a variety of low temperature application devices.

  19. Tunable plasmonic crystal

    DOE Patents [OSTI]

    Dyer, Gregory Conrad; Shaner, Eric A.; Reno, John L.; Aizin, Gregory

    2015-08-11

    A tunable plasmonic crystal comprises several periods in a two-dimensional electron or hole gas plasmonic medium that is both extremely subwavelength (.about..lamda./100) and tunable through the application of voltages to metal electrodes. Tuning of the plasmonic crystal band edges can be realized in materials such as semiconductors and graphene to actively control the plasmonic crystal dispersion in the terahertz and infrared spectral regions. The tunable plasmonic crystal provides a useful degree of freedom for applications in slow light devices, voltage-tunable waveguides, filters, ultra-sensitive direct and heterodyne THz detectors, and THz oscillators.

  20. Sagittal focusing of synchrotron x radiation with curved crystals

    SciTech Connect (OSTI)

    Sparks, C.J. Jr.; Ice, G.E.; Wong, J.; Batterman, B.W.

    1981-01-01

    We describe the sagittal focusing of x rays with singly bent crystals that accept the meridian plane divergence from a similar but flat crystal to form a pair in a nondispersive two-crystal Bragg monochromator. Curved crystals can intercept from 5 to 20 times the sagittal divergence of curved mirrors at x-ray energies above 10 keV. Anticlastic (transverse) bending of the crystal is made negligible in the meridian plane with reinforcing ribs cut parallel to the plane of scattering. Results show that at energies of 10, 20, and 30 keV the bent crystal performs efficiently and images the source size at the Cornell High Energy Synchrotron Source.

  1. PPO Single

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    40,001 to 80,000 58.50 105.50 122.50 169.50 80,001 to 120,000* 63.50 113.50 132.50 182.50 More than 120,000 77.50 139.00 162.00 223.50 HDHP Single Adult +...

  2. PPO Single

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    PPO Single Adult + Children Two Adults Family Salary range less than or = $40,000 $53.50 $96.00 $112.00 $154.50 $40,001 to $80,000 $58.50 $105.50 $122.50 $169.50 $80,001 to $120,000* $63.50 $113.50 $132.50 $182.50 More than $120,000 $77.50 $139.00 $162.00 $223.50 HDHP Single Adult + Children Two Adults Family Salary range less than or = $40,000 $38.50 $69.00 $80.50 $111.00 $40,001 to $80,000 $42.50 $75.50 $88.50 $121.50 $80,001 to $120,000* $45.50 $81.00 $95.00 $131.00 More than $120,000 $55.50

  3. Controlled growth of semiconductor crystals

    DOE Patents [OSTI]

    Bourret-Courchesne, E.D.

    1992-07-21

    A method is disclosed for growth of III-V, II-VI and related semiconductor single crystals that suppresses random nucleation and sticking of the semiconductor melt at the crucible walls. Small pieces of an oxide of boron B[sub x]O[sub y] are dispersed throughout the comminuted solid semiconductor charge in the crucible, with the oxide of boron preferably having water content of at least 600 ppm. The crucible temperature is first raised to a temperature greater than the melt temperature T[sub m1] of the oxide of boron (T[sub m1]=723 K for boron oxide B[sub 2]O[sub 3]), and the oxide of boron is allowed to melt and form a reasonably uniform liquid layer between the crucible walls and bottom surfaces and the still-solid semiconductor charge. The temperature is then raised to approximately the melt temperature T[sub m2] of the semiconductor charge material, and crystal growth proceeds by a liquid encapsulated, vertical gradient freeze process. About half of the crystals grown have a dislocation density of less than 1000/cm[sup 2]. If the oxide of boron has water content less than 600 ppm, the crucible material should include boron nitride, a layer of the inner surface of the crucible should be oxidized before the oxide of boron in the crucible charge is melted, and the sum of thicknesses of the solid boron oxide layer and liquid boron oxide layer should be at least 50 [mu]m. 7 figs.

  4. Controlled growth of semiconductor crystals

    DOE Patents [OSTI]

    Bourret-Courchesne, Edith D.

    1992-01-01

    A method for growth of III-V, II-VI and related semiconductor single crystals that suppresses random nucleation and sticking of the semiconductor melt at the crucible walls. Small pieces of an oxide of boron B.sub.x O.sub.y are dispersed throughout the comminuted solid semiconductor charge in the crucible, with the oxide of boron preferably having water content of at least 600 ppm. The crucible temperature is first raised to a temperature greater than the melt temperature T.sub.m1 of the oxide of boron (T.sub.m1 =723.degree. K. for boron oxide B.sub.2 O.sub.3), and the oxide of boron is allowed to melt and form a reasonably uniform liquid layer between the crucible walls and bottom surfaces and the still-solid semiconductor charge. The temperature is then raised to approximately the melt temperature T.sub.m2 of the semiconductor charge material, and crystal growth proceeds by a liquid encapsulated, vertical gradient freeze process. About half of the crystals grown have a dislocation density of less than 1000/cm.sup.2. If the oxide of boron has water content less than 600 ppm, the crucible material should include boron nitride, a layer of the inner surface of the crucible should be oxidized before the oxide of boron in the crucible charge is melted, and the sum of thicknesses of the solid boron oxide layer and liquid boron oxide layer should be at least 50 .mu.m.

  5. Crystals for neutron scattering studies of quantum magnetism

    SciTech Connect (OSTI)

    Yankova, Tantiana; Hüvonen, Dan; Mühlbauer, Sebastian; Schmidiger, David; Wulf, Erik; Hong, Tao; Garlea, Vasile O; Custelcean, Radu; Ehlers, Georg

    2012-01-01

    We review a strategy for targeted synthesis of large single crystal samples of prototype quantum magnets for inelastic neutron scattering experiments. Four case studies of organic copper halogenide S = 1/2 systems are presented. They are meant to illustrate that exciting experimental results pertaining to the forefront of many-body quantum physics can be obtained on samples grown using very simple techniques, standard laboratory equipment, and almost no experience in advanced crystal growth techniques.

  6. Structural and vibrational properties of single crystals of Scandia...

    Office of Scientific and Technical Information (OSTI)

    OSTI Identifier: 22492881 Resource Type: Journal Article Resource Relation: Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 16; Other Information: (c) ...

  7. Dislocation transport in shock-loaded single crystals

    SciTech Connect (OSTI)

    Johnson, J.N.

    1987-01-05

    It has been previously observed that the impact surface of (100) shock-loaded lithium fluoride is a strong source of dislocations. These dislocations, on one side of the impact surface, are nearly all of the same sign and move in the same direction when the driving (impact) stress is maintained. This produces an excess of like-signed dislocations between the impact surface and the advancing planar shock front. It is shown that inclusion of dislocation transport effects in the equation for dislocation regeneration is required when surface sources are present. A derivation of the general expression of dislocation transport is presented along with some specific results for (100) loaded lithium fluoride. These results have important consequences regarding proper analysis of elastic precursor decay and rate-dependent plastic deformation in shock-loaded solids.

  8. Stress-corrosion cracking of copper single crystals

    SciTech Connect (OSTI)

    Sieradzki, K.; Newman, R.C.; Sabatini, R.L.

    1984-10-01

    Constant extension rate tests have been carried out in a sodium nitrite solution. Crack velocities up to 30 nm per second were obtained at 30/sup 0/C. If dynamic straining is stopped, the cracks apparently stop growing within about 20 ..mu..m. The steps between adjacent flat facets are more energy-absorbing than in ..cap alpha..-brass, providing a possible explanation for the importance of dynamic strain. Simultaneous acoustic emission and electrochemical current transients suggest that cracking proceeds by discontinuous cleavage.

  9. Measurement of Single Electronic Charging of Semiconductor Nano-Crystals

    SciTech Connect (OSTI)

    Kastner, Marc A.

    2014-10-09

    We have studied charge transport in nanopatterned arrays of PbS colloidal quantum dots using conventional two-probe measurements as well as with an integrated chargesensor.

  10. Solid-state syntheses and single-crystal characterizations of...

    Office of Scientific and Technical Information (OSTI)

    Additional Journal Information: Journal Volume: 221; Journal Issue: C; Journal ID: ISSN 0022-4596 Publisher: Elsevier Sponsoring Org: USDOE Country of Publication: United States ...

  11. Single Crystal Preparation for High-Pressure Experiments in the...

    Office of Scientific and Technical Information (OSTI)

    Our sample preparation steps include cutting, classical metallographic polishing, and laser ablation. The key to our new process is the preservation of crystallinity during cutting ...

