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)

    gas, a reactant involved in many important industrial catalytic processes, including the Fischer-Tropsch process for making liquid hydrocarbons, the oxidation process in...

  2. Platinum Nanoclusters Out-Perform Single Crystals

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible for RenewableSpeedingBiomassPPPOPetroleum38 (1996) A213-A225. Printed ingunCONTRACT

  3. Platinum Nanoclusters Out-Perform Single Crystals

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible for RenewableSpeedingBiomassPPPOPetroleum38 (1996) A213-A225. Printed

  4. Platinum Nanoclusters Out-Perform Single Crystals

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible for RenewableSpeedingBiomassPPPOPetroleum38 (1996) A213-A225. PrintedPlatinum

  5. Platinum Nanoclusters Out-Perform Single Crystals

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible for RenewableSpeedingBiomassPPPOPetroleum38 (1996) A213-A225. PrintedPlatinumPlatinum

  6. Platinum Nanoclusters Out-Perform Single Crystals

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible for RenewableSpeedingBiomassPPPOPetroleum38 (1996) A213-A225.

  7. Platinum Nanoclusters Out-Perform Single Crystals

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible for RenewableSpeedingBiomassPPPOPetroleum38 (1996) A213-A225.Platinum Nanoclusters

  8. Platinum Nanoclusters Out-Perform Single Crystals

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible for RenewableSpeedingBiomassPPPOPetroleum38 (1996) A213-A225.Platinum

  9. Platinum Nanoclusters Out-Perform Single Crystals

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible for RenewableSpeedingBiomassPPPOPetroleum38 (1996) A213-A225.PlatinumPlatinum

  10. Platinum Nanoclusters Out-Perform Single Crystals

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)IntegratedSpeeding accessPeptoidLabPhysics PhysicsPlatinum Nanoclusters

  11. Platinum Nanoclusters Out-Perform Single Crystals

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)IntegratedSpeeding accessPeptoidLabPhysics PhysicsPlatinum NanoclustersPlatinum

  12. Platinum Nanoclusters Out-Perform Single Crystals

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)IntegratedSpeeding accessPeptoidLabPhysics PhysicsPlatinum

  13. Platinum Nanoclusters Out-Perform Single Crystals

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)IntegratedSpeeding accessPeptoidLabPhysics PhysicsPlatinumPlatinum Nanoclusters

  14. SINGLE CRYSTAL NEUTRON DIFFRACTION.

    SciTech Connect (OSTI)

    KOETZLE,T.F.

    2001-03-13T23:59:59.000Z

    Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.

  15. Arnold Schwarzenegger SINGLE CRYSTAL SILICON

    E-Print Network [OSTI]

    in this report. #12;ENERGY INNOVATIONS SMALL GRANT (EISG) PROGRAM INDEPENDENT ASSESSMENT REPORT (IAR) SINGLEArnold Schwarzenegger Governor SINGLE CRYSTAL SILICON SHEET GROWTH Prepared For: California Energy Commission Energy Innovations Small Grant Program Prepared By: Energy Materials Research

  16. Jefferson Lab Builds First Single Crystal Single Cell Accelerating...

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

    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...

  17. Ames Lab 101: Single Crystal Growth

    ScienceCinema (OSTI)

    Schlagel, Deborah

    2014-06-04T23:59:59.000Z

    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.

  18. Development of single crystal filaments. Final report

    SciTech Connect (OSTI)

    Milewski, J.V.; Shoultz, R.A.; Bourque-McConnell, M.M.

    1995-04-01T23:59:59.000Z

    The program just completed addresses a route to a more efficient longer-lasting electric light bulb filament. All current filaments for light bulbs are metallic in nature. They are subject to embrittlement with age (large grain growth) and relatively high vapor pressures which limits their operating temperature. There is evidence which suggests advantages to using high temperature refractory single crystal fibers as a filament for a light bulb. These refractory materials may include materials such as hafnium or tantalum carbide which have melting points about 500{degrees}C higher than tungsten. Another advantage is that single crystal fibers have a very high degree of crystalline perfection with very few voids and dislocations. Without these imperfections, the atomic mobility at high temperatures is highly restricted. Thus single crystal fibers are very stable at high temperature and will last longer. The efficiencies result from running these single crystal ceramic fiber filaments at higher temperatures and the higher emissivity of the carbide filaments compared to tungsten. The amount of visible light is proportional to the 4the power of the temperature thus a 500{degrees}C higher operating give about a 3-fold increase in radiation in the visible range. The program accomplishments can be summarized as follows: (1) Single crystal fibers of JfC sufficient crystal quality for light bulb filament applications were made. (2) The HfC fiber furnace growth chamber, power control and data collection system was developed for the laboratory scale plant. (3) method for mounting and apparatuses for testing the single crystal fiber filaments were developed and built.

  19. 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

    2009-07-15T23:59:59.000Z

    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.

  20. Transverse acoustic actuation of Ni-Mn-Ga single crystals

    E-Print Network [OSTI]

    Simon, Jesse Matthew

    2007-01-01T23:59:59.000Z

    Two methods for the transverse acoustic actuation of {110}-cut Ni-Mn-Ga single crystals are discussed. In this actuation mode, crystals are used that have the {110}- type twinning planes parallel to the base of the crystal. ...

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

    DOE Patents [OSTI]

    Pankove, Jacques I. (Princeton, NJ); Wu, Chung P. (Trenton, NJ)

    1983-01-01T23:59:59.000Z

    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.

  2. HYDROGEN CHEMISORPTION ON Pt SINGLE CRYSTAL SURFACES IN ACIDIC SOLUTIONS

    E-Print Network [OSTI]

    Ross, Jr., Philip N.

    2012-01-01T23:59:59.000Z

    t for the Adsorption of Hydrogen on Pt Single CrystalSubmitted to Surface Science HYDROGEN CHEMISORPTION ON Ptheats of adsorption of hydrogen on (111) and (100) sur-

  3. Variation in Machinability of Single Crystal Materials in Micromachining

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    impact on the critical DOC at which such materials can becritical depth of cut and crystallographic orientation was found on single crystal materials (

  4. Halide electroadsorption on single crystal surfaces

    SciTech Connect (OSTI)

    Ocko, B.M. [Brookhaven National Lab., Upton, NY (United States). Dept. of Physics; Wandlowski, T. [Univ. of Ulm (Germany). Dept. of Electrochemistry

    1997-07-01T23:59:59.000Z

    The structure and phase behavior of halides have been investigated on single crystals of Ag and Au using synchrotron x-ray scattering techniques. The adlayer coverages are potential dependent. For all halides studied the authors found that with increasing potential, at a critical potential, a disordered adlayer transforms into an ordered structure. Often these ordered phases are incommensurate and exhibit potential-dependent lateral separations (electrocompression). The authors have analyzed the electrocompression in terms of a model which includes lateral interactions and partial charge. A continuous compression is not observed for Br on Ag(100). Rather, they find that the adsorption is site-specific (lattice gas) in both the ordered and disordered phases. The coverage increases with increasing potential and at a critical potential the disordered phase transforms to a well-ordered commensurate structure.

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

    DOE Patents [OSTI]

    Todt, Volker (Lemont, IL); Miller, Dean J. (Darien, IL); Shi, Donglu (Oak Park, OH); Sengupta, Suvankar (Columbus, OH)

    1998-01-01T23:59:59.000Z

    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.

  6. Epitaxial electrodeposition of freestanding large area single crystal substrates

    SciTech Connect (OSTI)

    Shin, Jae Wook; Standley, Adam; Chason, Eric [Brown University, Box D, Providence, Rhode Island 02912 (United States)

    2007-06-25T23:59:59.000Z

    The authors report on a method for producing freestanding single crystal metal films over large areas using electrodeposition and selective etching. The method can be turned into an inexpensive continuous process for making long ribbons or a large area of single crystal films. Results from a 5x5 mm{sup 2} Ni single crystal film using electron backscattering pattern pole figures and x-ray diffraction demonstrate that the quality of material produced is equivalent to the initial substrate without annealing or polishing.

  7. Single crystal Processing and magnetic properties of gadolinium nickel

    SciTech Connect (OSTI)

    Shreve, Andrew John [Ames Laboratory

    2012-11-02T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    Siva Sankari, R. [Department of Physics, Agni College of Technology, Thalambur, Chennai 603103 (India); Perumal, Rajesh Narayana, E-mail: r.shankarisai@gmail.com [Department of Physics, SSN College of Engineering, Kalavakkam, Chennai 603110 (India)

    2014-03-01T23:59:59.000Z

    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 of temperature.

  9. Growing intermetallic single crystals using in situ decanting

    SciTech Connect (OSTI)

    Petrovic, Cedomir; Canfield, Paul; Mellen, Jonathan

    2012-05-16T23:59:59.000Z

    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 1200°C. 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.

  10. Simultaneous SHG of orthogonally polarized fundamentals in single QPM crystals

    E-Print Network [OSTI]

    -order parametric nonlinear processes in a single lithium niobate crystal is being undertaken using a new technique cascading interactions can be realized. The use of the higher QPM orders (3rd, 5th or7th) for the type-0, as the respective nonlinear coefficients are dzzz ~27 pm/V and dyyz ~ 4.7 pm/V in lithium niobate crystals. Possible

  11. Superconducting Proximity Effect in Single-Crystal Nanowires 

    E-Print Network [OSTI]

    Liu, Haidong

    2010-07-14T23:59:59.000Z

    This dissertation describes experimental studies of the superconducting proximity effect in single-crystal Pb, Sn, and Zn nanowires of lengths up to 60 um, with both ends of the nanowires in contact with macroscopic electrodes that are either...

  12. Synthesis and physical characterization of thermoelectric single crystals

    E-Print Network [OSTI]

    Porras Pérez Guerrero, Juan Pablo

    2012-01-01T23:59:59.000Z

    There is much current interest in thermoelectric devices for sustainable energy. This thesis describes a research project on the synthesis and physical characterization of thermoelectric single crystals. 1In?Se?-[delta] ...

  13. Constitutive modeling of creep of single crystal superalloys

    E-Print Network [OSTI]

    Prasad, Sharat Chand

    2006-10-30T23:59:59.000Z

    In this work, a constitutive theory is developed, within the context of continuum mechanics, to describe the creep deformation of single crystal superalloys. The con- stitutive model that is developed here is based on the fact that as bodies deform...

  14. Superconducting Proximity Effect in Single-Crystal Nanowires

    E-Print Network [OSTI]

    Liu, Haidong

    2010-07-14T23:59:59.000Z

    This dissertation describes experimental studies of the superconducting proximity effect in single-crystal Pb, Sn, and Zn nanowires of lengths up to 60 um, with both ends of the nanowires in contact with macroscopic electrodes that are either...

  15. al single crystal: Topics by E-print Network

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

    14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Low-Leakage Superconducting Tunnel Junctions with a Single-Crystal Al2O3 Barrier* Computer Technologies and...

  16. al single crystals: Topics by E-print Network

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

    14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Low-Leakage Superconducting Tunnel Junctions with a Single-Crystal Al2O3 Barrier* Computer Technologies and...

  17. Nanostructured Calcite Single Crystals with Gyroid Morphologies

    E-Print Network [OSTI]

    Steiner, Ullrich

    , the unconstrained crystallization of calcium carbonate (CaCO3) leads to the precipitation of brittle rhombohedral of these factors on CaCO3 nucleation and growth, which can also lead to control over polymorph and orientation. It is becoming increas- ingly apparent that the formation of crystalline CaCO3 is often preceded by an amorphous

  18. SINGLE CRYSTAL NIOBIUM TUBES FOR PARTICLE COLLIDERS ACCELERATOR CAVITIES

    SciTech Connect (OSTI)

    MURPHY, JAMES E [University of Nevada, Reno] [University of Nevada, Reno

    2013-02-28T23:59:59.000Z

    The objective of this research project is to produce single crystal niobium (Nb) tubes for use as particle accelerator cavities for the Fermi laboratory’s 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 increased 0.18 mm and eventually to 0.21 mm. Again, with these larger tubes, single crystal tubes were usually produced by the crystallization process. The power supply was generally operated at full output during these tests, and the traverse rate was 5 cm per hour. In a few tests, the traverse rate was increased to 10 cm per hour, and at the faster traverse rate, single crystal growth was not achieved. In these tests with a faster traverse rate, it was thought that the tube was not heated to a high enough temperature to achieve single crystal growth. In the next series of tests, the tube OD was unchanged at 3.8 cm and the wall thickness was increased to 0.30 mm. The increased wall thickness made it difficult to reach an operating temperature above 2,000 ?C, and although the single crystal process caused a large increase in the crystal grains, no single crystal tubes were produced. It was assumed that the operating temperature in these tests was not high enough to achieve single crystal growth. In FY 2012, a larger power supply was purchased and installed. With the new power supply, temperatures above the melting point of Nb were easily obtained regardless of the tube thickness. A series of crystallization tests was initiated to determine if indeed the operating temperature of the previous tests was too low to achieve single crystal growth. For these tests, the Nb tube OD remained at 3.8 cm and the wall thickness was 0.30 mm. The first test had an operating temperature of 2,000 ?C. and the operating temperature was increased by 50 ?C increments for each successive test. The final test was very near the Nb melting temperature, and indeed, the Nb tube eventually melted in the center of the tube. These tests showed that higher temperatures did yield larger grain sizes if the traverse rate was held constant at 5 cm per hour, but no single crystal tubes were produced even at the highest operating temperature. In addition, slowing the traverse rate to as low as 1 cm per hour did not yield a single crystal tube regardless of operating temperature. At this time, it

  19. Studying the magnetic properties of CoSi single crystals

    SciTech Connect (OSTI)

    Narozhnyi, V. N., E-mail: narozhnyivn@gmail.com; Krasnorussky, V. N. [Russian Academy of Sciences, Vereshchagin Institute for High Pressure Physics (Russian Federation)

    2013-05-15T23:59:59.000Z

    The magnetic properties of CoSi single crystals have been measured in a range of temperatures T = 5.5-450 K and magnetic field strengths H {<=} 11 kOe. A comparison of the results for crystals grown in various laboratories allowed the temperature dependence of magnetic susceptibility {chi}(T) = M(T)/H to be determined for a hypothetical 'ideal' (free of magnetic impurities and defects) CoSi crystal. The susceptibility of this ideal crystal in the entire temperature range exhibits a diamagnetic character. The {chi}(T) value significantly increases in absolute value with decreasing temperature and exhibits saturation at the lowest temperatures studied. For real CoSi crystals of four types, paramagnetic contributions to the susceptibility have been evaluated and nonlinear (with respect to the field) contributions to the magnetization have been separated and taken into account in the calculations of {chi}(T).

  20. 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 [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai- 400085 (India)

    2014-04-24T23:59:59.000Z

    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.

  1. Apparatus And Method For Producing Single Crystal Metallic Objects

    DOE Patents [OSTI]

    Huang, Shyh-Chin (Latham, NY); Gigliotti, Jr., Michael Francis X. (Scotia, NY); Rutkowski, Stephen Francis (Duanesburg, NY); Petterson, Roger John (Fultonville, NY); Svec, Paul Steven (Scotia, NY)

    2006-03-14T23:59:59.000Z

    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.

  2. Synthesis of mesoporous zeolite single crystals with cheap porogens

    SciTech Connect (OSTI)

    Tao Haixiang; Li Changlin; Ren Jiawen [Key Laboratory for Advanced Materials, Research Institute of Industrial Catalysis, East China University of Science and Technology, Shanghai 200237 (China); Wang Yanqin, E-mail: wangyanqin@ecust.edu.cn [Key Laboratory for Advanced Materials, Research Institute of Industrial Catalysis, East China University of Science and Technology, Shanghai 200237 (China); Lu Guanzhong, E-mail: gzhlu@ecust.edu.cn [Key Laboratory for Advanced Materials, Research Institute of Industrial Catalysis, East China University of Science and Technology, Shanghai 200237 (China)

    2011-07-15T23:59:59.000Z

    Mesoporous zeolite (silicalite-1, ZSM-5, TS-1) single crystals have been successfully synthesized by adding soluble starch or sodium carboxymethyl cellulose (CMC) to a conventional zeolite synthesis system. The obtained samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen sorption analysis, {sup 27}Al magic angle spinning nuclear magnetic resonance ({sup 27}Al MAS NMR), temperature-programmed desorption of ammonia (NH{sub 3}-TPD) and ultraviolet-visible spectroscopy (UV-vis). The SEM images clearly show that all zeolite crystals possess the similar morphology with particle size of about 300 nm, the TEM images reveal that irregular intracrystal pores are randomly distributed in the whole crystal. {sup 27}Al MAS NMR spectra indicate that nearly all of the Al atoms are in tetrahedral co-ordination in ZSM-5, UV-vis spectra confirm that nearly all of titanium atoms are incorporated into the framework of TS-1. The catalytic activity of meso-ZSM-5 in acetalization of cyclohexanone and meso-TS-1 in hydroxylation of phenol was also studied. The synthesis method reported in this paper is cost-effective and environmental friendly, can be easily expended to prepare other hierarchical structured zeolites. - Graphical abstract: Mesoporous zeolite single crystals were synthesized by using cheap porogens as template. Highlights: > Mesoporous zeolite (silicalite-1, ZSM-5, TS-1) single crystals were synthesized. > Soluble starch or sodium carboxymethyl cellulose (CMC) was used as porogens. > The mesoporous zeolites had connected mesopores although closed pores existed. > Higher catalytic activities were obtained.

  3. Ultrafast dynamics of excitons in tetracene single crystals

    SciTech Connect (OSTI)

    Birech, Zephania; Schwoerer, Heinrich, E-mail: heso@sun.ac.za [Laser Research Institute, Stellenbosch University, Stellenbosch 7600 (South Africa)] [Laser Research Institute, Stellenbosch University, Stellenbosch 7600 (South Africa); Schwoerer, Markus [Department of Physics, University of Bayreuth, Bayreuth (Germany)] [Department of Physics, University of Bayreuth, Bayreuth (Germany); Schmeiler, Teresa; Pflaum, Jens [Experimental Physics VI, University of Würzburg and Bavarian Center for Applied Energy Research, Würzburg (Germany)] [Experimental Physics VI, University of Würzburg and Bavarian Center for Applied Energy Research, Würzburg (Germany)

    2014-03-21T23:59:59.000Z

    Ultrafast exciton dynamics in free standing 200 nm thin tetracene single crystals were studied at room temperature by femtosecond transient absorption spectroscopy in the visible spectral range. The complex spectrally overlapping transient absorption traces of single crystals were systematically deconvoluted. From this, the ultrafast dynamics of the ground, excited, and transition states were identified including singlet exciton fission into two triplet excitons. Fission is generated through both, direct fission of higher singlet states S{sub n} on a sub-picosecond timescale, and thermally activated fission of the singlet exciton S{sub 1} on a 40 ps timescale. The high energy Davydov component of the S{sub 1} exciton is proposed to undergo fission on a sub-picoseconds timescale. At high density of triplet excitons their mutual annihilation (triplet-triplet annihilation) occurs on a <10 ps timescale.

  4. Large pyramid shaped single crystals of BiFeO{sub 3} by solvothermal synthesis method

    SciTech Connect (OSTI)

    Sornadurai, D.; Ravindran, T. R.; Paul, V. Thomas; Sastry, V. Sankara [Condensed Matter Physics Division, Materials Science Group, Physical Metallurgy Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India); Condensed Matter Physics Division, Materials Science Group (India)

    2012-06-05T23:59:59.000Z

    Synthesis parameters are optimized in order to grow single crystals of multiferroic BiFeO{sub 3}. 2 to 3 mm size pyramid (tetrahedron) shaped single crystals were successfully obtained by solvothermal method. Scanning electron microscopy with EDAX confirmed the phase formation. Raman scattering spectra of bulk BiFeO3 single crystals have been measured which match well with reported spectra.

  5. Diamond turning of Si and Ge single crystals

    SciTech Connect (OSTI)

    Blake, P.; Scattergood, R.O.

    1988-12-01T23:59:59.000Z

    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.

  6. Acquisition of Single Crystal Growth and Characterization Equipment

    SciTech Connect (OSTI)

    Maple, M. Brian; Zocco, Diego A.

    2008-12-09T23:59:59.000Z

    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 studies through efforts with numerous collaborators. These endeavors will assist the effort to explain various outstanding theoretical problems, such as order parameter symmetries and electron-pairing mechanisms in unconventional superconductors, the relationship between superconductivity and magnetic order in certain correlated electron systems, the role of disorder in non-Fermi liquid behavior and unconventional superconductivity, and the nature of interactions between localized and itinerant electrons in these materials. Understanding the mechanisms behind strongly correlated electron behavior has important technological implications.

  7. Epitaxial graphene prepared by chemical vapor deposition on single crystal thin iridium films on sapphire

    E-Print Network [OSTI]

    Boyer, Edmond

    Epitaxial graphene prepared by chemical vapor deposition on single crystal thin iridium films Cedex 9, France (Dated: 15 March 2011) Uniform single layer graphene was grown on single-crystal Ir. These graphene layers have a single crystallographic orientation and a very low density of defects, as shown

  8. Field emission properties of single crystal chromium disilicide nanowires

    SciTech Connect (OSTI)

    Valentin, L. A.; Carpena-Nunez, J.; Yang, D.; Fonseca, L. F. [Department of Physics, University of Puerto Rico, Rio Piedras Campus, P.O. Box 70377, San Juan, 00931 (Puerto Rico)

    2013-01-07T23:59:59.000Z

    The composition, crystal structure, and field emission properties of high-crystallinity chromium disilicide (CrSi{sub 2}) nanowires synthesized by a vapor deposition method have been studied. High resolution transmission electron microscopy, energy dispersive spectroscopy, and selected area electron diffraction studies confirm the single-crystalline structure and composition of the CrSi{sub 2} nanowires. Field emission measurements show that an emission current density of 0.1 {mu}A/cm{sup 2} was obtained at a turn-on electric field intensity of 2.80 V/{mu}m. The maximum emission current measured was 1.86 mA/cm{sup 2} at 3.6 V/{mu}m. The relation between the emission current density and the electric field obtained follows the Fowler-Nordheim equation, with an enhancement coefficient of 1140. The electrical conductivity of single nanowires was measured by using four-point-probe specialized microdevices at different temperatures, and the calculated values are close to those reported in previous studies for highly conductive single crystal bulk CrSi{sub 2}. The thermal tolerance of the nanowires was studied up to a temperature of 1100 Degree-Sign C. The stability of the field emission current, the I-E values, their thermal tolerance, and high electrical conductivity make CrSi{sub 2} nanowires a promising material for field emission applications.

  9. Free energy barrier for single-chain melting and crystallization

    E-Print Network [OSTI]

    Wenbing Hu; Daan Frenkel; Vincent B. F. Mathot

    2002-06-28T23:59:59.000Z

    In this paper, we report dynamic Monte Carlo simulations of melting and crystallization in a single-chain system. Their free energy barriers are calculated by the umbrella sampling method and can be described well by a simple expression DeltaF = n Deltaf+sigma (N-n)^(2/3), where n is the amount of molten bonds, Deltaf is the free energy change of each molten bond from a crystalline state, N is the chain length, and sigma is the surface free energy of crystallite. We found that, together with the expression Delta F = n Delta f+ sigma (N-n)^(1/2) for molecular nucleation, the molecular-weight dependent properties of the free-energy barriers for polymer primary and secondary nucleation, in particular, the molecular segregation during crystal growth, can be reproduced. Then for the mechanism of polymer crystallization, we suggested a quantitative model of intramolecular nucleation, as a direct development from the previous qualitative description of molecular nucleation model.

  10. 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

    2009-02-13T23:59:59.000Z

    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.

  11. Tantalum Shear Modulus from Homogenization of Single Crystal Data

    SciTech Connect (OSTI)

    Becker, R

    2007-09-14T23:59:59.000Z

    Elastic constants for tantalum single crystals have been calculated by Orlikowski, et al. [1] for a broad range of temperatures and pressures. These moduli can be utilized directly in continuum crystal simulations or dislocation dynamics calculations where the individual grains of the polycrystalline material are explicitly represented. For simulations on a larger size scale, the volume of material represented by the quadrature points of the simulation codes includes many grains, and average moduli are needed. Analytic bounding and averaging schemes exist, but since these do not account for nonuniform stress and strain within the interacting grains, the upper and lower bounds tend to diverge as the crystal anisotropy increases. Local deformation and stress equilibrium accommodate the anisotropic response of the individual grains. One method of including grain interactions in shear modulus averaging calculations is through a highly-descretized finite element model of a polycrystal volume. This virtual test sample (VTS) can be probed to determine the average response of the polycrystal. The desire to obtain isotropic moduli imposes attributes on the VTS. The grains should be equiax and the crystal orientation distribution function should be random. For these simulations, a cube, 300 {micro}m on a side, was discretized with 1 million finite elements on a regular rectangular mesh. The mesh was seeded with 1000 grains generated using a constrained-random placement algorithm, Figure 1. Since the orientations were simply painted in the mesh, the grain boundaries are irregular. The orientation distribution function is shown as pole figure in Figure 2. It has the appearance of being random. Analysis of the simulation results will be used to determine if the randomness of the texture and number of grains are adequate.

  12. Solidification microstructures in single-crystal stainless steel melt pools

    SciTech Connect (OSTI)

    Sipf, J.B.; Boatner, L.A.; David, S.A.

    1994-03-01T23:59:59.000Z

    Development of microstructure of stationary melt pools of oriented stainless steel single crystals (70%Fe-15%Ni-15%Cr was analyzed. Stationary melt pools were formed by electron-beam and gas-tungsten-arc heating on (001), (011), and (111) oriented planes of the austenitic, fcc-alloy crystals. Characterization and analysis of resulting microstructure was carried out for each crystallographic plane and welding method. Results showed that crystallography which favors ``easy growth`` along the <100> family of directions is a controlling factor in the microstructural formation along with the melt-pool shape. The microstructure was found to depend on the melting method, since each method forms a unique melt-pool shape. These results are used in making a three-dimensional reconstruction of the microstructure for each plane and melting method employed. This investigation also suggests avenues for future research into the microstructural properties of electron-beam welds as well as providing an experimental basis for mathematical models for the prediction of solidification microstructures.

  13. Single crystal metal wedges for surface acoustic wave propagation

    DOE Patents [OSTI]

    Fisher, Edward S. (Wheaton, IL)

    1982-01-01T23:59:59.000Z

    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.

  14. Shock compression experiments on Lithium Deuteride single crystals.

    SciTech Connect (OSTI)

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

    2014-10-01T23:59:59.000Z

    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.

  15. Single crystal metal wedges for surface acoustic wave propagation

    DOE Patents [OSTI]

    Fisher, E.S.

    1980-05-09T23:59:59.000Z

    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.

  16. Theoretical nonlinear response of complex single crystal under multi-axial tensile loading

    E-Print Network [OSTI]

    Misra, Anil; Ching, W. Y.

    2013-03-19T23:59:59.000Z

    The mechanical properties of single crystals are of interest as they represent the behavior of the basic building blocks. Using the density functional theory based ab initio technique we have devised an approach to analyze the behavior of single...

  17. Single-crystal YAG fiber optics for the transmission of high energy laser energy

    E-Print Network [OSTI]

    Single-crystal YAG fiber optics for the transmission of high energy laser energy X.S. Zhua , James. Thus, it is reasonable to assume that YAG fibers will have high laser damage thresholds. The optical of YAG fiber grown has been about 60 cm. Keywords: Infrared fiber optics, single-crystal fibers, oxide

  18. Oxygen diffusion in titanite: Lattice diffusion and fast-path diffusion in single crystals

    E-Print Network [OSTI]

    Watson, E. Bruce

    Oxygen diffusion in titanite: Lattice diffusion and fast-path diffusion in single crystals X June 2006 Editor: P. Deines Abstract Oxygen diffusion in natural and synthetic single-crystal titanite be recognized as responsible for oxygen diffusion. The diffusion profiles showed two segments: a steep one close

  19. A LIFETIME PREDICTION MODEL FOR SINGLE CRYSTAL SUPERALLOYS SUBJECTED TO THERMOMECHANICAL

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    materials tensile, creep and LCF test data at different temperatures. Some parameters, independentA LIFETIME PREDICTION MODEL FOR SINGLE CRYSTAL SUPERALLOYS SUBJECTED TO THERMOMECHANICAL CREEP for Single Crystal Superalloys operated at high temperatures and subjected to creep, fatigue and oxidation

  20. 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)

    2011-01-15T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    David A. Parks; Bernhard R. Tittmann

    2014-07-01T23:59:59.000Z

    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.

  2. Single Crystal Diamond Beam Position Monitors with Radiofrequency Electronic Readout

    SciTech Connect (OSTI)

    Solar, B.; Graafsma, H.; Potdevin, G.; Trunk, U. [Hasylab, Deutsches Elektronen Synchroton, Hamburg (Germany); Morse, J.; Salome, M. [Instrumentation Services and Development Division, European Synchroton Radiation Facility, Grenoble (France)

    2010-06-23T23:59:59.000Z

    Over the energy range 5{approx}30 keV a suitably contacted, thin ({approx}100 {mu}m) diamond plate can be operated in situ as a continuous monitor of X-ray beam intensity and position as the diamond absorbs only a small percentage of the incident beam. Single crystal diamond is a completely homogeneous material showing fast (ns), spatially uniform signal response and negligible (

  3. Single crystal silicon as a macro-world structural material : application to compact, lightweight high pressure vessels

    E-Print Network [OSTI]

    Garza, Tanya Cruz

    2011-01-01T23:59:59.000Z

    Single crystal silicon has promising inherent structural properties which are attractive for weight sensitive applications. Single crystal silicon, however, is a brittle material which makes the usable strength that can ...

  4. Thermopower, electrical and Hall conductivity of undoped and doped iron disilicide single crystals

    SciTech Connect (OSTI)

    Heinrich, A.; Behr, G.; Griessmann, H.; Teichert, S.; Lange, H.

    1997-07-01T23:59:59.000Z

    The electrical transport properties of {beta}-FeSi{sub 2} single crystals have been investigated in dependence on the purity of the source material and on doping with 3d transition metals. The transport properties included are electrical conductivity, Hall conductivity and thermopower mainly in the temperature range from 4K to 300K. The single crystals have been prepared by chemical transport reaction in a closed system with iodine as transport agent. In undoped single crystals prepared with 5N Fe both electrical conductivity and thermopower depend on the composition within the homogeneity range of {beta}-FeSi{sub 2} which is explained by different intrinsic defects at the Si-rich and Fe-rich phase boundaries. In both undoped and doped single crystals impurity band conduction is observed at low temperatures but above 100K extrinsic behavior determined by shallow impurity states. The thermopower shows between 100K and 200K a significant phonon drag contribution which depends on intrinsic defects and additional doping. The Hall resistivity is considered mainly with respect to an anomalous contribution found in p-type and n-type single crystals and thin films. In addition doped single crystals show at temperatures below about 130K an hysteresis of the Hall voltage. These results make former mobility data uncertain. Comparison will be made between the transport properties of single crystals and polycrystalline material.

  5. Single-Crystal Tungsten Oxide Nanosheets: Photochemical Water Oxidation in the Quantum Confinement Regime

    E-Print Network [OSTI]

    Osterloh, Frank

    Single-Crystal Tungsten Oxide Nanosheets: Photochemical Water Oxidation in the Quantum Confinement, catalysis, WO3, tungsten oxide, nanosheet, nanocrystal, quantum confinement, solar energy conversion INTRODUCTION Tungsten trioxide crystallizes in the ReO3 structure type and is an n-type semiconductor with a 2

  6. Molecular Surface Chemistry by Metal Single Crystals and Nanoparticles from Vacuum to High Pressure.

    SciTech Connect (OSTI)

    Somorjai, Gabor A.; Park, Jeong Y.

    2008-04-05T23:59:59.000Z

    Model systems for studying molecular surface chemistry have evolved from single crystal surfaces at low pressure to colloidal nanoparticles at high pressure. Low pressure surface structure studies of platinum single crystals using molecular beam surface scattering and low energy electron diffraction techniques probe the unique activity of defects, steps and kinks at the surface for dissociation reactions (H-H, C-H, C-C, O{double_bond}O bonds). High-pressure investigations of platinum single crystals using sum frequency generation vibrational spectroscopy have revealed the presence and the nature of reaction intermediates. High pressure scanning tunneling microscopy of platinum single crystal surfaces showed adsorbate mobility during a catalytic reaction. Nanoparticle systems are used to determine the role of metal-oxide interfaces, site blocking and the role of surface structures in reactive surface chemistry. The size, shape and composition of nanoparticles play important roles in determining reaction activity and selectivity.

  7. Carrier Dynamics in a-Fe2O3 (0001) Thin Films and Single Crystals...

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

    Carrier Dynamics in a-Fe2O3 (0001) Thin Films and Single Crystals Probed by Femtosecond Transient Absorption and Reflectivity. Carrier Dynamics in a-Fe2O3 (0001) Thin Films and...

  8. A Constitutive Model for the Mechanical Behavior of Single Crystal Silicon at Elevated Temperature

    E-Print Network [OSTI]

    Moon, H.-S.

    Silicon in single crystal form has been the material of choice for the first demonstration of the MIT microengine project. However, because it has a relatively low melting temperature, silicon is not an ideal material for ...

  9. Superelastic metal-insulator phase transition in single-crystal VO[subscript 2] nanobeams

    E-Print Network [OSTI]

    Fan, W.

    We investigated external-stress-induced metal-insulator phase transitions in cantilevered single-crystal VO[subscript 2] nanobeams at variable temperatures using a combined theoretical and experimental approach. An atomic ...

  10. Anisotropic dewetting in ultra-thin single-crystal silicon-on-insulator films

    E-Print Network [OSTI]

    Danielson, David T. (David Thomas)

    2008-01-01T23:59:59.000Z

    The single crystal silicon-on-insulator thin film materials system represents both an ideal model system for the study of anisotropic thin film dewetting as well as a technologically important system for the development ...

  11. A variable capacitor made from single crystal silicon fracture surface pairs

    E-Print Network [OSTI]

    Sprunt, Alexander D. (Alexander Dalziel), 1977-

    2005-01-01T23:59:59.000Z

    Complementary and nano-smooth single-crystal-silicon surfaces have been fabricated by deliberately fracturing a weakened portion of a larger structure whose flexural mechanism refines and concentrates an externally applied ...

  12. Fabrication of Ordered Array of Tips-pentacene Micro- and Nano-scale Single Crystals 

    E-Print Network [OSTI]

    Xia, Ning

    2013-04-26T23:59:59.000Z

    by nanofabrication techniques such as nanoimprint and photolithography. In the first method, the surface of a silicon substrate is treated by surfactant coating and Tips-pentacene single crystals are deposited in squared patterns. In the second method, we made...

  13. Fergusonite-type CeNbO{sub 4+?}: Single crystal growth, symmetry revision and conductivity

    SciTech Connect (OSTI)

    Bayliss, Ryan D. [Department of Materials, Imperial College London, Prince Consort Road, London, SW7 2BP (United Kingdom); Pramana, Stevin S.; An, Tao; Wei, Fengxia; Kloc, Christian L. [School of Materials Science and Engineering, 50 Nanyang Avenue, Nanyang Technological University, 639798 (Singapore); White, Andrew J.P. [Chemical Crystallography Laboratory, Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ (United Kingdom); Skinner, Stephen J. [Department of Materials, Imperial College London, Prince Consort Road, London, SW7 2BP (United Kingdom); White, Timothy J. [School of Materials Science and Engineering, 50 Nanyang Avenue, Nanyang Technological University, 639798 (Singapore); Baikie, Tom, E-mail: tbaikie@ntu.edu.sg [School of Materials Science and Engineering, 50 Nanyang Avenue, Nanyang Technological University, 639798 (Singapore)

    2013-08-15T23:59:59.000Z

    Large fergusonite-type (ABO{sub 4}, A=Ce, B=Nb) oxide crystals, a prototype electrolyte composition for solid oxide fuel cells (SOFC), were prepared for the first time in a floating zone mirror furnace under air or argon atmospheres. While CeNbO{sub 4} grown in air contained CeNbO{sub 4.08} as a minor impurity that compromised structural analysis, the argon atmosphere yielded a single phase crystal of monoclinic CeNbO{sub 4}, as confirmed by selected area electron diffraction, powder and single crystal X-ray diffraction. The structure was determined in the standard space group setting C12/c1 (No. 15), rather than the commonly adopted I12/a1. AC impedance spectroscopy conducted under argon found that stoichiometric CeNbO{sub 4} single crystals showed lower conductivity compared to CeNbO{sub 4+?} confirming interstitial oxygen can penetrate through fergusonite and is responsible for the higher conductivity associated with these oxides. - Graphical abstract: Large fergusonite-type CeNbO{sub 4} crystals were prepared for the first time in a floating zone mirror furnace. Crystal growth in an argon atmosphere yielded a single phase monoclinic CeNbO4, as confirmed by selected area electron diffraction, powder and single crystal X-ray diffraction. The structure was determined in the standard space group setting C12/c1 (No. 15), rather than the commonly adopted I12/a1. AC impedance spectroscopy found CeNbO{sub 4} single crystals showed lower conductivity compared to CeNbO{sub 4+?} confirming interstitial oxygen can penetrate through fergusonite and is responsible for the higher conductivity associated with these oxides. Highlights: • Preparation of single crystals of CeNbO{sub 4} using a floating zone mirror furnace. • Correction to the crystal symmetry of the monoclinic form of CeNbO{sub 4}. • Report the conductivity of a single crystal of CeNbO{sub 4}.