  12. Understanding Metal Directed-Assembly Growth of Single-Crystal...

    Office of Scientific and Technical Information (OSTI)

    The deterministic growth of oriented crystalline organic nanowires (CONs) from the vapor-solid chemical reaction (VSCR) between small-molecule reactants and metal nanoparticles has ...

  13. Superconducting properties in single crystals of the topological...

    Office of Scientific and Technical Information (OSTI)

    Publication Date: 2016-02-22 OSTI Identifier: 1238708 GrantContract Number: FG-02-05ER46200 Type: Publisher's Accepted Manuscript Journal Name: Physical Review B Additional ...

  14. Deformation of Single Crystal Molybdenum at High Pressure (Technical...

    Office of Scientific and Technical Information (OSTI)

    of conventional large sample (1cmsup 3) testing methods. ... and was not used in this study. less Authors: Bonner, B ... Country of Publication: United States Language: English ...

  15. Deformation of Single Crystal Molybdenum at High Pressure (Technical...

    Office of Scientific and Technical Information (OSTI)

    Experiments under hydrostatic pressure provide insight into the nature of materials under extreme conditions, and also provide a means for altering deformation behavior in a ...

  16. Preparation and characterization of single crystal samples for...

    Office of Scientific and Technical Information (OSTI)

    Citation Details In-Document Search Title: Preparation and ... Publication Date: 2005-10-26 OSTI Identifier: 951171 Report Number(s): UCRL-JRNL-216835 Journal ID: ISSN ...

  17. Photonic crystal surface-emitting lasers enabled by an accidental Dirac point

    DOE Patents [OSTI]

    Chua, Song Liang; Lu, Ling; Soljacic, Marin

    2014-12-02

    A photonic-crystal surface-emitting laser (PCSEL) includes a gain medium electromagnetically coupled to a photonic crystal whose energy band structure exhibits a Dirac cone of linear dispersion at the center of the photonic crystal's Brillouin zone. This Dirac cone's vertex is called a Dirac point; because it is at the Brillouin zone center, it is called an accidental Dirac point. Tuning the photonic crystal's band structure (e.g., by changing the photonic crystal's dimensions or refractive index) to exhibit an accidental Dirac point increases the photonic crystal's mode spacing by orders of magnitudes and reduces or eliminates the photonic crystal's distributed in-plane feedback. Thus, the photonic crystal can act as a resonator that supports single-mode output from the PCSEL over a larger area than is possible with conventional PCSELs, which have quadratic band edge dispersion. Because output power generally scales with output area, this increase in output area results in higher possible output powers.

  18. Efficient room-temperature source of polarized single photons

    DOE Patents [OSTI]

    Lukishova, Svetlana G.; Boyd, Robert W.; Stroud, Carlos R.

    2007-08-07

    An efficient technique for producing deterministically polarized single photons uses liquid-crystal hosts of either monomeric or oligomeric/polymeric form to preferentially align the single emitters for maximum excitation efficiency. Deterministic molecular alignment also provides deterministically polarized output photons; using planar-aligned cholesteric liquid crystal hosts as 1-D photonic-band-gap microcavities tunable to the emitter fluorescence band to increase source efficiency, using liquid crystal technology to prevent emitter bleaching. Emitters comprise soluble dyes, inorganic nanocrystals or trivalent rare-earth chelates.

  19. Design of a high-resolution high-stability positioning mechanism for crystal optics

    SciTech Connect (OSTI)

    Shu, D.; Toellner, T. S.; Alp, E. E.

    1999-10-11

    The authors present a novel miniature multi-axis driving structure that will allow positioning of two crystals with better than 50-nrad angular resolution and nanometer linear driving sensitivity.The precision and stability of this structure allow the user to align or adjust an assembly of crystals to achieve the same performance as does a single channel-cut crystal, so they call it an artificial channel-cut crystal. In this paper, the particular designs and specifications, as well as the test results,for a two-axis driving structure for a high-energy-resolution artificial channel-cut crystal monochromator are presented

  20. Magnetic anisotropy and order structure of L1{sub 0}-FePt(001) single-crystal films grown epitaxially on (001) planes of MgO, SrTiO{sub 3}, and MgAl{sub 2}O{sub 4} substrates

    SciTech Connect (OSTI)

    Hotta, A. Hatayama, M.; Tsumura, K.; Ono, T.; Kikuchi, N.; Okamoto, S.; Kitakami, O.; Shimatsu, T.

    2014-05-07

    L1{sub 0}–FePt(001) single-crystal films were grown epitaxially on SrTiO{sub 3}(001), MgAl{sub 2}O{sub 4}(001), and MgO(001) substrates. Their uniaxial magnetic anisotropy K{sub u} and the order structure were examined for the film thickness t range of 2–14 nm. All series of films show large K{sub u} of 4 × 10{sup 7} erg/cm{sup 3} in the thickness range higher than 10 nm, with order parameter S of 0.8 and saturation magnetization M{sub s} of 1120 emu/cm{sup 3}. K{sub u} decreased gradually as t decreased. The K{sub u} reduction was considerable when t decreased from 4 nm to 2 nm. No marked difference in the thickness dependence of K{sub u} was found in any series of films, although the lattice mismatch between FePt and the substrates was markedly different. K{sub u} reduction showed good agreement with the reduction of S for the films on MgAl{sub 2}O{sub 4} and MgO. The K{sub u} ∼ S{sup 2} plot showed an almost linear relation, which is in good agreement with theoretical predictions. Transmission electron microscopy images for a FePt film on MgO substrate revealed that the lattice mismatch between FePt(001) and MgO(001) was relaxed in the initial 1 or 2 layers of FePt(001) lattices, which is likely to be true also for two other series of films.

  1. Simultaneous presence of (Si{sub 3}O{sub 10}){sup 8−} and (Si{sub 2}O{sub 7}){sup 6−} groups in new synthetic mixed sorosilicates: BaY{sub 4}(Si{sub 2}O{sub 7})(Si{sub 3}O{sub 10}) and isotypic compounds, studied by single-crystal X-ray diffraction, Raman spectroscopy and DFT calculations

    SciTech Connect (OSTI)

    Wierzbicka-Wieczorek, Maria; Többens, Daniel M.; Kolitsch, Uwe; Tillmanns, Ekkehart

    2013-11-15

    Three new, isotypic silicate compounds, BaY{sub 4}(Si{sub 2}O{sub 7})(Si{sub 3}O{sub 10}), SrYb{sub 4}(Si{sub 2}O{sub 7})(Si{sub 3}O{sub 10}) and SrSc{sub 4}(Si{sub 2}O{sub 7})(Si{sub 3}O{sub 10}), were synthesized using high-temperature flux growth techniques, and their crystal structures were solved from single-crystal X-ray intensity data: monoclinic, P2{sub 1}/m, with a=5.532(1)/5.469(1)/5.278(1), b=19.734(4)/19.447(4)/19.221(4), c=6.868(1)/6.785(1)/6.562(1) Å, β=106.53(3)/106.20(3)/106.50(3)°, V=718.8(2)/693.0(2)/638.3(2) Å{sup 3}, R(F)=0.0225/0.0204/0.0270, respectively. The topology of the novel structure type contains isolated horseshoe-shaped Si{sub 3}O{sub 10} groups (Si–Si–Si=93.15–95.98°), Si{sub 2}O{sub 7} groups (Si–O{sub bridge}–Si=180°, symmetry-restricted) and edge-sharing M(1)O{sub 6} and M(2)O{sub 6} octahedra. Single-crystal Raman spectra of the title compounds were measured and compared with Raman spectroscopic data of chemically and topologically related disilicates and trisilicates, including BaY{sub 2}(Si{sub 3}O{sub 10}) and SrY{sub 2}(Si{sub 3}O{sub 10}). The band assignments are supported by additional theoretical calculation of Raman vibrations by DFT methods. - Graphical abstract: View of BaY{sub 4}(Si{sub 2}O{sub 7})(Si{sub 3}O{sub 10}) along [100], showing zigzag chains and the tri- and disilicate groups. The unit cell is outlined. Display Omitted - Highlights: • We report a novel interesting crystal structure type for mixed sorosilicates containing Y, Yb, and Sc. • Synthesis of such mixed sorosilicates is possible by a high-temperature flux-growth technique. • Calculation of Raman vibrations by advanced DFT methods allows a considerably improved interpretation of measured Raman spectra.

  2. Frequency doubling crystals

    DOE Patents [OSTI]

    Wang, Francis; Velsko, Stephan P.

    1989-01-01

    A systematic approach to the production of frequency conversion crystals is described in which a chiral molecule has attached to it a "harmonic generating unit" which contributes to the noncentrosymmetry of the molecule. Certain preferred embodiments of such harmonic generating units include carboxylate, guanadyly and imidazolyl units. Certain preferred crystals include L-arginine fluoride, deuterated L-arginine fluoride, L-arginine chloride monohydrate, L-arginine acetate, dithallium tartrate, ammonium N-acetyl valine, N-acetyl tyrosine and N-acetyl hydroxyproline. Chemical modifications of the chiral molecule, such as deuteration, halogenation and controlled counterion substitution are available to adapt the dispersive properties of a crystal in a particular wavelength region.

  3. Process of making cryogenically cooled high thermal performance crystal optics

    DOE Patents [OSTI]

    Kuzay, T.M.

    1992-06-23

    A method is disclosed for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N[sub 2] is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation. 7 figs.

  4. Process of making cryogenically cooled high thermal performance crystal optics

    DOE Patents [OSTI]

    Kuzay, Tuncer M.

    1992-01-01

    A method for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N.sub.2 is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation.

  5. ZnTeO{sub 3} crystal growth by a modified Bridgman technique

    SciTech Connect (OSTI)

    Nawash, Jalal M. Lynn, Kelvin G.

    2014-12-15

    Highlights: • ZnTeO{sub 3} single crystals were grown for the first time by a modified Bridgman method. • The growth is still possible in a system that lacks congruent melting. • A growth is best when melt is exposed to a steeper axial thermal gradient. • Optical and electrical properties were investigated for the grown crystals. - Abstract: Zinc Tellurite (ZnTeO{sub 3}) crystals were grown for the first time using a modified Bridgman method with a 2.5 kHz radio frequency (RF) furnace. Single crystal growth of ZnTeO{sub 3} was hindered by many complicating factors, such as the evaporation of TeO{sub 2} above 700 °C and the formation of more than one phase during crystal growth. While there were several successful runs that produced ZnTeO{sub 3} single crystals, it was found that large (≥10 cm{sup 3}) single ZnTeO{sub 3} crystals resulted when the crucible was exposed to a steeper vertical thermal gradient and when the temperature of the melt was raised to at least 860 °C. The results of powder X-ray diffraction (XRD) patterns were in accordance with the X-ray powder diffraction file (PDF) for ZnTeO{sub 3}. Some optical, electrical and structural properties of ZnTeO{sub 3} single crystals were reported in this paper.

  6. FRACTIONAL CRYSTALLIZATION FEED ENVELOPE

    SciTech Connect (OSTI)

    HERTING DL

    2008-03-19

    Laboratory work was completed on a set of evaporation tests designed to establish a feed envelope for the fractional crystallization process. The feed envelope defines chemical concentration limits within which the process can be operated successfully. All 38 runs in the half-factorial design matrix were completed successfully, based on the qualitative definition of success. There is no feed composition likely to be derived from saltcake dissolution that would cause the fractional crystallization process to not meet acceptable performance requirements. However, some compositions clearly would provide more successful operation than other compositions.

  7. Electro-optic crystal mosaics for the generation of terahertz radiation

    DOE Patents [OSTI]

    Carrig, T.J.; Taylor, A.J.; Stewart, K.R.

    1996-08-06

    Apparatus for the generation of high energy terahertz radiation is presented and comprises laser means effective to produce subpicosecond optical pulses and a mosaic comprising a plurality of planar electro-optic crystals fastened together edge to edge in the form of a grid. The electro-optic crystals are in optical communication with the subpicosecond optical pulses, and behave as a single large electro-optic crystal, producing high energy terahertz radiation by way of optical rectification. 5 figs.

  8. Photo of the Week: How to Grow Superconducting Crystals | Department of

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Energy How to Grow Superconducting Crystals Photo of the Week: How to Grow Superconducting Crystals September 13, 2013 - 11:29am Addthis Many of the materials that scientists work with at Brookhaven National Laboratory are too small and too precise for traditional tools. In cases like these, the labs grow materials instead of building them. Brookhaven physicist Genda Gu pioneered techniques that grow some of the largest single-crystal high-temperature superconductors in the world. The

  9. Electro-optic crystal mosaics for the generation of terahertz radiation

    DOE Patents [OSTI]

    Carrig, Timothy J.; Taylor, Antoinette J.; Stewart, Kevin R.

    1996-01-01

    Apparatus for the generation of high energy terahertz radiation is presented and comprises laser means effective to produce subpicosecond optical pulses and a mosaic comprising a plurality of planar electro-optic crystals fastened together edge to edge in the form of a grid. The electro-optic crystals are in optical communication with the subpicosecond optical pulses, and behave as a single large electro-optic crystal, producing high energy terahertz radiation by way of optical rectification.

  10. Phase equilibria in the quasi-ternary system Ag{sub 2}Se–Ga{sub 2}Se{sub 3}–In{sub 2}Se{sub 3} and physical properties of (Ga{sub 0.6}In{sub 0.4}){sub 2}Se{sub 3}, (Ga{sub 0.594}In{sub 0.396}Er{sub 0.01}){sub 2}Se{sub 3} single crystals

    SciTech Connect (OSTI)

    Ivashchenko, I.A.; Danyliuk, I.V.; Olekseyuk, I.D.; Halyan, V.V.

    2014-02-15

    The quasi-ternary system Ag{sub 2}Se–Ga{sub 2}Se{sub 3}–In{sub 2}Se{sub 3} was investigated by differential thermal, X-ray phase, X-ray structure, microstructure analysis and microhardness measurements. Five quasi-binary phase diagrams, six polythermal sections, isothermal section at 820 K and the liquidus surface projection were constructed. The character and temperature of the invariant processes were determined. The specific resistance of the single crystals (Ga{sub 0.6}In{sub 0.4}){sub 2}Se{sub 3}, (Ga{sub 0.594}In{sub 0.396}Er{sub 0.01}){sub 2}Se{sub 3} was measured, 7.5×10{sup 5} and 3.15×10{sup 5} Ω m, respectively, optical absorption spectra in the 600–1050 nm range were recorded at room temperature, and the band gap energy was estimated which is 1.95±0. 01 eV for both samples. - Graphical abstract: The article reports for the first time the investigated liquidus surface projection of the Ag{sub 2}Se–Ga{sub 2}Se{sub 3}–In{sub 2}Se{sub 3} system and isothermal section at 820 K of the system. Five phase diagrams, six polythermal sections, isothermal section at 820 K and the liquidus surface projection were built at the first time. The existence of the large region of the solid solutions based on AgIn{sub 5}Se{sub 8}, Ga{sub 2}Se{sub 3} and AgGa{sub 1−x}In{sub x}Se{sub 2} was investigated. The existence of two ternary phases was established in the Ga{sub 2}Se{sub 3}–In{sub 2}Se{sub 3} system. Two single crystals (Ga{sub 0.6}In{sub 0.4}){sub 2}Se{sub 3}, (Ga{sub 0.594}In{sub 0.396}Er{sub 0.01}){sub 2}Se{sub 3} were grown and some of optical properties of them were studied at first time. Display Omitted - Highlights: • Liquidus surface projection was built for Ag{sub 2}Se–Ga{sub 2}Se{sub 3}–In{sub 2}Se{sub 3} system. • Solid solution ranges of AgIn{sub 5}Se{sub 8}, Ga{sub 2}Se{sub 3} and AgGa{sub 1−x}In{sub x}Se{sub 2} were investigated. • Two single crystals (Ga{sub 0.6}In{sub 0.4}){sub 2}Se{sub 3}, (Ga{sub 0.594}In{sub 0.396}Er

  11. Direct flow crystal growth system

    DOE Patents [OSTI]

    Montgomery, Kenneth E.; Milanovich, Fred P.

    1992-01-01

    A crystal is grown in a constantly filtered solution which is flowed directly into the growing face of a crystal. In a continuous flow system, solution at its saturation temperature is removed from a crystal growth tank, heated above its saturation temperature, filtered, cooled back to its saturation temperature, and returned to the tank.

  12. Optimization of Cylindrical Bent Crystals with Small Radius

    SciTech Connect (OSTI)

    Li Zhongliang; Kang Le; Feng Liangjie; Zhao Feiyun; Xu Chaoyin

    2010-06-23

    To minimize the anticlastic curvature and lower the breaking risk of a sagittal bent crystal with a smaller bending radius, three types of crystal models including the stiffening ribs, the golden value and the assembly with metal were discussed in this paper. Overall structures of the models were predicted and the parameters were optimized by the finite element analysis method. Compared with the results of measurement by long-trace-profiler, theoretical calculations were in good agreed with practical tests. The single-crystal silicon strips glued on the titanium is preferred for the second crystal of the sagittal focusing monochromator at the NSRL-XAFS beamline. Because it not only minimizes the anticlastic distortion but also it achieves small radius less than one meter.