  14. Molecular dynamics simulations of the nano-scale room-temperature oxidation of aluminum single crystals

    E-Print Network [OSTI]

    Southern California, University of

    films that form on aluminum and aluminum alloys in air protect the surface against further oxidationMolecular dynamics simulations of the nano-scale room-temperature oxidation of aluminum single Abstract The oxidation of aluminum single crystals is studied using molecular dynamics (MD) simulations

  15. Optical properties of single-crystal sapphire fibers Rick K. Nubling and James A. Harrington

    E-Print Network [OSTI]

    Optical properties of single-crystal sapphire fibers Rick K. Nubling and James A. Harrington Single.4­0.3 dB m at 2.94 m. These fibers delivered 4.7 W at 10 Hz of Er:YAG laser power. © 1997 Optical Society of America Key words: Infrared fibers, sapphire fibers, Er:YAG lasers, optical properties. 1. Introduction

  16. Electrical and mechanical studies of high purity aluminum single crystals at 4.2 K under cyclic strain 

    E-Print Network [OSTI]

    Zou, Hong

    1995-01-01T23:59:59.000Z

    The objective of this research is to investigate the effects of orientation on strain hardening and resistivity degradation in high purity aluminum single crystals resulting from uniaxial cyclic strain at 4.2 K. Aluminum crystals with various...

  17. Electrical and mechanical studies of high purity aluminum single crystals at 4.2 K under cyclic strain

    E-Print Network [OSTI]

    Zou, Hong

    1995-01-01T23:59:59.000Z

    The objective of this research is to investigate the effects of orientation on strain hardening and resistivity degradation in high purity aluminum single crystals resulting from uniaxial cyclic strain at 4.2 K. Aluminum crystals with various...

  18. Synthesis, Crystal Structure, and Magnetism of ?-Fe1.00(2)Se1.00(3) Single Crystals

    SciTech Connect (OSTI)

    Petrovic, C.; Billinge, S.

    2011-06-20T23:59:59.000Z

    Understanding iron-based superconductors requires high-quality impurity-free single crystals. So far they have been elusive for {beta}-FeSe and extraction of intrinsic materials properties has been compromised by several magnetic-impurity phases. Here, we report synchrotron-clean {beta}-FeSe superconducting single crystals grown via LiCl/CsCl flux method. Phase purity yields evidence for a defect-induced weak ferromagnetism that coexists with superconductivity below T{sub c}. In contrast to Fe{sub 1+y}Te-based superconductors, our results reveal that the interstitial Fe(2) site is not occupied and that all contribution to density of states at the Fermi level must come from in-plane Fe(1).

  19. Synthesis, growth, structure determination and optical properties of chalcone derivative single crystal

    SciTech Connect (OSTI)

    Karthi, S., E-mail: girijaeaswaradas@gmail.com; Girija, E. K., E-mail: girijaeaswaradas@gmail.com [Department of Physics, Periyar University, Salem - 636011 (India)

    2014-04-24T23:59:59.000Z

    Acquiring large nonlinear optical (NLO) efficient organic material is essential for the development of optoelectronics and photonic devices. Chalcone is the donor - ? - acceptor - ? - donor (D-?-A-?-D) type conjugated molecule with appreciable hyperpolarizability of potential interest in NLO applications. The addition of vinyl and electron donor groups in the chalcone molecule may enhance the second harmonic generation (SHG) efficiency. Here we report the synthesis, crystal growth and characterization of a chalcone derivative 1-(4-methylphenyl)-5-(4-methoxyphenyl)-penta-2,4-dien-1-one (MPMPP). The MPMPP crystal was grown by slow evaporation solution growth technique from acetone. The grown crystal structure was studied by single crystal X-ray diffraction. The SHG efficiency of the grown crystal was determined by Kurtz and Perry method.

  20. Off-resonant coupling between a single quantum dot and a nanobeam photonic crystal cavity

    E-Print Network [OSTI]

    Armand Rundquist; Arka Majumdar; Jelena Vuckovic

    2011-10-05T23:59:59.000Z

    We demonstrate off-resonant coupling between a single quantum dot and a nanobeam photonic crystal cavity, under resonant excitation of the quantum dot or the cavity. These results are consistent with previous descriptions of off-resonant coupling as an incoherent phonon-mediated process. The extension of this phenomenon to a nanobeam photonic crystal cavity presents interesting possibilities for coherent control of this interaction by tailoring the phonon density of states.

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

    DOE Patents [OSTI]

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

    1998-06-23T23:59:59.000Z

    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.

  2. Measurement of the resistivity versus temperature in iodine single crystals

    E-Print Network [OSTI]

    Somoano, Robert Bonner

    1964-01-01T23:59:59.000Z

    ''vr'xcaT :. . -; '. conduction mec'hanism similar' to. that yropose'd bj'thi band thccxjr, ". '=. : ', . '::'-''-' in solid'state- phjsics -'ibis aiticje stimulated''considbrable / 9nterest 9. n''thc solid state p'rope'rites ox m'olecuinr crystals' ;' '. -'. , ; ? Nost of...'armies' ?' "-:-', ?&. ':: ~ of iodixio w. der . preseux'o ~&ne results of the war'- dona. in the punt few ?"eIxrs indicate t'hat, there is considerable cU, cn~reezent . ' ' . , -'acbO4ti-tIXe: C&n, -, e MMhe=:rSSXS4anba-af itijHne -With, -Prb~ure--XCnd , ?' '-' ji1sy...

  3. Single Particle Database of Natural Ice Crystals: Dimensions

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over Our Instagram Secretary Moniz9Morgan McCorkleSingin' in the Rain NewsSingle

  4. Experimental Analysis of the Elastic Plastic Transition During Nanoindentation of Single Crystal a-Silicon Nitride

    SciTech Connect (OSTI)

    Jang, Jae-il [Hanyang University, Korea; Bei, Hongbin [ORNL; Becher, Paul F [ORNL; Pharr, George M [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL)

    2012-01-01T23:59:59.000Z

    The elastic-to-plastic transition in single crystal a-silicon nitride was experimentally characterized through a series of nanoindentation experiments using a spherical indenter. The experimental results provide a quantitative description of the critical shear strengths for the transition, as well as estimates of the shear modulus and nanohardness of the material.

  5. Fractal Iron Oxide Single-Crystal Dendritic Micro-Pines of Magnetic

    E-Print Network [OSTI]

    Wang, Zhong L.

    Fractal Iron Oxide Single-Crystal Dendritic Micro-Pines of Magnetic a-Fe2O3: Large-Scale Synthesis,2] Fractal structures are common in nature across all length scales, from self-assembled molecules. On the nanoscale, dendritic fractals are one type of hyperbranched structure which are generally formed

  6. Bendable single crystal silicon thin film transistors formed by printing on plastic substrates

    E-Print Network [OSTI]

    Rogers, John A.

    Bendable single crystal silicon thin film transistors formed by printing on plastic substrates E on plastic substrates using an efficient dry transfer printing technique. In these devices, free standing-Si is then transferred, to a specific location and with a controlled orientation, onto a thin plastic sheet

  7. Active Slip Band Separation and the Energetics of Slip in Single Crystals

    E-Print Network [OSTI]

    Active Slip Band Separation and the Energetics of Slip in Single Crystals Abstract This research supports recent efforts to provide an energetic ap- proach the formulation of new measures of the active slip-band separation and of the number of lattice cells

  8. Transport and superconducting properties of RNi2B2C (R=Y, Lu) single crystals 

    E-Print Network [OSTI]

    Rathnayaka, KDD; Bhatnagar, AK; Parasiris, A.; Naugle, Donald G.

    1997-01-01T23:59:59.000Z

    Ni2B2C single crystals. The analysis shows that these are moderately strong-coupling type-II superconductors (similar to the A-15 compounds) with a value of the electron-phonon coupling parameter lambda(0) approximately equal to 1.2 for YNi2B2C and 1...

  9. Transport and superconducting properties of RNi2B2C (R=Y, Lu) single crystals

    E-Print Network [OSTI]

    Rathnayaka, KDD; Bhatnagar, AK; Parasiris, A.; Naugle, Donald G.

    1997-01-01T23:59:59.000Z

    and perpendicular to the c axis and the superconducting parameters derived from it do not show any anisotropy for the YNi2B2C single-crystal samples in agreement with magnetization and torque magnetometry measurements, but a small anisotropy is observed for the Lu...

  10. A macroscopic model for magnetic shape-memory single crystals Anne-Laure Bessoud

    E-Print Network [OSTI]

    Stefanelli, Ulisse

    A macroscopic model for magnetic shape-memory single crystals Anne-Laure Bessoud Martin Kruz Souza-Auricchio model for shape memory alloys is here combined with classical micro recoverable strains can be induced by thermo-mechanical and/or magnetic treatment. As ordinary shape memory

  11. Model catalytic studies of single crystal, polycrystalline metal, and supported catalysts

    E-Print Network [OSTI]

    Yan, Zhen

    2009-05-15T23:59:59.000Z

    supported Pd/Al2 O3 catalysts, a Pd(100) single crystal, as well as polycrystalline metals of rhodium, palladium, and platinum. A hyperactive state, corresponding to an oxygen covered surface, was observed at high O 2/CO ratios at elevated pressures...

  12. Point defects and high temperature creep of NiO single crystals (*) J. Cabrera-Cano

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    durations between 1 h and 18 h have been used, depending on temperature creep test, with no influence on mL-119 Point defects and high temperature creep of NiO single crystals (*) J. Cabrera MPa-150 MPa. Oxygen partial pressures were varied between 10-5 atm. and air. The steady state creep

  13. Single crystal growth and heteroepitaxy of polyacene thin films on arbitrary substrates

    E-Print Network [OSTI]

    Headrick, Randall L.

    in a number of low-cost, large area electronic applications such as flat panel displays. Organic thin film as other substrates.6-12 Recently, significant progress has been made towards fabricating high quality is to prepare single crystal films on arbitrary substrates. Here we describe two significant advances towards

  14. Structures with three dimensional nanofences comprising single crystal segments

    DOE Patents [OSTI]

    Goyal, Amit; Wee, Sung-Hun

    2013-08-27T23:59:59.000Z

    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.

  15. Development of large Grain/Single Crystal Niobium Cavity Technology at Jefferson Lab

    SciTech Connect (OSTI)

    Peter Kneisel; J. Sekutowicz; T. Carneiro; G. Ciovati

    2006-10-31T23:59:59.000Z

    Approximately two years ago we started to develop high performance niobium accelerating cavities based on large grain or single crystal high purity niobium. We have fabricated and tested 15 single cell cavities of various shapes and frequencies between 1300 MHz and 2300 MHz using material from a total of 9 different very large grain niobium ingots from four niobium suppliers. The materials differed not only in grain sizes, but also in RRR ? value and in the amount of Ta contained in the material. In one ingot supplied by CBMM the central grain exceeded 7 inches in diameter and this was used to fabricate two 2.2 GHz cavities. A single crystal 1300 MHz mono-cell cavity was also produced at DESY by rolling out a single crystal to the size required for this cavity. It was sent to Jlab for surface treatment and testing. In addition, we have fabricated three 7-cell cavities: two of the Jlab high gradient (HG) shape and one of the ILC Low Loss shape. Two 9-cell TESLA shape cavities are presently in fabrication at Jlab and are close to completion.

  16. Lithium ion diffusion in Li ?-alumina single crystals measured by pulsed field gradient NMR spectroscopy

    SciTech Connect (OSTI)

    Chowdhury, Mohammed Tareque, E-mail: mtareque@mail.tagen.tohoku.ac.jp; Takekawa, Reiji; Iwai, Yoshiki; Kuwata, Naoaki; Kawamura, Junichi [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba-ku Sendai 980-8577 (Japan)] [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba-ku Sendai 980-8577 (Japan)

    2014-03-28T23:59:59.000Z

    The lithium ion diffusion coefficient of a 93% Li ?-alumina single crystal was measured for the first time using pulsed field gradient (PFG) NMR spectroscopy with two different crystal orientations. The diffusion coefficient was found to be 1.2 × 10{sup ?11} m{sup 2}/s in the direction perpendicular to the c axis at room temperature. The Li ion diffusion coefficient along the c axis direction was found to be very small (6.4 × 10{sup ?13} m{sup 2}/s at 333 K), which suggests that the macroscopic diffusion of the Li ion in the ?-alumina crystal is mainly two-dimensional. The diffusion coefficient for the same sample was also estimated using NMR line narrowing data and impedance measurements. The impedance data show reasonable agreement with PFG-NMR data, while the line narrowing measurements provided a lower value for the diffusion coefficient. Line narrowing measurements also provided a relatively low value for the activation energy and pre-exponential factor. The temperature dependent diffusion coefficient was obtained in the temperature range 297–333 K by PFG-NMR, from which the activation energy for diffusion of the Li ion was estimated. The activation energy obtained by PFG-NMR was smaller than that obtained by impedance measurements, which suggests that thermally activated defect formation energy exists for 93% Li ?-alumina single crystals. The diffusion time dependence of the diffusion coefficient was observed for the Li ion in the 93% Li ?-alumina single crystal by means of PFG-NMR experiments. Motion of Li ion in fractal dimension might be a possible explanation for the observed diffusion time dependence of the diffusion coefficient in the 93% Li ?–alumina system.

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

    SciTech Connect (OSTI)

    Boatner, Lynn A [ORNL; Ramey, Joanne Oxendine [ORNL; Kolopus, James A [ORNL; Neal, John S [ORNL; Cherepy, Nerine [Lawrence Livermore National Laboratory (LLNL); Payne, Stephen A. [Lawrence Livermore National Laboratory (LLNL); Beck, P [Lawrence Livermore National Laboratory (LLNL); Burger, Arnold [Fisk University, Nashville; Rowe, E [Fisk University, Nashville; Bhattacharya, P. [Fisk University, Nashville

    2014-01-01T23:59:59.000Z

    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.

  18. Controlling the Spontaneous Emission Rate of Single Quantum Dots in a 2D Photonic Crystal

    E-Print Network [OSTI]

    Dirk Englund; David Fattal; Edo Waks; Glenn Solomon; Bingyang Zhang; Toshihiro Nakaoka; Yasuhiko Arakawa; Yoshihisa Yamamoto; Jelena Vuckovic

    2005-04-20T23:59:59.000Z

    We observe large spontaneous emission rate modification of individual InAs Quantum Dots (QDs) in 2D a photonic crystal with a modified, high-Q single defect cavity. Compared to QDs in bulk semiconductor, QDs that are resonant with the cavity show an emission rate increase by up to a factor of 8. In contrast, off-resonant QDs indicate up to five-fold rate quenching as the local density of optical states (LDOS) is diminished in the photonic crystal. In both cases we demonstrate photon antibunching, showing that the structure represents an on-demand single photon source with pulse duration from 210 ps to 8 ns. We explain the suppression of QD emission rate using Finite Difference Time Domain (FDTD) simulations and find good agreement with experiment.

  19. Lattice distortion in single crystal rare-earth arsenide/GaAs nanocomposites

    SciTech Connect (OSTI)

    Young, A. J. [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States); Schultz, B. D. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106-9560 (United States); Palmstrøm, C. J., E-mail: cpalmstrom@ece.ucsb.edu [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States); Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106-9560 (United States)

    2014-02-17T23:59:59.000Z

    Epitaxial single crystal nanocomposites comprised of rare-earth arsenide nanoparticles embedded in GaAs (001) layers produce a larger change in lattice parameter than expected from the lattice parameters of relaxed films. Despite similar cubic structures and lattice parameters, elongation of the interfacial bond length between the two materials induces additional strain causing an expansion in the nanocomposite lattice. The interface bond length is material dependent with an average atomic layer spacing at the ErAs:GaAs interface of 1.9?Å while the spacing at the ScAs:GaAs interface is only 1.4?Å. Implications for lattice matching various single crystal epitaxial nanostructures in semiconductors are discussed.

  20. Studies of Optical Damage in Photorefractive Single LiNbO3 Crystals using Imaging Polarimetry

    E-Print Network [OSTI]

    O. Krupych; I. Smaga; R. Vlokh

    2007-08-15T23:59:59.000Z

    The optical damage of photorefractive material, single LiNbO3 crystal, is experimentally studied. The specimen has been illuminated with the radiation of continuous Ar-laser (the wavelength of 488 nm) focused to 35?m spot. The induced birefringence map is obtained by means of imaging polarimeter. Promising resources of the experimental setup for detecting laser-induced damage in photorefractive materials is demonstrated.

  1. Short communication Single crystal X-ray characterization of the incommensurate mod-

    E-Print Network [OSTI]

    Boyer, Edmond

    in the high Tc superconductor Bi2Sr2CaCu2O8. P.-A. Albouy(1) , R. Moret(1) , M. Potel(2) ,P.Gougeon(2), J, Classification Physics Abstracts 61.50 - 74.70V Since the discovery of the bismuth based high Tc superconductors-cooled to room temperature. Single crystals separated from the melt were found to be superconductors with zero

  2. Deterministic coupling of a single nitrogen vacancy center to a photonic crystal cavity

    E-Print Network [OSTI]

    Dirk Englund; Brendan Shields; Kelley Rivoire; Fariba Hatami; Jelena Vuckovic; Hongkun Park; Mikhail D. Lukin

    2010-05-12T23:59:59.000Z

    We describe and experimentally demonstrate a technique for deterministic coupling between a photonic crystal (PC) nanocavity and single emitters. The technique is based on in-situ scanning of a PC cavity over a sample and allows the positioning of the cavity over a desired emitter with nanoscale resolution. The power of the technique, which we term a Scanning Cavity Microscope (SCM), is demonstrated by coupling the PC nanocavity to a single nitrogen vacancy (NV) center in diamond, an emitter system that provides optically accessible electron and nuclear spin qubits.

  3. The growth and characterization of LiGd?(Mo0?)? single crystals

    E-Print Network [OSTI]

    Reimund, James Allyn

    1981-01-01T23:59:59.000Z

    ' C/second 37 Pyroelectric Current vs. Temperature dT/dt = 30' C/second 180' Domains (Gd (MoO ) ) 37 39 INTRODUCTION This thesis discusses the growth and some single crystalline properties of lithium-gadolinium-molybdate of the type LiGd (Mo...O ) 3 45' This compound is one of the three thus far discovered compounds of the lithium ? gadolinium-molybdate (LGMO) system. In general, this system can be expressed as Li2Mo04. XGd2(Mo04)3, where LiGd3(MoO, )5 4 5 single crystals synthesize when X...

  4. Giant increase in critical current density of KxFe2-ySe? single crystals

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

    Lei, Hechang; Petrovic, C.

    2011-12-01T23:59:59.000Z

    The critical current density Jabc of KxFe2-ySe? single crystals can be enhanced by more than one order of magnitude, up to ~2.1×10? 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 (“?Tc pinning”).

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

    SciTech Connect (OSTI)

    Kumar, A.; Ravi, K. V.

    2011-06-01T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    Lunt, A. J. G., E-mail: alexander.lunt@eng.ox.ac.uk; Xie, M. Y.; Baimpas, N.; Korsunsky, A. M. [Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ (United Kingdom); Zhang, S. Y.; Kabra, S.; Kelleher, J. [ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell, Oxford OX11 0QX (United Kingdom); Neo, T. K. [Specialist Dental Group, Mount Elizabeth Orchard, 3 Mount Elizabeth, #08-03/08-08/08-10, Singapore 228510 (Singapore)

    2014-08-07T23:59:59.000Z

    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.

  7. FRACTIONAL CRYSTALLIZATION OF HANFORD SINGLE SHELL TANK (SST) WASTES FROM CONCEPT TO PILOT PLANT

    SciTech Connect (OSTI)

    GENIESSE, D.J.; NELSON, E.A.; HAMILTON, D.W.; MAJORS, J.H.; NORDAHL, T.K.

    2006-12-08T23:59:59.000Z

    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 US Department of Energy, the Environmental Protection Agency, and the State of Washington. Water will be used to retrieve the wastes and the resulting solution will be pumped to a proposed pretreatment 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. The aforementioned parameters, along with evaporation rate, proper agitation, and residence time, determine nucleation and growth kinetics and the resulting habit and size distribution of the product crystals. These crystals properties are important considerations for designing the crystallizer and solid/liquid separation equipment. A structured program was developed to (a) demonstrate that fractional crystallization could be used to pre-treat Hanford tank wastes and (b) provide data to develop a pilot plant design.

  8. 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)

    2014-09-29T23:59:59.000Z

    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.

  9. Irradiation damage of single crystal, coarse-grained, and nanograined copper under helium bombardment at 450 °C

    E-Print Network [OSTI]

    Han, Weizhong

    The irradiation damage behaviors of single crystal (SC), coarse-grained (CG), and nanograined (NG) copper (Cu) films were investigated under Helium (He) ion implantation at 450 °C with different ion fluences. In irradiated ...

  10. 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.

    1989-04-25T23:59:59.000Z

    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.

  11. Long-Lived, Coherent Acoustic Phonon Oscillations in GaN Single Crystals

    SciTech Connect (OSTI)

    Wu, S.; Geiser, P.; Jun, J.; Karpinski, J.; Park, J.-R.; Sobolewski, R.

    2006-01-31T23:59:59.000Z

    We report on coherent acoustic phonon (CAP) oscillations studied in high-quality bulk GaN single crystals with a two-color femtosecond optical pump-probe technique. Using a far-above-the-band gap ultraviolet excitation (~270 nm wavelength) and a near-infrared probe beam (~810 nm wavelength), the long-lived, CAP transients were observed within a 10 ns time-delay window between the pump and probe pulses, with a dispersionless (proportional to the probe-beam wave vector) frequency of ~45 GHz. The measured CAP attenuation corresponded directly to the absorption of the probe light in bulk GaN, indicating that the actual (intrinsic) phonon-wave attenuation in our crystals was significantly smaller than the measured 65.8 cm^-1 value. The velocity of the phonon propagation was equal to the velocity of sound in GaN.

  12. Synthesis and single crystal structure refinement of the one-layer hydrate of sodium brittle mica

    SciTech Connect (OSTI)

    Kalo, Hussein; Milius, Wolfgang [Lehrstuhl fuer Anorganische Chemie I, University of Bayreuth, D-95440 Bayreuth (Germany)] [Lehrstuhl fuer Anorganische Chemie I, University of Bayreuth, D-95440 Bayreuth (Germany); Braeu, Michael [BASF Construction Chemicals GmbH, 83308 Trostberg (Germany)] [BASF Construction Chemicals GmbH, 83308 Trostberg (Germany); Breu, Josef, E-mail: Josef.Breu@uni-bayreuth.de [Lehrstuhl fuer Anorganische Chemie I, University of Bayreuth, D-95440 Bayreuth (Germany)] [Lehrstuhl fuer Anorganische Chemie I, University of Bayreuth, D-95440 Bayreuth (Germany)

    2013-02-15T23:59:59.000Z

    A sodium brittle mica with the ideal composition [Na{sub 4}]{sup inter}[Mg{sub 6}]{sup oct}[Si{sub 4}Al{sub 4}]{sup tet}O{sub 20}F{sub 4} was synthesized via melt synthesis in a gas tight crucible. This mica is unusual inasmuch as the known mica structure holds only room for two interlayer cations per unit cell and inasmuch as it readily hydrates despite the high layer charge while ordinary micas and brittle micas are non-swelling. The crystal structure of one-layer hydrate sodium brittle mica was determined and refined from single crystal X-ray data. Interlayer cations reside at the center of the distorted hexagonal cavities and are coordinated by the three inner basal oxygen atoms. The coordination of the interlayer cation is completed by three interlayer water molecules residing at the center of the interlayer region. The relative position of adjacent 2:1-layers thus is fixed by these octahedrally coordinated interlayer cations. Pseudo-symmetry leads to extensive twinning. In total five twin operations generate the same environment for the interlayer species and are energetically degenerate. - Graphical abstract: The sodium brittle mica has been successfully synthesized by melt synthesis and the crystal structure of the one-layer hydrate of sodium brittle mica was determined from single crystal X-ray diffraction data. Highlights: Black-Right-Pointing-Pointer Melt synthesis yielded coarse grained sodium brittle mica which showed little disorder. Black-Right-Pointing-Pointer Sodium brittle mica hydrated completely to the state of one-layer hydrate. Black-Right-Pointing-Pointer Structure of one-layer hydrate of sodium brittle mica could therefore be determined and refined. Black-Right-Pointing-Pointer Arrangement of upper and lower tetrahedral sheet encompassing interlayer cation were clarified.

  13. Surface Structure Spread Single Crystals ((SC)-C-4): Preparation and characterization

    SciTech Connect (OSTI)

    de Alwis, A.; Holsclaw, B.; Pushkarev, V. V.; Reinicker, A.; Lawton, T. J.; Blecher, M. E.; Sykes, E. C. H.; Gellman, A. J.

    2013-02-01T23:59:59.000Z

    A set of six spherically curved Cu single crystals referred to as Surface Structure Spread Single Crystals (S{sup 4}Cs) has been prepared in such a way that their exposed surfaces collectively span all possible crystallographic surface orientations that can be cleaved from the face centered cubic Cu lattice. The method for preparing these S{sup 4}Cs and for finding the high symmetry pole point are described. Optical profilometry has been used to determine the true shapes of the S{sup 4}Cs and show that over the majority of the surface, the shape is extremely close to that of a perfect sphere. The local orientations of the surfaces lie within ±1{degree} of the orientation expected on the basis of the spherical shape; their orientation is as good as that of many commercially prepared single crystals. STM imaging has been used to characterize the atomic level structure of the Cu(111)±11{degree}-S{sup 4}C. This has shown that the average step densities and the average step orientations match those expected based on the spherical shape. In other words, although there is some distribution of step-step spacing and step orientations, there is no evidence of large scale reconstruction or faceting. The Cu S{sup 4}Cs have local structures based on the ideal termination of the face centered cubic Cu lattice in the direction of termination. The set of Cu S{sup 4}Cs will serve as the basis for high throughput investigations of structure sensitive surface chemistry on Cu.

  14. On-chip single photon sources based on quantum dots in photonic crystal structures

    E-Print Network [OSTI]

    Schwagmann, Andre

    2013-02-05T23:59:59.000Z

    of this dissertation have appeared or will appear in form of the following journal articles and contributed talks at international conferences. Articles A. Schwagmann, S. Kalliakos, I. Farrer, J. P. Griffiths, G. A. C. Jones, D. A. Ritchie, and A. J. Shields. “On... -chip single photon emission from an integrated semiconductor quantum dot into a photonic crystal waveguide.” Applied Physics Letters 99, 261108 (2011). A. Schwagmann, S. Kalliakos, D. J. P. Ellis, I. Farrer, J. P. Griffiths, G. A. C. Jones, D. A. Ritchie...

  15. Integration of neutron time-of-flight single-crystal Bragg peaks in reciprocal space

    SciTech Connect (OSTI)

    Schultz, Arthur J [ORNL] [ORNL; Joergensen, Mads [ORNL] [ORNL; Wang, Xiaoping [ORNL] [ORNL; Mikkelson, Ruth L [ORNL] [ORNL; Mikkelson, Dennis J [ORNL] [ORNL; Lynch, Vickie E [ORNL] [ORNL; Peterson, Peter F [ORNL] [ORNL; Green, Mark L [ORNL] [ORNL; Hoffmann, Christina [ORNL] [ORNL

    2014-01-01T23:59:59.000Z

    The intensity of single crystal Bragg peaks obtained by mapping neutron time-of-flight event data into reciprocal space and integrating in various ways are compared. These include spherical integration with a fixed radius, ellipsoid fitting and integrating of the peak intensity and one-dimensional peak profile fitting. In comparison to intensities obtained by integrating in real detector histogram space, the data integrated in reciprocal space results in better agreement factors and more accurate atomic parameters. Furthermore, structure refinement using integrated intensities from one-dimensional profile fitting is demonstrated to be more accurate than simple peak-minus-background integration.

  16. Resistivity measurements of iodine single crystals by an A.C. technique

    E-Print Network [OSTI]

    Intararithi, Thanom

    1965-01-01T23:59:59.000Z

    . measure- ment and could be responsible for the disagreement. Another object is to de- termine any frequency dependence of the resistivity of iodine single crystals which might give information concerning the reasons for the increase in acti- vation... the assembly used in the resublimation. TO DIFFUSION FUMP S, ;U I. IQUID NITRO&EN C 33 A O'LASS WOOJ- F EACrE NT-&'RADE IODINE The reagent-grade iodine is initially in tube A. A trap T filled with liquid nitrogen prevents the contamination of the pump...

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

    SciTech Connect (OSTI)

    Marquez Velasco, J. [National Center for Scientific Research “Demokritos,” 15310 Athens (Greece) [National Center for Scientific Research “Demokritos,” 15310 Athens (Greece); Department of Physics, National Technical University of Athens, Athens (Greece); Kelaidis, N.; Xenogiannopoulou, E.; Tsoutsou, D.; Tsipas, P.; Speliotis, Th.; Pilatos, G.; Likodimos, V.; Falaras, P.; Dimoulas, A., E-mail: dimoulas@ims.demokritos.gr [National Center for Scientific Research “Demokritos,” 15310 Athens (Greece); Raptis, Y. S. [Department of Physics, National Technical University of Athens, Athens (Greece)] [Department of Physics, National Technical University of Athens, Athens (Greece)

    2013-11-18T23:59:59.000Z

    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.

  18. Shape of isolated domains in lithium tantalate single crystals at elevated temperatures

    SciTech Connect (OSTI)

    Shur, V. Ya., E-mail: vladimir.shur@usu.ru; Akhmatkhanov, A. R.; Baturin, I. S. [Ferroelectric Laboratory, Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation) [Ferroelectric Laboratory, Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Labfer Ltd., 620014 Ekaterinburg (Russian Federation); Chezganov, D. S.; Lobov, A. I.; Smirnov, M. M. [Ferroelectric Laboratory, Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation)] [Ferroelectric Laboratory, Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation)

    2013-12-09T23:59:59.000Z

    The shape of isolated domains has been investigated in congruent lithium tantalate (CLT) single crystals at elevated temperatures and analyzed in terms of kinetic approach. The obtained temperature dependence of the growing domain shape in CLT including circular shape at temperatures above 190?°C has been attributed to increase of relative input of isotropic ionic conductivity. The observed nonstop wall motion and independent domain growth after merging in CLT as opposed to stoichiometric lithium tantalate have been attributed to difference in wall orientation. The computer simulation has confirmed applicability of the kinetic approach to the domain shape explanation.

  19. Chaotic magnetization dynamics in single-crystal thin-film structures

    SciTech Connect (OSTI)

    Shutyi, A. M., E-mail: shuty@mail.ru; Sementsov, D. I. [Ulyanovsk State University (Russian Federation)

    2009-01-15T23:59:59.000Z

    The nonlinear dynamics of homogeneously precessing magnetization in perpendicularly magnetized single-crystal films has been investigated in a wide range of ac field frequencies on the basis of a numerical solution to the Landau-Lifshitz equation and construction of the spectrum of Lyapunov exponents. The conditions for implementing and specific features of chaotic dynamic modes are revealed for films of three basic crystallographic orientations: (100), (110), and (111). It is shown that chaotic precession modes can be controlled using external magnetic fields. Time analogs of the Poincare section of chaotic mode trajectories are considered.

  20. Modelling off Hugoniot Loading Using Ramp Compression in Single Crystal Copper

    SciTech Connect (OSTI)

    Hawreliak, J; Remington, B A; Lorenzana, H; Bringa, E; Wark, J

    2010-11-29T23:59:59.000Z

    The application of a ramp load to a sample is a method by which the thermodynamic variables of the high pressure state can be controlled. The faster the loading rate, the higher the entropy and higher the temperature. This paper describes moleculer dynamics (MD) simulations with 25 million atoms which investigate ramp loading of single crystal copper. The simulations followed the propagation of a 300ps ramp load to 3Mbar along the [100] direction copper. The simulations were long enough to allow the wave front to steepen into a shock, at which point the simulated copper sample shock melted.

  1. From Ultrananocrystalline Diamond to Single Crystal Diamond Growth in Hot Filament and Microwave Plasma-Enhanced CVD Reactors: a Unified Model for Growth Rates and

    E-Print Network [OSTI]

    Bristol, University of

    From Ultrananocrystalline Diamond to Single Crystal Diamond Growth in Hot Filament and Microwave, Moscow State UniVersity, 119991 Moscow, Russia ReceiVed: April 29, 2008 CVD Diamond can now be deposited either in the form of single crystal homoepitaxial layers, or as polycrystalline films with crystal sizes

  2. ENHANCEMENT OF THE POSITRON INTENSITY BY A TUNGSTEN SINGLE-CRYSTAL TARGET AT THE KEKB INJECTOR LINAC

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    by these stimulating results, we proceeded to systematic studies on the positron-production efficiencies with tungstenENHANCEMENT OF THE POSITRON INTENSITY BY A TUNGSTEN SINGLE-CRYSTAL TARGET AT THE KEKB INJECTOR, Russia R. Chehab, IPNL, IN2P3-CNRS, Universite Claude Bernald 1, France Abstract A new tungsten single

  3. Critical Fields, Thermally Activated Transport, and Critical Current Density of Beta-FeSe Single Crystals

    SciTech Connect (OSTI)

    Petrovic, C.; Lei, H.; Hu, R.

    2011-07-27T23:59:59.000Z

    We present critical fields, thermally activated flux flow (TAFF), and critical current density of tetragonal phase {beta}-FeSe single crystals. The upper critical fields H{sub c2}(T) for H {parallel} (101) and H {perpendicular} (101) are nearly isotropic and are likely governed by the Pauli limiting process. The large Ginzburg-Landau parameter {Kappa} {approx} 72.3(2) indicates that {beta}-FeSe is a type-II superconductor with a smaller penetration depth than in Fe(Te, Se). The resistivity below T{sub c} follows Arrhenius TAFF behavior. For both field directions below 30 kOe, single-vortex pinning is dominant, whereas collective creep becomes important above 30 kOe. The critical current density J{sub c} from M-H loops for H {parallel} (101) is about five times larger than for H {perpendicular} (101), yet much smaller than in other iron-based superconductors.

  4. 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)

    2014-12-01T23:59:59.000Z

    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 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.

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

    SciTech Connect (OSTI)

    Carmody, M.; Gilmore, A.

    2011-05-01T23:59:59.000Z

    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.

  6. Pair distribution function-derived mechanism of a single-crystal to disordered to single-crystal transformation in a hemilabile metal-organic framework

    SciTech Connect (OSTI)

    Allan, P. K.; Chapman, K. W.; Chupas, P. J.; Hriljac, J. A.; Renouf, C. L.; Lucas, T. C. A.; Morris, R. E. (X-Ray Science Division); (Univ. of St. Andrews); (Univ. of Birmingham)

    2012-01-01T23:59:59.000Z

    Flexible metal-organic frameworks (MOFs) are materials of great current interest. A small class of MOFs show flexibility driven by reversible bonding rearrangements that lead directly to unusual properties. Cu-SIP-3 is a MOF based on the 5-sulfoisophthalate ligand, where the strong copper-carboxylate bonds ensure that the three-dimensional integrity of the structure is retained while allowing bonding changes to occur at the more weakly bonding sulfonate group leading to unusual properties such as the ultra-selective adsorption of only certain gases. While the integrity of the framework remains intact during bonding changes, crystalline order is not retained at all times during the transformations. X-Ray diffraction reveals that highly crystalline single crystals lose order during the transformation before regaining crystallinity once it is complete. Here we show how X-ray pair distribution function analysis can be used to reveal the mechanism of the transformations in Cu-SIP-3, identifying the sequence of atomic displacements that occur in the disordered phase. A similar approach reveals the underlying mechanism of Cu-SIP-3's ultra-selective gas adsorption.

  7. Creep property and microstructure evolution of a nickel-base single crystal superalloy in [011] orientation

    SciTech Connect (OSTI)

    Han, G.M., E-mail: gmhan@imr.ac.cn; Yu, J.J.; Hu, Z.Q.; Sun, X.F.

    2013-12-15T23:59:59.000Z

    The creep property and microstructure evolution of a single crystal superalloy with [011] orientation were investigated at the temperatures of 700 °C, 900 °C and 1040 °C. It is shown that there exist stages of primary, steady-state, and tertiary creep under the lower temperature 700 °C. As the temperature increases to high temperatures of 900 °C and 1040 °C, steady-state creep stage is reduced or disappears and the shape of creep curves is dominated by an extensive tertiary stage. The minimum creep strain rate exhibits power law dependence on the applied stress; the stress exponents at 700 °C, 900 °C and 1040 °C are 28, 13 and 6.5, respectively. Microstructure observation shows that the morphologies of ?? phase almost keep original shape at the lower temperature 700 °C and high applied stress. With the increasing creep temperature, ?? precipitates tend to link together and form lamellar structure at an angle of 45° inclined to the applied stress. Transmission electron microscopy (TEM) investigations reveal that multiple < 110 > (111) slip systems gliding in the matrix channels and shearing ?? precipitates by stacking faults or bending dislocation pairs are the main deformation mechanism at the lower temperature of 700 °C. At the high temperatures of 900 °C and 1040 °C, dislocation networks are formed at ?/?? interfaces and the ?? rafts are sheared by dislocation pairs. - Highlights: • Creep properties of < 011 >-oriented single crystal superalloys were investigated. • ?? phases become rafting at an angle of 45° inclined to the applied stress. • Creep deformation mechanisms depend on temperature and stress.

  8. 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

    2014-01-01T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    Mahadevan, M., E-mail: devanphysics@gmail.com [Department of Physics, Adhiparasakthi Engineering College, Melmaruvathur - 603319 (India); Ramachandran, K., E-mail: ramach76@yahoo.com [Department of Physics, SRM University - Vadapalani Campus, Chennai -600026 (India); Anandan, P., E-mail: anandantcet@gmail.com [Department of Physics, Thiruvalluvar College of Engineering and Technology, Vandavasi-604 505, India and Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-Ku, Hamamatsu 432-8011 (Japan); Arivanandhan, M., E-mail: arivucz@gmail.com, E-mail: royhaya@ipc.shizuoka.ac.jp; Hayakawa, Y., E-mail: arivucz@gmail.com, E-mail: royhaya@ipc.shizuoka.ac.jp [Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-Ku, Hamamatsu 432-8011 (Japan)

    2014-10-15T23:59:59.000Z

    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.

  10. Coherent and incoherent radiation from high-energy electron and the LPM effect in oriented single crystal

    E-Print Network [OSTI]

    V. N. Baier; V. M. Katkov

    2005-12-01T23:59:59.000Z

    The process of radiation from high-energy electron in oriented single crystal is considered using the method which permits inseparable consideration of both coherent and incoherent mechanisms of photon emission. The total intensity of radiation is calculated. The theory, where the energy loss of projectile has to be taken into account, agrees quite satisfactory with available CERN data. It is shown that the influence of multiple scattering on radiation process is suppressed due to action of crystal field.

  11. EPR investigation of defects in Bi12GeO20:Cr single crystal irradiated by high energy uranium ions

    E-Print Network [OSTI]

    Stefaniuk, I; Rogalska, I; Wróbel, D

    2013-01-01T23:59:59.000Z

    The results of investigations of EPR spectra of chromium doped $Bi_{12} GeO_{20} (BGO)$ single crystals are presented. The crystals were studied before and after irradiation by the $^{235}U$ ions with energy 9.47 MeV/u and fluency $5 \\cdot 10^{2} cm^{-2}$. The effect of heating irradiated samples in air on the EPR spectra is also studied.

  12. Mesoscale Heterogeneity in the Plastic Deformation of a Copper Single Crystal

    SciTech Connect (OSTI)

    Magid, K R; Florando, J N; Lassila, D H; LeBlanc, M M; Tamura, N; Morris Jr., J W

    2007-02-21T23:59:59.000Z

    The work reported here is part of a 'multiscale characterization' study intended to clarify the deformation pattern in a Cu single crystal deformed in compression. A copper single crystal was oriented for single slip in the (111)[{bar 1}01] slip system and tested to {approx}10% strain in uniaxial compression, using a specifically designed '6 degree of freedom' compressive test device to achieve uniaxial strain. The macroscopic strain field was monitored during the test by optical 'image correlation' methods that mapped the strain field with a spatial resolution of about 100 {micro}m. The strain field was measured on orthogonal surfaces, one of which (the x-face) was oriented perpendicular to [1{bar 2}1] and contained the [{bar 1}01] direction of the preferred slip system. The macroscopic strain produced is an inhomogeneous pattern of broad, crossed shear bands in the x-face. One, the primary band, lay parallel to (111). The second, the 'conjugate' band, was oriented perpendicular to (111) and contains no common slip plane of the fcc crystal. The mesoscopic structure of the inhomogeneous macroscopic deformation pattern was explored with selected area diffraction, using a focused synchrotron radiation polychromatic beam with a resolution of 1-3 {micro}m. Areas within the primary, conjugate and primary + conjugate strain regions of the x-face were identified and mapped for their orientation, excess defect density and shear stress. The mesoscopic defect structure consisted of broad, somewhat irregular primary bands that lay nominally parallel to (111) in a almost periodic distribution with a period of about 30 {micro}m. These primary bands were dominant even in the region of conjugate strain. There were also broad conjugate defect bands, almost precisely perpendicular to the primary bands that tended to bridge primary bands and terminate at them. The residual shear stresses were large (ranging to well above 500 MPa) and strongly correlated with the primary shear bands. The results are compared to the mesoscopic defect patterns found in Cu in etch pit studies done some decades ago.

  13. The growth of single-crystals of Pb-K-Niobate and temperature dependence of dielectric property

    E-Print Network [OSTI]

    Islam, Faizul

    1986-01-01T23:59:59.000Z

    THE GROWTH OF SINGLE-CRYSTALS OF PB-K-NIOBATE AND TEMPERATURE DEPENDENCE OF DIELECTRIC PROPERTY A Thesis FAIZUL ISLAM Submitted to the Graduate College of Texas AdrM University in partial ful6llment of the requirement for the degree of MASTER... OF SCIENCE August 1986 Major Subject: Electrical Engineering THE GROWTH OF SINGLE-CRYSTALS OF PB-K-NIOBATE AND CHARACTERIZATION OF DIELECTRIC PROPERTY A Thesis by FAIZUL ISLAM Approved as to style and content by: Dr. Raghvendra y (Chairman...

  14. TEM and SIMS Analysis of (100), (110), and (111) Single Crystal Niobium

    SciTech Connect (OSTI)

    A. D. Batchelor; D. N. Leonard; P. E. Russell; F. A. Stevie; D. P. Griffis; G. R. Myneni

    2006-10-30T23:59:59.000Z

    Single crystal niobium specimens of (100), (110) and (111) crystal orientations have been analyzed using TEM and SIMS. The TEM specimens were prepared using Focused Ion Beam (FIB) and show niobium oxide thicknesses ranging from 4.9 to 8.3 nm for the three specimens after buffer chemical polishing. The oxide layers appear uniform and no significant sub-oxide region was noted. SIMS analysis was made for all three orientations on hydrogen, carbon, and oxygen before and after heat treatments at 90, 600, and 1250ºC. Hydrogen is at a high level between the oxide layer and niobium, but at a relatively low level in the oxide. No high oxygen concentration region was noted in the niobium below the oxide. C contamination on the surface is detected mainly at the surface. Analysis after heat treatments showed some decrease in hydrogen after the 600ºC heat treatment, and significant oxidation of the niobium after the 1250ºC heat treatment.

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

    SciTech Connect (OSTI)

    Rainer Wallny

    2012-10-15T23:59:59.000Z

    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.

  16. Deformation of Diopside Single Crystal at Mantle Pressure 2 TEM Characterization of Deformation Microstructures

    SciTech Connect (OSTI)

    E Amiguet; P Cordier; P Raterron

    2011-12-31T23:59:59.000Z

    The dislocation microstructures of diopside single crystals deformed at high-pressure (4 {<=} P {<=} 9 GPa), high-temperature (1100{sup o} {<=} T {<=} 1400 {sup o}C) using a Deformation-DIA high-pressure apparatus (D-DIA) have been characterized by transmission electron microscopy using weak-beam dark-field (WBDF), precession electron diffraction (PED), large-angle convergent-beam electron diffraction (LACBED) and the thickness-fringe method. Dislocation glide is the dominant deformation mechanism under these conditions. The 1/2<110>{l_brace}110{r_brace} glide is controlled by lattice friction on the edge segments and shows extensive cross-slip. The [001] glide occurs mostly on {l_brace}110{r_brace}; no evidence for [001](010) glide has been found. The [100] dislocations bear a strong lattice friction probably due to complex (out of glide) core structures.

  17. Infrared phonon modes in multiferroic single-crystal FeTe2O5Br

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

    Miller, K. H.; Xu, X. S.; Berger, H.; Craciun, V.; Xi, Xiaoxiang; Martin, C.; Carr, G. L.; Tanner, D. B.

    2013-06-01T23:59:59.000Z

    Reflection and transmission as a function of temperature (7–300 K and 5–300 K respectively) have been measured on single crystals of the multiferroic compound FeTe2O5Br utilizing light spanning from the far infrared to the visible. The complex dielectric function and other optical properties were obtained via Kramers-Kronig analysis and by fits to a Drude-Lortentz model. Analysis of the anisotropic excitation spectra via Drude-Lorentz fitting and lattice dynamical calculations have led to the observation of 43 of the 53 modes predicted along the b axis of the monoclinic cell. The phonon response parallel to the a and c axes are also presented. Assignments to groups (clusters) of phonons have been made and trends within them are discussed in light of our calculated displacement patterns.

  18. Homoepitaxial Growth of Single Crystal Diamond Membranes for Quantum Information Processing

    E-Print Network [OSTI]

    Igor Aharonovich; Jonathan C. Lee; Andrew P. Magyar; Bob B. Buckley; Christopher G. Yale; David D. Awschalom; Evelyn L. Hu

    2012-01-18T23:59:59.000Z

    Fabrication of devices designed to fully harness the unique properties of quantum mechanics through their coupling to quantum bits (qubits) is a prominent goal in the field of quantum information processing (QIP). Among various qubit candidates, nitrogen vacancy (NV) centers in diamond have recently emerged as an outstanding platform for room temperature QIP. However, formidable challenges still remain in processing diamond and in the fabrication of thin diamond membranes, which are necessary for planar photonic device engineering. Here we demonstrate epitaxial growth of single crystal diamond membranes using a conventional microwave chemical vapor deposition (CVD) technique. The grown membranes, only a few hundred nanometers thick, show bright luminescence, excellent Raman signature and good NV center electronic spin coherence times. Microdisk cavities fabricated from these membranes exhibit quality factors of up to 3000, overlapping with NV center emission. Our methodology offers a scalable approach for diamond device fabrication for photonics, spintronics, optomechanics and sensing applications.

  19. Homoepitaxial Growth of Single Crystal Diamond Membranes for Quantum Information Processing

    E-Print Network [OSTI]

    Aharonovich, Igor; Magyar, Andrew P; Buckley, Bob B; Yale, Christopher G; Awschalom, David D; Hu, Evelyn L

    2011-01-01T23:59:59.000Z

    Fabrication of devices designed to fully harness the unique properties of quantum mechanics through their coupling to quantum bits (qubits) is a prominent goal in the field of quantum information processing (QIP). Among various qubit candidates, nitrogen vacancy (NV) centers in diamond have recently emerged as an outstanding platform for room temperature QIP. However, formidable challenges still remain in processing diamond and in the fabrication of thin diamond membranes, which are necessary for planar photonic device engineering. Here we demonstrate epitaxial growth of single crystal diamond membranes using a conventional microwave chemical vapor deposition (CVD) technique. The grown membranes, only a few hundred nanometers thick, show bright luminescence, excellent Raman signature and good NV center electronic spin coherence times. Microdisk cavities fabricated from these membranes exhibit quality factors of up to 3000, overlapping with NV center emission. Our methodology offers a scalable approach for dia...

  20. Nanoporous films for epitaxial growth of single crystal semiconductor materials : final LDRD report.

    SciTech Connect (OSTI)

    Rowen, Adam M.; Koleske, Daniel David; Fan, Hongyou; Brinker, C. Jeffrey; Burckel, David Bruce; Williams, John Dalton; Arrington, Christian L.; Steen, William Arthur

    2007-10-01T23:59:59.000Z

    This senior council Tier 1 LDRD was focused on exploring the use of porous growth masks as a method for defect reduction during heteroepitaxial crystal growth. Initially our goal was to investigate porous silica as a growth mask, however, we expanded the scope of the research to include several other porous growth masks on various size scales, including mesoporous carbon, photolithographically patterned SU-8 and carbonized SU-8 structures. Use of photolithographically defined growth templates represents a new direction, unique in the extensive literature of patterned epitaxial growth, and presents the possibility of providing a single step growth mask. Additional research included investigation of pore viability via electrochemical deposition into high aspect ratio photoresist. This project was a small footprint research effort which, nonetheless, produced significant progress towards both the stated goal as well as unanticipated research directions.

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

    SciTech Connect (OSTI)

    Daniel, D. Joseph; Ramasamy, P. [Centre for Crystal Growth, SSN College of Engineering, kalavakkam, Tamilnadu- 603 110 (India); Nithya, R. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu - 603 102 (India); Madhusoodanan, U. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu - 603 102 (India)

    2013-02-05T23:59:59.000Z

    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.

  2. 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, E-mail: vivek-gupta2k2@hotmail.com; Gupta, Vivek K., E-mail: vivek-gupta2k2@hotmail.com [Department of Physics and Electronics, University of Jammu, Jammu Tawi - 180006 (India); Jadeja, R. N. [Department of Chemistry, Faculty of Science, The M. S. University of Baroda, Vadodara-390002 (India)

    2014-04-24T23:59:59.000Z

    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.

  3. Thermal transport of the single-crystal rare-earth nickel borocarbides RNi2B2C

    E-Print Network [OSTI]

    Hennings, BD; Naugle, Donald G.; Canfield, PC.

    2002-01-01T23:59:59.000Z

    superconductivity in this material above T-N. Unlike the case for the non-magnetic superconductors in the family, R=Y and Lu, a phonon peak in the thermal conductivity below T-c is not observed down to T=1.4 K for the magnetic superconductors. Single-crystal quality...

  4. Fabrication and optical properties of single-crystal YAG fiber optics Brian.T. Laustsen and James A. Harrington

    E-Print Network [OSTI]

    . In this method a CO2 laser is used to melt the tip of a crystalline source rod and a fiber is pulled upward from reservoir. In one method a high temperature crucible usually made of tungsten is used to contain the meltFabrication and optical properties of single-crystal YAG fiber optics Brian.T. Laustsen and James A

  5. Study of the superconducting gap in RNi2B2C,,RY, Lu... single crystals by inelastic light scattering

    E-Print Network [OSTI]

    Yang, In-Sang

    Study of the superconducting gap in RNi2B2C,,RÃ?Y, Lu... single crystals by inelastic light Initiative Center for Superconductivity, Department of Physics, Pohang University of Science and Technology, 790-390 Pohang, Korea Received 28 February 2000 Superconductivity-induced changes in the electronic

  6. Patterned aluminum nanowires produced by electron beam at the surfaces of AlF3 single crystals

    E-Print Network [OSTI]

    Wang, Zhong L.

    Patterned aluminum nanowires produced by electron beam at the surfaces of AlF3 single crystals C is demonstrated for fabricating patterned aluminum nanowires in AlF3 substrate in a scanning electron microscope nanowires of different sizes. The aluminum nanowires may act as nano- interconnects for nanoelectronics

  7. PHYSICAL REVIEW B 83, 104511 (2011) Superconducting energy gap in MgCNi3 single crystals: Point-contact spectroscopy

    E-Print Network [OSTI]

    Boyer, Edmond

    2011-01-01T23:59:59.000Z

    PHYSICAL REVIEW B 83, 104511 (2011) Superconducting energy gap in MgCNi3 single crystals: Point Center for Superconductivity, Sogang University, Seoul 100-611, Republic of Korea (Received 14 December that a superconducting energy gap is fully open on the whole Fermi surface, in agreement with our previous magnetic

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

    SciTech Connect (OSTI)

    Zhu, Xiaoyang

    2014-12-10T23:59:59.000Z

    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 charge carriers is known to evolve as the carrier concentration increases, due to the presence of intrinsic disorder in organic semiconductors. Thus, a complementary question is: how does the nature of charge transport change as a function of carrier concentration?

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

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

    Pandey, Abhishek [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Quirinale, D. G. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Jayasekara, W. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Sapkota, A. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Kim, M. G. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Dhaka, R. S. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Lee, Y. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Heitmann, T. W. [Univ. of Missouri, Columbia, MO (United States). Missouri Research Reactor; Stephens, P. W. [State Univ. of New York (SUNY), Plattsburgh, NY (United States); Ogloblichev, V. [Russian Academy of Sciences, Urals Div., Ekaterinburg (Russian Federation). Inst. of Metal Physics; Kreyssig, A. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; McQueeney, R. J. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Goldman, A. I. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Kaminski, Adam [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Harmon, B. N. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Furukawa, Y. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Johnston, D. C. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy

    2013-07-01T23:59:59.000Z

    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 between 1.3 and 300 K and we propose that metallic SrCo2As2 has a gapless quantum spin-liquid ground state.

  10. Mapping mesoscale heterogeneity in the plastic deformation of a copper single crystal

    SciTech Connect (OSTI)

    Magid, K. R.; Florando, J.N.; Lassila, D.H.; Leblanc, M.M.; Tamura, N.; Morris Jr, J. W.

    2008-10-01T23:59:59.000Z

    The work reported here is part of a 'multiscale characterization' study of heterogeneous deformation patterns in metals. A copper single crystal was oriented for single slip in the (111)[{bar 1}01] slip system and tested to {approx}10% strain in roughly uniaxial compression. The macroscopic strain field was monitored during the test by optical 'image correlation'. The strain field was measured on orthogonal surfaces, one of which (the x-face) was oriented perpendicular to [1{bar 2}1] and contained the [{bar 1}01] direction of the preferred slip system. The macroscopic strain developed in an inhomogeneous pattern of broad, crossed shear bands in the x-face. One, the primary band, lay parallel to (111). The second, the 'conjugate' band, was oriented perpendicular to (111) with an overall ({bar 1}01) habit that contains no common slip plane of the fcc crystal. The mesoscopic deformation pattern was explored with selected area diffraction, using a focused synchrotron radiation polychromatic beam with a resolution of 1-3 {micro}m. Areas within the primary, conjugate and mixed (primary + conjugate) strain regions of the x-face were identified and mapped for their orientation, excess defect density and shear stress. The mesoscopic defect structure was concentrated in broad, somewhat irregular primary bands that lay nominally parallel to (111) in an almost periodic distribution with a period of about 30 {micro}m. These primary bands were dominant even in the region of conjugate strain. There were also broad conjugate defect bands, almost precisely perpendicular to the primary bands, that tended to bridge primary bands and terminate at them. The residual shear stresses were large (ranging to well above 500 MPa) and strongly correlated with the primary shear bands; interband stresses were small. The maximum resolved shear stresses within the primary bands were oriented out of the plane of the bands, and, hence, could not recover the dislocation structure in the bands. The maximum resolved shear stresses in the interband regions lay predominantly in {l_brace}111{r_brace} planes. The results are compared to the mesoscopic defect patterns found in Cu in etch pit studies done some decades ago, which also revealed a mesoscopic dislocation structure made up of orthogonal bands.

  11. Pressure effect on ionic conductivity in yttrium-oxide-doped single-crystal zirconium oxide

    SciTech Connect (OSTI)

    Park, E.T.; Park, J.H.

    1998-06-01T23:59:59.000Z

    In this study, the authors investigated the effect of pressure on the ionic conductivity of a 9.5 mol% yttria-stabilized zirconia (YSZ) single crystal. The experiment was conducted in the elastic region, and the oxygen ion transport number was unity (t{sub ion} > 0.99999). A conventional four-probe DC method was used to measure the ionic conductivity of the rectangular-shaped sample under uniaxial pressures up to 600 atm at 750 C in air. Measured ionic conductivity decreased as applied pressure increased. Based on henry Eyring`s absolute reaction rate theory, which states that the calculated activation volume has a positive value ({Delta}V{sup 2} = 2.08 cm{sup 3}/mol of O{sup {minus}2}) for oxygen ion transport in the fluoride cubic lattice, they concluded that the results they obtained could be explained by an oxygen ion transport mechanism. This mechanism can explain the fact that the interionic distance increases during oxygen ion transport from one unit cell to neighboring unit cells.

  12. Direct observation of plasticity and quantitative hardness measurements in single crystal cyclotrimethylene trinitramine by nanoindention

    SciTech Connect (OSTI)

    Ramos, Kyle J [Los Alamos National Laboratory; Hooks, David E [Los Alamos National Laboratory; Bahr, David F [WSU

    2008-01-01T23:59:59.000Z

    Investigation of deformation beginning with elasticity and continuing through the elastic-plastic transition to incipient cracking has been conducted for (210), (021), and (001) oriented single crystals of the explosive cyclotrimethylene trinitramine, commonly known as 'RDX' Instrumented indentation was performed with a conical tip over a range of loads. The resulting load-depth data exhibited distinct, reproducible, orientation dependent load excursions demonstrating elastic-plastic transitions. Indent impressions were imaged by scanning probe microscopy. Impressions on the (210) and (001) planes showed deformation pileup features associated with zone axes of slip planes. Clearly discernable slip traces were evident on the (210) plane. The (021) indentations produced significant material pile-up surrounding the impression, but did not contain discrete features associable with specific zone axes. All of the orientations exhibited cracking thresholds at very low loads. The reduced moduli were anisotropic and the hardness's were isotropic indicating limited plasticity. Maximum shear stresses estimated from a Hertzian model, at load excursions, were within a factor of 10 of published shear moduli indicating deformation initiated near the theoretical yield strength presumably by homogeneous nucleation of dislocations. The material strength parameters and apparent deformation pathways inferred from this work are compared to historical microhardness testing and interpretation of anisotropic hardness in which ambiguity of results can be attributed to the effects of cracking and simultaneous slip on multiple systems.

  13. Prediction method of basic domain structure in Fe3%Si(110) single crystal with grooved surface

    SciTech Connect (OSTI)

    Iwata, K., E-mail: iwata.24h.keiji@jp.nssmc.com [Advanced Technology Research Laboratories, Nippon Steel and Sumitomo Metal Corporation, Futtsu, Chiba 293-8511 (Japan); Research Institute of Electrical Communication, Tohoku University, Aoba, Sendai 980-8577 (Japan); Fujikura, M. [Yawata R and D Laboratories, Nippon Steel and Sumitomo Metal Corporation, Tobata, Kitakyushu, Fukuoka 804-8501 (Japan); Arai, S. [Steel Research Laboratories, Nippon Steel and Sumitomo Metal Corporation, Futtsu, Chiba 293-8511 (Japan); Ishiyama, K. [Research Institute of Electrical Communication, Tohoku University, Aoba, Sendai 980-8577 (Japan)

    2014-05-07T23:59:59.000Z

    This paper proposes the method to accurately predict the 180° basic domain width (D{sub w}) in demagnetized states of the grooved Fe3%Si(110) single crystal with the tilt angle of [001] out of the sheet surface (?). The evaluation of D{sub w} enables the estimation of the anomalous eddy current losses. In this paper, D{sub w} is optimized to minimize the magnetic Gibbs free energy represented by vector potentials using the finite element method and the conjugate gradient method. The ?*-method is adopted to approximate the magnetization relaxation. The stray field energy generated by the magnetic charges occurring on both grooves cross section and sheet surfaces is considered in our proposed method. The validity of the proposed method was confirmed by comparison with the observed D{sub w}. As a result, we could reveal the ? dependence of D{sub w} against the groove depth. Moreover, the theoretical threshold of the domain refinement due to the grooves has been suggested.

  14. Single-crystal diamond plate liftoff achieved by ion implantation and subsequent annealing

    SciTech Connect (OSTI)

    Parikh, N.R.; Hunn, J.D.; McGucken, E.; Swanson, M.L. (University of North Carolina, Chapel Hill, North Carolina 27599-3255 (United States)); White, C.W. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6048 (United States)); Rudder, R.A.; Malta, D.P.; Posthill, J.B.; Markunas, R.J. (Research Triangle Institute, Research Triangle Park, North Carolina 27709-2194 (United States))

    1992-12-28T23:59:59.000Z

    We describe a new method for removing thin, large area sheets of diamond from bulk or homoepitaxial diamond crystals. This method consists of an ion implantation step, followed by a selective etching procedure. High energy (4--5 MeV) implantation of carbon or oxygen ions creates a well-defined layer of damaged diamond that is buried at a controlled depth below the surface. For C implantations, this layer is graphitized by annealing in vacuum, and then etched in either an acid solution, or by heating at 550--600 [degree]C in oxygen. This process successfully lifts off the diamond plate above the graphite layer. For O implantations of a suitable dose (3[times]10[sup 17] cm[sup [minus]2] or greater), the liftoff is achieved by annealing in vacuum or flowing oxygen. In this case, the O required for etching of the graphitic layer is also supplied internally by the implantation. This liftoff method, combined with well-established homoepitaxial growth processes, has considerable potential for the fabrication of large area single crystalline diamond sheets.

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

    SciTech Connect (OSTI)

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

    2014-01-23T23:59:59.000Z

    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).

  16. 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

    2013-07-01T23:59:59.000Z

    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 thatmore »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 between 1.3 and 300 K and we propose that metallic SrCo2As2 has a gapless quantum spin-liquid ground state.« less

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

    DOE Patents [OSTI]

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

    1991-04-23T23:59:59.000Z

    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.

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

    DOE Patents [OSTI]

    Curlee, Richard M. (Tijeras, NM); Tuthill, Clinton D. (Edgewood, NM); Watkins, Randall D. (Albuquerque, NM)

    1991-01-01T23:59:59.000Z

    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.

  19. 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.

    2012-12-25T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    Chen Yong [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Key Laboratory of Tropic Biological Resources, MOE, Hainan University, 58 Renmin Road, Haikou 570228 (China); Liu Chenguang; Liu Chang [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Lu Gaoqing [ARC Centre for Functional Nanomaterials, Australian Institute of Bioengineering and Nanotechnology, University of Queensland, QLD 4072 (Australia); Cheng Huiming [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)], E-mail: cheng@imr.ac.cn

    2007-11-06T23:59:59.000Z

    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.

  1. 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. [National Center for Scientific Research “Demokritos,” 15310 Athens (Greece)] [National Center for Scientific Research “Demokritos,” 15310 Athens (Greece); Grazianetti, C.; Fanciulli, M. [Laboratorio MDM, IMM-CNR, I-20864, Agrate Brianza (MB) (Italy) [Laboratorio MDM, IMM-CNR, I-20864, Agrate Brianza (MB) (Italy); Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca, I-20126, Milano (Italy); Chiappe, D.; Molle, A. [Laboratorio MDM, IMM-CNR, I-20864, Agrate Brianza (MB) (Italy)] [Laboratorio MDM, IMM-CNR, I-20864, Agrate Brianza (MB) (Italy)

    2013-12-16T23:59:59.000Z

    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.

  2. Tetracene air-gap single-crystal field-effect transistors Yu Xia, Vivek Kalihari, and C. Daniel Frisbiea

    E-Print Network [OSTI]

    Rogers, John A.

    Tetracene air-gap single-crystal field-effect transistors Yu Xia, Vivek Kalihari, and C. Daniel FETs utilizing an air or vacuum gap as the gate dielectric. The linear mobility of the device can be as high as 1.6 cm2 /V s in air, with a subthreshold slope lower than 0.5 V nF/decade cm2 . By changing

  3. Influence of composition on microstructural parameters of single crystal nickel-base superalloys

    SciTech Connect (OSTI)

    MacKay, R.A., E-mail: Rebecca.A.MacKay@nasa.gov [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States); Gabb, T.P. [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States); Garg, A. [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States); University of Toledo, 2801 W. Bancroft, Toledo, Ohio 43606 (United States); Rogers, R.B.; Nathal, M.V. [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States)

    2012-08-15T23:59:59.000Z

    Fourteen nickel-base superalloy single crystals containing a range of chromium (Cr), cobalt (Co), molybdenum (Mo), and rhenium (Re) levels, and fixed amounts of aluminum (Al) and tantalum (Ta), were examined to determine the effect of bulk composition on basic microstructural parameters, including {gamma} Prime solvus, {gamma} Prime volume fraction, topologically close-packed (TCP) phases, {gamma} and {gamma} Prime phase chemistries, and {gamma}-{gamma} Prime lattice mismatch. Regression models describing the influence of bulk alloy composition on each of the microstructural parameters were developed and compared to predictions by a commercially-available software tool that used computational thermodynamics. Co produced the largest change in {gamma} Prime solvus over the wide compositional range explored and Mo produced the biggest effect on the {gamma} lattice parameter over its range, although Re had a very potent influence on all microstructural parameters investigated. Changing the Cr, Co, Mo, and Re contents in the bulk alloy had an impact on their concentrations in the {gamma} matrix and to a smaller extent in the {gamma} Prime phase. The software tool under-predicted {gamma} Prime solvus temperatures and {gamma} Prime volume fractions, and over-predicted TCP phase volume fractions at 982 Degree-Sign C. However, the statistical regression models provided excellent estimations of the microstructural parameters and demonstrated the usefulness of such formulas. - Highlights: Black-Right-Pointing-Pointer Effects of Cr, Co, Mo, and Re on microstructure in new low density superalloys Black-Right-Pointing-Pointer Co produced a large change in {gamma} Prime solvus; Mo had a large effect on lattice mismatch. Black-Right-Pointing-Pointer Re exhibited very potent influence on all microstructural parameters was investigated. Black-Right-Pointing-Pointer {gamma} and {gamma} Prime phase chemistries both varied with temperature and alloy composition. Black-Right-Pointing-Pointer Computational thermodynamic modeling tool did not accurately predict microstructure.

  4. Proton irradiation effects on critical current of bulk single-crystal superconducting YBCO wire

    SciTech Connect (OSTI)

    Khanna, S.M. [Defence Research Establishment Ottawa, Ontario (Canada)] [Defence Research Establishment Ottawa, Ontario (Canada); Figueredo, A.M. [National Research Council, Boucherville, Quebec (Canada). Industrial Materials Inst.] [National Research Council, Boucherville, Quebec (Canada). Industrial Materials Inst.

    1997-12-01T23:59:59.000Z

    The authors have investigated the effects of 10 MeV proton irradiation on the magnetization M and critical current density J{sub c} of bulk single-crystal YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) superconducting thick wire filaments produced through laser-heated floating zone (LHFZ) technique. M and J{sub c} were determined both along the length and perpendicular to the length of the wire. Radiation-induced enhancement of J{sub c} along the length of the wire was observed while there was a small decrease in J{sub c} {perpendicular} to its length. J{sub c} values along the length of the wire up to {approximately}1.4 {times} 10{sup 5} A/cm{sup 2} at 77K and {approximately}1.3 {times} 10{sup 6} A/cm{sup 2} at 30K and in applied magnetic field H = 1 T were observed in the irradiated samples. In the unirradiated sample, the difference in magnetization {Delta}M at a given field in the magnetic hysteresis loop for increasing and decreasing field applied {perpendicular} to the sample length was observed to depend on the orientation of the sample about its axis. This indicates anisotropy in J{sub c} along the sample length. This anisotropy increased on irradiation relative to the direction of irradiation. They believe that these J{sub c} values along the length are amongst the highest published J{sub c} values for bulk high temperature superconductor (HTS) thick wire filament.

  5. Alignment of micro-crystals of Mn12-acetate and direct observation of single molecules thereof

    E-Print Network [OSTI]

    Seo, Dongmin

    2009-05-15T23:59:59.000Z

    This dissertation focuses on three separate studies. First, magnetization of the Mn12- acetate was studied by low temperature hysteresis loops and DC magnetization data on magnetically aligned Mn12-acetate micro-crystals. Secondly, Mn12-acetate thin...

  6. Fabrication of Ordered Array of Tips-pentacene Micro- and Nano-scale Single Crystals

    E-Print Network [OSTI]

    Xia, Ning

    2013-04-26T23:59:59.000Z

    As an important type of organic semiconductors, organic small molecule crystals have great potential for low-cost applications such as plastic solar cells (PSC), organic light emitting diodes (OLED) and organic field-effect transistors (OFET). Among...

  7. A Nano-Quantum Photonic Model for Justification of Dispersion in Single Crystal Film of NPP

    E-Print Network [OSTI]

    Hassan Kaatuzian; AliAkbar Wahedy Zarch

    2006-11-28T23:59:59.000Z

    In this paper, we present a nano-quantum photonic model for justification of normal dispersion in a thin crystal film of NPP. In this method, we assume a laser beam consists of a flow of energetic particles. By precise analyzing of photon interaction with pi-electron system of benzene ring in NPP crystal, we will attain refractive index (RI) in any wavelength and compare the results with experimental data.

  8. Chain-oxygen ordering in twin-free YBa2Cu3O7-single crystals driven by 20-keV electron irradiation

    E-Print Network [OSTI]

    Johansen, Tom Henning

    Chain-oxygen ordering in twin-free YBa2Cu3O7- single crystals driven by 20-keV electron irradiation 2005 We have examined the effects of 20-keV electron irradiation on the -Cu 1 -O 1 - n chain-oxygen arrange- ments in oxygen-deficient but otherwise twin-free YBa2Cu3O7- single crystals. Comparison

  9. 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.

    2015-05-01T23:59:59.000Z

    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 < Fe. The absence of superconductivity coincides with the absence of crystalline Fe vacancy order.

  10. 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.

    2015-05-01T23:59:59.000Z

    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 more »with the absence of crystalline Fe vacancy order.« less

  11. Mounting a thermocouple of type E onto a Cu single crystal for use in a magnetically sensitive environment below 77?K

    SciTech Connect (OSTI)

    Potzuweit, Alexander; Schaffner, Anuschka; Jänsch, Heinz Julius, E-mail: heinz.jaensch@physik.uni-marburg.de [Fachbereich Physik, Philipps-Universität Marburg, Renthof 5, 35032 Marburg (Germany)

    2014-09-01T23:59:59.000Z

    Type E thermocouples show magnetic effects at liquid nitrogen temperature and below. This may cause trouble in experiments that are sensitive to magnetic stray fields like nuclear magnetic resonance, photoemission or high resolution electron energy loss spectroscopy. Here, a solution for the temperature measurement of a single crystal is presented. The authors weld a copper rod onto the back side of the single crystal, thereby relocating the sensitive sample from the thermocouple attachment position. They show that it is possible to measure the crystal temperature at the end of the rod while significantly reducing the ferromagnetic influence due to the increased distance.

  12. Piezoelectric and ferroelectric properties of lead-free niobium-rich potassium lithium tantalate niobate single crystals

    SciTech Connect (OSTI)

    Li, Jun, E-mail: lijuna@hit.edu.cn [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Li, Yang [Department of chemistry, Harbin Institute of Technology, Harbin 150001 (China); Zhou, Zhongxiang [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Guo, Ruyan; Bhalla, Amar S. [Multifunctional Electronic Materials and Device Research Lab, Department of Electrical and Computer Engineering, The University of Texas at San Antonio, San Antonio 78249 (United States)

    2014-01-01T23:59:59.000Z

    Graphical abstract: - Highlights: • Lead-free K{sub 0.95}Li{sub 0.05}Ta{sub 1?x}Nb{sub x}O{sub 3} single crystals were grown using the top-seeded melt growth method. • The piezoelectric and ferroelectric properties of as-grown crystals were systematically investigated. • The piezoelectric properties are very attractive, e.g. for x = 0.60 composition, k{sub t} ? 70%, k{sub 31} ? 70%, k{sub 33} ? 77%, d{sub 31} ? 230 pC/N, d{sub 33} ? 600 pC/N. • The coercive fields of P–E hysteresis loops are quite small, about or less than 1 kV/mm. - Abstract: Lead-free potassium lithium tantalate niobate single crystals with the composition of K{sub 0.95}Li{sub 0.05}Ta{sub 1?x}Nb{sub x}O{sub 3} (abbreviated as KLTN, x = 0.51, 0.60, 0.69, 0.78) were grown using the top-seeded melt growth method. Their piezoelectric and ferroelectric properties in as-grown crystals have been systematically investigated. The phase transitions and Curie temperatures were determined from dielectric and pyroelectric measurements. Piezoelectric coefficients and electromechanical coupling factors in thickness mode, length-extensional mode and longitudinal mode were obtained. The piezoelectric properties are very attractive, e.g. for x = 0.60 composition, k{sub t} ? 70%, k{sub 31} ? 70%, k{sub 33} ? 77%, d{sub 31} ? 230 pC/N, d{sub 33} ? 600 pC/N are comparable to the lead-based PZT composition. The polarization versus electric field hysteresis loops show saturated shapes. In short, lead-free niobium-rich KLTN system possesses comparable properties to those in important lead-based piezoelectric material nowadays.

  13. Spontaneous Generation of Voltage in Single-Crystal Gd5Si2Ge2 During Magnetostructural Phase Transformations

    SciTech Connect (OSTI)

    M. Zou; H. Tang; D.L. Schlagel; T.A. Lograsso; K.A. Gschneidner,jr.; V.K. Pecharsky

    2006-04-19T23:59:59.000Z

    The spontaneous generation of voltage (SGV) in single-crystal and polycrystalline Gd{sub 5}Si{sub 2}Ge{sub 2} during the coupled magnetostructural transformation has been examined. Our experiments show reversible, measurable, and repeatable SGV responses of the materials to the temperature and magnetic field. The parameters of the response and the magnitude of the signal are anisotropic and rate dependent. The magnitude of the SGV signal and the critical temperatures and critical magnetic fields at which the SGV occurs vary with the rate of temperature and magnetic-field changes.

  14. 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, E-mail: dpchen2008@aliyun.com [Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, Hui [Navigation Staff Room, Anhui Bengbu Petty Officer Academy of Navy, Bengbu 233000 (China); Qiu, Jianrong [Institute of Optical Communication Materials, South China University of Technology, Guangzhou 510641 (China)

    2014-03-31T23:59:59.000Z

    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??m, 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 ?, the rod diameter d, and their ratio d/?, implying that much attention should be given in employing optimal parameters to achieve excellent laser performance.

  15. A statistical model approximation for perovskite solid-solutions: a Raman study of lead-zirconate- titanate single crystal

    SciTech Connect (OSTI)

    Frantti, Johannes [Aalto University, Finland; Fujioka, Y [Aalto University, Finland; Puretzky, Alexander A [ORNL; Xie, Y [Simon Fraser University, Canada; Glazer, A [Clarendon Laboratory, Department of Physics, University of Oxford

    2013-01-01T23:59:59.000Z

    Lead titanate (PbTiO3) is a classical example of a ferroelectric perovskite oxide illustrating a displacive phase transition accompanied by a softening of a symmetry-breaking mode. The underlying assumption justifying the soft-mode theory is that the crystal is macroscopically sufficiently uniform so that a meaningful free energy function can be formed. In contrast to PbTiO3, experimental studies show that the phase transition behaviour of lead-zirconate-titanate solid solution (PZT) is far more subtle. Most of the studies on the PZT system have been dedicated to ceramic or powder samples, in which case an unambiguous soft-mode study is not possible, as modes with different symmetries appear together. Our Raman scattering study on titanium-rich PZT single crystal shows that the phase transitions in PZT cannot be described by a simple soft-mode theory. In strong contrast to PbTiO3, splitting of transverse E-symmetry modes reveals that there are different locally-ordered regions. The role of crystal defects, random distribution of Ti and Zr at the B- cation site and Pb ions shifted away from their ideal positions, dictates the phase transition mechanism. A statistical model explaining the observed peak splitting and phase transformation to a complex state with spatially varying local order in the vicinity of the morphotropic phase boundary is given.