  13. Silicon crystal growing by oscillating crucible technique

    DOE Patents [OSTI]

    Schwuttke, G.H.; Kim, K.M.; Smetana, P.

    1983-08-03

    A process for growing silicon crystals from a molten melt comprising oscillating the container during crystal growth is disclosed.

  14. Plenum type crystal growth process

    DOE Patents [OSTI]

    Montgomery, Kenneth E.

    1992-01-01

    Crystals are grown in a tank which is divided by a baffle into a crystal growth region above the baffle and a plenum region below the baffle. A turbine blade or stirring wheel is positioned in a turbine tube which extends through the baffle to generate a flow of solution from the crystal growing region to the plenum region. The solution is pressurized as it flows into the plenum region. The pressurized solution flows back to the crystal growing region through return flow tubes extending through the baffle. Growing crystals are positioned near the ends of the return flow tubes to receive a direct flow of solution.

  15. Crystal growth, structure and characterizations of a new semiorganic nonlinear optical material-{beta}-Alanine zinc chloride

    SciTech Connect (OSTI)

    Anbuchezhiyan, M.; Ponnusamy, S.; Muthamizhchelvan, C.; Sivakumar, K.

    2010-08-15

    The title compound, {beta}-alanine zinc chloride-a new semiorganic nonlinear optical crystal was grown by slow evaporation technique. Single crystals of {beta}-alanine zinc chloride have been subjected to X-ray diffraction analysis to determine the crystal structure. The powder X-ray diffractogram of the crystal has also been recorded. The amount of carbon, nitrogen and hydrogen in the crystals was also estimated. Fourier Transform Infrared and Raman spectral measurements have been carried out on the grown crystals in order to identify the functional groups. The presence of hydrogen and carbon in the {beta}-alanine zinc chloride was confirmed by using proton and carbon nuclear magnetic resonance spectral analyses. The percentage of zinc in the crystal was determined by atomic absorption spectroscopy. Optical behavior such as ultraviolet-vis-near infrared transmittance spectrum and second harmonic generation has been investigated. The mechanical strength and thermal behavior of the grown crystal have been analyzed.

  16. Anomalous deflection of a charged-particle beam by bent crystals

    SciTech Connect (OSTI)

    Taratin, A.M.; Vorobev, S.A.

    1986-05-01

    Using computer simulations of particle trajectory, a deflection of part of the beam in the direction opposite to the curvature is discovered for charged particles passing through a bent crystal. The passage of a proton beam of energy E(0) = 1 GeV through a curved silicon single crystal is considered, and only particles that move through the single crystal in a quasi-channel mode are deflected. It is suggested that the observed anomalous deflection can be used to deflect beams of high energy charged particles through angles that are tens of times greater than the critical angle for channeling, with application to experimental nuclear physics. 6 references.

  17. Crystal face temperature determination means

    DOE Patents [OSTI]

    Nason, D.O.; Burger, A.

    1994-11-22

    An optically transparent furnace having a detection apparatus with a pedestal enclosed in an evacuated ampule for growing a crystal thereon is disclosed. Temperature differential is provided by a source heater, a base heater and a cold finger such that material migrates from a polycrystalline source material to grow the crystal. A quartz halogen lamp projects a collimated beam onto the crystal and a reflected beam is analyzed by a double monochromator and photomultiplier detection spectrometer and the detected peak position in the reflected energy spectrum of the reflected beam is interpreted to determine surface temperature of the crystal. 3 figs.

  18. Versatile collimating crystal stage for Bonse-Hart USAXS instrument.

    SciTech Connect (OSTI)

    Ilavsky, J.; Shu, D.; Jemian, P. R.; Long, G. G.

    2007-01-01

    An advanced ultra-small-angle X-ray scattering (USAXS) instrument, using the Bonse-Hart design and installed at APS, is a robust and reliable instrument, providing a scattering vector (q) range of nearly 4 decades (0.00015 to 1 {angstrom}{sup -1}), an intensity dynamic range of up to 9 decades, standard-less absolute intensity calibration, and USAXS imaging capabilities. This type of instrument typically uses channel-cut crystals in both the collimating (before sample) and analyzing (after sample) stages. The optical surfaces of these crystals are finished by etching processes, which leave an orange-peel surface texture, which would compromise the USAXS imaging quality. Therefore optics with highly polished surfaces using separated crystals in both collimating and analyzing stages were developed. A novel design of the optics and mechanical stage uses a fixed gap between the two separated collimating crystals in which a triangular section of the first crystal is removed, allowing for a variable number (1, 2, 4, 6, or 8) of crystal reflections for X-ray energies between 7 and 19 keV. The number of reflections is selected by lateral translation of the collimating crystal pair. Rotational alignment of the second crystal in the pair by an artificial channel-cut crystal mechanism, implemented with a novel high-stiffness weak link actuated by both a picomotor and a piezo-electric transducer, provides the capability to align or adjust an assembly of crystals to achieve the same performance as a single channel-cut crystal with integral weak link. The arrangement of both crystals is held on a removable base that can be remounted with precision within the Si(111) rocking curve on a three-point kinematic mount. Additional tilt adjustments are also provided for initial alignment. This monochromator has proven to be highly robust with respect to motions and vibrations, as well as flexible with respect to selection of number of reflections, and its performance directly resulted

  19. Computer simulation of beam steering by crystal channeling

    SciTech Connect (OSTI)

    Biryukov, V.

    1995-04-01

    The Monte Carlo computer program CATCH for the simulation of planar channeling in bent crystals is presented. The program tracks a charged particle through the deformed crystal lattice with the use of the continuous-potential approximation and by taking into account the processes of both single and multiple scattering on electrons and nuclei. The output consists of the exit angular distributions, the energy loss spectra, and the spectra of any close-encounter process of interest. The program predictions for the feed-out and feed-in rates, energy loss spectra, and beam bending efficiency are compared with the recent experimental data.

  20. Lamella settler crystallizer

    DOE Patents [OSTI]

    Maimoni, A.

    1990-12-18

    A crystallizer is described which incorporates a lamella settler and which is particularly applicable for use in batteries and power cells for electric vehicles or stationary applications. The lamella settler can be utilized for coarse particle separation or for agglomeration, and is particularly applicable to aluminum-air batteries or power cells for solving the hydrargillite (aluminum-hydroxide) removal problems from such batteries. This invention provides the advantages of very low energy consumption, turbulence, shear, cost and maintenance. Thus, due to the low shear and low turbulence of this invention, it is particularly effective in the control of aluminum hydroxide particle size distribution in the various sections of an aluminum-air system, as well as in other electrochemical systems requiring separation for phases of different densities. 3 figs.

  1. Lamella settler crystallizer

    DOE Patents [OSTI]

    Maimoni, Arturo

    1990-01-01

    A crystallizer which incorporates a lamella settler and which is particularly applicable for use in batteries and power cells for electric vehicles or stationary applications. The lamella settler can be utilized for coarse particle separation or for agglomeration, and is particularly applicable to aluminum-air batteries or power cells for solving the hydrargillite (aluminum-hydroxide) removal problems from such batteries. This invention provides the advantages of very low energy consumption, turbulence, shear, cost and maintenance. Thus, due to the low shear and low turbulence of this invention, it is particularly effective in the control of aluminum hydroxide particle size distribution in the various sections of an aluminum-air system, as well as in other electrochemical systems requiring separation for phases of different densities.

  2. Frequency mixing crystal

    DOE Patents [OSTI]

    Ebbers, Christopher A.; Davis, Laura E.; Webb, Mark

    1992-01-01

    In a laser system for converting infrared laser light waves to visible light comprising a source of infrared laser light waves and means of harmoic generation associated therewith for production of light waves at integral multiples of the frequency of the original wave, the improvement of said means of harmonic generation comprising a crystal having the chemical formula X.sub.2 Y(NO.sub.3).sub.5 .multidot.2 nZ.sub.2 o wherein X is selected from the group consisting of Li, Na, K, Rb, Cs, and Tl; Y is selected from the group consisting of Sc, Y, La, Ce, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, and In; Z is selected from the group consisting of H and D; and n ranges from 0 to 4.

  3. Erratum: Evolution of precipitate morphology during heat treatment and its implications for the superconductivity in KxFe1.6+ySe2 single crystals [Phys. Rev. B 86 , 144507 (2012)

    SciTech Connect (OSTI)

    Liu, Y.; Xing, Q.; Dennis, K. W.; McCallum, R. W.; Lograsso, T. A.