  16. Hydrostatic pressure (8 GPa) dependence of electrical resistivity of BaCo{sub 2}As{sub 2} single crystal

    SciTech Connect (OSTI)

    Ganguli, Chandreyee; Matsubayashi, Kazuyuki; Ohgushi, Kenya [Institute for Solid State Physics, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Uwatoko, Yoshiya, E-mail: uwatoko@issp.u-tokyo.ac.jp [Institute for Solid State Physics, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Kanagaraj, Moorthi [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli 620024 (India); Arumugam, Sonachalam, E-mail: sarumugam1963@yahoo.com [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli 620024 (India)

    2013-10-15T23:59:59.000Z

    Graphical abstract: - Highlights: • Single crystals of BaCo{sub 2}As{sub 2} were grown by CoAs self-flux method. • We have studied pressure effects (8 GPa) on dc electrical resistivity of BaCo{sub 2}As{sub 2}. • On applied external pressure BaCo{sub 2}As{sub 2} remains a metallic state up to 8 GPa. • Superconductivity is absent in BaCo{sub 2}As{sub 2} because of its proximity to ferromagnetism. - Abstract: The pressure dependence of the electrical resistivity of BaCo{sub 2}As{sub 2} single crystal as a function of temperature was measured at ambient and high pressures up to 8 GPa for the first time using cubic anvil high pressure cell. It is observed that at room temperature the resistivity monotonically decreases with increasing pressure and it remains in the metallic state even at an applied pressure of 8 GPa. From the temperature dependence of the resistivity measurements under pressure, we found that superconductivity is absent up to 8 GPa. The value of the electron's scattering factor (A) is found to be large at ambient pressure and it decreases with the application of pressure, indicating that the substantial electron correlation effect of BaCo{sub 2}As{sub 2} is reduced under pressure, revealing a dramatic change of density of states at the Fermi energy.

  17. Single-crystal sup 40 Ar/ sup 39 Ar dating of the Olorgesailie Formation, southern Kenya rift

    SciTech Connect (OSTI)

    Deino, A. (Geochronology Center of the Inst. of Human Origins, Berkeley, CA (United States)); Potts, R. (Smithsonian Institution, Washington, DC (United States))

    1990-06-10T23:59:59.000Z

    Single-crystal laser fusion {sup 40}Ar/{sup 39}Ar analyses and several conventional bulk fusion {sup 40}K- {sup 40}Ar dates have been used to determine the age of volcaniclastic strata within the Olorgesailie Formation and of associated volcanic and sedimentary units of the southern Kenya rift. In the principal exposures along the southern edge of the Legemunge Plain, the formation spans the interval from approximately 500 to 1,000 ka. Deposition continued to the east along the Ol Keju Nyiro river where a tuff near the top of the formation has been dated at 215 ka. In these exposures, the formation is unconformably overlain by sediments dated at 49 ka. A possible source for the Olorgesailie tephra, the Ol Doinyo Nyokie volcanic complex, contains as ash flow dated at {approximately} 1 Ma, extending the known age range of this complex to encompass that of virtually the entire Olorgesailie Formation in the Legemunge Plain. These geologic examples illustrate the importance of the single-crystal {sup 40}Ar/{sup 39}Ar dating technique whereby contaminant, altered, or otherwise aberrant grains can be identified and eliminated from the determination of eruptive ages for reworked or altered pyroclastic deposits. The authors have presented a computer-modeling procedure based on an inverse-isochron analysis that promotes a more objective approach to trimming {sup 40}Ar/{sup 39}Ar isotope data sets of this type.

  18. THE STRUCTURE SENSITIVITY OF n-HEPTANE DEHYDROCYCLIZATION AND HYDROGENOLYSIS CATALYZED BY PLATINUM SINGLE CRYSTALS AT ATMOSPHERIC PRESSURE

    SciTech Connect (OSTI)

    Gillespie, W. D.; Herz, R. K.; Petersen, E. E.; Somorjai, G. A.

    1980-09-01T23:59:59.000Z

    The dehydrocyclization and hydrogenolysis of n~heptane catalyzed by platinum single crystal surfaces have been investigated at temperatures from 533 to 603 K in the range of one atmosphere total pressure, The flat (111), stepped (557), and kinked (10,8,7) and (25,10,7) surfaces used tn this study were characterized in ultrahigh vacuum by low energy electron diffraction and Auger electron spectroscopy before and after reaction experiments. The rate of dehydrocyclization to toluene on the four surfaces increased in the order (111) (25,10,7) (557) (10,8,7), Hydrogenolysis, however, increased in the order (557) (10,8,7) (111) (25,10,7), As a result, the selectivity of toluene production versus hydrogenolysis increased by an order of magnitude in the order (25,10,7) (111) (10,8,7) (557). The sum of the rates of hydrogenolysis and toluene production remains relatively constant. The effect of preoxidation of the single crystal catalysts was to increase the rate of hydrogenolysis and decrease the rate of dehydrocyclization, Iri general, the reaction rates decreased with increasing reaction time. This decrease was shown to be the result of the depositon of irreversibly adsorbed carbonaceous species.

  19. 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 [College of Mechanical Science and Engineering, Jilin University, Renmin Street 5988, Changchun, Jilin 130025 (China)] [College of Mechanical Science and Engineering, Jilin University, Renmin Street 5988, Changchun, Jilin 130025 (China)

    2013-10-15T23:59:59.000Z

    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.

  20. Synthesis and characterization of low-OH?fluor-chlorapatite: A single-crystal XRD and NMR spectroscopic study

    SciTech Connect (OSTI)

    McCubbin, Francis M.; Mason, Harris E.; Park, Hyunsoo; Phillips, Brian L.; Parise, John B.; Nekvasil, Hanna; Lindsley, Donald H. (SBU)

    2008-12-12T23:59:59.000Z

    Los-OH apatite of the compositional range Ca{sub 4.99-5.06}(PO{sub 4}){sub 2.98-3.00}F{sub 0.51-0.48}Cl{sub 0.38-0.36}OH{sub 0.14-0.12} was synthesized and characterized structurally by synchrotron-based single-crystal X-ray diffraction (XRD), and multiple nuclear magnetic resonance (NMR) spectroscopic techniques. the average structure is hexagonal with space group P6{sub 3}/m. The presence of scattering in the single-crystal diffraction data set, which is incommensurate within the average hexagonal structure, suggests the presence of localized short-range monoclinic domains. Complex lineshapes in the {sup 31}P and {sup 19}F MAS NMR spectra are also consistent with the presence of an incommensurate phase. No evidence was detected for splitting of the Ca2 site into two distinct sites (as had been previously reported for hexagonal ternary apatities). Structure refinement and {sup 19}F{l_brace}{sup 35}Cl{r_brace} TRAPDOR NMR experiments verified intercolumnal neighboring of F and Cl atoms (inter-column distance of 2.62 {angstrom}) within this low-OH{sup -} apatite suggesting that long-range neighboring of F and Cl within the apatite anion channels is feasible.

  1. Mid- and Far-Infrared Reflection/Absorption Spectroscopy (IRAS) Studies of NO on Rh Single Crystal Surfaces

    SciTech Connect (OSTI)

    Peden, Charles HF; He, Ting; Pilling, M.; Hirschmugl, Carol J.; Gardner, P.

    2001-02-01T23:59:59.000Z

    The NO/CO reaction over Rh metal in automobile catalytic converters is critical to the control of emissions of these pollutant molecules. As part of a program to determine the elementary mechanism(s) of this reaction, we have been performing mid- and far-infrared reflection/absorption spectroscopic (IRAS) measurements of the adsorption and co-adsorption and co-adsorption of NO and CO on Rh single crystal surfaces. Of particular interest is the low-frequency range of the IRAS spectra where we hoped to observe features due to metal-N stretching and/or bending vibrational motions. In particular, we hoped to obtain information regarding the site-requirements for the dissociation of the NO molecule on various Rh single crystal surfaces. An important result from our earlier work is that the selectivity of the reaction for the two nitrogen-containing products, N2 and N2O, is a strong function of the Rh surface structure. On the basis of ancillary data, we suggested that the location of adsorbed NO and N-atoms (formed from dissociation of adsorbed NO) on various Rh surfaces could, perhaps account for the selectivity differences.

  2. A systematic analysis of the spectra of the lanthanides doped into single crystal LaF/sub 3/

    SciTech Connect (OSTI)

    Carnall, W.T.; Goodman, G.L.; Rajnak, K.; Rana, R.S.

    1988-02-01T23:59:59.000Z

    The optical spectra of the lanthanides doped into single crystal LaF/sub 3/ have been interpreted in terms of transitions within 4f/sup N/ configurations. Energy-level calculations were based on a simultaneous diagonalization of the free-ion and crystal-field matrices using an approximate model with C/sub 2v/ site symmetry instead of the actual C/sub 2/ symmetry. Excellent correlations between experimental transition energies and the computed level structures were obtained; predicted levels are given for Pm/sup 3 +/. Previously unpublished experimental results for Nd/sup 3 +/ and Sm/sup 3 +/:LaF/sub 3/ are included in the tabulations. The spectroscopic data for each ion were analyzed independently, then the parameters of the effective-operator model were intercompared and systematic trends were identified. Since many of the 4f/sup N/ configurations extend well into the vacuum ultraviolet region, and thus beyond any presently available experimental observations, some of the free-ion (atomic) parameters were found to be only approximately defined by the accessible levels. However, the crystal-field parameters seem for the most part to be well established by fits to data at low energies. A new chart of the lanthanide ion 4f/sup N/ configuration energy level structures is presented. It was generated by including all of the computed crystal-field levels in the 0-50000 cm/sup -1/ range. In most cases, experimental analyses of individual ions extended to /approximately/40000 cm/sup /minus/1/. 94 refs., 23 figs., 10 tabs.

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

    SciTech Connect (OSTI)

    Shanmugam, G. [Department of Physics, Anna University of Technology Tiruchirappalli, Tiruchirappalli 620024 (India)] [Department of Physics, Anna University of Technology Tiruchirappalli, Tiruchirappalli 620024 (India); Ravi Kumar, K.; Sridhar, B. [X-ray Crystallography Division, Indian Institute of Chemical Technology, CSIR, Hyderabad 500007 (India)] [X-ray Crystallography Division, Indian Institute of Chemical Technology, CSIR, Hyderabad 500007 (India); Brahadeeswaran, S., E-mail: sbrag67@yahoo.com [Department of Physics, Anna University of Technology Tiruchirappalli, Tiruchirappalli 620024 (India)

    2012-09-15T23:59:59.000Z

    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) ?, b = 18.033(4) ?, c = 10.577(5) ?, ? = 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.

  4. 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., E-mail: hjkimble@caltech.edu [Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, California 91125 (United States); Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125 (United States); Norte, Richard; Meenehan, Seán M.; Cohen, Justin D.; Painter, Oskar, E-mail: opainter@caltech.edu [Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125 (United States); Thomas J. Watson, Sr., Laboratory of Applied Physics 128-95, California Institute of Technology, Pasadena, California 91125 (United States)

    2014-03-17T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    K. Gofryk; N. Harrison; M. Jaime

    2014-12-01T23:59:59.000Z

    Conclusions: 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.

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

    SciTech Connect (OSTI)

    Parkhomenko, V. D., E-mail: parkhomenko@imp.uran.ru; Dubinin, S. F.; Maksimov, V. I. [Russian Academy of Sciences, Institute of Metal Physics, Ural Branch (Russian Federation)

    2011-12-15T23:59:59.000Z

    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.

  7. 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. [Institute for Shock Physics and Department of Physics, Washington State University, Pullman, Washington 99164 (United States)

    2014-07-21T23:59:59.000Z

    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 broadly, the present work demonstrates the potential of shock wave propagation along low-symmetry directions to examine, and discriminate between, different inelastic deformation mechanisms in crystalline solids.

  8. Evaluation of the dosimetric properties of a synthetic single crystal diamond detector in high energy clinical proton beams

    SciTech Connect (OSTI)

    Mandapaka, A. K.; Ghebremedhin, A.; Patyal, B. [Department of Radiation Medicine, Loma Linda University Medical Center, 11234 Anderson Street, Loma Linda, California 92354 (United States)] [Department of Radiation Medicine, Loma Linda University Medical Center, 11234 Anderson Street, Loma Linda, California 92354 (United States); Marinelli, Marco; Prestopino, G.; Verona, C.; Verona-Rinati, G. [INFN–Dipartimento di Ingegneria Industriale, Università di Roma ‘Tor Vergata’, Via del Politecnico 1, 00133 Roma (Italy)] [INFN–Dipartimento di Ingegneria Industriale, Università di Roma ‘Tor Vergata’, Via del Politecnico 1, 00133 Roma (Italy)

    2013-12-15T23:59:59.000Z

    Purpose: To investigate the dosimetric properties of a synthetic single crystal diamond Schottky diode for accurate relative dose measurements in large and small field high-energy clinical proton beams.Methods: The dosimetric properties of a synthetic single crystal diamond detector were assessed by comparison with a reference Markus parallel plate ionization chamber, an Exradin A16 microionization chamber, and Exradin T1a ion chamber. The diamond detector was operated at zero bias voltage at all times. Comparative dose distribution measurements were performed by means of Fractional depth dose curves and lateral beam profiles in clinical proton beams of energies 155 and 250 MeV for a 14 cm square cerrobend aperture and 126 MeV for 3, 2, and 1 cm diameter circular brass collimators. ICRU Report No. 78 recommended beam parameters were used to compare fractional depth dose curves and beam profiles obtained using the diamond detector and the reference ionization chamber. Warm-up/stability of the detector response and linearity with dose were evaluated in a 250 MeV proton beam and dose rate dependence was evaluated in a 126 MeV proton beam. Stem effect and the azimuthal angle dependence of the diode response were also evaluated.Results: A maximum deviation in diamond detector signal from the average reading of less than 0.5% was found during the warm-up irradiation procedure. The detector response showed a good linear behavior as a function of dose with observed deviations below 0.5% over a dose range from 50 to 500 cGy. The detector response was dose rate independent, with deviations below 0.5% in the investigated dose rates ranging from 85 to 300 cGy/min. Stem effect and azimuthal angle dependence of the diode signal were within 0.5%. Fractional depth dose curves and lateral beam profiles obtained with the diamond detector were in good agreement with those measured using reference dosimeters.Conclusions: The observed dosimetric properties of the synthetic single crystal diamond detector indicate that its behavior is proton energy independent and dose rate independent in the investigated energy and dose rate range and it is suitable for accurate relative dosimetric measurements in large as well as in small field high energy clinical proton beams.

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

    SciTech Connect (OSTI)

    Manna, Kaustuv, E-mail: kaustuvmanna@gmail.com; Elizabeth, Suja; Anil Kumar, P. S. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Bhadram, Venkata Srinu; Narayana, Chandrabhas [Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)

    2014-07-28T23:59:59.000Z

    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.

  10. 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)

    2008-04-21T23:59:59.000Z

    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}.

  11. Designing the Mode solving of the photonic crystal fiber via BPM and Exploring the Single-Mode Properties

    E-Print Network [OSTI]

    Debbal, Mohammed

    2012-01-01T23:59:59.000Z

    Microstructured optical fibers (MOFs) are one of the most exciting recent developments in fiber optics. A MOF usually consists of a hexagonal arrangement of air holes running down the length of a silica fiber surrounding a central core of solid silica or, in some cases air. MOFs can exhibit a number of unique properties, including zero dispersion at visible wavelengths and low or high effective nonlinearity [3]-[17], By varying the size of the holes and their number and position, one can also design MOFs with carefully controlled dispersive and modal properties. In this paper, we analyze and modeling the behavior of the photonic crystal fiber (PCF) by using in the first step a propagator method based on the BPM method. With our BPM software, the electric field contour of the fundamental mode of PCF was demonstrated. We also used it to see the variation of the effective index; an effective index model confirms that such a fiber can be single mode for any wavelength. It would make a study of photonic crystal fi...

  12. Single-crystal structure of vanadium-doped La{sub 2}Mo{sub 2}O{sub 9}

    SciTech Connect (OSTI)

    Alekseeva, O. A., E-mail: olalex@ns.crys.ras.ru; Antipin, A. M. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)] [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Gagor, A.; Pietraszko, A. [Polish Academy of Sciences, Trzebiatowski Institute of Low Temperature and Structure Research (Poland)] [Polish Academy of Sciences, Trzebiatowski Institute of Low Temperature and Structure Research (Poland); Novikova, N. E.; Sorokina, N. I. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)] [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Kharitonova, E. P.; Voronkova, V. I. [Moscow State University (Russian Federation)] [Moscow State University (Russian Federation)

    2013-11-15T23:59:59.000Z

    A high-precision X-ray diffraction study of single crystals of two compositions-La{sub 2}Mo{sub 1.78}V{sub 0.22}O{sub 8.89} and La{sub 2}Mo{sub 1.64}V{sub 0.36}O{sub 8.82}-was performed. In the vanadium-doped compounds, as in the structure of the metastable {beta}{sub ms} phase of pure La{sub 2}Mo{sub 2}O{sub 9}, the La and Mo atoms and one of the three oxygen atoms are displaced from the threefold axis, on which they are located in the high-temperature {beta} phase. The structure contains two partially occupied oxygen sites. It was shown that molybdenum atoms are partially replaced by vanadium atoms, which are not involved in the disordering, are located on the threefold axis, and are shifted toward one of the oxygen atoms. This is consistent with the temperature-induced changes in the structure of La{sub 2}Mo{sub 2}O{sub 9} and the changes in the properties of these crystals caused by the introduction of vanadium atoms into the structure.

  13. Origins of low resistivity and Ge donor level in Ge ion-implanted ZnO bulk single crystals

    SciTech Connect (OSTI)

    Kamioka, K.; Oga, T.; Izawa, Y.; Kuriyama, K. [College of Engineering and Research Center of Ion Beam Technology, Hosei University Koganei, Tokyo 184-8584 (Japan); Kushida, K. [Departments of Arts and Sciences, Osaka Kyoiku University Kashiwara, Osaka 582-8582 (Japan)

    2013-12-04T23:59:59.000Z

    The energy level of Ge in Ge-ion implanted ZnO single crystals is studied by Hall-effect and photoluminescence (PL) methods. The variations in resistivity from ?10{sup 3} ?cm for un-implanted samples to ?10{sup ?2} ?cm for as-implanted ones are observed. The resistivity is further decreased to ?10{sup ?3} ?cm by annealing. The origins of the low resistivity are attributed to both the zinc interstitial (Zn{sub i}) related defects and the electrical activated Ge donor. An activation energy of Ge donors estimated from the temperature dependence of carrier concentration is 102 meV. In PL studies, the new peak at 372 nm (3.33 eV) related to the Ge donor is observed in 1000 °C annealed samples.

  14. 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.; Béard, J.; Nicolin, J. P.; Rikken, G. L. J. A. [Laboratoire National des Champs Magnétiques Intenses, CNRS-INSA-UJF-UPS, 143, avenue de Rangueil, F-31400 Toulouse (France); Fabrèges, X. [Laboratoire National des Champs Magnétiques Intenses, CNRS-INSA-UJF-UPS, 143, avenue de Rangueil, F-31400 Toulouse (France); Laboratoire Léon Brillouin, UMR12 CEA-CNRS Bât 563 CEA Saclay, 91191 Gif sur Yvette Cedex (France); Roth, T. [European Synchrotron Radiation Facility, Boîte Postale 220, F-38043 Grenoble Cedex (France); European XFEL GmbH, Albert-Einstein-Ring 19, D-22761 Hamburg (Germany); Detlefs, C.; Lesourd, M.; Zhang, L. [European Synchrotron Radiation Facility, Boîte Postale 220, F-38043 Grenoble Cedex (France)

    2014-05-15T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    Fisher, Ian Randal

    2012-05-08T23:59:59.000Z

    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.

  16. 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., E-mail: cslynch@seas.ucla.edu [Department of Mechanical and Aerospace Engineering, University of California Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095 (United States); Tian, Jian [H. C. Materials Corporation, 479 Quadrangle Dr., Suite-E, Bolingbrook, Illinois 60440 (United States)

    2014-08-04T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    Zhang, Jin S., E-mail: zhang72@illinois.edu; Bass, Jay D. [Department of Geology, University of Illinois, Urbana-Champaign, Illinois 61801 (United States); Shieh, Sean R. [Departments of Earth Sciences and Physics and Astronomy, University of Western Ontario, London, Ontario N6A 5B7 (Canada); Dera, Przemyslaw [Hawaii Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, Hawaii 96822 (United States); Prakapenka, Vitali [Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637 (United States)

    2014-04-07T23:59:59.000Z

    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.

  18. Generation and transfer of single photons on a photonic crystal chip

    E-Print Network [OSTI]

    Dirk Englund; Andrei Faraon; Bingyang Zhang; Yoshihisa Yamamoto; Jelena Vuckovic

    2006-09-07T23:59:59.000Z

    We present a basic building block of a quantum network consisting of a quantum dot coupled to a source cavity, which in turn is coupled to a target cavity via a waveguide. The single photon emission from the high-Q/V source cavity is characterized by a twelve-fold spontaneous emission (SE) rate enhancement that results in a SE coupling efficiency near 0.98 into the source cavity mode. Single photons are efficiently transferred into the target cavity through the waveguide, with a source/target field intensity ratio of 0.12 (up to 0.49 observed in other structures without coupled quantum dots). This system shows great promise as a building block of future on-chip quantum information processing systems.

  19. Superconducting gap evolution in overdoped BaFe?(As1-xPx)? 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.

    2015-06-01T23:59:59.000Z

    We report on specific heat measurements on clean overdoped BaFe?(As1-xPx)? single crystals performed with a high resolution membrane-based nanocalorimeter. A nonzero residual electronic specific heat coefficient at zero temperature ?r=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 ? model in order to investigate the gap structure. Close to optimal doping we detect a single zero-temperature gap of ??~5.3 me V, corresponding to ??/kBTc ~ 2.2. Increasing the phosphorus concentration x, the main gap reduces tillmore »a value of ?? ~ 1.9 meV for x = 0.55 and a second weaker gap becomes evident. From the magnetic field effect on ?r, all samples however show similar behavior [?r(H) - ?r (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

  20. Superconducting gap evolution in overdoped BaFe?(As1-xPx)? 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.

    2015-06-01T23:59:59.000Z

    We report on specific heat measurements on clean overdoped BaFe?(As1-xPx)? single crystals performed with a high resolution membrane-based nanocalorimeter. A nonzero residual electronic specific heat coefficient at zero temperature ?r=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 ? model in order to investigate the gap structure. Close to optimal doping we detect a single zero-temperature gap of ??~5.3 me V, corresponding to ??/kBTc ~ 2.2. Increasing the phosphorus concentration x, the main gap reduces till a value of ?? ~ 1.9 meV for x = 0.55 and a second weaker gap becomes evident. From the magnetic field effect on ?r, all samples however show similar behavior [?r(H) - ?r (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.

  1. Single crystal growth and characterization of ilmenite, FeTiO?, for electronic applications

    E-Print Network [OSTI]

    Gries, Brian Leonard

    1988-01-01T23:59:59.000Z

    . It is relatively abundant on the moon and has thus been considered as a candidate for the production of oxygen, hydrogen, and electricity on the lunar surface by utilizing its photoanodic and photovoltaic properties. Single crystalline samples of pure ilmenite... of new electronic materials. One class of materials that has been studied in recent years is the titanates, which are represented as M?TiyOz, where M is an alkaline earth or transition metal. Of particular interest are the iron titanates: ilmenite (Fe...

  2. Electrical resistivity and thermopower of single-crystal RNi2B2C (R=Dy, Ho, Er, Tm) magnetic superconductors

    E-Print Network [OSTI]

    Bhatnagar, AK; Rathnayaka, KDD; Naugle, Donald G.; Canfield, PC.

    1997-01-01T23:59:59.000Z

    The in-plane resistivity rho and thermopower S of single crystal RNi2B2C (R=Dy, Ho, Er, Tm) has been measured from 4 to 300 K. The resistivity is linear in temperature from about 100 to 300 K, but the low-temperature dependence goes as T-p With p...

  3. Interaction of wide-band-gap single crystals with 248-nm excimer laser radiation. XI. The effect of water vapor and temperature on laser desorption

    E-Print Network [OSTI]

    Dickinson, J. Thomas

    . Significantly, introducing water vapor lowers the particle velocities and thus the effective surface temperature systems, simultaneous electronic excitation and exposure to aggressive chemicals can acceler- ate etching-induced neutral particle desorption and surface erosion on single- crystal sodium chloride in the presence of low

  4. PHYSICAL REVIEW B 83, 104526 (2011) Fe Mossbauer study of magnetic ordering in superconducting K0.80Fe1.76Se2.00 single crystals

    E-Print Network [OSTI]

    Ryan, Dominic

    2011-01-01T23:59:59.000Z

    PHYSICAL REVIEW B 83, 104526 (2011) 57 Fe M¨ossbauer study of magnetic ordering in superconducting 31 March 2011) The magnetic ordering of superconducting single crystals of K0.80Fe1.76Se2.00 has been studied between 10 and 550 K using 57 Fe M¨ossbauer spectroscopy. Despite being superconducting below Tsc

  5. JOURNAL DE PHYSIQUE Colloque C6, supplbment au no 8, Tome 39, aofit 1978, page C6-635 FLUX DENSITY GRADIENTS IN PLASTICALLY DEFORMED NIOBIUM SINGLE CRYSTALS

    E-Print Network [OSTI]

    Boyer, Edmond

    GRADIENTS IN PLASTICALLY DEFORMED NIOBIUM SINGLE CRYSTALS H.U. Habermeier, W. Klein and H. Kronmiiller de Shubnikov dans des monocristaux d niobium dGformds plastiquement. L'anisotropie de l'inter- action of the Faraday magneto-optical technique the penetration of the Shubnikov phase into plastically deformed niobium

  6. Anisotropic magnetoresistance of single-crystal HoNi2B2C and the interplay of magnetic and superconducting order

    E-Print Network [OSTI]

    Rathnayaka, KDD; Naugle, Donald G.; Cho, BK; Canfield, PC.

    1996-01-01T23:59:59.000Z

    The in-plane resistivity and magnetization measurements as a function of the magnitude and direction of the magnetic field and the temperature are reported for single-crystal samples of the HoNi2B2C magnetic superconductor. Features corresponding...

  7. Epitaxial europium oxide on Ni(100) with single-crystal quality

    SciTech Connect (OSTI)

    Foerster, Daniel F.; Klinkhammer, Juergen; Busse, Carsten; Altendorf, Simone G.; Michely, Thomas; Hu Zhiwei; Chin Yiying; Tjeng, L. H.; Coraux, Johann; Bourgault, Daniel [II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln (Germany); II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln, Germany and Max Planck Institute for Chemical Physics of Solids, Noethnitzerstr. 40, D-01187 Dresden (Germany); Institut Neel, CNRS-UJF, 25 rue des Martyrs, F-38042 Grenoble Cedex 9 (France)

    2011-01-15T23:59:59.000Z

    High quality epitaxy of EuO on Ni(100) is developed in an in situ scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) study. A careful selection of the initial growth parameters is decisive to obtain a surface oxide suitable for the subsequent epitaxy of single phase EuO(100). After the creation of a three layer thick coalesced oxide film for the subsequent growth a distillation technique is applied. Appropriate annealing of films with up to 100 nm thickness generates sufficient conductivity for STM and electron spectroscopies. Oxygen vacancies are directly imaged by STM. They are of decisive importance for the metal-to-insulator transition around the temperature of the ferromagnetic-to-paramagnetic transition. A fast relaxation of the initial biaxial strain observed by LEED leaves little hope for an increase of the Curie temperature through epitaxial compression. Ex situ x-ray adsorption spectroscopy and magneto-optical Kerr effect microscopy measurements of thicker films are consistent with the stoichiometric single phase EuO with bulk properties.

  8. JOURNAL DE PHYSIQUE Colloque C 3, supplkment au no 7-8, Tome 27, juilbet-aodt 1966, page C 3-193 THE PLASTICITY OF PURE NIOBIUM SINGLE CRYSTALS

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    -193 THE PLASTICITY OF PURE NIOBIUM SINGLE CRYSTALS M. S. DUESBERY,R. A. FOXALLand P. B. HIRSCH Cavendish Laboratory, University of Cambridge. R6sumb. - On ktudie la dkformation de monocristaux de niobium purifiks par recuit of single crystals of niobium purified by annealing in ultra-high vacua is studied. The stress-strain curves

  9. High-pressure single-crystal X-ray diffraction of Tl{sub 2}SeO{sub 4}

    SciTech Connect (OSTI)

    Grzechnik, Andrzej [Departamento de Fisica de la Materia Condensada, Universidad del Pais Vasco, E-48080 Bilbao (Spain)], E-mail: andrzej.grzechnik@ehu.es; Breczewski, Tomasz; Friese, Karen [Departamento de Fisica de la Materia Condensada, Universidad del Pais Vasco, E-48080 Bilbao (Spain)

    2008-11-15T23:59:59.000Z

    The effect of pressure on the crystal structure of thallium selenate (Tl{sub 2}SeO{sub 4}) (Pmcn, Z=4), containing the Tl{sup +} cations with electron lone pairs, has been studied with single-crystal X-ray diffraction in a diamond anvil cell up to 3.64 GPa at room temperature. No phase transition has been observed. The compressibility data are fitted by a Murnaghan equation of state with the zero-pressure bulk modulus B{sub 0}=29(1) GPa and the unit-cell volume at ambient pressure V{sub 0}=529.6(8) A{sup 3} (B'=4.00). Tl{sub 2}SeO{sub 4} is the least compressible in the c direction, while the pressure-induced changes of the a and b lattice parameters are quite similar. These observations can be explained by different pressure effects on the nine- and 11-fold coordination polyhedra around the two non-equivalent Tl atoms. The SeO{sub 4}{sup 2-} tetrahedra are not rigid units and become more distorted. Their contribution to the compressibility is small. The effect of pressure on the isotypical oxide materials A{sub 2}TO{sub 4} with the {beta}-K{sub 2}SO{sub 4} structure is discussed. It appears that the presence of electron lone pairs on the Tl{sup +} cation does not seem to influence the compressibility of Tl{sub 2}SeO{sub 4}. - Graphical abstract: Pressure dependence of normalized lattice parameters and unit-cell volumes in Tl{sub 2}SeO{sub 4} (Pmcn, Z=4). The solid line is the Murnaghan equation of state.

  10. Monte Carlo simulations of temperature-programmed and isothermal desorption from single-crystal surfaces

    SciTech Connect (OSTI)

    Lombardo, S.J. (California Inst. of Tech., Pasadena, CA (USA). Dept. of Chemical Engineering Lawrence Berkeley Lab., CA (USA))

    1990-08-01T23:59:59.000Z

    The kinetics of temperature-programmed and isothermal desorption have been simulated with a Monte Carlo model. Included in the model are the elementary steps of adsorption, surface diffusion, and desorption. Interactions between adsorbates and the metal as well as interactions between the adsorbates are taken into account with the Bond-Order-Conservation-Morse-Potential method. The shape, number, and location of the TPD peaks predicted by the simulations is shown to be sensitive to the binding energy, coverage, and coordination of the adsorbates. In addition, the occurrence of lateral interactions between adsorbates is seen to strongly effect the distribution of adsorbates is seen to strongly effect the distribution of adsorbates on the surface. Temperature-programmed desorption spectra of a single type of adsorbate have been simulated for the following adsorbate-metal systems: CO on Pd(100); H{sub 2} on Mo(100); and H{sub 2} on Ni(111). The model predictions are in good agreement with experimental observation. TPD spectra have also been simulated for two species coadsorbed on a surface; the model predictions are in qualitative agreement with the experimental results for H{sub 2} coadsorbed with strongly bound atomic species on Mo(100) and Fe(100) surfaces as well as for CO and H{sub 2} coadsorbed on Ni(100) and Rh(100) surfaces. Finally, the desorption kinetics of CO from Pd(100) and Ni(100) in the presence of gas-phase CO have been examined. The effect of pressure is seen to lead to an increase in the rate of desorption relative to the rate observed in the absence of gas-phase CO. This increase arises as a consequence of higher coverages and therefore stronger lateral interactions between the adsorbed CO molecules.

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

    SciTech Connect (OSTI)

    Huang, Hsu-Cheng [Columbia Univ., New York, NY (United States); Zhang, Lihua [Brookhaven National Lab. (BNL), Upton, NY (United States); Malladi, Girish [SUNY Polytechnic Inst., Albany, NY (United States); Dadap, Jerry I. [Columbia Univ., New York, NY (United States); Manandhar, Sandeep [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kisslinger, Kim [Brookhaven National Lab. (BNL), Upton, NY (United States); Vemuri, Rama Sesha R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shutthanandan, Vaithiyalingam [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bakhru, Hassaram [SUNY Polytechnic Inst., Albany, NY (United States); Osgood, Jr., Richard M. [Columbia Univ., New York, NY (United States)

    2015-01-01T23:59:59.000Z

    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 formation than 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)

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

    SciTech Connect (OSTI)

    Sternlieb, B.; Shapiro, S. [Brookhaven National Lab., Upton, NY (United States); Stassis, C.; Goldman, A.I.; Canfield, P. [Iowa State Univ., Ames, IA (United States)

    1997-02-01T23:59:59.000Z

    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.

  13. Single-crystal sapphire resonator at millikelvin temperatures: Observation of thermal bistability in high-Q factor whispering gallery modes

    SciTech Connect (OSTI)

    Creedon, Daniel L.; Tobar, Michael E.; Le Floch, Jean-Michel; Reshitnyk, Yarema; Duty, Timothy [School of Physics (M013), University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009 (Australia); School of Mathematics and Physics, University of Queensland, St. Lucia, Queensland 4072 (Australia)

    2010-09-01T23:59:59.000Z

    Resonance modes in single crystal sapphire ({alpha}-Al{sub 2}O{sub 3}) exhibit extremely high electrical and mechanical Q factors ({approx_equal}10{sup 9} at 4 K), which are important characteristics for electromechanical experiments at the quantum limit. We report the cool down of a bulk sapphire sample below superfluid liquid-helium temperature (1.6 K) to as low as 25 mK. The electromagnetic properties were characterized at microwave frequencies, and we report the observation of electromagnetically induced thermal bistability in whispering gallery modes due to the material T{sup 3} dependence on thermal conductivity and the ultralow dielectric loss tangent. We identify ''magic temperatures'' between 80 and 2100 mK, the lowest ever measured, at which the onset of bistability is suppressed and the frequency-temperature dependence is annulled. These phenomena at low temperatures make sapphire suitable for quantum metrology and ultrastable clock applications, including the possible realization of the quantum-limited sapphire clock.

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

    SciTech Connect (OSTI)

    Boatner, Lynn A [ORNL; Ramey, Joanne Oxendine [ORNL; Kolopus, James A [ORNL; Hawrami, Rastgo [Radiation Monitoring Devices, Watertown, MA; Higgins, William [Radiation Monitoring Devices, Watertown, MA; Van Loef, Edgar [Radiation Monitoring Devices, Watertown, MA; Glodo, J. [Radiation Monitoring Devices, Watertown, MA; Shah, Kanai [Radiation Monitoring Devices, Watertown, MA; Bhattacharya, P. [Fisk University, Nashville, TN; Tupitsyn, E [Fisk University, Nashville, TN; Groza, Michael [Fisk University, Nashville, TN; Burger, Arnold [Fisk University, Nashville, TN

    2013-01-01T23:59:59.000Z

    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.

  15. Evaluation of the intrinsic magneto-dielectric coupling 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. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Joshi, Rajeev S. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Department of Physics, Central University of Karnataka, Gulbarga 585106 (India)

    2014-05-19T23:59:59.000Z

    The magneto-dielectric coupling in (l00) oriented LaMn{sub 0.5}Co{sub 0.5}O{sub 3} single crystals has been investigated using temperature, frequency, and magnetic field dependent dielectric response. Electronic transport data divulges that polaronic hopping arises due to Emin-Holstein adiabatic small polarons. Spin realignment through external magnetic field favors faster polaronic hopping by lowering activation energy for dielectric relaxation. Finally, positive magneto-dielectricity and magnetoloss under increasing magnetic field at high frequency of the exciting ac field confirms intrinsic magneto-dielectric effect in disordered ferromagnetic-insulator LaMn{sub 0.5}Co{sub 0.5}O{sub 3}. This study also emphasizes the need to use single crystals as well as the frequencies higher than the corresponding inverse relaxation time.

  16. Vortex line pinning in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} single crystals with columnar defects

    SciTech Connect (OSTI)

    van der Beek, C.J.; Vinokur, V.M.; Crabtree, G.W. [Argonne National Lab., IL (United States); Schmidt, B.; Konczykowski, M. [CEA-Ecole Polytechnique, 91 - Palaiseau (France). Lab. d`Etudes des Solides Irradies

    1994-05-01T23:59:59.000Z

    The ac transmittivity of heavy-ion irradiated Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} single crystals shows a sharp cusp as function of the dc field orientation with respect to the columnar defects. This unambiguously demonstrates the connected nature of vortices in these samples. In contrast, the irreversibility line does not reveal a cusp.

  17. Diffuse phase transition from the superionic to non-superionic state in Cu{sub 1.8}Se single crystal

    SciTech Connect (OSTI)

    Bikkulova, N. N.; Stepanov, Yu. M.; Bikkulova, L. V., E-mail: bickulova@mail.ru; Kurbangulov, A. R.; Kutov, A. Kh.; Karagulov, R. F. [Bashkir State University, Sterlitamak Branch (Russian Federation)

    2013-07-15T23:59:59.000Z

    The phase transition from the superionic to non-superionic state in a Cu{sub 1.8}Se single crystal is studied by neutron diffraction. In the superionic state, a diffuse halo related to the disordering of the cation subsystem is observed. It is established that the phase transition from the superionic to non-superionic state is the diffuse first-order phase transition occurring in the temperature range 250-180 K.

  18. Measurement of the Young's modulus and internal friction of single crystal and polycrystalline copper, and copper-graphite composites as a function of temperature and orientation 

    E-Print Network [OSTI]

    Wickstrom, Steven Norman

    1988-01-01T23:59:59.000Z

    MEASUREMENT OF THE YOUNG'S MODULUS AND INTERNAL FRICTION OF SINGLE CRYSTAL AND POLYCRYSTALLINE COPPER, AND COPPER- GRAPHITE COMPOSITES AS A FUNCTION OF TEMPERATURE AND ORIENTATION A Thesis by S teven Norman Wicks trom Submitted... AND POLYCRYSTALLINE COPPER, AND COPPER- GRAPHITE COMPOSITES AS A FUNCTION OF TEMPERATURE AND ORIENTATION A Thesis by Steven Norman Wickstrom Approved as to style and content by: A(J ~a Alan Wolfenden (Chairman of Committee) Don E. Bray (Member) Donald G...

  19. Epitaxial TiN(001) wetting layer for growth of thin single-crystal Cu(001) J. S. Chawla, X. Y. Zhang, and D. Galla)

    E-Print Network [OSTI]

    Gall, Daniel

    Epitaxial TiN(001) wetting layer for growth of thin single-crystal Cu(001) J. S. Chawla, X. Y.5-nm-thick TiN(001) buffer layer. X-ray diffraction and reflection indicate that the TiN(001) surface continuous Cu layer on MgO. The wet- ting of Cu on TiN is expected to be better, due to the surface energy

  20. On-line spectrophotometric method for monitoring weak residual absorption of CaMoO{sub 4} single crystals near the intrinsic luminescence peak

    SciTech Connect (OSTI)

    Buzanov, O. A., E-mail: fedorov-metrology@yandex.ru [OAO Fomos-Materials (Russian Federation); Kanevskii, V. M. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)] [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Kornoukhov, V. N. [OAO Fomos-Materials (Russian Federation)] [OAO Fomos-Materials (Russian Federation); Nabatov, B. V.; Nabatov, V. V.; Fedorov, V. A. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)] [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2013-11-15T23:59:59.000Z

    The optical and spectral characteristics of isotopically enriched Czochralski-grown {sup 40}Ca{sup 100}MoO{sub 4} single crystals have been investigated. This material is promising for detecting double neutrinoless {beta} decay. The possibility and the technique of spectrophotometric monitoring of weak residual absorption near the intrinsic luminescence peak of this scintillation material, which is designed for developing new-generation detectors of elementary particles, are considered.

  1. Dissolution-induced surface modifications and permeability changes associated with fluid flow through an abraded saw-cut in single crystal quartz 

    E-Print Network [OSTI]

    Bowman, James Albert

    1992-01-01T23:59:59.000Z

    DISSOLUTION-INDUCED SURFACE MODIFICATIONS AND PERMEABILITY CHANGES ASSOCIATED WITH FLUID FLOW THROUGH AN ABRADED SAW-CUT IN SINGLE CRYSTAL QUARTZ A Thesis by JAlvlES ALBERT BOWMAN, JR, Submined to the Oflice of Graduate Studies of Texas A8r...M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Xiay I992 Major Subject: Geology DISSOLUTION-INDUCED SURFACE MODIFICATIONS AND PERMEABILITY CHANGES ASSOCIATED WITH FLUID FLOW THROUGH AN ABRADED SAW...

  2. Torque magnetometry study of metamagnetic transitions in single-crystal HoNi(2)B(2)C at T approximate to 1.9 K

    E-Print Network [OSTI]

    Rathnayaka, K. D. D.; Belevtsev, B. I.; Naugle, Donald G.

    2007-01-01T23:59:59.000Z

    Torque magnetometry study of metamagnetic transitions in single-crystal HoNi2B2C at T?1.9 K K. D. D. Rathnayaka,1 B. I. Belevtsev,2,* and D. G. Naugle1,? 1Department of Physics, Texas A&M University, College Station, Texas 77843-4242, USA 2B... of superconductivity and long-range magnetic order. Although the borocarbides were studied quite intensively, certain important issues remain open. We report a torque magnetometry study of metamagnetic transitions at low tem- perature #1;T#3;1.9 K#2; in a single...

  3. 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.

    2015-01-01T23:59:59.000Z

    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 formationmore »than 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

  4. The effect of deuteration and doping on the phase transition temperature of grown glycine phosphite single crystals

    SciTech Connect (OSTI)

    Perumal, R., E-mail: perumal-cgc@yahoo.co.uk [Department of Physics, Vel Tech Dr.RR and Dr.SR Technical University, Chennai-600062, India and Crystal Growth Centre Anna University, Chennai-600025 (India); Chandru, A. Lakshmi [Department of Physics, Vel Tech Dr.RR and Dr.SR Technical University, Chennai-600062 (India); Babu, S. Moorthy [Crystal Growth Centre Anna University, Chennai-600025 (India)

    2014-04-24T23:59:59.000Z

    The Glycinium Phosphite (GPI) compound is a representative of hydrogen-bonded ferroelectric crystals. The ordering of protons could be expected below the room temperature (225 K). Crystals grown from the milipore water as well as deuterated solvents respectively. The corresponding hydrogen bond distance was stretched out due to the effect of isotopic substitution that increase the phase transition temperature. Further to improve the phase transition temperature, GPI crystal was doped with organic complexing agent and various metals and the obtained results are presented.

  5. Electronic stiffness of a superconducting niobium nitride single crystal under pressure Xiao-Jia Chen, Viktor V. Struzhkin, Zhigang Wu, Ronald E. Cohen, Simon Kung,* Ho-kwang Mao, and Russell J. Hemley

    E-Print Network [OSTI]

    Wu, Zhigang

    Electronic stiffness of a superconducting niobium nitride single crystal under pressure Xiao report a quantitative study of pressure effects on the superconducting transition temperature Tc transition temperatures Tc's of materials, pur- suing new classes of superconductors and shedding light

  6. JOURNAL DE PHYSIQUE CoIIoque C I , supplkment au no2-3, Tome 32, Fkvrier-Mars 1971, page C 1 -372 MAGNETIC PROPERTIES OF SINGLE CRYSTALS OF EUROPIUM,

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    MAGNETIC PROPERTIES OF SINGLE CRYSTALS OF EUROPIUM, NEODYMIUM, AND PRASEODYMIUM T. JOHANSSON, K. A. Mc EWEN will be described in turn. 2. Europium. - The magnetization of polycrys- talline Eu has previously been measured [I

  7. Measurements and simulations on position dependencies in the response of single PWO crystals and a prototype for the $\\overline{P}ANDA$ EMC

    E-Print Network [OSTI]

    Bremer, Daniel Andreas

    The PANDA experiment, which will be located at the future Facility for Antiproton and Ion Research, aims at the study of strong interaction within the charm sector via antiproton- proton collisions. An essential component of the PANDA detector to achieve the ambitious physics goals is the Electromagnetic Calorimeter (EMC). Reason for this is particularly its high detection efficiency for photons and electrons over a large dynamic range, since most of the expected physics channels are accompanied by secondary photons. The EMC is based on second generation lead tungstate scintillator crystals and thus features a very compact design and improved performance. To guarantee a homogeneous and precise energy and momentum response, an exact knowledge on the incident particle position is mandatory. In the scope of this work, non-uniformities in the light yield of single lead tungstate crystals with tapered geometry are investigated. This effect was studied with the SLitrani simulation package in comparison to a series ...

  8. Magnetic structure of Sr{sub 2}Fe{sub 2}O{sub 5} brownmillerite by single-crystal Mössbauer spectroscopy

    SciTech Connect (OSTI)

    Waerenborgh, J.C. [UCQR, IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, CFMC-UL, Estrada Nacional 10, 2686-953 Sacavém (Portugal); Tsipis, E.V. [UCQR, IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, CFMC-UL, Estrada Nacional 10, 2686-953 Sacavém (Portugal); Department of Materials and Ceramic Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Auckett, J.E.; Ling, C.D. [School of Chemistry, The University of Sydney, Sydney 2006 (Australia); Kharton, V.V., E-mail: kharton@ua.pt [Department of Materials and Ceramic Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Institute of Solid State Physics RAS, Chernogolovka 142432, Moscow Region (Russian Federation)

    2013-09-15T23:59:59.000Z

    In order to determine orientation of the Fe{sup 3+} magnetic moments and electric field gradient (efg) axes in the brownmillerite-type strontium ferrite structure for both iron sublattices where the efg tensor is not axially symmetric, the Mössbauer spectra of powdered and oriented single-crystal Sr{sub 2}Fe{sub 2}O{sub 5} were analyzed by solving the complete Hamiltonian for hyperfine interactions in the excited and ground states of the {sup 57}Fe nuclei. The magnetic moments of both octahedrally and tetrahedrally coordinated iron cations lie on the ac-plane of the orthorhombic unit cell and are parallel to the shortest c-axis, whilst the main efg axes are parallel to the longest crystallographic axis, b. This orientation is similar to that in Ca{sub 2}Fe{sub 2}O{sub 5}, in spite of the structural differences of strontium and calcium ferrite brownmillerites at low temperatures. - Graphical abstract: Mössbauer spectra of powdered and oriented single-crystal Sr{sub 2}Fe{sub 2}O{sub 5}, analyzed by solving the complete Hamiltonian for hyperfine interactions in the excited and ground states of the {sup 57}Fe nuclei, show that the magnetic moments of both octahedrally and tetrahedrally coordinated iron cations are parallel to the shortest c-axis of the orthorhombic brownmillerite unit cell . Display Omitted - Highlights: • Single-crystal Mössbauer spectroscopy is used to study magnetic structure of Sr{sub 2}Fe{sub 2}O{sub 5}. • Complete Hamiltonian for hyperfine interactions in excited and ground states was solved. • Fe{sup 3+} magnetic moments are parallel to the shortest crystallographic axis c. • The orientation of nuclear electric field gradient is similar to that in Ca{sub 2}Fe{sub 2}O{sub 5}.

  9. Terahertz field enhancement via coherent superposition of the pulse sequences after a single optical-rectification crystal

    SciTech Connect (OSTI)

    Sajadi, Mohsen, E-mail: sajadi@fhi-berlin.mpg.de; Wolf, Martin; Kampfrath, Tobias [Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin (Germany)

    2014-03-03T23:59:59.000Z

    Terahertz electromagnetic pulses are frequently generated by optical rectification of femtosecond laser pulses. In many cases, the efficiency of this process is known to saturate with increasing intensity of the generation beam because of two-photon absorption. Here, we demonstrate two routes to reduce this effect in ZnTe(110) crystals and enhance efficiency, namely, by (i) recycling the generation pulses and by (ii) splitting each generation pulse into two pulses before pumping the crystal. In both methods, the second pulse arrives ?1?ns after the first one, sufficiently long for optically generated carriers to relax. Enhancement is achieved by coherently superimposing the two resulting terahertz fields.

  10. Multisource-sputtered ErBa/sub 2/Cu/sub 3/O/sub 7-x/ films on single-crystal and buffered crystalline substrates

    SciTech Connect (OSTI)

    Simon, R.W.; Platt, C.E.; Lee, A.E.; Daly, K.P.; Wagner, M.K.

    1988-09-01T23:59:59.000Z

    High-quality superconducting films of erbium-barium-copper-oxide have been produced in a multisource sputtering system on a variety of substrates, including buffered sapphire and silicon wafers as well as various single-crystal materials. Fine-grained polycrystalline films with narrow (<4 K) resistive transitions have been grown on a number of different substrates. The use of erbium in the 1-2-3 compound leads to improved film morphology and to more forgiving conditions for establishing of the superconducting phase. Sputtered neutral mass spectroscopy (SNMS) yields useful information about the compositional profile of the films.

  11. Rabi Waves and Peculiarities of Raman Scattering in Carbon Nanotubes, Produced by High Energy Ion Beam Modification of Diamond Single Crystals

    E-Print Network [OSTI]

    Dmitry Yearchuck; Alla Dovlatova

    2011-03-06T23:59:59.000Z

    QED-model for multichain coupled qubit system, proposed in \\cite{Part1}, was confirmed by Raman scattering studies of carbon zigzag-shaped nanotubes, produced by high energy ion beam modification of natural diamond single crystals. New quantum optics phenomenon - Rabi waves - has been experimentally identified for the first time. Raman spectra in perfect quasi-1D carbon nanotubes are quite different in comparison with well known Raman spectra in 2D carbon nanotubes of larger diameter. They characterized by vibronic mode of Su-Schriffer-Heeger $\\sigma$-polaron lattice and its revival part in frequency representation, which is the consequence of Rabi wave packet formation.

  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

    2014-09-16T23:59:59.000Z

    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. PHONON DISPERSION CURVES OF ORDERED PHASES OF T.B.B.A. Abstract. --The lattice dynamics of a deuterated single crystal of T.B.B.A. have been measured

    E-Print Network [OSTI]

    Boyer, Edmond

    of a deuterated single crystal of T.B.B.A. have been measured by mean of inelastic neutron scattering of the molecules. Previous neutron inelastic scattering measurements have been done on non-deuterated single of a melting of the terminal aliphatic chains. So neutron coherent inelastic scattering measure- ments have

  14. Magnetic Field Induced Phase Transitions in Gd5(Si1.95Ge2.05)Single Crystal and the Anisotropic Magnetocaloric Effect

    SciTech Connect (OSTI)

    H. Tang; V.K. Pecharsky; A.O. Pecharsky; D.L. Schlagel; T.A. Lograsso; K.A. Gschneidner,jr.

    2004-09-30T23:59:59.000Z

    The magnetization measurements using a Gd{sub 5}(Si{sub 1.95}Ge{sub 2.05}) single crystal with the magnetic field applied along three crystallographic directions, [001], [010] and [100], were carried out as function of applied field (0-56 kOe) at various temperatures ({approx}5-320 K). The magnetic-field induced phase transformations at temperature above the zero-field critical temperature, i.e. the paramagnetic (PM) {leftrightarrow} ferromagnetic (FM) transitions with application or removal of magnetic field, are found to be temperature dependent and hysteretic. The corresponding critical fields increase with increasing temperature. The magnetic field (H)-temperature (T) phase diagrams have been constructed for the Gd{sub 5}(Si{sub 1.95}Ge{sub 2.05}) single crystal with field along the three directions. A small anisotropy has been observed. The magnetocaloric effect (MCE) has been calculated from the isothermal magnetization data, and the observed anisotropy correlates with H-T phase diagrams. The results are discussed in connection with the magnetic-field induced martensitic-like structural transition observed in the Gd{sub 5}(Si{sub 2}Ge{sub 2})-type compounds.

  15. All-optical preparation of coherent dark states of a single rare earth ion spin in a crystal

    E-Print Network [OSTI]

    Xia, Kangwei; Wang, Ya; Siyushev, Petr; Reuter, Rolf; Kornher, Thomas; Kukharchyk, Nadezhda; Wieck, Andreas D; Villa, Bruno; Yang, Sen; Wrachtrup, Jörg

    2015-01-01T23:59:59.000Z

    All-optical addressing and control of single solid-state based qubits allows for scalable architectures of quantum devices such as quantum networks and quantum simulators. So far, all-optical addressing of qubits was demonstrated only for color centers in diamond and quantum dots. Here, we demonstrate generation of coherent dark state of a single rare earth ion in a solid, namely a cerium ion in yttrium aluminum garnet (YAG). The dark state was formed under the condition of coherent population trapping. Furthermore, high-resolution spectroscopic studies of native and implanted single Ce ions have been performed. They revealed narrow and spectrally stable optical transitions between the spin sublevels of the ground and excited optical states, indicating the feasibility of interfacing single photons with a single electron spin of a cerium ion.

  16. The growth and optical properties of large, high-quality AlN single crystals Martin Strassburg,a)

    E-Print Network [OSTI]

    Nabben, Reinhard

    made GaN and AlN the most serious candidates for the high-power and high-frequency electronic and deep emission and absorption properties of the crystals revealed bands around 3.5 and 4.3 eV at room temperature. Absorption edges ranging between 4.1 and 5.95 eV were observed. Since no straight correlation of the oxygen

  17. Sm(Co{sub 1?x}Ni{sub x}){sub 5} ordered alloy thin films formed on Cr(100) single-crystal underlayers

    SciTech Connect (OSTI)

    Yanagawa, Takato, E-mail: yanagawa@futamoto.elect.chuo-u.ac.jp; Hotta, Yusuke; Yamada, Makoto; Ohtake, Mitsuru; Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi [Graduate School of Fine Arts, Tokyo University of the Arts, Taito-ku, Tokyo 110-8714 (Japan)

    2014-05-07T23:59:59.000Z

    Sm{sub 17}(Co{sub 1?x}Ni{sub x}){sub 83} (at.?%, x?=?0, 0.2, 0.8, and 1) alloy thin films are deposited on Cr(100) single-crystal underlayers at temperatures ranging between 100 and 500?°C by molecular beam epitaxy. The effects of substrate temperature and Ni/Co composition on the film growth behavior and the detailed resulting structure are investigated. Formation of epitaxial RT{sub 5} (R: rare earth metal, T: transition metal) ordered crystals is, respectively, recognized for the films with x of 0, 0.2, 0.8, and 1 deposited at temperatures higher than 400, 400, 300, and 300?°C, whereas the films deposited below the respective temperatures consist of amorphous phases. The order degree increases with increasing the substrate temperature and the Ni content. The order degrees of films with x of 0, 0.2, 0.8, and 1 deposited at 500?°C are 0.6, 0.7, 0.8, and 0.9, respectively. A replacement of Co site in SmCo{sub 5} structure with Ni atom is useful for enhancing the formation of RT{sub 5} ordered phase.

  18. Optical constants of silicon carbide for astrophysical applications. II. Extending optical functions from IR to UV using single-crystal absorption spectra

    E-Print Network [OSTI]

    Hofmeister, A M; Goncharov, A F; Speck, A K

    2009-01-01T23:59:59.000Z

    Laboratory measurements of unpolarized and polarized absorption spectra of various samples and crystal stuctures of silicon carbide (SiC) are presented from 1200--35,000 cm$^{-1}$ ($\\lambda \\sim$ 8--0.28 $\\mu$m) and used to improve the accuracy of optical functions ($n$ and $k$) from the infrared (IR) to the ultraviolet (UV). Comparison with previous $\\lambda \\sim$ 6--20 $\\mu$m thin-film spectra constrains the thickness of the films and verifies that recent IR reflectivity data provide correct values for $k$ in the IR region. We extract $n$ and $k$ needed for radiative transfer models using a new ``difference method'', which utilizes transmission spectra measured from two SiC single-crystals with different thicknesses. This method is ideal for near-IR to visible regions where absorbance and reflectance are low and can be applied to any material. Comparing our results with previous UV measurements of SiC, we distinguish between chemical and structural effects at high frequency. We find that for all spectral re...

  19. Single crystal neutron diffraction study of lattice and magnetic structures of 5M modulated Ni2Mn1.14Ga0.86

    SciTech Connect (OSTI)

    Pramanick, Abhijit [ORNL] [ORNL; Wang, Xiaoping [ORNL] [ORNL; An, Ke [ORNL] [ORNL; Stoica, Alexandru Dan [ORNL] [ORNL; Hoffmann, Christina [ORNL] [ORNL; Wang, Xun-Li [ORNL] [ORNL

    2012-01-01T23:59:59.000Z

    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.

  20. Infrared phonon modes in multiferroic single-crystal FeTe2O5Br

    SciTech Connect (OSTI)

    Miller, K. H.; Xu, X. S.; Berger, H.; Craciun, V.; Xi, Xiaoxiang; Martin, C.; Carr, G. L.; Tanner, D. B.

    2013-06-01T23:59:59.000Z

    Reflection and transmission as a function of temperature (7–300 K and 5–300 K respectively) have been measured on single crystals of the multiferroic compound FeTe2O5Br utilizing light spanning from the far infrared to the visible. The complex dielectric function and other optical properties were obtained via Kramers-Kronig analysis and by fits to a Drude-Lortentz model. Analysis of the anisotropic excitation spectra via Drude-Lorentz fitting and lattice dynamical calculations have led to the observation of 43 of the 53 modes predicted along the b axis of the monoclinic cell. The phonon response parallel to the a and c axes are also presented. Assignments to groups (clusters) of phonons have been made and trends within them are discussed in light of our calculated displacement patterns.

  1. Effect of electron irradiation on superconductivity in single crystals of Ba(Fe1-xRux)2As2 (x=0.24)

    SciTech Connect (OSTI)

    Prozorov, Ruslan [Ames Laboratory; Konczykowski, M [Laboratoire des Solides Irradies; Tanatar, Makariy A. [Ames Laboratory; Thaler, Alexander [Ames Laboratory; Budko, Serguei L [Ames Laboratory; Canfield, Paul C [Ames Laboratory; Mishra, V [Argonne National Laboratory; Hirschfeld, P J [University of Florida

    2014-11-01T23:59:59.000Z

    A single crystal of isovalently substituted Ba(Fe1?xRux)2As2 (x=0.24) is sequentially irradiated with 2.5 MeV electrons up to a maximum dose of 2.1×1019 e?/cm2. The electrical resistivity is measured in situ at T=22??K during the irradiation and ex situ as a function of temperature between subsequent irradiation runs. Upon irradiation, the superconducting transition temperature Tc decreases and the residual resistivity ?0 increases. We find that electron irradiation leads to the fastest suppression of Tc compared to other types of artificially introduced disorder, probably due to the strong short-range potential of the pointlike irradiation defects. A more detailed analysis within a multiband scenario with variable scattering potential strength shows that the observed Tc versus ?0 is fully compatible with s± pairing, in contrast to earlier claims that this model leads to a too rapid suppression of Tc with scattering.

  2. TL and PL studies on cubic fluoroperovskite single crystal (KMgF{sub 3}: Eu{sup 2+}, Ce{sup 3+})

    SciTech Connect (OSTI)

    Daniel, D. Joseph, E-mail: josephd@ssn.edu.in; Ramasamy, P. [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam, Tamilnadu-603110 (India); Madhusoodanan, U.; Annalakshmi, O. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu - 603102 (India)

    2014-04-24T23:59:59.000Z

    The perovskite-like KMgF{sub 3} polycrystalline compounds were synthesized by standard solid state reaction technique. Phase purity of the synthesized compounds was analyzed by powder X-ray diffraction technique. Single crystals of (0.2 mol% of EuF{sub 3} and CeF{sub 3}) Co-doped KMgF{sub 3} have been grown from melt by using a vertical Bridgman-Stockbarger method. Thermoluminescence (TL) characteristics of KMgF{sub 3} samples doped with Eu{sub 2+} and Ce{sub 3+} have been studied after ?-ray irradiation. At ambient conditions the photoluminescence spectra consisted of sharp line peaked of Eu{sub 2+} at 360 nm attributed to the f ? f transition ({sup 6}P{sub 7/2}?{sup 8}S{sub 7/2}) could only be observed due to the energy transfer from Ce{sub 3+} to Eu{sub 2+}.

  3. 4D STUDY OF STRAIN GRADIENTS EVOLUTION IN TWINNED NiMnGa SINGLE CRYSTALS UNDER MAGNETIC FIELD

    SciTech Connect (OSTI)

    Barabash, Rozaliya [ORNL; Xu, Ruqing [Argonne National Laboratory (ANL); Barabash, Oleg M [ORNL; Sozinov, Alexei [AdaptaMat, Finland

    2014-01-01T23:59:59.000Z

    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.

  4. Combined Charge Carrier Transport and Photoelectrochemical Characterization of BiVO4 Single Crystals: Intrinsic Behavior of a Complex Metal Oxide

    SciTech Connect (OSTI)

    Rettie, Alexander J.; Lee, Heung Chan; Marshall, Luke G.; Lin, Jung-Fu; Capen, Cigdem; Lindemuth, Jeffrey; McCloy, John S.; Zhou, Jianshi; Bard, Allen J.; Mullins, C. Buddie

    2013-07-08T23:59:59.000Z

    ABSTRACT: Bismuth vanadate (BiVO4) is a promising photoelectrode material for the oxidation of water, but fundamental studies of this material are lacking. To address this, we report electrical and photoelectrochemical (PEC) properties of BiVO4 single crystals (undoped, 0.6% Mo and 0.3% W:BiVO4) grown using the floating zone technique. We demonstrate that a small polaron hopping conduction mechanism dominates from 250-400 K, transitioning to a variable range hopping mechanism at lower temperatures. An anisotropy ratio of ~3 was observed along the c-axis, attributed to the layered structure of BiVO4. Measurements of the AC field Hall effect yielded an electron mobility of ~0.2 cm2 V-1 s-1 for Mo and W:BiVO4 at 300 K. By application of the Gärtner model, a hole diffusion length of ~140 nm was estimated. As a result of low carrier mobility, attempts to measure the DC Hall effect were unsuccessful. Analyses of the Raman spectra showed that Mo and W substituted for V and acted as donor impurities. Mott-Schottky analysis of electrodes with the (001) face exposed yielded a flat band potential of 0.03-0.08 V vs. RHE, while incident photon conversion efficiency tests showed that the dark coloration of the doped single crystals did not result in additional photocurrent. Comparison of these intrinsic properties to other metal oxides for PEC applications gives valuable insight into this material as a photoanode.

  5. Thermally Processed High-Mobility MOS Thin-Film Transistors on Transferable Single-Crystal Elastically Strain-Sharing Si/SiGe/Si Nanomembranes

    SciTech Connect (OSTI)

    Yuan, H.-C.; Kelly, M. M.; Savage, D. E.; Lagally, M. G.; Celler, G. K.; Zhenqiang, M.

    2008-03-01T23:59:59.000Z

    Demonstration of high-performance MOS thin-film transistors (TFTs) on elastically strain-sharing single-crystal Si/SiGe/Si nanomembranes (SiNMs) that are transferred to foreign substrates is reported. The transferable SiNMs are realized by first growing pseudomorphic SiGe and Si layers on silicon-on-insulator (SOI) substrates, and then, selectively removing the buried oxide (BOX) layer from the SOI. Before the release, only the SiGe layer is compressively strained. Upon release, part of the compressive strain in the SiGe layer is transferred to the thin Si layers, and the Si layers, thus, become tensile strained. Both the initial compressive strain state in the SiGe layer and the final strain sharing state between the SiGe and the Si layers are verified with X-ray diffraction measurements. The TFTs are fabricated employing the conventional high-temperature MOS process on the strain-shared SiNMs that are transferred to an oxidized Si substrate. The transferred strained-sharing SiNMs show outstanding thermal stability and can withstand the high-temperature TFT process on the new host substrate. The strained-channel TFTs fabricated on the new host substrate show high current drive capability and an average electron effective mobility of 270 cm{sup 2}/V ldr s. The results suggest that transferable and thermally stable single-crystal elastically strain- sharing SiNMs can serve as excellent active material for high-speed device application with a simple and scalable transfer method. The demonstration of MOS TFTs on the transferable nanomembranes may create the opportunity for future high-speed Si CMOS heterogeneous integration on any substrate.

  6. Symmetry of piezoelectric (1–x)Pb(Mg1/3Nb2/3)O?-xPbTiO? (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

    2012-11-01T23:59:59.000Z

    We use probes of three different length scales to examine symmetry of (1–x)Pb(Mg1/3Nb2/3)O?-xPbTiO? (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, 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.

  7. Optical interband transitions in relaxor-based ferroelectric 0.93Pb,,Zn1/3Nb2/3...O30.07PbTiO3 single crystal

    E-Print Network [OSTI]

    Cao, Wenwu

    Optical interband transitions in relaxor-based ferroelectric 0.93Pb,,Zn1/3Nb2/3...O3­0.07PbTiO3 June 2010 The optical transmission spectrum of 111 c poled relaxor-based ferroelectric single crystal 0. The optical absorption edge has been determined and the wavelength dependence of the absorption coefficient

  8. Photorefractive properties of undoped, cerium-doped, and iron-doped single-crystal Sr/sub 0. 6/Ba/sub 0. 4/Nb/sub 2/O/sub 6/

    SciTech Connect (OSTI)

    Rakuljic, G.A.; Yariv, A.; Neurgaonkar, R.

    1986-11-01T23:59:59.000Z

    The authors present the results of theoretical and experimental studies of the photorefractive effort in single-crystal SBN:60, SBN:Ce, and SBN:Fe. The two-beam coupling coefficients, response times, and absorption coefficients of these materials are given.

  9. 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

    2004-12-15T23:59:59.000Z

    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.

  10. OPTICAL CONSTANTS OF SILICON CARBIDE FOR ASTROPHYSICAL APPLICATIONS. II. EXTENDING OPTICAL FUNCTIONS FROM INFRARED TO ULTRAVIOLET USING SINGLE-CRYSTAL ABSORPTION SPECTRA

    SciTech Connect (OSTI)

    Hofmeister, A. M.; Pitman, K. M. [Department of Earth and Planetary Sciences, Washington University, St. Louis, MO 63130 (United States); Goncharov, A. F. [Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015 (United States); Speck, A. K. [Department of Physics and Astronomy, University of Missouri-Columbia, Columbia, MO 65211 (United States)], E-mail: hofmeist@levee.wustl.edu

    2009-05-10T23:59:59.000Z

    Laboratory measurements of unpolarized and polarized absorption spectra of various samples and crystal structures of silicon carbide (SiC) are presented from 1200-35000 cm{sup -1} ({lambda} {approx} 8-0.28 {mu}m) and used to improve the accuracy of optical functions (n and k) from the infrared (IR) to the ultraviolet (UV). Comparison with previous {lambda} {approx} 6-20 {mu}m thin-film spectra constrains the thickness of the films and verifies that recent IR reflectivity data provide correct values for k in the IR region. We extract n and k needed for radiative transfer models using a new 'difference method', which utilizes transmission spectra measured from two SiC single-crystals with different thicknesses. This method is ideal for near-IR to visible regions where absorbance and reflectance are low and can be applied to any material. Comparing our results with previous UV measurements of SiC, we distinguish between chemical and structural effects at high frequency. We find that for all spectral regions, 3C ({beta}-SiC) and the E-vector perpendicular c-vector polarization of 6H (a type of {alpha}-SiC) have almost identical optical functions that can be substituted for each other in modeling astronomical environments. Optical functions for E-vector || c-vector of 6H SiC have peaks shifted to lower frequency, permitting identification of this structure below {lambda} {approx} 4 {mu}m. The onset of strong UV absorption for pure SiC occurs near 0.2 {mu}m, but the presence of impurities redshifts the rise to 0.33 {mu}m. Optical functions are similarly impacted. Such large differences in spectral characteristics due to structural and chemical effects should be observable and provide a means to distinguish chemical variation of SiC dust in space.

  11. Ti-Sn alloy nanodot composites embedded in single-crystal SiO{sub 2} by low energy dynamic coimplantation

    SciTech Connect (OSTI)

    Zhao, J. P.; Meng, Y.; Huang, D. X.; Rayabarapu, R. K.; Rabalais, J. W. [Department of Chemistry, University of Houston, Houston, Texas 77204 (United States); Department of Chemistry and Physics, Lamar University, P.O. Box 10022 Beaumont, Texas 77710 (United States)

    2006-10-15T23:59:59.000Z

    Organized extremely small Ti-Sn alloy nanodots have been formed in the subsurface of SiO{sub 2} by dynamic coimplantation of isotopic {sup 48}Ti{sup +} and {sup 120}Sn{sup +} at a low kinetic energy of 9 keV into (0001) Z-cut quartz at different substrate temperatures. Transmission electron microscopy images show that the Ti-Sn alloy nanodots are single crystal and have been formed uniformly at room temperature. They are distributed in a two-dimensional array with similar size of {approx}4 nm and constant interdot spacing between each dot. The regions beyond and below the two-dimensional array are depleted of detectable nanodots. At high temperature, the distribution and crystallinity were destroyed with much smaller amorphous nanodots in a slightly deeper region. The implantation was carried out by dynamic coimplantation, rather than the commonly used sequential implantation. These results indicate that dynamic low energy coimplantation is capable of forming well-ordered two-dimensional array of alloy nanodots.

  12. Magnetic structures and interplay between rare-earth Ce and Fe magnetism in single-crystal CeFeAsO

    SciTech Connect (OSTI)

    Zhang, Qiang [Ames Laboratory; Tian, Wei [Ames Laboratory; Li, Haifeng [Ames Laboratory; Kim, Jong-Woo [Argonne Naitonal Laboratory; Yan, Jiaqiang [Ames Laboratory; McCallum, Robert William [Ames Laboratory; Lograsso, Thomas A. [Ames Laboratory; Zarestky, Jerel L. [Ames Laboratory; Budko, Sergey L. [Ames Laboratory; McQueeney, Robert J. [Ames Laboratory; Vaknin, David [Ames Laboratory

    2013-11-27T23:59:59.000Z

    Neutron and synchrotron resonant x-ray magnetic scattering (RXMS) complemented by heat capacity and resistivity measurements reveal the evolution of the magnetic structures of Fe and Ce sublattices in a CeFeAsO single crystal. The RXMS of magnetic reflections at the Ce LII edge shows a magnetic transition that is specific to the Ce antiferromagnetic long-range ordering at TCe? 4 K with short-range Ce ordering above TCe, whereas neutron diffraction measurements of a few magnetic reflections indicate a transition at T?? 12 K with an unusual order parameter. Detailed order-parameter measurements on several magnetic reflections by neutrons show a weak anomaly at 4 K that we associate with the Ce ordering. The successive transitions at TCe and T? can also be clearly identified by two anomalies in heat capacity and resistivity measurements. The higher transition temperature at T?? 12 K is mainly ascribed to Fe spin reorientation transition, below which Fe spins rotate uniformly and gradually in the ab plane. The Fe spin reorientation transition and short-range Ce ordering above TCe reflect the strong Fe-Ce couplings prior to long-range ordering of the Ce. The evolution of the intricate magnetic structures in CeFeAsO going through T? and TCe is proposed.

  13. 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.

    1999-02-12T23:59:59.000Z

    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.

  14. Cascade phonon-assisted trapping of positrons by divacancies in n-FZ-Si(P) single crystals irradiated with 15 MeV protons

    SciTech Connect (OSTI)

    Arutyunov, N. Yu., E-mail: n-arutyunov@yahoo.com [Martin Luther University Halle, Department of Physics, 06120 Halle, Germany and Inst. of Ion-Plasma and Laser Technologies (Inst. of Electronics), 700187 Tashkent (Uzbekistan); Emtsev, V. V.; Oganesyan, G. A. [Ioffe Physico-Technical Institute, 194021 St. Petersburg (Russian Federation); Krause-Rehberg, R.; Kessler, C. [Martin Luther University Halle, Department of Physics, 06120 Halle (Germany); Elsayed, M. [Martin Luther University Halle, Department of Physics, 06120 Halle, Germany and Minia university, Faculty of Science, Physics Department, P.O. box 61519 Minia (Egypt); Kozlovski, V. V. [St. Petersburg State Polytechnic University, 195251 St. Petersburg (Russian Federation)

    2014-02-21T23:59:59.000Z

    The trapping of positrons by the radiation defects in moderately doped oxygen-lean n-FZ-Si(P) single crystal irradiated with 15 MeV protons has been investigated in a comparative way using the positron lifetime spectroscopy and Hall effect measurements. The experiments were carried out within a wide temperature interval ranging from 25 K – 29 K to 300 K. The positron trapping rate for divacancies was reconstructed in the course of many-stage isochronal annealing. The concentration and the charged states of divacancies (V{sub 2}{sup ?} and V{sub 2}{sup ??}) were estimated. The temperature dependency of the trapping cross section of positrons by the negatively charged divacancies is in a good agreement with the data of calculations based on the assumptions of the cascade phonon-assisted mechanism of exchange of the energy between the positron and acoustic long-wave phonons. Obeying ? T{sup ?3} law, the cross-section of the trapping of positrons by divacancies changes considerably ranging from ?1.7×10{sup ?12} cm{sup 2} (66 – 100 K) to ?2×10{sup ?14} cm{sup 2} (? 250 K). The characteristic length of trapping of the positron by V{sub 2}{sup ??} divacancy was estimated to be l{sub 0}(V{sub 2}{sup ??})?(3.4±0.2)×10{sup ?8} cm.