    2015-08-14

    In this article, we study the relationship between precipitate morphology and superconductivity in KxFe1.6+ySe2 single crystals grown by self-flux method. Scanning electron microscopy (SEM) measurements revealed that the superconducting phase forms a network in the samples quenched above iron vacancy order-disorder transition temperature Ts, whereas it aggregates into micrometer-sized rectangular bars and aligns as disconnected chains in the furnace-cooled samples.

  4. Shallow Melt Apparatus for Semicontinuous Czochralski Crystal Growth

    DOE Patents [OSTI]

    Wang, T.; Ciszek, T. F.

    2006-01-10

    In a single crystal pulling apparatus for providing a Czochralski crystal growth process, the improvement of a shallow melt crucible (20) to eliminate the necessity supplying a large quantity of feed stock materials that had to be preloaded in a deep crucible to grow a large ingot, comprising a gas tight container a crucible with a deepened periphery (25) to prevent snapping of a shallow melt and reduce turbulent melt convection; source supply means for adding source material to the semiconductor melt; a double barrier (23) to minimize heat transfer between the deepened periphery (25) and the shallow melt in the growth compartment; offset holes (24) in the double barrier (23) to increase melt travel length between the deepened periphery (25) and the shallow growth compartment; and the interface heater/heat sink (22) to control the interface shape and crystal growth rate.

  5. Watching a Liquid-Crystal Helix Unwind

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    science. Introducing molecular chirality into a liquid crystal may lead to a twisting force that can modify the equilibrium state usually observed in liquid crystals, resulting...

  6. Kondo behavior, ferromagnetic correlations, and crystal fields...

    Office of Scientific and Technical Information (OSTI)

    and crystal fields in the heavy Fermion compounds Ce3X (XIn, Sn) Citation Details In-Document Search Title: Kondo behavior, ferromagnetic correlations, and crystal fields in ...

  7. A double crystal monochromator using tangentially bend crystals in combination with toroidal mirror focusing

    SciTech Connect (OSTI)

    Feng, Jun, Thompson,A.C.; Padmore,H.A.

    2000-02-24

    In collaboration with the Chemistry Department at the University of California at Berkeley, the ALS is building a beamline for structural determination in materials chemistry. The system will be used for single crystal x-ray diffraction on crystals that are too small or disordered for examination on laboratory systems, and typically will be used for crystals in the 5 - 20 micron regime. As some of the materials being designed are of the size of small proteins, phasing using direct methods is problematic, and so use of multiple wavelength anomalous dispersion techniques will be employed in many cases. The production of new compounds has been revolutionized in recent years with the development of combinatorial synthesis techniques, and a major b2048 to further advances in this field is access to rapid measurement of structural parameters. The specification of the beamline follows from these points. It must have a small focal spot to match closely the size of the crystals, high resolution for MAD techniques, and a high flux in the small focus. The strategy for satisfying these constraints is to us a system which is compact and which uses the minimum number of components. This is done in this case by using a pseudo channel cut crystal monochromator with tangentially bent crystals, in combination with a 1:1 focusing toroidal mirror. The toroidal mirror at 1:1 magnification has only very small aberrations, and from a 220 (h) by 25 (v) [micro] m FWHM source, an image of 220 by 45 [micro]m FWHM should be produced for a 3 mrad horizontal aperture for a full vertical aperture. This has already been achieved on an existing beamline. The crystal monochromator uses tangentially bent crystals in a concave - convex configuration to achieve matching of Bragg angles to the divergent source, while maintaining zero focusing power. A useful feature of this arrangement is that while there is an optimum crystal curvature for each energy that gives the expected Darwin width limited

  8. Tapered fiber coupling of single photons emitted by a deterministically positioned single nitrogen vacancy center

    SciTech Connect (OSTI)

    Liebermeister, Lars Petersen, Fabian; Münchow, Asmus v.; Burchardt, Daniel; Hermelbracht, Juliane; Tashima, Toshiyuki; Schell, Andreas W.; Benson, Oliver; Meinhardt, Thomas; Krueger, Anke; Stiebeiner, Ariane; Rauschenbeutel, Arno; Weinfurter, Harald; Weber, Markus

    2014-01-20

    A diamond nano-crystal hosting a single nitrogen vacancy (NV) center is optically selected with a confocal scanning microscope and positioned deterministically onto the subwavelength-diameter waist of a tapered optical fiber (TOF) with the help of an atomic force microscope. Based on this nano-manipulation technique, we experimentally demonstrate the evanescent coupling of single fluorescence photons emitted by a single NV-center to the guided mode of the TOF. By comparing photon count rates of the fiber-guided and the free-space modes and with the help of numerical finite-difference time domain simulations, we determine a lower and upper bound for the coupling efficiency of (9.5 ± 0.6)% and (10.4 ± 0.7)%, respectively. Our results are a promising starting point for future integration of single photon sources into photonic quantum networks and applications in quantum information science.

  9. Crystal-Tolerant Glass Approach For Mitigation Of Crystal Accumulation In Continuous Melters Processing Radioactive Waste

    SciTech Connect (OSTI)

    Kruger, Albert A.; Rodriguez, Carmen P.; Lang, Jesse B.; Huckleberry, Adam R.; Matyas, Josef; Owen, Antoinette T.

    2012-08-28

    High-level radioactive waste melters are projected to operate in an inefficient manner as they are subjected to artificial constraints, such as minimum liquidus temperature (T{sub L}) or maximum equilibrium fraction of crystallinity at a given temperature. These constraints substantially limit waste loading, but were imposed to prevent clogging of the melter with spinel crystals [(Fe, Ni, Mn, Zn)(Fe, Cr){sub 2}O{sub 4}]. In the melter, the glass discharge riser is the most likely location for crystal accumulation during idling because of low glass temperatures, stagnant melts, and small diameter. To address this problem, a series of lab-scale crucible tests were performed with specially formulated glasses to simulate accumulation of spinel in the riser. Thicknesses of accumulated layers were incorporated into empirical model of spinel settling. In addition, T{sub L} of glasses was measured and impact of particle agglomeration on accumulation rate was evaluated. Empirical model predicted well the accumulation of single crystals and/or smallscale agglomerates, but, excessive agglomeration observed in high-Ni-Fe glass resulted in an under-prediction of accumulated layers, which gradually worsen over time as an increased number of agglomerates formed. Accumulation rate of ~14.9 +- 1 nm/s determined for this glass will result in ~26 mm thick layer in 20 days of melter idling.

  10. Crystal growth and annealing method and apparatus

    DOE Patents [OSTI]

    Gianoulakis, Steven E.; Sparrow, Robert

    2001-01-01

    A method and apparatus for producing crystals that minimizes birefringence even at large crystal sizes, and is suitable for production of CaF.sub.2 crystals. The method of the present invention comprises annealing a crystal by maintaining a minimal temperature gradient in the crystal while slowly reducing the bulk temperature of the crystal. An apparatus according to the present invention includes a thermal control system added to a crystal growth and annealing apparatus, wherein the thermal control system allows a temperature gradient during crystal growth but minimizes the temperature gradient during crystal annealing. An embodiment of the present invention comprises a secondary heater incorporated into a conventional crystal growth and annealing apparatus. The secondary heater supplies heat to minimize the temperature gradients in the crystal during the annealing process. The secondary heater can mount near the bottom of the crucible to effectively maintain appropriate temperature gradients.

  11. FRACTIONAL CRYSTALLIZATION LABORATORY TESTING WITH INTERIM PRETREATMENT SYSTEM FEEDS

    SciTech Connect (OSTI)

    HERTING DL

    2008-09-17

    The fractional crystallization process was developed as a pretreatment method for saltcake waste retrieved from Hanford single-shell tanks (SST). The process separates the retrieved SST waste into a high-level waste stream containing the bulk of the radionuclides and a low-activity waste stream containing the bulk of the nonradioactive sodium salts. The Interim Pretreatment System project shifted the focus on pretreatment planning from SST waste to double-shell tank waste.

  12. Studies of Dynamic Properties of Shock Compressed FCC Crystals by in Situ Dynamic X-Ray Diffraction

    SciTech Connect (OSTI)

    Baldis, H.; Kalantar, D.H.; Remington, B.A.; Belak, J.; Colvin, J.; Boehly, T.R.; Meyers, M.A.; Wark, J.S.; Paisley, D.; Hollan, B.; Lomdahl, P.; German, T.

    2001-08-14

    There were 5 laser experiments conducted to date in FY-01 under the ongoing project to study the response of single crystal fcc materials under shock compression. An additional 10 laser shots are planned for August, 2001. This work has focused on developing capability to record diffraction from multiple lattice planes during the passage of a shock through a thin foil of single crystal copper, while simultaneously performing separate shock sample recovery experiments to study the residual deformation structure in the recovered samples.