  15. Atomic control and characterization of surface defect states of TiO{sub 2} terminated SrTiO{sub 3} single crystals

    SciTech Connect (OSTI)

    Kareev, M.; Prosandeev, S.; Liu, J.; Gan, C.; Kareev, A.; Xiao, Min; Chakhalian, J. [University of Arkansas, Fayetteville, Arkansas 72701 (United States); Freeland, J. W. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2008-08-11T23:59:59.000Z

    By using an alternative wet-etch procedure, we have obtained high-quality atomically flat TiO{sub 2} terminated surfaces of SrTiO{sub 3} single crystals with the morphology equivalent to that of the conventional wet-etch methods. By applying a combined power of photoluminescence (PL) spectroscopy, reflection high-energy electron diffraction, atomic force microscopy imaging, and soft x-ray absorption (XAS), we were able to identify and monitor the complex evolution of oxygen defect states and Ti valency at the surface and near-surface layers. Our experiments revealed a high level of local defects resulting in the presence of the Ti{sup 3+} states at the surface. We have developed a method to control the defect states capable of a marked reduction of the defect concentration. We have demonstrated that the PL and XAS are able to distinguish the surface-related Ti{sup 3+} states from oxygen vacancies trapping charge transfer vibronic excitons that define the PL intensity. The experimental findings will have important implications for the growth of high-quality ultrathin complex oxide heterostructures.

  16. Atomic control and characterization of surface defect states of TiO(sub 2) terminated SrTiO(sub 3) single crystals.

    SciTech Connect (OSTI)

    Kareev, M.; Prosandeev, S.; Liu, J.; Gan, C.; Kareev, A.; Freeland, J. W.; Xiao, M.; Chakhalian, J.; Univ. of Arkansas

    2008-08-11T23:59:59.000Z

    By using an alternative wet-etch procedure, we have obtained high-quality atomically flat TiO{sub 2} terminated surfaces of SrTiO{sub 3} single crystals with the morphology equivalent to that of the conventional wet-etch methods. By applying a combined power of photoluminescence (PL) spectroscopy, reflection high-energy electron diffraction, atomic force microscopy imaging, and soft x-ray absorption (XAS), we were able to identify and monitor the complex evolution of oxygen defect states and Ti valency at the surface and near-surface layers. Our experiments revealed a high level of local defects resulting in the presence of the Ti{sup 3+} states at the surface. We have developed a method to control the defect states capable of a marked reduction of the defect concentration. We have demonstrated that the PL and XAS are able to distinguish the surface-related Ti{sup 3+} states from oxygen vacancies trapping charge transfer vibronic excitons that define the PL intensity. The experimental findings will have important implications for the growth of high-quality ultrathin complex oxide heterostructures.

  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., E-mail: irzhak@iptm.ru; Roshchupkin, D., E-mail: rochtch@iptm.ru [Institute of Microelectronics Technology and High-Purity Materials Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation)

    2014-06-28T23:59:59.000Z

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

    SciTech Connect (OSTI)

    Pandey, Abhishek [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Quirinale, D. G. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Jayasekara, W. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Sapkota, A. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Kim, M. G. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Dhaka, R. S. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Lee, Y. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Heitmann, T. W. [Univ. of Missouri, Columbia, MO (United States). Missouri Research Reactor; Stephens, P. W. [State Univ. of New York (SUNY), Plattsburgh, NY (United States); Ogloblichev, V. [Russian Academy of Sciences, Urals Div., Ekaterinburg (Russian Federation). Inst. of Metal Physics; Kreyssig, A. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; McQueeney, R. J. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Goldman, A. I. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Kaminski, Adam [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Harmon, B. N. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Furukawa, Y. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Johnston, D. C. [Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy

    2013-07-01T23:59:59.000Z

    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 between 1.3 and 300 K and we propose that metallic SrCo2As2 has a gapless quantum spin-liquid ground state.

  19. Guided wave propagation in 0.67Pb,,Mg1/3Nb2/3...O30.33PbTiO3 single crystal plate poled along 001c

    E-Print Network [OSTI]

    Cao, Wenwu

    Guided wave propagation in 0.67Pb,,Mg1/3Nb2/3...O3­0.33PbTiO3 single crystal plate poled along 001c relations of Lamb waves and shear horizontal SH waves propagating in the 100 and 110 directions of 0.67Pb Mg, respectively, for waves propagating along 100 and 110 directions. These limiting velocities

  20. Metal-semiconductor-transition observed in Bi{sub 2}Ca(Sr, Ba){sub 2}Co{sub 2}O{sub 8+?} single crystals

    SciTech Connect (OSTI)

    Dong, Song-Tao [National Laboratory of Solid State Microstructures and Department of Material Science and Engineering, Nanjing University, Nanjing 210093 (China); Institute of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Zhang, Bin-Bin; Zhang, Lun-Yong; Yao, Shu-Hua, E-mail: ybchen@nju.edu.cn, E-mail: shyao@nju.edu.cn; Zhou, Jian; Zhang, Shan-Tao; Gu, Zheng-Bin; Chen, Yan-Feng [National Laboratory of Solid State Microstructures and Department of Material Science and Engineering, Nanjing University, Nanjing 210093 (China); Chen, Y. B., E-mail: ybchen@nju.edu.cn, E-mail: shyao@nju.edu.cn [National Laboratory of Solid State Microstructures and Department of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2014-07-28T23:59:59.000Z

    Electrical property evolution of Bi{sub 2}AE{sub 2}Co{sub 2}O{sub 8+?} single crystals (AE?=?Ca, Sr and Ba) is systematically explored. When AE changes from Ca to Ba, the electrical property of Bi{sub 2}Ca{sub 2}Co{sub 2}O{sub 8+?} and Bi{sub 2}Sr{sub 2}Co{sub 2}O{sub 8+?} demonstrates semiconductor-like properties. But Bi{sub 2}Ba{sub 2}Co{sub 2}O{sub 8+?} shows the metallic behavior. Analysis of temperature-dependent resistance substantiates that from metallic Bi{sub 2}Ba{sub 2}Co{sub 2}O{sub 8+?} to semiconductor-like Bi{sub 2}Sr{sub 2}Co{sub 2}O{sub 8+?} can be attributed to Anderson localization. However the semiconductor behaviour of Bi{sub 2}Sr{sub 2}Co{sub 2}O{sub 8+?} and Bi{sub 2}Ca{sub 2}Co{sub 2}O{sub 8+?} is related to electronic correlations effect that is inferred by large negative magnetoresistance (?70%). The theoretical electronic structures and valence X-ray photoemission spectroscopy substantiate that there is a relative large density of state around Fermi level in Bi{sub 2}Ba{sub 2}Co{sub 2}O{sub 8+?} compared with other two compounds. It suggests that Bi{sub 2}Ba{sub 2}Co{sub 2}O{sub 8+?} is more apt to be metal in this material system.

  1. Upper critical fields and thermally-activated transport of Nd(0.7Fe0.3) FeAs single crystal

    SciTech Connect (OSTI)

    Balakirev, Fedor F [Los Alamos National Laboratory; Jaroszynski, J [NHMFL, FSU; Hunte, F [NHMFL, FSU; Balicas, L [NHMFL, FSU; Jo, Youn - Jung [NHMFL, FSU; Raicevic, I [NHMFL, FSU; Gurevich, A [NHMFL, FSU; Larbalestier, D C [NHMFL, FSU; Fang, L [CHINA; Cheng, P [CHINA; Jia, Y [CHINA; Wen, H H [CHINA

    2008-01-01T23:59:59.000Z

    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.

  2. High field magnetotransport and point contact Andreev reflection measurements on CuCr{sub 2}Se{sub 4} and CuCr{sub 2}Se{sub 3}Br—Degenerate magnetic semiconductor single crystals

    SciTech Connect (OSTI)

    Borisov, K., E-mail: borisovk@tcd.ie; Coey, J. M. D.; Stamenov, P. [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland); Alaria, J. [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom)

    2014-05-07T23:59:59.000Z

    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.

  3. 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.

    2013-05-01T23:59:59.000Z

    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.

  4. Nanotwin and phase transformation in tetragonal Pb,,Fe1/2Nb1/2...1-xTixO3 single crystal

    E-Print Network [OSTI]

    . INTRODUCTION Polar nanostructures are possibly the most important fea- ture in relaxor ferroelectrics FEs crystals have demonstrated their value in piezoelectric and medical ultrasonic imaging devices.4 parameters have drawn much attention recently because of potential applications in infor- mation storage

  5. Synthesis and single-crystal X-ray diffraction studies of new framework substituted type II clathrates, Cs{sub 8}Na{sub 16}Ag{sub x}Ge{sub 136-x} (x<7)

    SciTech Connect (OSTI)

    Beekman, M. [Department of Physics, University of South Florida, 4202 East Fowler Ave., PHY 114, Tampa, FL 33620 (United States); Wong-Ng, W. [Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Kaduk, J.A. [INEOS Technologies, Naperville, IL 60566 (United States); Shapiro, A. [Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Nolas, G.S. [Department of Physics, University of South Florida, 4202 East Fowler Ave., PHY 114, Tampa, FL 33620 (United States)], E-mail: gnolas@cas.usf.edu

    2007-03-15T23:59:59.000Z

    New inorganic type II clathrates with Ag atoms substituting for framework Ge atoms, Cs{sub 8}Na{sub 16}Ag{sub x}Ge{sub 136-x} (x=0, 5.9, and 6.7), have been synthesized by reaction of the pure elements at high temperature. Structural refinements have been performed using single crystal X-ray diffraction. The materials crystallize with the cubic type II clathrate crystal structure (space group Fd3-barm) with a=15.49262(9)A, 15.51605(6)A, and 15.51618(9) for x=0, 5.9, and 6.7, respectively, and Z=1. The structure is formed by a covalently bonded Ag-Ge framework, in which the Cs and Na atoms are found inside two types of polyhedral cages. Ag substitutes for Ge in the tetrahedrally bonded framework positions, and was found to preferentially occupy the most asymmetric 96g site. The proven ability to substitute atoms for the germanium framework should offer a route to the synthesis of new compositions of type II clathrates, materials that are of interest for potential thermoelectrics applications.

  6. EPR studies of S(M(CO) sub 5 ) sub 2 sup minus radicals (M = Cr, W) trapped in single crystals of PPN sup + HS(M(CO) sub 5 ) sub 2 sup minus

    SciTech Connect (OSTI)

    Hynes, R.C.; Preston, K.F.; Springs, J.J.; Williams, A.J. (National Research Council of Canada, Ottawa, Ontario (Canada))

    1991-01-01T23:59:59.000Z

    Persistent anisotropic EPR spectra detected in {gamma}-irradiated single crystals of PPN{sup +}HSM{sub 2}(CO){sub 10}{sup {minus}} (M = Cr, W) are attributed to the anion radicals produced by loss of a hydrogen atom from the undamaged anions. The g tensors were determined from measurements taken throughout three mutually orthogonal planes of crystallographically aligned single-crystal specimens: g(Cr) = (2.0008, 2.1142, 2.0472); g(W) = (1.9899, 2.2461, 2.0900). X-ray diffractometry showed that the undamaged crystals were isomorphous and belonged to the triclinic space group P{bar 1}. A full structure determination was carried out for the Cr compound only. Cell parameters for the Cr compound are as follows: a = 9.6629 (10) {angstrom}, b = 14.1626 (11) {angstrom}, c = 16.9509 (14) {angstrom}, {alpha} = 78.226 (7){degree}, {beta} = 85.711 (8){degree}, {gamma} = 89.615 (8){degree}, Z = 2. Cell parameters for the W compound are as follows: a = 9.825 (2) {angstrom}, b = 14.097 (4) {angstrom}, c = 17.019 (9) {angstrom}, {alpha} = 78.47 (3){degree}, {beta} = 85.72 (3){degree}, {gamma} = 89.91 (2){degree}. The anion structures showed an approximately octahedral arrangement of five carbonyls and a (shared) sulfur about each metal atom. Carbonyls from opposite ends of the anion are staggered with respect to each other. Cr-S bonds are 2.46 and 2.48 {angstrom} long and 122.8{degree} apart. A good correlation was established for both Cr- and W-containing crystals between principal g values and the M-M direction (maximum g), the bisector of the M-S-M angle (intermediate g), and the perpendicular to the MSM plane (minimum g). The observations are interpreted in terms of a {pi}'-radical structure, analogous to that of SO{sub 2}{sup {minus}} in which unpaired spin density is shared between a S 3p{sub x} orbital directed perpendicular to the CrSCr plane and Cr 3d{sub xz} orbitals.

  7. Structural and proton-dynamical effects in a proton-irradiated KH{sub 2}PO{sub 4} single crystal

    SciTech Connect (OSTI)

    Kim, S. H.; Oh, B. H.; Lee, K. W.; Lee, Cheol Eui; Hong, K. S. [Department of Physics and Institute for Nano Science, Korea University, Seoul 136-713 (Korea, Republic of); Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of)

    2006-04-01T23:59:59.000Z

    A KH{sub 2}PO{sub 4} (KDP) crystal, irradiated by a 1 MeV hydrogen ion beam to a dose of 10{sup 15} ions/cm{sup 2}, was studied by means of x-ray diffraction (XRD), {sup 1}H nuclear magnetic resonance (NMR), and dielectric constant measurements. The XRD pattern for the a-cut KDP crystal revealed a decrease in the lattice constant along the a axis after the proton irradiation. According to the {sup 1}H NMR spin-lattice relaxation rate measurements, the proton irradiation gave rise to reduction in the activation energy in the paraelectric phase, from 0.42 to 0.28 eV, in agreement with the temperature dependent second moment measurements indicating the proton motion is more activated after the proton irradiation. Besides, analysis of the temperature-dependent dielectric constants using a mean-field approximation revealed a change in the hydrogen bond induced by the proton irradiation.

  8. Spin-waves in antiferromagnetic single-crystal LiFePO4 Jiying Li,* Vasile O. Garlea, Jerel L. Zarestky, and David Vaknin

    E-Print Network [OSTI]

    Vakni, David

    -wave theory by including in the spin Hamiltonian in-plane nearest- and next-nearest-neighbor interactions J1 and J2 , inter-plane nearest-neighbor interactions J and a single-ion anisotropy D . A weak 0 number s : 75.25. z, 75.30.Ds, 75.50.Ee I. INTRODUCTION Lithium-orthophosphates LiMPO4 M=Mn,Fe,Co,Ni have

  9. X-ray and electrochemical studies of Cu UPD on Au(111) single-crystal electrodes in the presence of bromide

    SciTech Connect (OSTI)

    Herrero, E.; Glazier, S.; Abruna, H.D. [Cornell Univ., Ithaca, NY (United States)] [Cornell Univ., Ithaca, NY (United States)

    1998-12-03T23:59:59.000Z

    The underpotential deposition (UPD) of copper on Au(111) in the presence of bromide anions has been investigated employing electrochemical techniques, in-situ grazing incidence X-ray diffraction (GIXD), and crystal truncation rod (CTR) measurements. At potentials positive of +0.55 V (vs Ag/AgCl), bromide adsorbs on the electrode surface forming an ordered and rotated hexagonal structure. The rotation angle of this structure with respect to the Au(01) direction and the Br-Br distance change with the applied potential. At potentials below +0.55 V, the bromide overlayer becomes disordered although its coverage remains high. The initial stages of copper deposition (at ca. +0.36 V) lower the gold`s work function, giving rise to an increase in the bromide coverage and the formation of an ordered bromide layer with a coverage of 0.51. At +0.32 V there is a sharp voltammetric feature that corresponds to a phase transition to give a (4 x 4) bromide layer with a coverage of 0.563. Over the potential range from +0.32 to ca. +0.20 there are two voltammetric features associated with additional copper deposition, giving rise to a stoichiometric CuBr layer. At +0.47 V there is another sharp voltammetric feature which, again, is ascribed to a phase transition giving rise to a (1 x 1) copper layer with a bromide (4 x 4) structure adsorbed over the copper layer. At this potential, the distances between the bromide and copper layers are similar to those found in solid CuBr. At potentials negative of +0.147 V, bulk copper deposition begins.

  10. 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)

    2014-08-18T23:59:59.000Z

    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.

  11. Crystal_Reporting_9_1 LSUNO_LSUSH

    E-Print Network [OSTI]

    , products and services. Oracle Corporation and its affiliates will not be responsible for any loss, costs........................................................................................3 Running Crystal Reports......................................................................................................13 Run a Single Report for Multiple Departments

  12. Coherent multilayer crystals and method of making

    DOE Patents [OSTI]

    Schuller, I.K.; Falco, C.M.

    1980-10-30T23:59:59.000Z

    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.

  13. 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: zhw3789@sina.com, E-mail: hsluo@mail.sic.ac.cn; Chen, Chao; Deng, Hao; Li, Long [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China) [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao, Xiangyong; Lin, Di; Li, Xiaobing; Ren, Bo; Luo, Haosu, E-mail: zhw3789@sina.com, E-mail: hsluo@mail.sic.ac.cn [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China)] [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China); Yan, Jun [Shibei Power Supply Branch, Shanghai Municipal Electric Power Company, Shanghai 200072 (China)] [Shibei Power Supply Branch, Shanghai Municipal Electric Power Company, Shanghai 200072 (China)

    2013-11-18T23:59:59.000Z

    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.

  14. Photo-effects in iodine single crystals

    E-Print Network [OSTI]

    Rieves, John Michael

    1967-01-01T23:59:59.000Z

    energy distribution for the nsrcury Ianp is sbo?n in pig. 9(c) . No curve ws available for the tuagsten leaps ho?aver, Cbs gsesral profile of tbe spectral energy output is hnoun to folio?a snooth curve ?hicb increases gradually fron ~ vary lo...

  15. Electronic conduction through single crystals of polyethylene

    E-Print Network [OSTI]

    Samson, Gerald Maurice

    1966-01-01T23:59:59.000Z

    'iec elec r' c f" cld, ~ J 1 ard ~ne dielectric arc iz. posed. Thi- y'elds the Eichcrcsoz;Schot ! y ccu tion, !"inslly, the Fo' ler-. "!ordhcim ecuat-'on for field ez icsion is sic. tcd ar;d di cussed, ne Sozaaerzcld odc "o" elect;ons in a -etal, thc iz...

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

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn12 Investigation PeerNOON...January 2015H8/0UpgradeJefferson

  17. Getting Crystals Your Crystallographer Will Treasure Richard J. Staples 03/09/2005 1 X-Ray Crystallography Laboratory

    E-Print Network [OSTI]

    Meagher, Mary

    . What information do we get? A crystal structure provides positive identification of a single crystal to be able to perform these analysis. The positive identification of the compound leaves no interpretation material, solvents? What do we grow the crystals in? Other concerns · Crystal Growth · Crystallization

  18. Optomechanical Crystals

    E-Print Network [OSTI]

    Eichenfield, Matt; Camacho, Ryan M; Vahala, Kerry J; Painter, Oskar

    2009-01-01T23:59:59.000Z

    Structured, periodic optical materials can be used to form photonic crystals capable of dispersing, routing, and trapping light. A similar phenomena in periodic elastic structures can be used to manipulate mechanical vibrations. Here we present the design and experimental realization of strongly coupled optical and mechanical modes in a planar, periodic nanostructure on a silicon chip. 200-Terahertz photons are co-localized with mechanical modes of Gigahertz frequency and 100-femtogram mass. The effective coupling length, which describes the strength of the photon-phonon interaction, is as small as 2.9 microns, which, together with minute oscillator mass, allows all-optical actuation and transduction of nanomechanical motion with near quantum-limited sensitivity. Optomechanical crystals have many potential applications, from RF-over-optical communication to the study of quantum effects in mesoscopic mechanical systems.

  19. 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)

    2012-10-15T23:59:59.000Z

    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.

  20. High energy resolution, high angular acceptance crystal monochromator

    DOE Patents [OSTI]

    Alp, Ercan E. (Bolingbrook, IL); Mooney, Timothy M. (Westmont, IL); Toellner, Thomas (Green Bay, WI)

    1996-06-04T23:59:59.000Z

    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.

  1. High energy resolution, high angular acceptance crystal monochromator

    DOE Patents [OSTI]

    Alp, E.E.; Mooney, T.M.; Toellner, T.

    1996-06-04T23:59:59.000Z

    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.

  2. Crystal Chemistry of Th in Fluorapatite

    SciTech Connect (OSTI)

    Y Luo; J Rakovan; Y Tang; M Lupulescu; J Hughes; Y Pan

    2011-12-31T23:59:59.000Z

    Through the complementary use of single-crystal X-ray diffraction and X-ray absorption spectroscopy, we present in this paper the first direct results on the site occupancy of thorium in the fluorapatite structure and the structural distortion created by its substitution. Structure refinements based on single-crystal X-ray diffraction data from synthetic Th-doped fluorapatite indicates that Th substitutes almost exclusively in the M2 site. A single-crystal X-ray study of natural fluorapatite from Mineville, New York, also indicated that substituting heavy scatterers (including Th) are concentrated in the apatite M2 site, but definitive site assignments of specific elements were not possible. Extended X-ray absorption fine-structure spectroscopy (EXAFS) was used to probe the local structure of Th in the synthetic fluorapatite (single-crystal form) with a Th concentration of roughly 20000 ppm, as well as Th in the natural Mineville fluorapatite (powder form) with a Th concentration of {approx}2000 ppm. The EXAFS fitting results also indicate that Th partitions into the M2 site and yield a {approx}0.05-0.08 {angstrom} decrease of average M2-O bond distances associated with local structure distortions that are not obtainable from single-crystal X-ray diffraction studies.

  3. Method for solid state crystal growth

    DOE Patents [OSTI]

    Nolas, George S.; Beekman, Matthew K.

    2013-04-09T23:59:59.000Z

    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.

  4. 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)

  5. Spectroscopic, thermal and structural studies on manganous malate crystals

    SciTech Connect (OSTI)

    Thomas, J., E-mail: smartlabindia@gmail.com; Lincy, A., E-mail: lincymaria@gmail.com; Mahalakshmi, V.; Saban, K. V. [Smart Materials Analytic Research and Technology (SMART), Department of Physics, St. Berchmans College (India)] [Smart Materials Analytic Research and Technology (SMART), Department of Physics, St. Berchmans College (India)

    2013-01-15T23:59:59.000Z

    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.

  6. Effects of substrate crystallographic orientations on crystal growth and microstructure development in laser

    E-Print Network [OSTI]

    DuPont, John N.

    in laser surface-melted superalloy single crystals. Mathematical modeling of single-crystal growth model developed for single-crystalline solidification in laser surface melting (LSM) described in Part I the magnitude and distribution of dendrite growth velocity in the melt pool. The selected Æ1 0 0æ growth

  7. Pressure cryocooling protein crystals

    DOE Patents [OSTI]

    Kim, Chae Un (Ithaca, NY); Gruner, Sol M. (Ithaca, NY)

    2011-10-04T23:59:59.000Z

    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.

  8. BRF Crystal_Reporting_9_1 Version Date: February 2014

    E-Print Network [OSTI]

    . Oracle Corporation and its affiliates will not be responsible for any loss, costs, or damages incurred........................................................................................1 Running Crystal Reports ...............................................................................................................................9 Run a Single Report for Multiple Departments

  9. Growth and characterization of new organic nonlinear optical crystal (R)-2-cyano-N-(1-phenylethyl) acetamide

    SciTech Connect (OSTI)

    Hemaraju, B. C.; Gnana Prakash, A. P., E-mail: gnanaprakash@physics.uni-mysore.ac.in [Department of Studies in Physics, University of Mysore, Mysore-570006, Karnataka (India); Madhukar, B. S.; Bhadregowda, D. G. [Department of Chemistry, Yuvaraja's College Mysore-570005, Karnataka (India)

    2014-04-24T23:59:59.000Z

    (R)-2-Cyano-N-(1-phenylethyl) acetamide (RCNPA) single crystals were grown by slow evaporation of the aqueous solution at room temperature (300K) using ethanol. The grown crystals were characterized by single crystal X-ray diffraction, powder X-ray diffraction, FTIR, UV-Vis-NIR transmittance, scanning electron microscopy (SEM) and powder second harmonic generation (SHG)

  10. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    SciTech Connect (OSTI)

    KRUGER AA; HRMA PR

    2009-10-08T23:59:59.000Z

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  11. Electrically driven photonic crystal nanocavity devices

    E-Print Network [OSTI]

    Shambat, Gary; Petykiewicz, Jan; Mayer, Marie A; Majumdar, Arka; Sarmiento, Tomas; Harris, James; Haller, Eugene E; Vuckovic, Jelena

    2012-01-01T23:59:59.000Z

    Interest in photonic crystal nanocavities is fueled by advances in device performance, particularly in the development of low-threshold laser sources. Effective electrical control of high performance photonic crystal lasers has thus far remained elusive due to the complexities associated with current injection into cavities. A fabrication procedure for electrically pumping photonic crystal membrane devices using a lateral p-i-n junction has been developed and is described in this work. We have demonstrated electrically pumped lasing in our junctions with a threshold of 181 nA at 50K - the lowest threshold ever demonstrated in an electrically pumped laser. At room temperature we find that our devices behave as single-mode light-emitting diodes (LEDs), which when directly modulated, have an ultrafast electrical response up to 10 GHz corresponding to less than 1 fJ/bit energy operation - the lowest for any optical transmitter. In addition, we have demonstrated electrical pumping of photonic crystal nanobeam LEDs...

  12. HANFORD MEDIUM-LOW CURIE WASTE PRETREATMENT ALTERNATIVES PROJECT FRACTIONAL CRYSTALLIZATION PILOT SCALE TESTING FINAL REPORT

    SciTech Connect (OSTI)

    HERTING DL

    2008-09-16T23:59:59.000Z

    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.

  13. Method for the preparation of photochromic insulating crystals

    DOE Patents [OSTI]

    Abraham, Marvin M. (Oak Ridge, TN); Boldu, Jose L. (Mexico City, MX); Chen, Yok (Oak Ridge, TN); Orera, Victor M. (Zaragosa, ES)

    1986-01-01T23:59:59.000Z

    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.

  14. Polar nanoregions and dielectric properties in high-strain lead-free 0.93(Bi{sub 1/2}Na{sub 1/2})TiO{sub 3}-0.07BaTiO{sub 3} piezoelectric single crystals

    SciTech Connect (OSTI)

    Chen, Cheng-Sao, E-mail: rickchen@cc.hwh.edu.tw [Department of Mechanical Engineering, Hwa-Hsia Institute of Technology, New Taipei City 23567, Taiwan (China); Chen, Pin-Yi [Department of Mechanical Engineering, Ming-Chi University of Technology, New Taipei City 24301, Taiwan (China); Tu, Chi-Shun [Graduate Institute of Applied Science and Engineering, Fu Jen Catholic University, New Taipei City 24205, Taiwan (China)

    2014-01-07T23:59:59.000Z

    A structural coexistence of rhombohedral (R) and tetragonal (T) phases has been revealed in the (001){sub c}-cut lead-free 0.93(Bi{sub 1/2}Na{sub 1/2})TiO{sub 3}–0.07BaTiO{sub 3} (BNB7T) piezoelectric crystals, which grown by the self-flux method, in the lower temperatures by high-resolution synchrotron X-ray diffraction, reciprocal space mapping, and transmission electron microscopy. The dielectric permittivity exhibits a thermal hysteresis in the region of 120–260?°C, implying a first-order-like phase transition from R+T to T. The real part (??) of dielectric permittivity begins to deviates from the Curie-Weiss equation, ???=?C/(T ? T{sub o}), from the Burns temperature T{sub B}?=?460?°C, below which the polar nanoregions (or nanoclusters) develop and attenuate dielectric responses. The polar nanoregions of 5–10?nm were revealed by high-resolution transmission electron microscope. The normal piezoelectric coefficient d{sub 33} exhibits a rapid increase at E?=?15–20?kV/cm and reaches a maximum of d{sub 33} ?450 pC/N. The high piezoelectric response and E-field induced strain in BNB7T single crystals can be attributed to structural phase transitions under an E-field application.

  15. Generation and manipulation of nonclassical light using photonic crystals

    E-Print Network [OSTI]

    Jelena Vuckovic; Dirk Englund; David Fattal; Edo Waks; Yoshihisa Yamamoto

    2005-10-07T23:59:59.000Z

    Photonic crystal cavities can localize light into nanoscale volumes with high quality factors. This permits a strong interaction between light and matter, which is important for the construction of classical light sources with improved properties (e.g., low threshold lasers) and of nonclassical light sources (such as single and entangled photon sources) that are crucial pieces of hardware of quantum information processing systems. This article will review some of our recent experimental and theoretical results on the interaction between single quantum dots and photonic crystal cavity fields, and on the integration of multiple photonic crystal devices into functional circuits for quantum information processing.

  16. Shallow melt apparatus for semicontinuous czochralski crystal growth

    DOE Patents [OSTI]

    Wang, Tihu; Ciszek, Theodore F.

    2006-01-10T23:59:59.000Z

    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. Crystal symmetry breaking in few-quintuple Bi2Te3 films: Applications in nanometrology of topological insulators

    E-Print Network [OSTI]

    -Raman spectroscopy investigation of mechanically exfoliated single-crystal bismuth telluride films with thickness demonstrated "graphene-like" me- chanical exfoliation of the atomically-thin single-crystal films11 and ribbons with the thickness down to 1 nm, which corresponds to a single quintuple.11 The exfoliation process was analogous

  18. Photonic crystal light source

    DOE Patents [OSTI]

    Fleming, James G. (Albuquerque, NM); Lin, Shawn-Yu (Albuquerque, NM); Bur, James A. (Corrales, NM)

    2004-07-27T23:59:59.000Z

    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.

  19. Neutron scattering study of underdoped Ba1-xKxFe?As? (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.

    2012-04-01T23:59:59.000Z

    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-xKxFe?As? (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 BaFe?As?, 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

  20. Neutron scattering study of underdoped Ba1-xKxFe?As? (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.

    2012-04-01T23:59:59.000Z

    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-xKxFe?As? (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 BaFe?As?, 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.

  1. Neutron scattering study of underdoped Ba1-xKxFe?As? (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.

    2012-04-01T23:59:59.000Z

    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-xKxFe?As? (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 BaFe?As?, 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.

  2. Ion Coulomb Crystals

    E-Print Network [OSTI]

    Richard C. Thompson

    2014-11-18T23:59:59.000Z

    Ion Coulomb crystals (ICC), formed by atomic ions at low temperatures in radiofrequency and Penning ion traps, are structures that have remarkable properties and many applications. Images of Coulomb crystals are striking and reveal the crystal structure, which arises from a balance between the trapping forces acting on the ions and their mutual Coulomb repulsion. Applications of these structures range from frequency standards and quantum simulation through to measurement of the cross sections of chemical reactions of ions.

  3. Phononic crystal devices

    DOE Patents [OSTI]

    El-Kady, Ihab F. (Albuquerque, NM); Olsson, Roy H. (Albuquerque, NM)

    2012-01-10T23:59:59.000Z

    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.

  4. Liquid Crystal Optofluidics

    SciTech Connect (OSTI)

    Vasdekis, Andreas E.; Cuennet, J. G.; Psaltis, D.

    2012-10-11T23:59:59.000Z

    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.

  5. Channeling through Bent Crystals

    SciTech Connect (OSTI)

    Mack, Stephanie; /Ottawa U. /SLAC

    2012-09-07T23:59:59.000Z

    Bent crystals have demonstrated potential for use in beam collimation. A process called channeling is when accelerated particle beams are trapped by the nuclear potentials in the atomic planes within a crystal lattice. If the crystal is bent then the particles can follow the bending angle of the crystal. There are several different effects that are observed when particles travel through a bent crystal including dechanneling, volume capture, volume reflection and channeling. With a crystal placed at the edge of a particle beam, part of the fringe of the beam can be deflected away towards a detector or beam dump, thus helping collimate the beam. There is currently FORTRAN code by Igor Yazynin that has been used to model the passage of particles through a bent crystal. Using this code, the effects mentioned were explored for beam energy that would be seen at the Facility for Advanced Accelerator Experimental Tests (FACET) at a range of crystal orientations with respect to the incoming beam. After propagating 5 meters in vacuum space past the crystal the channeled particles were observed to separate from most of the beam with some noise due to dechanneled particles. Progressively smaller bending radii, with corresponding shorter crystal lengths, were compared and it was seen that multiple scattering decreases with the length of the crystal therefore allowing for cleaner detection of the channeled particles. The input beam was then modified and only a portion of the beam sent through the crystal. With the majority of the beam not affected by the crystal, most particles were not deflected and after propagation the channeled particles were seen to be deflected approximately 5mm. After a portion of the beam travels through the crystal, the entire beam was then sent through a quadrupole magnet, which increased the separation of the channeled particles from the remainder of the beam to a distance of around 20mm. A different code, which was developed at SLAC, was used to create an angular profile plot which was compared to what was produced by Yazynin's code for a beam with no multiple scattering. The results were comparable, with volume reflection and channeling effects observed and the range of crystal orientations at which volume reflection is seen was about 1 mrad in both simulations.

  6. CrystalPlan: an Experiment Planning Tool for Crystallography

    SciTech Connect (OSTI)

    Zikovsky, Janik L [ORNL; Peterson, Peter F [ORNL; Wang, Xiaoping [ORNL; Frost, Matthew J [ORNL; Hoffmann, Christina [ORNL

    2011-01-01T23:59:59.000Z

    Beam time at large user program based x-ray and neutron scattering facilities is in high demand and always at a premium. CrystalPlan, a highly efficient experiment planning software has been developed to maximize the use of available beamtime per sample per experiment. This program can calculate and optimize the data coverage of a crystal in reciprocal space in a single-crystal diffraction time-of- flight experiment. CrystalPlan can help a user build an experiment plan that will acquire the most data possible, with sufficient coverage but limited redundancy, therefore increasing scientific productivity. A user friendly GUI including a 3D viewer, an automated coverage optimizer, and an option to reorient the crystal for the measurement of selected hkls on specific detector positions are among its useful features. A sample use case of the program with the TOPAZ beamline at SNS will be presented.

  7. Photonic crystal surface-emitting lasers enabled by an accidental Dirac point

    DOE Patents [OSTI]

    Chua, Song Liang; Lu, Ling; Soljacic, Marin

    2014-12-02T23:59:59.000Z

    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.

  8. Controlled growth of semiconductor crystals

    DOE Patents [OSTI]

    Bourret-Courchesne, E.D.

    1992-07-21T23:59:59.000Z

    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.

  9. Controlled growth of semiconductor crystals

    DOE Patents [OSTI]

    Bourret-Courchesne, Edith D. (Richmond, CA)

    1992-01-01T23:59:59.000Z

    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.

  10. Efficient room-temperature source of polarized single photons

    DOE Patents [OSTI]

    Lukishova, Svetlana G. (Honeoye Falls, NY); Boyd, Robert W. (Rochester, NY); Stroud, Carlos R. (Rochester, NY)

    2007-08-07T23:59:59.000Z

    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.

  11. Process of making cryogenically cooled high thermal performance crystal optics

    DOE Patents [OSTI]

    Kuzay, T.M.

    1992-06-23T23:59:59.000Z

    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.

  12. Process of making cryogenically cooled high thermal performance crystal optics

    DOE Patents [OSTI]

    Kuzay, Tuncer M. (Naperville, IL)

    1992-01-01T23:59:59.000Z

    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.

  13. Electro-optic crystal mosaics for the generation of terahertz radiation

    DOE Patents [OSTI]

    Carrig, Timothy J. (Los Alamos, NM); Taylor, Antoinette J. (Los Alamos, NM); Stewart, Kevin R. (Schenectady, NY)

    1996-01-01T23:59:59.000Z

    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.

  14. 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, E-mail: maria.wierzbicka-wieczorek@uni-jena.de [Institut für Geowissenschaften, Friedrich-Schiller-Universität Jena, Carl-Zeiss-Promenade 10, D-07745 Jena (Germany); Többens, Daniel M. [Abteilung Kristallographie, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Kolitsch, Uwe [Mineralogisch-Petrographische Abt., Naturhistorisches Museum, Burgring 7, A-1010 Wien (Austria); Institut für Mineralogie und Kristallographie, Universität Wien, Geozentrum, Althanstraße 14, A-1090 Wien (Austria); Tillmanns, Ekkehart [Institut für Mineralogie und Kristallographie, Universität Wien, Geozentrum, Althanstraße 14, A-1090 Wien (Austria)

    2013-11-15T23:59:59.000Z

    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, ?=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.

  15. Plasmon excitation by the Gaussian-like core mode of a photonic crystal

    E-Print Network [OSTI]

    Skorobogatiy, Maksim

    Plasmon excitation by the Gaussian-like core mode of a photonic crystal waveguide Maksim excitation of a plasmon by the Gaussian- like leaky mode of an effectively single mode photonic crystal (PC) waveguide. Plasmon is phase matched by design with a waveguide mode, and travels in a metallic layer

  16. ANOMALOUS DISPERSION OF SLOW NEUTRONS IN CRYSTALS By H. G. SMITH and S. W. PETERSON (1),

    E-Print Network [OSTI]

    Boyer, Edmond

    Studies of anomalous scattering of neutrons from CdI2 single crystals were conti- nued over an energy neutron scattering by nuclei and crystals has been fairly well understood for many years. An incident, and depends on the neutron-nucleus interactions. In general, the scattering amplitude can be expressed

  17. Light Scattering by Ice Crystals and Mineral Dust Aerosols in the Atmosphere

    E-Print Network [OSTI]

    Bi, Lei

    2012-07-16T23:59:59.000Z

    Modeling the single-scattering properties of nonspherical particles in the atmo¬sphere (in particular, ice crystals and dust aerosols) has important applications to climate and remote sensing studies. The ?rst part of the dissertation (Chapters II...

  18. 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., E-mail: hotta@riec.tohoku.ac.jp; Hatayama, M.; Tsumura, K. [Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578 (Japan); Ono, T. [Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578 (Japan); Fuji Electric Co., Ltd., Tokyo 191-8502 (Japan); Kikuchi, N.; Okamoto, S.; Kitakami, O. [Institute of Multidisciplinary Research for Advanced Material, Tohoku University, Sendai 980-8577 (Japan); Shimatsu, T. [Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578 (Japan); Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan)

    2014-05-07T23:59:59.000Z

    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.

  19. Frequency doubling crystals

    DOE Patents [OSTI]

    Wang, Francis (Danville, CA); Velsko, Stephan P. (Livermore, CA)

    1989-01-01T23:59:59.000Z

    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.

  20. Pulse-field actuation of collinear magnetic single crystals

    E-Print Network [OSTI]

    Jenkins, Catherine A. (Catherine Ann), 1981-

    2004-01-01T23:59:59.000Z

    Ferromagnetic shape memory alloys (FSMAs) are a class of alloys that exhibits the shape memory effect, as in the alloy nickel-titanium, sometimes known as Nitinol. In FSMAs, though, the shape changes are not brought on ...

  1. Single-Crystal Calcium Hexaboride Nanowires: Synthesis and

    E-Print Network [OSTI]

    at 860-900 °C and 155 mTorr in a quartz tube furnace. TEM electron diffraction and Raman spectroscopy tantalum crucible,21 by carbothermal reduction of calcium carbonate (CaCO3) and boron carbide (B4C) at 1400

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

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

    cancer, anemia gleaned from ribosome research Complex systems influence melting of Greenland ice sheet Related Articles All Stories Secure computing for the 'Everyman' goes to...

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

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

    on HIPPO," Vogel said. HIPPO handles a wide range of materials including rocks, battery materials, alloys, and nuclear fuel mock-ups. History of Rakovan and the Lujan...

  4. Single-crystal germanium growth on amorphous silicon

    E-Print Network [OSTI]

    McComber, Kevin A

    2011-01-01T23:59:59.000Z

    The integration of photonics with electronics has emerged as a leading platform for microprocessor technology and the continuation of Moore's Law. As electronic device dimensions shrink, electronic signals encounter crippling ...

  5. Epitaxial Single Crystal Nanostructures for Batteries & PVs > Research

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem NotEnergy,ARMFormsGasReleaseSpeeches EnergyActive

  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)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengtheningWildfires may contribute more toConsensus InitiativeWorld's largest

  7. Atomic- Resolution Crystal Structure of the Antiviral Lectin Scytovirin

    SciTech Connect (OSTI)

    Moulaei,T.; Botos, I.; Ziolkowska, N.; Bokesch, H.; Krumpe, L.; McKee, T.; O'Keefe, B.; Dauter, Z.; Wlodawer, A.

    2007-01-01T23:59:59.000Z

    The crystal structures of the natural and recombinant antiviral lectin scytovirin (SVN) were solved by single-wavelength anomalous scattering and refined with data extending to 1.3 Angstroms and 1.0 Angstroms resolution, respectively. A molecule of SVN consists of a single chain 95 amino acids long, with an almost perfect sequence repeat that creates two very similar domains (RMS deviation 0.25 Angstroms for 40 pairs of Ca atoms). The crystal structure differs significantly from a previously published NMR structure of the same protein, with the RMS deviations calculated separately for the N- and C-terminal domains of 5.3 Angstroms and 3.7 Angstroms, respectively, and a very different relationship between the two domains. In addition, the disulfide bonding pattern of the crystal structures differs from that described in the previously published mass spectrometry and NMR studies.

  8. 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., E-mail: inna.ivashchenko@mail.ru [Department of Inorganic and Physical Chemistry, Eastern European National University, Voli Ave 13, Lutsk 43025 (Ukraine); Danyliuk, I.V.; Olekseyuk, I.D. [Department of Inorganic and Physical Chemistry, Eastern European National University, Voli Ave 13, Lutsk 43025 (Ukraine); Halyan, V.V. [Department of General Physics, Eastern European National University, Voli Ave 13, Lutsk 43025 (Ukraine)

    2014-02-15T23:59:59.000Z

    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} ? 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{sub 0.01}){sub 2}Se{sub 3} were grown. • Some optical properties of these single crystals were studied.

  9. Heiniger, Wlti: Novel Single Crystal Diamonds for Waterjet Cutting Applications Novel Single Crystal Diamonds for Waterjet Cutting

    E-Print Network [OSTI]

    change in the cutting head. Furthermore water produced employing a reduced water treatment is sufficient of such orifices are strongly limited to only dozens of hours due to the high water pressure environment (typically 350 MPa) and contacts with abra- sives through the water hammer effect during cut-offs. Due to its

  10. Journal of Crystal Growth ] (

    E-Print Network [OSTI]

    ) at high pressure of CO2 (initial PCO2 ¼ 55 bar) and moderate to high temperature (30 and 90 1C) was used and the dissolved quantity of CO2 have a significant effect on the average particle size, specific surface areaJournal of Crystal Growth ] (

  11. Silicon crystal growing by oscillating crucible technique

    DOE Patents [OSTI]

    Schwuttke, G.H.; Kim, K.M.; Smetana, P.

    1983-08-03T23:59:59.000Z

    A process for growing silicon crystals from a molten melt comprising oscillating the container during crystal growth is disclosed.

  12. Parameterization of the scattering and absorption properties of individual ice crystals

    SciTech Connect (OSTI)

    Yang, Ping [Department of Atmospheric Sciences, University of California, Los Angeles (United States)] [Department of Atmospheric Sciences, University of California, Los Angeles (United States); Liou, K. N. [Department of Atmospheric Sciences, University of California, Los Angeles (United States)] [Department of Atmospheric Sciences, University of California, Los Angeles (United States); Wyser, Klaus [Department of Meteorology, Stockholm University, Stockholm (Sweden)] [Department of Meteorology, Stockholm University, Stockholm (Sweden); Mitchell, David [Atmospheric Sciences Center, Desert Research Institute, Reno, Nevada (United States)] [Atmospheric Sciences Center, Desert Research Institute, Reno, Nevada (United States)

    2000-02-27T23:59:59.000Z

    We present parameterizations of the single-scattering properties for individual ice crystals of various habits based on the results computed from the accurate light scattering calculations. The projected area, volume, and single-scattering properties of ice crystals with various shapes and sizes are computed for 56 narrow spectral bands covering 0.2-5 {mu}m. The ice crystal habits considered in this study are hexagonal plates, solid and hollow columns, planar and spatial bullet rosette, and aggregates that are commonly observed in cirrus clouds. Using the observational relationships between the aspect ratios and the sizes of ice crystals, we can define the three-dimensional structure of these ice crystal habits with respect to their maximum dimensions for light scattering calculations. The volume and projected area of ice crystals, expressed in terms of the diameters of the corresponding equivalent spheres, are first parameterized by employing the ice crystal maximum dimensions. Further, various analytical expressions as functions of the effective dimensions of ice crystals have been developed to parameterize the extinction and absorption efficiencies, asymmetry factor, and the truncation of the forward peak energy in the phase function. The present parameterization scheme provides an efficient approach to obtain the basic scattering and absorption properties of nonspherical ice crystals. (c) 2000 American Geophysical Union.

  13. Large mode-volume, large beta, photonic crystal laser resonator

    SciTech Connect (OSTI)

    Dezfouli, Mohsen Kamandar; Dignam, Marc M. [Department of Physics, Engineering Physics and Astronomy, Queen’s University, Kingston, ON K7L 3N6 (Canada)

    2014-12-15T23:59:59.000Z

    We propose an optical resonator formed from the coupling of 13, L2 defects in a triangular-lattice photonic crystal slab. Using a tight-binding formalism, we optimized the coupled-defect cavity design to obtain a resonator with predicted single-mode operation, a mode volume five times that of an L2-cavity mode and a beta factor of 0.39. The results are confirmed using finite-difference time domain simulations. This resonator is very promising for use as a single mode photonic crystal vertical-cavity surface-emitting laser with high saturation output power compared to a laser consisting of one of the single-defect cavities.

  14. Mid-Infrared Single Photon Counting

    E-Print Network [OSTI]

    Guilherme Temporao; Sebastien Tanzilli; Hugo Zbinden; Nicolas Gisin; Thierry Aellen; Marcella Giovannini; Jerome Faist

    2005-11-29T23:59:59.000Z

    We report a procedure to detect mid-infrared single photons at 4.65 um via a two-stage scheme based on Sum Frequency Generation, using a Periodically Poled Lithium Niobate (PPLN) nonlinear crystal and a Silicon Avalanche Photodiode. An experimental investigation shows that, in addition to a high timing resolution, this technique yields a detection sensitivity of 1.24 pW with 63mW of net pump power.

  15. Nano-manipulation of diamond-based single photon sources

    E-Print Network [OSTI]

    E. Ampem-Lassen; D. A. Simpson; B. C. Gibson; S. Trpkovski; F. M. Hossain; S. T. Huntington; K. Ganesan; L. C. L. Hollenberg; S. Prawer

    2009-05-18T23:59:59.000Z

    The ability to manipulate nano-particles at the nano-scale is critical for the development of active quantum systems. This paper presents a new technique to manipulate diamond nano-crystals at the nano-scale using a scanning electron microscope, nano-manipulator and custom tapered optical fibre probes. The manipulation of a ~ 300 nm diamond crystal, containing a single nitrogen-vacancy centre, onto the endface of an optical fibre is demonstrated. The emission properties of the single photon source post manipulation are in excellent agreement with those observed on the original substrate.

  16. Crystal face temperature determination means

    DOE Patents [OSTI]

    Nason, D.O.; Burger, A.

    1994-11-22T23:59:59.000Z

    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.

  17. Florida Nuclear Profile - Crystal River

    U.S. Energy Information Administration (EIA) Indexed Site

    Crystal River1" "Unit","Summer capacity (mw)","Net generation (thousand mwh)","Summer capacity factor (percent)","Type","Commercial operation date","License expiration date"...

  18. Nanofluidic tuning of photonic crystal circuits David Erickson,* Troy Rockwood, Teresa Emery, Axel Scherer, and Demetri Psaltis

    E-Print Network [OSTI]

    Erickson, David

    Nanofluidic tuning of photonic crystal circuits David Erickson,* Troy Rockwood, Teresa Emery, Axel; accepted September 16, 2005 By integrating soft-lithography-based nanofluidics with silicon nanophotonics spectral filtering through nanofluidic targeting of a single row of holes within a planar photonic crystal

  19. Shallow Melt Apparatus for Semicontinuous Czochralski Crystal Growth

    DOE Patents [OSTI]

    Wang, T.; Ciszek, T. F.

    2006-01-10T23:59:59.000Z

    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.

  20. crystal nickel a hree dimension

    E-Print Network [OSTI]

    Braun, Paul

    Zhenting 1 Department 2 Departmen ABSTRACT This pape crystal nickel a hree dimension photonic cryst polystyrene op silicon chips, volume fraction can be controlle nickel structure hen sacrificed volume fraction reports microm crystal structur or alumina she nickel microca microstructure further electrop volume

  1. Fast quantum dot single photon source triggered at telecommunications wavelength

    E-Print Network [OSTI]

    Kelley Rivoire; Sonia Buckley; Arka Majumdar; Hyochul Kim; Pierre Petroff; Jelena Vuckovic

    2010-12-20T23:59:59.000Z

    We demonstrate a quantum dot single photon source at 900 nm triggered at 300 MHz by a continuous wave telecommunications wavelength laser followed by an electro-optic modulator. The quantum dot is excited by on-chip-generated second harmonic radiation, resonantly enhanced by a GaAs photonic crystal cavity surrounding the InAs quantum dot. Our result suggests a path toward the realization of telecommunications-wavelength-compatible quantum dot single photon sources with speeds exceeding 1 GHz.

  2. Radiopurity of CaWO$_4$ Crystals for Direct Dark Matter Search with CRESST and EURECA

    E-Print Network [OSTI]

    Münster, A; Angloher, G; Bento, A; Bucci, C; Canonica, L; Erb, A; Feilitzsch, F v; Gorla, P; Gütlein, A; Hauff, D; Jochum, J; Kraus, H; Lanfranchi, J -C; Laubenstein, M; Loebell, J; Ortigoza, Y; Petricca, F; Potzel, W; Pröbst, F; Puimedon, J; Reindl, F; Roth, S; Rottler, K; Sailer, C; Schäffner, K; Schieck, J; Scholl, S; Schönert, S; Seidel, W; Stodolsky, L; Strandhagen, C; Strauss, R; Tanzke, A; Uffinger, M; Ulrich, A; Usherov, I; Wawoczny, S; Willers, M; Wüstrich, M; Zöller, A

    2014-01-01T23:59:59.000Z

    The direct dark matter search experiment CRESST uses scintillating CaWO$_4$ single crystals as targets for possible WIMP scatterings. An intrinsic radioactive contamination of the crystals as low as possible is crucial for the sensitivity of the detectors. In the past CaWO$_4$ crystals operated in CRESST were produced by institutes in Russia and the Ukraine. Since 2011 CaWO$_4$ crystals have also been grown at the crystal laboratory of the Technische Universit\\"at M\\"unchen (TUM) to better meet the requirements of CRESST and of the future tonne-scale multi-material experiment EURECA. The radiopurity of the raw materials and of first TUM-grown crystals was measured by ultra-low background $\\gamma$-spectrometry. Two TUM-grown crystals were also operated as low-temperature detectors at a test setup in the Gran Sasso underground laboratory. These measurements were used to determine the crystals' intrinsic $\\alpha$-activities which were compared to those of crystals produced at other institutes. The total $\\alpha$...

  3. Single Ion Implantation and Deterministic Doping

    SciTech Connect (OSTI)

    Schenkel, Thomas

    2010-06-11T23:59:59.000Z

    The presence of single atoms, e.g. dopant atoms, in sub-100 nm scale electronic devices can affect the device characteristics, such as the threshold voltage of transistors, or the sub-threshold currents. Fluctuations of the number of dopant atoms thus poses a complication for transistor scaling. In a complementary view, new opportunities emerge when novel functionality can be implemented in devices deterministically doped with single atoms. The grand price of the latter might be a large scale quantum computer, where quantum bits (qubits) are encoded e.g. in the spin states of electrons and nuclei of single dopant atoms in silicon, or in color centers in diamond. Both the possible detrimental effects of dopant fluctuations and single atom device ideas motivate the development of reliable single atom doping techniques which are the subject of this chapter. Single atom doping can be approached with top down and bottom up techniques. Top down refers to the placement of dopant atoms into a more or less structured matrix environment, like a transistor in silicon. Bottom up refers to approaches to introduce single dopant atoms during the growth of the host matrix e.g. by directed self-assembly and scanning probe assisted lithography. Bottom up approaches are discussed in Chapter XYZ. Since the late 1960's, ion implantation has been a widely used technique to introduce dopant atoms into silicon and other materials in order to modify their electronic properties. It works particularly well in silicon since the damage to the crystal lattice that is induced by ion implantation can be repaired by thermal annealing. In addition, the introduced dopant atoms can be incorporated with high efficiency into lattice position in the silicon host crystal which makes them electrically active. This is not the case for e.g. diamond, which makes ion implantation doping to engineer the electrical properties of diamond, especially for n-type doping much harder then for silicon. Ion implantation is usually a highly statistical process, where high fluences of energetic ions, ranging from {approx}10{sup 9} to >10{sup 16} cm{sup -2} are implanted. For single atom device development, control over the absolute number of ions is needed and ions have to be placed with high spatial resolution. In the following sections we will discuss a series of approaches to single ion implantation with regard to single ion impact sensing and control of single ion positioning.

  4. Lamella settler crystallizer

    DOE Patents [OSTI]

    Maimoni, A.

    1990-12-18T23:59:59.000Z

    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.

  5. Lamella settler crystallizer

    DOE Patents [OSTI]

    Maimoni, Arturo (Orinda, CA)

    1990-01-01T23:59:59.000Z

    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.

  6. Frequency mixing crystal

    DOE Patents [OSTI]

    Ebbers, Christopher A. (Livermore, CA); Davis, Laura E. (Manteca, CA); Webb, Mark (Salida, CA)

    1992-01-01T23:59:59.000Z

    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.

  7. Design of photonic crystal microcavities for cavity QED

    E-Print Network [OSTI]

    Jelena Vuckovic; Marko Loncar; Hideo Mabuchi; Axel Scherer

    2002-08-15T23:59:59.000Z

    We discuss the optimization of optical microcavity designs based on 2D photonic crystals for the purpose of strong coupling between the cavity field and a single neutral atom trapped within a hole. We present numerical predictions for the quality factors and mode volumes of localized defect modes as a function of geometric parameters, and discuss some experimental challenges related to the coupling of a defect cavity to gas-phase atoms.

  8. Crystal-Tolerant Glass Approach For Mitigation Of Crystal Accumulation In Continuous Melters Processing Radioactive Waste

    SciTech Connect (OSTI)

    Kruger, Albert A. [Department of Energy, Office of River Protection, Richland, Washington (United States); Rodriguez, Carmen P. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Lang, Jesse B. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Huckleberry, Adam R. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Matyas, Josef [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Owen, Antoinette T. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

    2012-08-28T23:59:59.000Z

    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.

  9. Inclusion free cadmium zinc tellurium and cadmium tellurium crystals and associated growth method

    DOE Patents [OSTI]

    Bolotnikov, Aleskey E. (South Setauket, NY); James, Ralph B. (Ridge, NY)

    2010-07-20T23:59:59.000Z

    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.

  10. Sixty years from discovery to solution: crystal structure of bovine liver catalase form III

    SciTech Connect (OSTI)

    Foroughi, Leila M.; Kang, You-Na; Matzger, Adam J. (Michigan)

    2012-03-27T23:59:59.000Z

    The crystallization and structural characterization of bovine liver catalase (BLC) has been intensively studied for decades. Forms I and II of BLC have previously been fully characterized using single-crystal X-ray diffraction. Form III has previously been analyzed by electron microscopy, but owing to the thinness of this crystal form an X-ray crystal structure had not been determined. Here, the crystal structure of form III of BLC is presented in space group P212121, with unit-cell parameters a = 68.7, b = 173.7, c = 186.3 {angstrom}. The asymmetric unit is composed of the biological tetramer, which is packed in a tetrahedron motif with three other BLC tetramers. This higher resolution structure has allowed an assessment of the previously published electron-microscopy studies.

  11. CARS polarized microscopy of three-dimensional director structures in liquid crystals

    E-Print Network [OSTI]

    A. V. Kachynski; A. N. Kuzmin; P. N. Prasad; I. I. Smalyukh

    2007-10-18T23:59:59.000Z

    We demonstrate three-dimensional vibrational imaging of director structures in liquid crystals using coherent anti-Stokes Raman scattering (CARS) polarized microscopy. Spatial mapping of the structures is based on sensitivity of a polarized CARS signal to orientation of anisotropic molecules in liquid crystals. As an example, we study structures in a smectic material and demonstrate that single-scan CARS and two-photon fluorescence images of molecular orientation patterns are consistent with each other and with the structure model.

  12. Synthesis and crystal structure studies of ethyl 5-methyl-1, 3-diphenyl-1H-pyrazole-4-carboxylate

    SciTech Connect (OSTI)

    Chandra,; Babu, E. A. Jithesh; Mahendra, M., E-mail: mahendra@physics.uni-mysore.ac.in [Department of Studies in Physics, Manasagangotri, University of Mysore, Mysore-570006 (India); Srikantamurthy, N.; Umesha, K. B. [Department of Chemistry, Yuvaraja's College, University of Mysore, Mysore-570005 (India)

    2014-04-24T23:59:59.000Z

    The title compound, C{sub 19}H{sub 18}N{sub 2}O{sub 2}, was investigated by single crystal X-ray diffraction method. It crystallizes in monoclinic class under the space group P2{sub 1}/c with cell parameters a= 8.4593(4) Å, b=15.6284(6) Å, c=12.4579(5) Å, ?=90°, ?=98.241(3)°, ?=90° and Z=2. The ethoxycarbonyl group is slightly twisted from the pyrazole ring, and adopts syn-periplanar conformation. The crystal structure is stabilized by intermolecular C-H….O hydrogen bonds, which help in stabilizing the crystal structure.

  13. 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

    2008-02-12T23:59:59.000Z

    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.

  14. Spontaneous parametric down conversion in chirped, aperiodically-poled crystals

    E-Print Network [OSTI]

    X. Sanchez-Lozano; Jose Luis Lucio; Alfred U'Ren

    2014-12-23T23:59:59.000Z

    We present a theoretical analysis of the process of spontaneous parametric down conversion (SPDC) in a non-linear crystal characterized by a linearly-chirped X(2) grating along the direction of propagation. Our analysis leads to an expression for the joint spectral amplitude, based on which we can derive various spectral-temporal properties of the photon pairs and of the heralded single photons obtained from the photon pairs, including: the single photon spectrum, the chronocyclic Wigner function and the Schmidt number. The simulations that we present are for the specific case of a collinear SPDC source based on a PPLN crystal with the signal and idler photons emitted close to the telecom window. We discuss the mechanism for spectral broadening due to the presence of a linearly chirped X(2) grating, showing that not only the width but also to some extent the shape of the SPDC spectrum maybe controlled. Also, we discuss how the fact that the different spectral components are emitted on different planes in the crystal leads to single-photon chirp.

  15. Enhanced photoacoustic detection using photonic crystal substrate

    SciTech Connect (OSTI)

    Zhao, Yunfei; Liu, Kaiyang [Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa 50011 (United States); McClelland, John [Ames Laboratory-USDOE, Ames, Iowa 50011 (United States); Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States); Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011 (United States); Lu, Meng, E-mail: menglu@iastate.edu [Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa 50011 (United States); Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2014-04-21T23:59:59.000Z

    This paper demonstrates the enhanced photoacoustic sensing of surface-bound light absorbing molecules and metal nanoparticles using a one-dimensional photonic crystal (PC) substrate. The PC structure functions as an optical resonator at the wavelength where the analyte absorption is strong. The optical resonance of the PC sensor provides an intensified evanescent field with respect to the excitation light source and results in enhanced optical absorption by surface-immobilized samples. For the analysis of a light absorbing dye deposited on the PC surface, the intensity of photoacoustic signal was enhanced by more than 10-fold in comparison to an un-patterned acrylic substrate. The technique was also applied to detect gold nanorods and exhibited more than 40 times stronger photoacoustic signals. The demonstrated approach represents a potential path towards single molecule absorption spectroscopy with greater performance and inexpensive instrumentation.

  16. Crystal diffraction lens telescope for focusing nuclear gamma rays

    SciTech Connect (OSTI)

    Smither, R.K.; Fernandez, P.B.; Graber, T. [Argonne National Lab., IL (United States). Advanced Photon Source; Ballmoos, P. von; Naya, J.; Albernhe, F.; Vedrenne, G. [Centre d`Etude Spatiale des Rayonnements, Toulouse (France); Faiz, M. [KFUPM, Dhahran (Saudi Arabia). Physics Dept.

    1996-08-01T23:59:59.000Z

    A crystal diffraction lens was constructed at Argonne National Laboratory for use as a telescope to focus nuclear gamma rays. It consisted of 600 single crystals of germanium arranged in 8 concentric rings. The mounted angle of each crystal was adjusted to intercept and diffract the incoming gamma rays with an accuracy of a few arc sec. The performance of the lens was tested in two ways. In one case, the gamma rays were focused on a single medium size germanium detector. In the second case, the gamma rays were focused on the central germanium detector of a 3 x 3 matrix of small germanium detectors. The efficiency, image concentration and image quality, and shape were measured. The tests performed with the 3 x 3 matrix detector system were particularly interesting. The wanted radiation was concentrated in the central detector. The 8 other detectors were used to detect the Compton scattered radiation, and their energy was summed with coincident events in the central detector. This resulted in a detector with the efficiency of a large detector (all 9 elements) and the background of a small detector (only the central element). The use of the 3 x 3 detector matrix makes it possible to tell if the source is off axis and, if so, to tell in which direction. The crystal lens acts very much like a simple convex lens for visible light. Thus if the source is off to the left then the image will focus off to the right illuminating the detector on the right side: telling one in which direction to point the telescope. Possible applications of this type of crystal lens to balloon and satellite experiments will be discussed.

  17. Crystal-Like geometric modeling

    E-Print Network [OSTI]

    Landreneau, Eric Benjamin

    2006-08-16T23:59:59.000Z

    faces, symmetry, and fractal geometry. The techniques have also been implemented in software, as a proof of concept. They are used in an interactive geometric modeling system, in which users can use these techniques to create crystal-like shapes...

  18. Active materials in photonic crystals

    E-Print Network [OSTI]

    Bermel, Peter (Peter A.)

    2007-01-01T23:59:59.000Z

    I analyze new phenomena arising from embedding active materials inside of photonic crystal structures. These structures strongly modify the photonic local density of states (LDOS), leading to quantitative and qualitative ...

  19. Minimizing radiation damage in nonlinear optical crystals

    DOE Patents [OSTI]

    Cooke, D. Wayne (Santa Fe, NM); Bennett, Bryan L. (Los Alamos, NM); Cockroft, Nigel J. (Santa Fe, NM)

    1998-01-01T23:59:59.000Z

    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.

  20. Minimizing radiation damage in nonlinear optical crystals

    DOE Patents [OSTI]

    Cooke, D.W.; Bennett, B.L.; Cockroft, N.J.

    1998-09-08T23:59:59.000Z

    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.

  1. Crystal Potential Formula for the Calculation of Crystal Lattice Sums1 Don Steiger and Calvin Ahlbrandt

    E-Print Network [OSTI]

    Glaser, Rainer

    Crystal Potential Formula for the Calculation of Crystal Lattice Sums1 Don Steiger and Calvin; In Final Form: April 7, 1998 A new formula is derived for the determination of the potential energy of the central unit cell of a finite crystal; this formula is called the crystal potential formula. The crystal

  2. Growth and optical characterizations on 3-aminophenol perchlorate (3-AMPP) crystal

    SciTech Connect (OSTI)

    Boopathi, K., E-mail: ramasamyp@ssn.edu.in; Ramasamy, P., E-mail: ramasamyp@ssn.edu.in [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam-603110 (India)

    2014-04-24T23:59:59.000Z

    A single crystal of organic nonlinear optical material 3-aminophenol perchlorate (3-AMP) was successfully grown by the slow evaporation solution method. Single-crystal X-ray diffractrometer was utilized to measure unit cell parameters and to confirm lattice parameter. 3-aminophenol perchlorate belongs to monoclinic space group P2{sub 1}. The optical transparency window in the UV-vis-NIR region is found to be good for nonlinear optical applications second harmonic studies were carried out. The second harmonic output intensity was tested using the Kurtz and Perry powder method and was found to be 1.1 times that of potassium dihydrogen phosphate (KDP)

  3. 1 Plasmodium falciparum SSB Tetramer Wraps 2 Single-Stranded DNA with Similar Topology but

    E-Print Network [OSTI]

    Lohman, Timothy M.

    1 Plasmodium falciparum SSB Tetramer Wraps 2 Single-Stranded DNA with Similar Topology but 3 methods, we show that Pf-SSB forms a stable homo-tetramer 32 alone and when bound to single-stranded DNA (ssDNA). We also present a 33 crystal structure at 2.1 Å resolution of the Pf-SSB tetramer bound

  4. Synthesis and crystal structure of CuZrTiO{sub 5}-A new crystal structure type

    SciTech Connect (OSTI)

    Troitzsch, Ulrike [Research School of Earth Sciences, Australian National University, Canberra ACT 0200 (Australia); Christy, Andrew G., E-mail: Andrew.Christy@anu.edu.a [Research School of Earth Sciences, Australian National University, Canberra ACT 0200 (Australia); Willis, Anthony C. [Research School of Chemistry, Australian National University, Canberra ACT 0200 (Australia); Ellis, David J. [Research School of Earth Sciences, Australian National University, Canberra ACT 0200 (Australia)

    2010-03-15T23:59:59.000Z

    A new compound, CuZrTiO{sub 5}, was synthesized as strongly pleochroic green crystals from the oxides between 995 and 1010 deg. C, 1 atm. Its crystal structure was determined by single crystal XRD, resulting in R (F{sup 2}>2sigma(F{sup 2}))=0.032 and wR (all data)=0.079). CuZrTiO{sub 5} is orthorhombic, space group P2{sub 1}2{sub 1}2{sub 1}, a=3.5871(3) A, b=6.6968(4) A, c=14.6679(9) A, V=352.35(4) A{sup 3}, Z=4. The structure is topologically similar to In{sub 2}TiO{sub 5} but differs in space group and cation coordination. CuZrTiO{sub 5} has relatively regular TiO{sub 6} polyhedra, but coordination is 7+1 for Zr, and 4+2 for Cu due to the Jahn-Teller effect. Ordering of the long Cu-O bonds causes reduction in symmetry relative to In{sub 2}TiO{sub 5}. Layers of Cu alternate with Ti+Zr on (001), giving rise to a distinct cleavage. Bond valence sums on Ti and Zr are far from ideal, which appears due to the limited ability of this structural topology to avoid close next-nearest neighbour distances. - Graphical abstract: The new compound CuZrTiO{sub 5} is orthorhombic (P2{sub 1}2{sub 1}2{sub 1}), with a=3.5871(3) A, b=6.6968(4) A, c=14.6679(9) A. The structure, determined with single crystal XRD, represents a new crystal structure type that is a slight distortion of that of In{sub 2}TiO{sub 5} but differs in space group and cation coordination.

  5. Adaptive Liquid Crystal Windows

    SciTech Connect (OSTI)

    Taheri, Bahman; Bodnar, Volodymyr

    2011-12-31T23:59:59.000Z

    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 world’s 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 AlphaMicron’s 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 consumption by ALCWs allows for on-board power electronics for automatic matching of transmission through windows to varying climate conditions without drawing the power from the power grid. ALCWs are capable of transmitting more sunlight in winters to assist in heating and less sunlight in summers to minimize overheating. As such, they can change the window from being a source of energy loss to a source of energy gain. In addition, the scalable AMI’s roll-to-roll process, proved by making 1ft × 1ftALCW prototype panels, allows for cost-effective production of large-scale window panels along with capability to change easily their color and shape. In addition to architectural glazing in houses and commercial buildings, ALCWs can be used in other applications where control of sunlight is needed, such as green houses, used by commercial produce growers and botanical gardens, cars, aircrafts, etc.

  6. World's Largest Gold Crystal Studied at Los Alamos

    ScienceCinema (OSTI)

    Vogel, Sven; Nakotte, Heinz

    2015-01-07T23:59:59.000Z

    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.

  7. automated crystal screening: Topics by E-print Network

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

    high crystallization rates and the production of diffraction-quality crystals. microfluidics Quake, Stephen R. 5 Data Mining Crystallization Databases: Knowledge-Based...

  8. Inclusion property of Cs, Sr, and Ba impurities in LiCl crystal formed by layer-melt crystallization

    SciTech Connect (OSTI)

    Choi, Jung-Hoon; Cho, Yung-Zun; Lee, Tae-Kyo; Eun, Hee-Chul; Kim, Jun-Hong; Park, Hwan-Seo; Kim, In-Tae; Park, Geun-Il [Nuclear Fuel Cycle Waste Treatment Research Division, Korea Atomic Energy Research Institute, Daejeon, 305-353 (Korea, Republic of)

    2013-07-01T23:59:59.000Z

    Pyroprocessing is one of the promising technologies enabling the recycling of spent nuclear fuels from a commercial light water reactor (LWR). In general, pyroprocessing uses dry molten salts as electrolytes. In particular, LiCl waste salt after pyroprocessing contains highly radioactive I/II group fission products mainly composed of Cs, Sr, and Ba impurities. Therefore, it is beneficial to reuse LiCl salt in the pyroprocessing as an electrolyte for economic and environmental issues. Herein, to understand the inclusion property of impurities within LiCl crystal, the physical properties such as lattice parameter change, bulk modulus, and substitution enthalpy of a LiCl crystal having 0-6 at% Cs{sup +} or Ba{sup 2+} impurities under existence of 1 at% Sr{sup 2+} impurity were calculated via the first-principles density functional theory. The substitution enthalpy of LiCl crystals having 1 at% Sr{sup 2+} showed slightly decreased value than those without Sr{sup 2+} impurity. Therefore, through the substitution enthalpy calculation, it is expected that impurities will be incorporated within LiCl crystal as co-existed form rather than as a single component form. (authors)

  9. Simulation of the Extinction Efficiency, the Absorption Efficiency and the Asymmetry Factor of Ice Crystals and Relevant Applications to the Study of Cirrus Cloud Radiative Properties

    E-Print Network [OSTI]

    Lu, Kai

    2010-10-12T23:59:59.000Z

    The single-scattering properties of six non-spherical ice crystals, droxtals, plates, solid columns, hollow columns, aggregates and 6-branch bullet rosettes are simulated. The anomalous diffraction theory (ADT) is applied to the simulation...

  10. Importance of excitonic effects and the question of internal electric fields in stacking faults and crystal phase quantum discs: The model-case of GaN

    E-Print Network [OSTI]

    Corfdir, Pierre; Lefebvre, Pierre

    2012-01-01T23:59:59.000Z

    , a significant binding and a rather strong oscillator strength are preserved by excitonic effects. When adjacent crystal phase QWs are coupled together, we compute increased as well as decreased exciton oscillator strength with respect to the single...

  11. Precision Crystal Calorimeters in High Energy Physics

    ScienceCinema (OSTI)

    Ren-Yuan Zhu

    2010-01-08T23:59:59.000Z

    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.

  12. Crystallization during processing of nuclear waste glass

    SciTech Connect (OSTI)

    Hrma, Pavel R.

    2010-12-01T23:59:59.000Z

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glassmaking are reviewed.

  13. Studies on L-citrulline doped potassium dihydrogen phosphate- A non linear crystal with significant nonlinear properties

    SciTech Connect (OSTI)

    Sreevalsa, V. G., E-mail: sreevalsavg@gmail.com, E-mail: jayalekshmi@cusat.ac.in; Jayalekshmi, S., E-mail: sreevalsavg@gmail.com, E-mail: jayalekshmi@cusat.ac.in [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Kochi, 682022, Kerala (India)

    2014-01-28T23:59:59.000Z

    Potassium Dihydrogen Phosphate (KDP) single crystal is considered as one of the best representative of nonlinear optical crystals. Recently, amino acids having excellent nonlinear optical characteristics are being investigated as prospective dopants to improve the non linear optical characteristics of KDP. The present work is an attempt in this direction and L citrulline, one of the non essential amino acids showing good non linear optical characteristics is used as the dopant for KDP. Good quality crystals of L-citrulline doped KDP crystals were grown by slow evaporation technique. From the powder X-ray diffraction studies of doped KDP crystal, the structure of the doped crystals was determined by direct method and refined by Pawley method employing Topaz version program using the single crystal X-ray data for pure KDP. The lattice parameters for L citrulline doped KDP are a=7.467A{sup 0}, b=7.467 A{sup 0}, c=6.977 A{sup 0}. The crystal falls into the tetragonal crystal system with space group I42 d. The presence of carbon and oxygen, which are primary components of amino acids, in the EDAX spectrum confirms the effectiveness of doping. The absorption spectra of the doped samples show that the crystals are transparent in the entire visible region. The second harmonic generation efficiency of the doped samples was determined by Kurtz powder technique using the Q-switched Nd:YAG laser beam and is found to be 2.2 times that of KDP. The nonlinear optical properties can be well studied by the open aperture Z scan technique. The open aperture curve exhibits a normalized transmittance valley. The nonlinear absorption coefficient ? is obtained by theoretical fitting for two photon absorption. It is inferred that doping KDP with L citrulline has enhanced the nonlinearity considerably. This obviously suggests the potentiality of the crystal as an optical power limiter and also for various optical device applications.

  14. Crystal-field effects in fluoride crystals for optical refrigeration

    SciTech Connect (OSTI)

    Hehlen, Markus P [Los Alamos National Laboratory

    2010-01-01T23:59:59.000Z

    The field of optical refrigeration of rare-earth-doped solids has recently seen an important breakthrough. The cooling of a YLiF{sub 4} (YLF) crystal doped with 5 mol% Yb3+ to 155 K by Seletskiy et al [NPhot] has surpassed the lowest temperatures ({approx}170 K for {approx}100 mW cooling capacity) that are practical with commercial multi-stage thermoelectric coolers (TEC) [Glaister]. This record performance has advanced laser cooling into an application relevant regime and has put first practical optical cryocoolers within reach. The result is also relevant from a material perspective since for the first time, an Yb3+-doped crystal has outperformed an Yb3+-doped glass. The record temperature of 208 K was held by the Yb3+-doped fluorozirconate glass ZBLAN. Advanced purification and glass fabrication methods currently under development are expected to also advance ZBLAN:Yb3+ to sub-TEC temperatures. However, recent achievements with YLF:Yb3+ illustrate that crystalline materials may have two potentially game-changing advantajes over glassy materials. First, the crystalline environment reduces the inhomogeneous broadening of the Yb3+ electronic transitions as compared to a glassy matrix. The respective sharpening of the crystal-field transitions increases the peak absorption cross section at the laser excitation wavelength and allows for more efficient pumping of the Yb3+ ions, particularly at low temperatures. Second, many detrimental impurities present in the starting materials tend to be excluded from the crystal during its slow growth process, in contrast to a glass where all impurities present in the starting materials are included in the glass when it is formed by temperature quenching a melt. The ultra high purity required for laser cooling materials [PRB] therefore may be easier to realize in crystals than in glasses. Laser cooling occurs by laser excitation of a rare-earth ion followed by anti-Stokes luminescence. Each such laser-cooling cycle extracts thermal energy from the solid and carries it away as high-entropy light, thereby cooling the material. In the ideal case, the respective laser-cooling power is given by the pump wavelength ({lambda}{sub p}), the mean fluorescence wavelength ({bar {lambda}}{sub L}), and the absorption coefficient (a{sub r}) of the pumped transition. These quantities are solely determined by crystal field interactions. On one hand, a large crystal-field splitting offers a favorably large difference of {lambda}{sub p} - {bar {lambda}}{sub L} and thus a high cooling efficiency {eta}{sub cool} = ({lambda}{sub p} - {bar {lambda}}{sub L})/{bar {lambda}}{sub L}. On the other hand, a small crystal-field splitting offers a high thermal population (n{sub i}) of the initial state of the pumped transition, giving a high pump absorption coefficient and thus high laser cooling power, particularly at low temperatures. A quantitative description of crystal-field interactions is therefore critical to the understanding and optimization of optical refrigeration. In the case of Yb3+ as the laser cooling ion, however, development of a crystal-field model is met with substantial difficulties. First, Yb3+ has only two 4/multiplets, {sup 2}F{sub 7/2} and {sup 2}F{sub 5/2}, which lead to at most 7 crystal-field levels. This makes it difficult, and in some cases impossible, to evaluate the crystal-field Hamiltonian, which has at least 4 parameters for any Yb3+ point symmety lower than cubic. Second, {sup 2}F{sub 7/2}{leftrightarrow}{sup 2}F{sub 5/2} transitions exhibit an exceptionally strong electron-phonon coupling compared to 4f transitions of other rare earths. This makes it difficult to distinguish electronic from vibronic transitions in the absorption and luminescence spectra and to reliably identify the crystal-field levels. Yb3+ crystal-field splittings reported in the literature should thus generally be viewed with caution. This paper explores the effects of crystal-field interactions on the laser cooling performance of Yb3+-doped fluoride crystals. It is shown that the total crystal-field splitting o

  15. 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

    2013-01-29T23:59:59.000Z

    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.