  13. PREPARATION OF REFRACTORY OXIDE CRYSTALS

    DOE Patents [OSTI]

    Grimes, W.R.; Shaffer, J.H.; Watson, G.M.

    1962-11-13

    A method is given for preparing uranium dioxide, thorium oxide, and beryllium oxide in the form of enlarged individual crystals. The surface of a fused alkali metal halide melt containing dissolved uranium, thorium, or beryllium values is contacted with a water-vapor-bearing inert gas stream at a rate of 5 to 10 cubic centimeters per minute per square centimeter of melt surface area. Growth of individual crystals is obtained by prolonged contact. Beryllium oxide-coated uranium dioxide crystals are prepared by disposing uranium dioxide crystals 5 to 20 microns in diameter in a beryllium-containing melt and contacting the melt with a water-vapor-bearing inert gas stream in the same manner. (AEC)

  14. Crystal face temperature determination means

    DOE Patents [OSTI]

    Nason, Donald O.; Burger, Arnold

    1994-01-01

    An optically transparent furnace (10) having a detection apparatus (29) with a pedestal (12) enclosed in an evacuated ampule (16) for growing a crystal (14) thereon. Temperature differential is provided by a source heater (20), a base heater (24) and a cold finger (26) such that material migrates from a polycrystalline source material (18) to grow the crystal (14). A quartz halogen lamp (32) projects a collimated beam (30) onto the crystal (14) and a reflected beam (34) is analyzed by a double monochromator and photomultiplier detection spectrometer (40) and the detected peak position (48) in the reflected energy spectrum (44) of the reflected beam (34) is interpreted to determine surface temperature of the crystal (14).

  15. Adaptive Liquid Crystal Windows

    SciTech Connect (OSTI)

    Taheri, Bahman; Bodnar, Volodymyr

    2011-12-31

    Energy consumption by private and commercial sectors in the U.S. has steadily grown over the last decade. The uncertainty in future availability of imported oil, on which the energy consumption relies strongly, resulted in a dramatic increase in the cost of energy. About 20% of this consumption are used to heat and cool houses and commercial buildings. To reduce dependence on the foreign oil and cut down emission of greenhouse gases, it is necessary to eliminate losses and reduce total energy consumption by buildings. To achieve this goal it is necessary to redefine the role of the conventional windows. At a minimum, windows should stop being a source for energy loss. Ideally, windows should become a source of energy, providing net gain to reduce energy used to heat and cool homes. It is possible to have a net energy gain from a window if its light transmission can be dynamically altered, ideally electronically without the need of operator assistance, providing optimal control of the solar gain that varies with season and climate in the U.S. In addition, the window must not require power from the building for operation. Resolution of this problem is a societal challenge and of national interest and will have a broad global impact. For this purpose, the year-round, allclimate window solution to provide an electronically variable solar heat gain coefficient (SHGC) with a wide dynamic range is needed. AlphaMicron, Inc. (AMI) developed and manufactured 1ft 1ft prototype panels for the worlds first auto-adjusting Adaptive Liquid Crystal Windows (ALCWs) that can operate from sunlight without the need for external power source and demonstrate an electronically adjustable SHGC. This novel windows are based on AlphaMicrons patented e-Tint technology, a guesthost liquid crystal system implemented on flexible, optically clear plastic films. This technology is suitable both for OEM and aftermarket (retro-fitting) lamination to new and existing windows. Low level of power

  16. PROGRESS ON LARGE GRAIN AND SINGLE GRAIN NIOBIUM: INGOTS AND SHEET AND REVIEW OF PROGRESS ON LARGE GRAIN AND SINGLE GRAIN NIOBIUM CAVITIES

    SciTech Connect (OSTI)

    Peter Kneisel

    2008-02-12

    Large grain and single crystal niobium has been proposed several years ago as an alternative material to poly-crystalline niobium for superconducting cavities, exhibiting potential advantages such as ¿stream-lined¿ procedures, reduced costs and better reproducibility in performance. Several major laboratories have investigated the use of large grain and single crystal material in the past years and the niobium producing industry has responded in providing ingot material with enlarged grain sizes. Besides a large number of single cell and multi-cell cavities from large grain niobium, several single crystal cavities have been fabricated and tested with good performances. This contribution will review the progress since the SRF workshop in 2005 in material processing and handling and in cavity performances.

  17. Evaluation the microwave heating of spinel crystals in high-level waste glass

    SciTech Connect (OSTI)

    Christian, J. H.; Washington, A. L.

    2015-08-18

    In this report, the microwave heating of a crystal-free and a partially (24 wt%) trevorite-crystallized waste glass simulant were evaluated. The results show that a 500 mg piece of partially crystallized waste glass can be heated from room-temperature to above 1600 °C (as measured by infrared radiometry) within 2 minutes using a single mode, highly focused, 2.45 GHz microwave, operating at 300 W. X-ray diffraction measurements show that the partially crystallized glass experiences an 87 % reduction in trevorite following irradiation and thermal quenching. When a crystal-free analogue of the same waste glass simulant composition is exposed to the same microwave radiation it could not be heated above 450 °C regardless of the heating time.

  18. Inclusion free cadmium zinc tellurium and cadmium tellurium crystals and associated growth method

    DOE Patents [OSTI]

    Bolotnikov, Aleskey E.; James, Ralph B.

    2010-07-20

    The present disclosure provides systems and methods for crystal growth of cadmium zinc tellurium (CZT) and cadmium tellurium (CdTe) crystals with an inverted growth reactor chamber. The inverted growth reactor chamber enables growth of single, large, high purity CZT and CdTe crystals that can be used, for example, in X-ray and gamma detection, substrates for infrared detectors, or the like. The inverted growth reactor chamber enables reductions in the presence of Te inclusions, which are recognized as an important limiting factor in using CZT or CdTe as radiation detectors. The inverted growth reactor chamber can be utilized with existing crystal growth techniques such as the Bridgman crystal growth mechanism and the like. In an exemplary embodiment, the inverted growth reactor chamber is a U-shaped ampoule.

  19. Cupric oxide inclusions in cuprous oxide crystals grown by the floating zone method

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Frazer, Laszlo; Chang, Kelvin B.; Poeppelmeier, Kenneth R.; Ketterson, John B.

    2015-05-08

    Phase-pure cuprous oxide (Cu2O) crystals are difficult to grow since cupric oxide can form within the crystal as the crystal is cooled to ambient conditions. Vacancies are the solute which causes precipitation of macroscopic defects. Therefore, even when a mostly phase-pure single crystal is used as a feed rod, cupric oxide inclusions persist in the recrystallized solid. Control of the thermal profile during crystal growth, however, can improve phase-purity; a slow counter-rotation rate of the feed and seed rods results in fewer inclusions. Cupric oxide can be removed by annealing, which produces a factor of 540 ± 70 increase inmore » phase-purity.« less

  20. Cupric oxide inclusions in cuprous oxide crystals grown by the floating zone method

    SciTech Connect (OSTI)

    Frazer, Laszlo; Chang, Kelvin B.; Poeppelmeier, Kenneth R.; Ketterson, John B.

    2015-05-08

    Phase-pure cuprous oxide (Cu2O) crystals are difficult to grow since cupric oxide can form within the crystal as the crystal is cooled to ambient conditions. Vacancies are the solute which causes precipitation of macroscopic defects. Therefore, even when a mostly phase-pure single crystal is used as a feed rod, cupric oxide inclusions persist in the recrystallized solid. Control of the thermal profile during crystal growth, however, can improve phase-purity; a slow counter-rotation rate of the feed and seed rods results in fewer inclusions. Cupric oxide can be removed by annealing, which produces a factor of 540 ± 70 increase in phase-purity.

  1. Residual strains in amorphous silicon films measured by x-ray double crystal topography

    SciTech Connect (OSTI)

    Kuo, C.L.; Vanier, P.E.; Bilello, J.C.

    1984-01-15

    A new application of double crystal topography using selected diffraction from portions of bent crystals was used to determine the curvature of single crystal Si wafers coated with hydrogenated amorphous Si (a-Si:H) films. This direct imaging method allowed measurements of the radii of curvature R of bent crystals over a range approx. =0.2--1000 m. Using this procedure two different series of a-Si:H films were measured to compare the internal strains and monitor these as a function of film thickness. The curvature of the sample crystals was shown to be inversely proportional to the thickness of the film. The internal stress was found to be independent of film thickness, but only depended on the processing conditions.

  2. Minimizing radiation damage in nonlinear optical crystals

    DOE Patents [OSTI]

    Cooke, D. Wayne; Bennett, Bryan L.; Cockroft, Nigel J.

    1998-01-01

    Methods are disclosed for minimizing laser induced damage to nonlinear crystals, such as KTP crystals, involving various means for electrically grounding the crystals in order to diffuse electrical discharges within the crystals caused by the incident laser beam. In certain embodiments, electrically conductive material is deposited onto or into surfaces of the nonlinear crystals and the electrically conductive surfaces are connected to an electrical ground. To minimize electrical discharges on crystal surfaces that are not covered by the grounded electrically conductive material, a vacuum may be created around the nonlinear crystal.

  3. Minimizing radiation damage in nonlinear optical crystals

    DOE Patents [OSTI]

    Cooke, D.W.; Bennett, B.L.; Cockroft, N.J.

    1998-09-08

    Methods are disclosed for minimizing laser induced damage to nonlinear crystals, such as KTP crystals, involving various means for electrically grounding the crystals in order to diffuse electrical discharges within the crystals caused by the incident laser beam. In certain embodiments, electrically conductive material is deposited onto or into surfaces of the nonlinear crystals and the electrically conductive surfaces are connected to an electrical ground. To minimize electrical discharges on crystal surfaces that are not covered by the grounded electrically conductive material, a vacuum may be created around the nonlinear crystal. 5 figs.

  4. Channeling, Volume Reection and Gamma Emission Using 14GeV Electrons in Bent Silicon Crystals

    SciTech Connect (OSTI)

    Benson, Brandon

    2015-08-14

    High energy electrons can be deflected with very tight bending radius using a bent silicon crystal. This produces gamma radiation. As these crystals can be thin, a series of bent silicon crystals with alternating direction has the potential to produce coherent gamma radiation with reasonable energy of the driving electron beam. Such an electron crystal undulator offers the prospect for higher energy radiation at lower cost than current methods. Permanent magnetic undulators like LCLS at SLAC National Accelerator Laboratory are expensive and very large (about 100 m in case of the LCLS undulator). Silicon crystals are inexpensive and compact when compared to the large magnetic undulators. Additionally, such a high energy coherent light source could be used for probing through materials currently impenetrable by x-rays. In this work we present the experimental data and analysis of experiment T523 conducted at SLAC National Accelerator Laboratory. We collected the spectrum of gamma ray emission from 14 GeV electrons on a bent silicon crystal counting single photons. We also investigated the dynamics of electron motion in the crystal i.e. processes of channeling and volume reflection at 14 GeV, extending and building off previous work. Our single photon spectrum for the amorphous crystal orientation is consistent with bremsstrahlung radiation and the volume reflection crystal orientation shows a trend consistent with synchrotron radiation at a critical energy of 740 MeV. We observe that in these two cases the data are consistent, but we make no further claims because of statistical limitations. We also extended the known energy range of electron crystal dechanneling length and channeling efficiency to 14 GeV.

  5. Watching a Liquid-Crystal Helix Unwind

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Watching a Liquid-Crystal Helix Unwind Print Liquid crystals have many versatile applications but are best known for the liquid-crystal displays that drive the billion-dollar smartphone and flat-screen industries. Chirality, the absence of inversion symmetry, plays an important role in chemistry, biology, and materials science. Introducing molecular chirality into a liquid crystal may lead to a twisting force that can modify the equilibrium state usually observed in liquid crystals, resulting in

  6. Watching a Liquid-Crystal Helix Unwind

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Watching a Liquid-Crystal Helix Unwind Print Liquid crystals have many versatile applications but are best known for the liquid-crystal displays that drive the billion-dollar smartphone and flat-screen industries. Chirality, the absence of inversion symmetry, plays an important role in chemistry, biology, and materials science. Introducing molecular chirality into a liquid crystal may lead to a twisting force that can modify the equilibrium state usually observed in liquid crystals, resulting in

  7. Watching a Liquid-Crystal Helix Unwind

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Watching a Liquid-Crystal Helix Unwind Print Liquid crystals have many versatile applications but are best known for the liquid-crystal displays that drive the billion-dollar smartphone and flat-screen industries. Chirality, the absence of inversion symmetry, plays an important role in chemistry, biology, and materials science. Introducing molecular chirality into a liquid crystal may lead to a twisting force that can modify the equilibrium state usually observed in liquid crystals, resulting in

  8. Watching a Liquid-Crystal Helix Unwind

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Watching a Liquid-Crystal Helix Unwind Watching a Liquid-Crystal Helix Unwind Print Wednesday, 09 December 2015 00:00 Liquid crystals have many versatile applications but are best known for the liquid-crystal displays that drive the billion-dollar smartphone and flat-screen industries. Chirality, the absence of inversion symmetry, plays an important role in chemistry, biology, and materials science. Introducing molecular chirality into a liquid crystal may lead to a twisting force that can

  9. Watching a Liquid-Crystal Helix Unwind

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Watching a Liquid-Crystal Helix Unwind Print Liquid crystals have many versatile applications but are best known for the liquid-crystal displays that drive the billion-dollar smartphone and flat-screen industries. Chirality, the absence of inversion symmetry, plays an important role in chemistry, biology, and materials science. Introducing molecular chirality into a liquid crystal may lead to a twisting force that can modify the equilibrium state usually observed in liquid crystals, resulting in

  10. A spin-wave logic gate based on a width-modulated dynamic magnonic crystal

    SciTech Connect (OSTI)

    Nikitin, Andrey A.; Ustinov, Alexey B.; Semenov, Alexander A.; Kalinikos, Boris A.; Chumak, Andrii V.; Serga, Alexander A.; Vasyuchka, Vitaliy I.; Hillebrands, Burkard; Lhderanta, Erkki

    2015-03-09

    An electric current controlled spin-wave logic gate based on a width-modulated dynamic magnonic crystal is realized. The device utilizes a spin-wave waveguide fabricated from a single-crystal Yttrium Iron Garnet film and two conducting wires attached to the film surface. Application of electric currents to the wires provides a means for dynamic control of the effective geometry of waveguide and results in a suppression of the magnonic band gap. The performance of the magnonic crystal as an AND logic gate is demonstrated.

  11. High throughput screening using acoustic droplet ejection to combine protein crystals and chemical libraries on crystallization plates at high density

    SciTech Connect (OSTI)

    Teplitsky, Ella; Joshi, Karan; Ericson, Daniel L.; Scalia, Alexander; Mullen, Jeffrey D.; Sweet, Robert M.; Soares, Alexei S.

    2015-07-01

    We describe a high throughput method for screening up to 1728 distinct chemicals with protein crystals on a single microplate. Acoustic droplet ejection (ADE) was used to co-position 2.5 nL of protein, precipitant, and chemicals on a MiTeGen in situ-1 crystallization plate™ for screening by co-crystallization or soaking. ADE-transferred droplets follow a precise trajectory which allows all components to be transferred through small apertures in the microplate lid. The apertures were large enough for 2.5 nL droplets to pass through them, but small enough so that they did not disrupt the internal environment created by the mother liquor. Using this system, thermolysin and trypsin crystals were efficiently screened for binding to a heavy-metal mini-library. Fluorescence and X-ray diffraction were used to confirm that each chemical in the heavy-metal library was correctly paired with the intended protein crystal. Moreover, a fragment mini-library was screened to observe two known lysozyme We describe a high throughput method for screening up to 1728 distinct chemicals with protein crystals on a single microplate. Acoustic droplet ejection (ADE) was used to co-position 2.5 nL of protein, precipitant, and chemicals on a MiTeGen in situ-1 crystallization plate™ for screening by co-crystallization or soaking. ADE-transferred droplets follow a precise trajectory which allows all components to be transferred through small apertures in the microplate lid. The apertures were large enough for 2.5 nL droplets to pass through them, but small enough so that they did not disrupt the internal environment created by the mother liquor. Using this system, thermolysin and trypsin crystals were efficiently screened for binding to a heavy-metal mini-library. Fluorescence and X-ray diffraction were used to confirm that each chemical in the heavy-metal library was correctly paired with the intended protein crystal. A fragment mini-library was screened to observe two known lysozyme

  12. High throughput screening using acoustic droplet ejection to combine protein crystals and chemical libraries on crystallization plates at high density

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Teplitsky, Ella; Joshi, Karan; Ericson, Daniel L.; Scalia, Alexander; Mullen, Jeffrey D.; Sweet, Robert M.; Soares, Alexei S.

    2015-07-01

    We describe a high throughput method for screening up to 1728 distinct chemicals with protein crystals on a single microplate. Acoustic droplet ejection (ADE) was used to co-position 2.5 nL of protein, precipitant, and chemicals on a MiTeGen in situ-1 crystallization plate™ for screening by co-crystallization or soaking. ADE-transferred droplets follow a precise trajectory which allows all components to be transferred through small apertures in the microplate lid. The apertures were large enough for 2.5 nL droplets to pass through them, but small enough so that they did not disrupt the internal environment created by the mother liquor. Using thismore » system, thermolysin and trypsin crystals were efficiently screened for binding to a heavy-metal mini-library. Fluorescence and X-ray diffraction were used to confirm that each chemical in the heavy-metal library was correctly paired with the intended protein crystal. Moreover, a fragment mini-library was screened to observe two known lysozyme We describe a high throughput method for screening up to 1728 distinct chemicals with protein crystals on a single microplate. Acoustic droplet ejection (ADE) was used to co-position 2.5 nL of protein, precipitant, and chemicals on a MiTeGen in situ-1 crystallization plate™ for screening by co-crystallization or soaking. ADE-transferred droplets follow a precise trajectory which allows all components to be transferred through small apertures in the microplate lid. The apertures were large enough for 2.5 nL droplets to pass through them, but small enough so that they did not disrupt the internal environment created by the mother liquor. Using this system, thermolysin and trypsin crystals were efficiently screened for binding to a heavy-metal mini-library. Fluorescence and X-ray diffraction were used to confirm that each chemical in the heavy-metal library was correctly paired with the intended protein crystal. A fragment mini-library was screened to observe two known

  13. Creation and recovery of a W(111) single atom gas field ion source

    SciTech Connect (OSTI)

    Pitters, Jason L.; Urban, Radovan; Wolkow, Robert A.

    2012-04-21

    Tungsten single atom tips have been prepared from a single crystal W(111) oriented wire using the chemical assisted field evaporation and etching method. Etching to a single atom tip occurs through a symmetric structure and leads to a predictable last atom unlike etching with polycrystalline tips. The single atom tip formation procedure is shown in an atom by atom removal process. Rebuilds of single atom tips occur on the same crystalline axis as the original tip such that ion emission emanates along a fixed direction for all tip rebuilds. This preparation method could be utilized and developed to prepare single atom tips for ion source development.

  14. Magnetotransport of single crystalline NbAs

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ghimire, N. J.; Luo, Yongkang; Neupane, M.; Williams, D. J.; Bauer, E. D.; Ronning, F.

    2015-03-27

    We report transport measurement in zero and applied magnetic field on a single crystal of NbAs. Transverse and longitudinal magnetoresistance in the plane of this tetragonal structure does not saturate up to 9 T. In the transverse configuration (H ∥ c, I ⊥ c) it is 230,000% at 2 K. The Hall coefficient changes sign from hole-like at room temperature to electron-like below ~150 K. The electron carrier density and mobility calculated at 2 K based on a single band approximation are 1.8 × 1019 cm-3 and 3.5 × 105 cm2/Vs, respectively. These values are similar to reported values formore » TaAs and NbP, and further emphasize that this class of noncentrosymmetric, transition-metal monopnictides is a promising family to explore the properties of Weyl semimetals and the consequences of their novel electronic structure.« less

  15. Modification of the crystal structure of gadolinium gallium garnet by helium ion irradiation

    SciTech Connect (OSTI)

    Ostafiychuk, B. K.; Yaremiy, I. P. Yaremiy, S. I.; Fedoriv, V. D.; Tomyn, U. O.; Umantsiv, M. M.; Fodchuk, I. M.; Kladko, V. P.

    2013-12-15

    The structure of gadolinium gallium garnet (GGG) single crystals before and after implantation by He{sup +} ions has been investigated using high-resolution X-ray diffraction methods and the generalized dynamic theory of X-ray scattering. The main types of growth defects in GGG single crystals and radiation-induced defects in the ion-implanted layer have been determined. It is established that the concentration of dislocation loops in the GGG surface layer modified by ion implantation increases and their radius decreases with an increase in the implantation dose.

  16. Manufacturing method of photonic crystal

    DOE Patents [OSTI]

    Park, In Sung; Lee, Tae Ho; Ahn, Jin Ho; Biswas, Rana; Constant, Kristen P.; Ho, Kai-Ming; Lee, Jae-Hwang

    2013-01-29

    A manufacturing method of a photonic crystal is provided. In the method, a high-refractive-index material is conformally deposited on an exposed portion of a periodic template composed of a low-refractive-index material by an atomic layer deposition process so that a difference in refractive indices or dielectric constants between the template and adjacent air becomes greater, which makes it possible to form a three-dimensional photonic crystal having a superior photonic bandgap. Herein, the three-dimensional structure may be prepared by a layer-by-layer method.

  17. Calibrating Curved Crystals Used for Plasma Spectroscopy

    SciTech Connect (OSTI)

    Haugh, M. J., Jacoby, K. D., Ross, P. W., Rochau, G. Wu, M., Regan, S. P., Barrios, M. A.

    2012-10-29

    The throughput and resolving power of an X-ray spectrometer that uses a curved crystal as the diffraction element is determined primarily by the crystal X-ray reflectivity properties. This poster presents a measurement technique for these crystal parameters using a simple diode source to produce a narrow spectral band. The results from measurements on concave elliptical polyethylene terephthalate (PET) crystals and convex potassium acid phthalate (KAP) crystals show large variations in the key parameters compared to those from the flat crystal.

  18. Precision Crystal Calorimeters in High Energy Physics

    ScienceCinema (OSTI)

    Ren-Yuan Zhu

    2010-01-08

    Precision crystal calorimeters traditionally play an important role in high energy physics experiments. In the last two decades, it faces a challenge to maintain its precision in a hostile radiation environment. This paper reviews the performance of crystal calorimeters constructed for high energy physics experiments and the progress achieved in understanding crystal?s radiation damage as well as in developing high quality scintillating crystals for particle physics. Potential applications of new generation scintillating crystals of high density and high light yield, such as LSO and LYSO, in particle physics experiments is also discussed.

  19. World's Largest Gold Crystal Studied at Los Alamos

    ScienceCinema (OSTI)

    Vogel, Sven; Nakotte, Heinz

    2015-01-07

    When geologist John Rakovan needed better tools to investigate whether a dazzling 217.78-gram piece of gold was in fact the world's largest single-crystal specimen - a distinguishing factor that would not only drastically increase its market value but also provide a unique research opportunity - he traveled to Los Alamos National Laboratory's Lujan Neutron Scattering Center to peer deep inside the mineral using neutron diffractometry. Neutrons, different from other probes such as X-rays and electrons, are able to penetrate many centimeters deep into most materials. Revealing the inner structure of a crystal without destroying the sample - imperative, as this one is worth an estimated $1.5 million - would allow Rakovan and Lujan Center collaborators Sven Vogel and Heinz Nakotte to prove that this exquisite nugget, which seemed almost too perfect and too big to be real, was a single crystal and hence a creation of nature. Its owner, who lives in the United States, provided the samples to Rakovan to assess the crystallinity of four specimens, all of which had been found decades ago in Venezuela.

  20. Magnetic dipole interactions in crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Johnston, David

    2016-01-13

    transition temperature T m and the ordered moment, magnetic heat capacity, and anisotropic magnetic susceptibility χ versus temperature T . The anisotropic Weiss temperature θ p in the Curie-Weiss law for T>T m is calculated. A quantitative study of the competition between FM and AFM ordering on cubic Bravais lattices versus the demagnetization factor in the absence of FM domain effects is presented. The contributions of Heisenberg exchange interactions and of the MDIs to T m and to θ p are found to be additive, which simplifies analysis of experimental data. Some properties in the magnetically-ordered state versus T are presented, including the ordered moment and magnetic heat capacity and, for AFMs, the dipolar anisotropy of the free energy and the perpendicular critical field. The anisotropic χ for dipolar AFMs is calculated both above and below the Néel temperature T N and the results are illustrated for a simple tetragonal lattice with c/a>1, c/a=1 (cubic), and c/a<1 , where a change in sign of the χ anisotropy is found at c/a=1 . Finally, following the early work of Keffer [Phys. Rev. 87, 608 (1952)], the dipolar anisotropy of χ above T N =69 K of the prototype collinear Heisenberg-exchange-coupled tetragonal compound MnF 2 is calculated and found to be in excellent agreement with experimental single-crystal literature data above 130 K, where the smoothly increasing deviation of the experimental data from the theory on cooling from 130 K to T N is deduced to arise from dynamic short-range collinear c -axis AFM ordering in this temperature range driven by the exchange interactions.« less