  16. X-ray imaging crystal spectrometer for extended X-ray sources

    DOE Patents [OSTI]

    Bitter, Manfred L. (Princeton, NJ); Fraenkel, Ben (Jerusalem, IL); Gorman, James L. (Bordentown, NJ); Hill, Kenneth W. (Lawrenceville, NJ); Roquemore, A. Lane (Cranbury, NJ); Stodiek, Wolfgang (Princeton, NJ); von Goeler, Schweickhard E. (Princeton, NJ)

    2001-01-01T23:59:59.000Z

    Spherically or toroidally curved, double focusing crystals are used in a spectrometer for X-ray diagnostics of an extended X-ray source such as a hot plasma produced in a tokomak fusion experiment to provide spatially and temporally resolved data on plasma parameters using the imaging properties for Bragg angles near 45. For a Bragg angle of 45.degree., the spherical crystal focuses a bundle of near parallel X-rays (the cross section of which is determined by the cross section of the crystal) from the plasma to a point on a detector, with parallel rays inclined to the main plain of diffraction focused to different points on the detector. Thus, it is possible to radially image the plasma X-ray emission in different wavelengths simultaneously with a single crystal.

  17. Heat Transfer Measurements for a Horizontal Micro-Tube Using Liquid Crystal Thermography

    E-Print Network [OSTI]

    Ghajar, Afshin J.

    62 TC02-007 Heat Transfer Measurements for a Horizontal Micro-Tube Using Liquid Crystal thermography (LCT) method was developed for surface temperature measurements on a horizontal 2000m macro-tube and 1000m micro-tube. In the single-phase heat transfer experiments, the fully-developed flow heat transfer

  18. Sub-wavelength nanofluidics in photonic crystal Min Huang,1,2

    E-Print Network [OSTI]

    Sub-wavelength nanofluidics in photonic crystal sensors Min Huang,1,2 Ahmet Ali Yanik,1,2 , Tsung: We introduce a novel sensor scheme combining nano-photonics and nano-fluidics on a single platform and mechanical approaches to biomolecular detection at the nanoscale." Microfluid. Nanofluid. 4(1­2), 33­52 (2007

  19. Integration of sub-wavelength nanofluidics on suspended photonic crystal sensors

    E-Print Network [OSTI]

    Huang, Min

    In this paper, we introduce a novel sensor scheme which merges nano-photonics and nano-fluidics on a single platform through the use of free-standing photonic crystals (PhCs). PhCs offer great freedom to manipulate the ...

  20. Measurement of reflective liquid crystal displays S. T. Tang and H. S. Kwoka)

    E-Print Network [OSTI]

    Measurement of reflective liquid crystal displays S. T. Tang and H. S. Kwoka) Department . Existing measurement methods only apply to transmittive LC cells. These methods are obviously unsuitable for measuring the cell gaps of reflective LCDs with internal reflectors. This kind of LCD includes single

  1. Crystallization in High-Level Waste Glasses

    SciTech Connect (OSTI)

    Hrma, Pavel R. (BATTELLE (PACIFIC NW LAB)); Dane R Spearing, Gary L Smith, SK Sundaram

    2002-01-01T23:59:59.000Z

    This review outlines important aspects of crystallization in HLW glasses, such as equilibrium, nucleation, growth, and dissolution. The impact of crystallization on continuous melters and the chemical durability of high-level waste glass are briefly discussed.

  2. A Diamond Nanowire Single Photon Antenna

    E-Print Network [OSTI]

    Tom Babinec; Birgit J. M. Hausmann; Mughees Khan; Yinan Zhang; Jero Maze; Philip R. Hemmer; Marko Loncar

    2009-10-28T23:59:59.000Z

    The development of a robust light source that emits one photon at a time is an outstanding challenge in quantum science and technology. Here, at the transition from many to single photon optical communication systems, fully quantum mechanical effects may be utilized to achieve new capabilities, most notably perfectly secure communication via quantum cryptography. Practical implementations place stringent requirements on the device properties, including stable photon generation, room temperature operation, and efficient extraction of many photons. Single photon light emitting devices based on fluorescent dye molecules, quantum dots, and carbon nanotube material systems have all been explored, but none have simultaneously demonstrated all criteria. Here, we describe the design, fabrication, and characterization of a bright source of single photons consisting of an individual Nitrogen-vacancy color center (NV center) in a diamond nanowire operating in ambient conditions. The nanowire plays a positive role in increasing the number of single photons collected from the NV center by an order of magnitude over devices based on bulk diamond crystals, and allows operation at an order of magnitude lower power levels. This result enables a new class of nanostructured diamond devices for room temperature photonic and quantum information processing applications, and will also impact fields as diverse as biological and chemical sensing, opto-mechanics, and scanning-probe microscopy.

  3. Potash Crystallization Lynn Batten1

    E-Print Network [OSTI]

    Tsatsomeros, Michael

    fertilizer and industrial chemical, from saturated brines. Typically, hot brine at about 100 C is cooled, knowledge of the spatial distribution of the chemical supersaturation state of the brine would help to improve the process control objectives: · Define conditions for crystal growth · Minimize occluded brine

  4. Robotic CCD microscope for enhanced crystal recognition

    DOE Patents [OSTI]

    Segelke, Brent W. (San Ramon, CA); Toppani, Dominique (Livermore, CA)

    2007-11-06T23:59:59.000Z

    A robotic CCD microscope and procedures to automate crystal recognition. The robotic CCD microscope and procedures enables more accurate crystal recognition, leading to fewer false negative and fewer false positives, and enable detection of smaller crystals compared to other methods available today.

  5. Crystal structure, growth and characterization of LiPbB?O??: A new congruent melting nonlinear optical crystal

    SciTech Connect (OSTI)

    Xia, M.J.; Li, R.K., E-mail: rkli@mail.ipc.ac.cn

    2013-05-01T23:59:59.000Z

    A new congruent-melting crystal LiPbB?O?? (LPBO) has been grown and its structure was determined by single crystal X-ray diffraction. LPBO crystallizes in a polar space group R3c with a large unit cell of a=b=21.649(11) Å, c=17.193(11) Å, and Z=24. The basic anionic unit, (B?O?)?? group, is connected by terminal O atoms to build an infinite [(B?O?)?]? helical chain along the c axis. Second harmonic generation (SHG) measurements of the title compound indicate that LPBO can be phase matchable and its SHG coefficient is almost equal to that of KDP, which is about 3.3 times that of its analog BaLiB?O??. This significant enhancement of the SHG effect can be tentatively attributed to the lone pair Pb²? cations with severely distorted coordination. LPBO has a wide transparent region from 410 to 2500 nm with a UV absorption edge about 261 nm according to the reflectance spectra. - Graphical abstract: The crystal structure of LiPbB?O?? composed of the (B?O?)?? anionic group and the lone pair Pb and Li polyhedra along c axis. Highlights: • A new congruent-melt NLO crystal LiPbB?O?? (LPBO) has been grown. • The basic structural unit of LPBO is B?O? group same as that found in LiB?O?. • LPBO is phase matchable with SHG signal 10 times that of its Ba-analog. • LPBO is highly transparent within 410–1700 nm with a UV cut-off of 261 nm.

  6. Optical properties of two-dimensional metamaterial photonic crystals

    SciTech Connect (OSTI)

    Mejía-Salazar, J. R. [Departamento de Física, Universidad del Valle, AA 25360, Cali, Colombia and Instituto de Física, UNICAMP, Campinas-SP 13083-859 (Brazil)

    2013-12-14T23:59:59.000Z

    In the present work, we theoretically study a 2D photonic crystal (PC) comprised by double negative (DNG) metamaterial cylinders, showing that such a system presents a superior light-matter interaction when compared with their single negative (SNG) plasmonic PC counterparts, suggesting a route to enhance the performance of sensors and photovoltaic cells. On the other hand, we have observed that depending on the frequency, the mode symmetry resembles either the case of SNG electric (SNG-E) or SNG magnetic (SNG-M) PC, suggesting that either the electric or magnetic character of the DNG metamaterial dominates in each case.

  7. An ion trap built with photonic crystal fibre technology

    E-Print Network [OSTI]

    F. Lindenfelser; B. Keitch; D. Kienzler; D. Bykov; P. Uebel; M. A. Schmidt; P. St. J. Russell; J. P. Home

    2015-01-20T23:59:59.000Z

    We demonstrate a surface-electrode ion trap fabricated using techniques transferred from the manufacture of photonic-crystal fibres. This provides a relatively straightforward route for realizing traps with an electrode structure on the 100 micron scale with high optical access. We demonstrate the basic functionality of the trap by cooling a single ion to the quantum ground state, allowing us to measure a heating rate from the ground state of 787(24) quanta/s. Variation of the fabrication procedure used here may provide access to traps in this geometry with trap scales between 100 um and 10 um.

  8. An ion trap built with photonic crystal fibre technology

    E-Print Network [OSTI]

    Lindenfelser, F; Kienzler, D; Bykov, D; Uebel, P; Schmidt, M A; Russell, P St J; Home, J P

    2015-01-01T23:59:59.000Z

    We demonstrate a surface-electrode ion trap fabricated using techniques transferred from the manufacture of photonic-crystal fibres. This provides a relatively straightforward route for realizing traps with an electrode structure on the 100 micron scale with high optical access. We demonstrate the basic functionality of the trap by cooling a single ion to the quantum ground state, allowing us to measure a heating rate from the ground state of 787(24) quanta/s. Variation of the fabrication procedure used here may provide access to traps in this geometry with trap scales between 100 um and 10 um.

  9. High-power efficient cw and pulsed lasers based on bulk Yb : KYW crystals with end diode pumping

    SciTech Connect (OSTI)

    Kim, G H; Yang, G H; Lee, D S; Kulik, Alexander V; Sall', E G; Chizhov, S A; Yashin, V E; Kang, U

    2012-04-30T23:59:59.000Z

    End-diode-pumped lasers based on one and two Yb : KYW crystals operating in cw and Q-switched regimes, as well as in the regime of mode-locking, are studied. The single-crystal laser generated stable ultrashort (shorter than 100 fs) laser pulses at wavelengths of 1035 and 1043 nm with an average power exceeding 1 W. The average output power of the two-crystal laser exceeded 18 W in the cw regime and 16 W in the Q-switched regime with a slope efficiency exceeding 30%.

  10. Crystal structure refinement with SHELXL

    SciTech Connect (OSTI)

    Sheldrick, George M., E-mail: gsheldr@shelx.uni-ac.gwdg.de [Department of Structural Chemistry, Georg-August Universität Göttingen, Tammannstraße 4, Göttingen 37077 (Germany)

    2015-01-01T23:59:59.000Z

    New features added to the refinement program SHELXL since 2008 are described and explained. The improvements in the crystal structure refinement program SHELXL have been closely coupled with the development and increasing importance of the CIF (Crystallographic Information Framework) format for validating and archiving crystal structures. An important simplification is that now only one file in CIF format (for convenience, referred to simply as ‘a CIF’) containing embedded reflection data and SHELXL instructions is needed for a complete structure archive; the program SHREDCIF can be used to extract the .hkl and .ins files required for further refinement with SHELXL. Recent developments in SHELXL facilitate refinement against neutron diffraction data, the treatment of H atoms, the determination of absolute structure, the input of partial structure factors and the refinement of twinned and disordered structures. SHELXL is available free to academics for the Windows, Linux and Mac OS X operating systems, and is particularly suitable for multiple-core processors.

  11. Commercial Application of Freeze Crystallization

    E-Print Network [OSTI]

    Gorgol, R. G.

    COMMERCIAL APPLICATION OF FREEZE CRYSTALLIZATION ROBERT G. GORGOL, MARKETING MANAGER, HPD INCORPORATED, NAPERVILLE, ILLINOIS ABSTRACT Industrial usc of frcezing for componcnt purification and separation is well understood, but commercial... of purification, but they did understand the water they obtained from ice was potable. RECENT APPLICATIONS Scientists have understood the basic mechanism of the freezing phase change for many years. ID an effort to harness the power of this phenomena...

  12. Abstract crystals Department of Mathematics

    E-Print Network [OSTI]

    Ram, Arun

    is a normal crystal define a bijection si : B B by sib = ~f wti(b) i b, if wti(b) 0, ~e -wti(b) i b, if wti, b2 B2} with wti(b1 b2) = wti(b1) + wti(b2), i(b1 b2) = max{i(b1), i(b2) - wt(b1), i }, i(b1 b2

  13. Single Top Quark

    SciTech Connect (OSTI)

    Heidi Schellman and Ann Heinson

    2009-03-12T23:59:59.000Z

    Fermilab researchers Heidi Schellman and Ann Heinson take a whimsical look at the recent announcement of the discovery of the single top quark, by Fermilab's CDF and DZero experiments.

  14. Bent core liquid crystal elastomers

    SciTech Connect (OSTI)

    Verduzco, R.; DiMasi, E.; Luchette, P.; Ho Hong, S.; Harden, J.; Palffy-Muhoray, P.; Kilbey II, S.M.; Sprunt, S.; Gleeson, G.T. Jakli, A.

    2010-07-28T23:59:59.000Z

    Liquid crystal (LC) elastomers with bent-core side-groups incorporate the properties of bent-core liquid crystals in a flexible and self-supporting polymer network. Bent-core liquid crystal elastomers (BCEs) with uniform alignment were prepared by attaching a reactive bent-core LC to poly(hydrogenmethylsiloxane) and crosslinking with a divinyl crosslinker. Phase behavior studies indicate a nematic phase over a wide temperature range that approaches room temperature, and thermoelastic measurements show that these BCEs can reversibly change their length by more than a factor of two upon heating and cooling. Small-angle X-ray scattering studies reveal multiple, broad low-angle peaks consistent with short-range smectic C order of the bent-core side groups. A comparison of these patterns with predictions of a Landau model for short-range smectic C order shows that the length scale for smectic ordering in BCEs is similar to that seen in pure bent-core LCs. The combination of rubber elasticity and smectic ordering of the bent-core side groups suggests that BCEs may be promising materials for sensing, actuating, and other advanced applications.

  15. Split green fluorescent protein as a modular binding partner for protein crystallization

    SciTech Connect (OSTI)

    Nguyen, Hau B. [Los Alamos National Laboratory, MS M888, Los Alamos, NM 87545 (United States); Hung, Li-Wei [Los Alamos National Laboratory, MS D454, Los Alamos, NM 87545 (United States); Yeates, Todd O. [University of California, PO Box 951569, Los Angeles, CA 90095 (United States); Terwilliger, Thomas C., E-mail: terwilliger@lanl.gov; Waldo, Geoffrey S., E-mail: terwilliger@lanl.gov [Los Alamos National Laboratory, MS M888, Los Alamos, NM 87545 (United States)

    2013-12-01T23:59:59.000Z

    A strategy using a new split green fluorescent protein (GFP) as a modular binding partner to form stable protein complexes with a target protein is presented. The modular split GFP may open the way to rapidly creating crystallization variants. A modular strategy for protein crystallization using split green fluorescent protein (GFP) as a crystallization partner is demonstrated. Insertion of a hairpin containing GFP ?-strands 10 and 11 into a surface loop of a target protein provides two chain crossings between the target and the reconstituted GFP compared with the single connection afforded by terminal GFP fusions. This strategy was tested by inserting this hairpin into a loop of another fluorescent protein, sfCherry. The crystal structure of the sfCherry-GFP(10–11) hairpin in complex with GFP(1–9) was determined at a resolution of 2.6 Å. Analysis of the complex shows that the reconstituted GFP is attached to the target protein (sfCherry) in a structurally ordered way. This work opens the way to rapidly creating crystallization variants by reconstituting a target protein bearing the GFP(10–11) hairpin with a variety of GFP(1–9) mutants engineered for favorable crystallization.

  16. Interfacing Superconducting Qubits and Telecom Photons via a Rare-Earth Doped Crystal

    E-Print Network [OSTI]

    Christopher O'Brien; Nikolai Lauk; Susanne Blum; Giovanna Morigi; Michael Fleischhauer

    2014-07-25T23:59:59.000Z

    We propose a scheme to couple short single photon pulses to superconducting qubits. An optical photon is first absorbed into an inhomogeneously broadened rare-earth doped crystal using controlled reversible inhomogeneous broadening. The optical excitation is then mapped into a spin state using a series of $\\pi$-pulses and subsequently transferred to a superconducting qubit via a microwave cavity. To overcome the intrinsic and engineered inhomogeneous broadening of the optical and spin transitions in rare earth doped crystals, we make use of a special transfer protocol using staggered $\\pi$-pulses. We predict total transfer efficiencies on the order of 90%.

  17. Laboratory Investigation of Contact Freezing and the Aerosol to Ice Crystal Transformation Process

    SciTech Connect (OSTI)

    Shaw, Raymond A. [Michigan Technological University

    2014-10-28T23:59:59.000Z

    This project has been focused on the following objectives: 1. Investigations of the physical processes governing immersion versus contact nucleation, specifically surface-induced crystallization; 2. Development of a quadrupole particle trap with full thermodynamic control over the temperature range 0 to –40 °C and precisely controlled water vapor saturation ratios for continuous, single-particle measurement of the aerosol to ice crystal transformation process for realistic ice nuclei; 3. Understanding the role of ice nucleation in determining the microphysical properties of mixed-phase clouds, within a framework that allows bridging between laboratory and field measurements.

  18. SHELXT – Integrated space-group and crystal-structure determination

    SciTech Connect (OSTI)

    Sheldrick, George M., E-mail: gsheldr@shelx.uni-ac.gwdg.de [Georg-August Universität Göttingen, Tammannstrasse 4, Göttingen, 37077 (Germany)

    2015-01-01T23:59:59.000Z

    SHELXT automates routine small-molecule structure determination starting from single-crystal reflection data, the Laue group and a reasonable guess as to which elements might be present. The new computer program SHELXT employs a novel dual-space algorithm to solve the phase problem for single-crystal reflection data expanded to the space group P1. Missing data are taken into account and the resolution extended if necessary. All space groups in the specified Laue group are tested to find which are consistent with the P1 phases. After applying the resulting origin shifts and space-group symmetry, the solutions are subject to further dual-space recycling followed by a peak search and summation of the electron density around each peak. Elements are assigned to give the best fit to the integrated peak densities and if necessary additional elements are considered. An isotropic refinement is followed for non-centrosymmetric space groups by the calculation of a Flack parameter and, if appropriate, inversion of the structure. The structure is assembled to maximize its connectivity and centred optimally in the unit cell. SHELXT has already solved many thousand structures with a high success rate, and is optimized for multiprocessor computers. It is, however, unsuitable for severely disordered and twinned structures because it is based on the assumption that the structure consists of atoms.

  19. Electromagnetic Wave Propagation in Two-Dimensional Photonic Crystals

    SciTech Connect (OSTI)

    Stavroula Foteinopoulou

    2003-12-12T23:59:59.000Z

    In this dissertation, they have undertaken the challenge to understand the unusual propagation properties of the photonic crystal (PC). The photonic crystal is a medium where the dielectric function is periodically modulated. These types of structures are characterized by bands and gaps. In other words, they are characterized by frequency regions where propagation is prohibited (gaps) and regions where propagation is allowed (bands). In this study they focus on two-dimensional photonic crystals, i.e., structures with periodic dielectric patterns on a plane and translational symmetry in the perpendicular direction. They start by studying a two-dimensional photonic crystal system for frequencies inside the band gap. The inclusion of a line defect introduces allowed states in the otherwise prohibited frequency spectrum. The dependence of the defect resonance state on different parameters such as size of the structure, profile of incoming source, etc., is investigated in detail. For this study, they used two popular computational methods in photonic crystal research, the Finite Difference Time Domain method (FDTD) and the Transfer Matrix Method (TMM). The results for the one-dimensional defect system are analyzed, and the two methods, FDTD and TMM, are compared. Then, they shift their attention only to periodic two-dimensional crystals, concentrate on their band properties, and study their unusual refractive behavior. Anomalous refractive phenomena in photonic crystals included cases where the beam refracts on the ''wrong'' side of the surface normal. The latter phenomenon, is known as negative refraction and was previously observed in materials where the wave vector, the electric field, and the magnetic field form a left-handed set of vectors. These materials are generally called left-handed materials (LHM) or negative index materials (NIM). They investigated the possibility that the photonic crystal behaves as a LHM, and how this behavior relates with the observed negatively refractive phenomena. They found that in the PC system, negative refraction is neither a prerequisite nor guarantees left-handed behavior. They examined carefully the condition to obtain left-handed behavior in the PC. They proposed a wedge type of experiment, in accordance with the experiment performed on the traditional LHM, to test these conditions. They found that for certain frequencies the PC shows left-handed behavior and acts in some respects like a homogeneous medium with a negative refractive index. they used the realistic PC system for this case to show how negative refraction occurs at the interface between a material with a positive and a material with a negative refractive index. Their findings indicate that the formation of the negatively refracted beam is not instantaneous and involves a transient time. With this time-dependent analysis, they were able to address previous controversial issues about negative refraction concerning causality and the speed of light limit. Finally, they attempt a systematic study of anomalous refractive phenomena that can occur at the air-PC interface. They observe cases where only a single refracted beam (in the positive or negative direction) is present, as well as cases with birefringence. they classify these different effects according to their origin and type of propagation (left-handed or not). For a complete study of the system, they also obtain expressions for the energy and group velocities, and show their equality. For cases with very low index contrast, band folding becomes an artificiality. They discuss the validity of their findings when they move to the limit of photonic crystals with a low index modulation.

  20. Phonon manipulation with phononic crystals.

    SciTech Connect (OSTI)

    Kim Bongsang; Hopkins, Patrick Edward; Leseman, Zayd C.; Goettler, Drew F.; Su, Mehmet F. (University of New Mexico, Albuquerque, NM); El-Kady, Ihab Fathy; Reinke, Charles M.; Olsson, Roy H., III

    2012-01-01T23:59:59.000Z

    In this work, we demonstrated engineered modification of propagation of thermal phonons, i.e. at THz frequencies, using phononic crystals. This work combined theoretical work at Sandia National Laboratories, the University of New Mexico, the University of Colorado Boulder, and Carnegie Mellon University; the MESA fabrication facilities at Sandia; and the microfabrication facilities at UNM to produce world-leading control of phonon propagation in silicon at frequencies up to 3 THz. These efforts culminated in a dramatic reduction in the thermal conductivity of silicon using phononic crystals by a factor of almost 30 as compared with the bulk value, and about 6 as compared with an unpatterned slab of the same thickness. This work represents a revolutionary advance in the engineering of thermoelectric materials for optimal, high-ZT performance. We have demonstrated the significant reduction of the thermal conductivity of silicon using phononic crystal structuring using MEMS-compatible fabrication techniques and in a planar platform that is amenable to integration with typical microelectronic systems. The measured reduction in thermal conductivity as compared to bulk silicon was about a factor of 20 in the cross-plane direction [26], and a factor of 6 in the in-plane direction. Since the electrical conductivity was only reduced by a corresponding factor of about 3 due to the removal of conductive material (i.e., porosity), and the Seebeck coefficient should remain constant as an intrinsic material property, this corresponds to an effective enhancement in ZT by a factor of 2. Given the number of papers in literature devoted to only a small, incremental change in ZT, the ability to boost the ZT of a material by a factor of 2 simply by reducing thermal conductivity is groundbreaking. The results in this work were obtained using silicon, a material that has benefitted from enormous interest in the microelectronics industry and that has a fairly large thermoelectric power factor. In addition, the techniques and scientific understanding developed in the research can be applied to a wide range of materials, with the caveat that the thermal conductivity of such a material be dominated by phonon, rather than electron, transport. In particular, this includes several thermoelectric materials with attractive properties at elevated temperatures (i.e., greater than room temperature), such as silicon germanium and silicon carbide. It is reasonable that phononic crystal patterning could be used for high-temperature thermoelectric devices using such materials, with applications in energy scavenging via waste-heat recovery and thermoelectric cooling for high-performance microelectronic circuits. The only part of the ZT picture missing in this work was the experimental measurement of the Seebeck coefficient of our phononic crystal devices. While a first-order approximation indicates that the Seebeck coefficient should not change significantly from that of bulk silicon, we were not able to actually verify this assumption within the timeframe of the project. Additionally, with regards to future high-temperature applications of this technology, we plan to measure the thermal conductivity reduction factor of our phononic crystals as elevated temperatures to confirm that it does not diminish, given that the nominal thermal conductivity of most semiconductors, including silicon, decreases with temperature above room temperature. We hope to have the opportunity to address these concerns and further advance the state-of-the-art of thermoelectric materials in future projects.

  1. Single-exciton nanocrystal laser

    DOE Patents [OSTI]

    Klimov, Victor I. (Los Alamos, NM); Ivanov, Sergei A. (Albuquerque, NM)

    2012-01-17T23:59:59.000Z

    A laser system employing amplification via a single exciton regime and to optical gain media having single exciton amplification is provided.

  2. Singular Limits in Polymer Stabilized Liquid Crystals

    E-Print Network [OSTI]

    1910-31-00T23:59:59.000Z

    We investigate equilibrium configurations for a polymer stabilized liquid crys- tal material ... eling the cross section of the liquid crystal-polymer fiber composite.

  3. Photonic crystals for high temperature applications

    E-Print Network [OSTI]

    Yeng, Yi Xiang

    2014-01-01T23:59:59.000Z

    This thesis focuses on the design, optimization, fabrication, and experimental realization of metallic photonic crystals (MPhCs) for high temperature applications, for instance thermophotovoltaic (TPV) energy conversion ...

  4. Mixed-Ligand MetalOrganic Frameworks with Large Pores: Gas Sorption Properties and Single-Crystal-to-Single-Crystal Transformation on Guest

    E-Print Network [OSTI]

    Paik Suh, Myunghyun

    temperature storage data are far less than 1% (0.62 wt%).[24] The highest CO2 uptake data reported so far% (total) at 77 K and 70 bar) with high isosteric heat (7.74 kJmolÀ1 ), and high CO2 adsorption capacity of CO2 from a gaseous mixture is important because CO2 gas is a major source of greenhouse gas emissions

  5. Crystal Systems | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directedAnnual Siteof Energy 2,AUDIT REPORTEnergy Offshore Place:WindOilCowal Wind Energy LtdCrystal

  6. Phases and domain structures in tungsten-doped Pb,,Mg1/3Nb2/3...1-xTixO3 ,,x=0.35... crystal

    E-Print Network [OSTI]

    Phases and domain structures in tungsten-doped Pb,,Mg1/3Nb2/3...1-xTixO3 ,,x=0.35... crystal F and piezoelectric response, has the great potential of applications in wireless photoactuators. The tungsten ferroelectric physics of tungsten-doped PMNT single crystals is still unclear. In this study, temperature

  7. Journal of Crystal Growth 250 (2003) 499515 Induction time in crystallization of gas hydrates

    E-Print Network [OSTI]

    Firoozabadi, Abbas

    2003-01-01T23:59:59.000Z

    Journal of Crystal Growth 250 (2003) 499­515 Induction time in crystallization of gas hydrates Dimo. Kern Abstract The kinetics of the initial stage of crystallization of one-component gas hydrates of gas consumed are determined. Expressions are derived for the supersaturation dependence of the hydrate

  8. Scintillation properties of some Ce[sup 3+] and Pr[sup 3+] doped inorganic crystals

    SciTech Connect (OSTI)

    Dorenbos, P.; Visser, R.; Eijk, C.W.E. van (Delft Univ. of Technology (Netherlands). Dept. of Applied Physics); Khaidukov, N.M. (N.S. Kurnakov Inst. of General and Inorganic Chemistry, Moscow (Russian Federation)); Korzhik, M.V. (Inst. of Nuclear Problems, Minsk (Russian Federation))

    1993-08-01T23:59:59.000Z

    The scintillations properties of Ce[sup 3+] and Pr[sup 3+] doped complex fluoride crystals of composition CsGd[sub 2]F[sub 7] and K[sub 2]YF[sub 5] and of Pr[sup 3+] doped Y[sub 3]Al[sub 5]O[sub 12] single crystals were studied by means of x-ray and gamma ray excitation. The Ce[sub 3+] and Pr[sub 3+] doped fluoride crystals show 5d-4f luminescences at wavelengths near 340 nm and 240 nm, respectively. 5d-4f luminescence of Pr[sup 3+] doped Y[sub 3]Al[sub 5]O[sub 12] is observed between 300 and 400 nm. The authors present the absolute light yield in photons/MeV together with results from scintillation decay time experiments.

  9. Surface Topography of 'Hotspot' Regions from a Single Cell SRF Cavity

    SciTech Connect (OSTI)

    Xin Zhao, Gianluigi Ciovati, Charles Reece, Andy Wu

    2009-05-01T23:59:59.000Z

    Performance of SRF cavities are limited by non-linear localized effects. The variation of local material characters between "hot" and "cold" spots is thus of intense interest. Such locations were identified in a BCP-etched large-grain single-cell cavity and removed for examination by high resolution electron microscopy (SEM), electron-back scattering diffraction microscopy (EBSD), optical microscopy, and 3D profilometry. Pits with clearly discernable crystal facets were observed in both "hotspot" and "coldspot" specimens. The pits were found in-grain, at bi-crystal boundaries, and on tri-crystal junctions. They are interpreted as etch pits induced by surface crystal defects (e.g. dislocations). All "coldspots" examined had qualitatively low density of etching pits or very shallow tri-crystal boundary junction. EBSD revealed the crystal structure surrounding the pits via crystal phase orientation mapping, while 3D profilometry gave information on the depth and size of the pits. In addition, a survey of the samples by energy dispersive X-ray analysis (EDX) did not show any significant contamination of the samples surface.

  10. Study of Etching Pits in a Large-grain Single Cell Bulk Niobium Cavity

    SciTech Connect (OSTI)

    Zhao, Xin [William and Mary College; Ciovati, Gianluigi [JLAB; Reece, Charles E. [JLAB; Wu, Andy T. [JLAB

    2009-11-01T23:59:59.000Z

    Performance of SRF cavities are limited by non-linear localized effects. The variation of local material characters between "hot" and "cold" spots is thus of intense interest. Such locations were identified in a BCP-etched large-grain single-cell cavity and removed for examination by high resolution electron microscopy (SEM), electron-back scattering diffraction microscopy (EBSD), optical microscopy, and 3D profilometry. Pits with clearly discernable crystal facets were observed in both "hotspot" and "coldspot" specimens. The pits were found in-grain, at bi-crystal boundaries, and on tri-crystal junctions. They are interpreted as etch pits induced by surface crystal defects (e.g. dislocations). All "coldspots" examined had qualitatively low density of etching pits or very shallow tri-crystal boundary junction. EBSD revealed crystal structure surrounding the pits via crystal phase orientation mapping, while 3D profilometry gave information on the depth and size of the pits. In addition, a survey of the samples by energy dispersive X-ray analysis (EDX) did not show any significant contamination of the samples surface.

  11. Crystallization, dehydration and experimental phasing of WbdD, a bifunctional kinase and methyltransferase from Escherichia coli O9a

    SciTech Connect (OSTI)

    Hagelueken, Gregor; Huang, Hexian [The University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland (United Kingdom); Harlos, Karl [University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Clarke, Bradley R.; Whitfield, Chris [University of Guelph, Ontario N1G 2W1 (Canada); Naismith, James H., E-mail: naismith@st-and.ac.uk [The University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland (United Kingdom)

    2012-10-01T23:59:59.000Z

    The optimization of WbdD crystals using a novel dehydration protocol and experimental phasing at 3.5 Å resolution by cross-crystal averaging followed by molecular replacement of electron density into a non-isomorphous 3.0 Å resolution native data set are reported. WbdD is a bifunctional kinase/methyltransferase that is responsible for regulation of lipopolysaccharide O antigen polysaccharide chain length in Escherichia coli serotype O9a. Solving the crystal structure of this protein proved to be a challenge because the available crystals belonging to space group I23 only diffracted to low resolution (>95% of the crystals diffracted to resolution lower than 4 Å and most only to 8 Å) and were non-isomorphous, with changes in unit-cell dimensions of greater than 10%. Data from a serendipitously found single native crystal that diffracted to 3.0 Å resolution were non-isomorphous with a lower (3.5 Å) resolution selenomethionine data set. Here, a strategy for improving poor (3.5 Å resolution) initial phases by density modification and cross-crystal averaging with an additional 4.2 Å resolution data set to build a crude model of WbdD is desribed. Using this crude model as a mask to cut out the 3.5 Å resolution electron density yielded a successful molecular-replacement solution of the 3.0 Å resolution data set. The resulting map was used to build a complete model of WbdD. The hydration status of individual crystals appears to underpin the variable diffraction quality of WbdD crystals. After the initial structure had been solved, methods to control the hydration status of WbdD were developed and it was thus possible to routinely obtain high-resolution diffraction (to better than 2.5 Å resolution). This novel and facile crystal-dehydration protocol may be useful for similar challenging situations.

  12. Coherent Control of a Single Silicon-29 Nuclear Spin Qubit

    E-Print Network [OSTI]

    Jarryd J. Pla; Fahd A. Mohiyaddin; Kuan Y. Tan; Juan P. Dehollain; Rajib Rahman; Gerhard Klimeck; David N. Jamieson; Andrew S. Dzurak; Andrea Morello

    2014-08-06T23:59:59.000Z

    Magnetic fluctuations caused by the nuclear spins of a host crystal are often the leading source of decoherence for many types of solid-state spin qubit. In group-IV materials, the spin-bearing nuclei are sufficiently rare that it is possible to identify and control individual host nuclear spins. This work presents the first experimental detection and manipulation of a single $^{29}$Si nuclear spin. The quantum non-demolition (QND) single-shot readout of the spin is demonstrated, and a Hahn echo measurement reveals a coherence time of $T_2 = 6.3(7)$ ms - in excellent agreement with bulk experiments. Atomistic modeling combined with extracted experimental parameters provides possible lattice sites for the $^{29}$Si atom under investigation. These results demonstrate that single $^{29}$Si nuclear spins could serve as a valuable resource in a silicon spin-based quantum computer.

  13. On the electronic properties of a single dislocation

    SciTech Connect (OSTI)

    Reiche, Manfred, E-mail: reiche@mpi-halle.de; Erfurth, Wilfried; Pippel, Eckhard; Sklarek, Kornelia; Blumtritt, Horst; Haehnel, Angelika [Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Saale) (Germany); Kittler, Martin [IHP microelectronics, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); IHP/BTU JointLab, K.-Wachsmann-Allee 1, 03046 Cottbus (Germany); Uebensee, Hartmut [CIS Research Institute of Microsensorics and Photovoltaics, K.-Zuse-Str. 14, 99099 Erfurt (Germany)

    2014-05-21T23:59:59.000Z

    A detailed knowledge of the electronic properties of individual dislocations is necessary for next generation nanodevices. Dislocations are fundamental crystal defects controlling the growth of different nanostructures (nanowires) or appear during device processing. We present a method to record electric properties of single dislocations in thin silicon layers. Results of measurements on single screw dislocations are shown for the first time. Assuming a cross-section area of the dislocation core of about 1?nm{sup 2}, the current density through a single dislocation is J?=?3.8?×?10{sup 12}?A/cm{sup 2} corresponding to a resistivity of ????1?×?10{sup ?8} ? cm. This is about eight orders of magnitude lower than the surrounding silicon matrix. The reason of the supermetallic behavior is the high strain in the cores of the dissociated dislocations modifying the local band structure resulting in high conductive carrier channels along defect cores.

  14. TRANSVERSITY SINGLE SPIN ASYMMETRIES.

    SciTech Connect (OSTI)

    BOER,D.

    2001-04-27T23:59:59.000Z

    The theoretical aspects of two leading twist transversity single spin asymmetries, one arising from the Collins effect and one from the interference fragmentation functions, are reviewed. Issues of factorization, evolution and Sudakov factors for the relevant observables are discussed. These theoretical considerations pinpoint the most realistic scenarios towards measurements of transversity.

  15. Single-field $?$-attractors

    E-Print Network [OSTI]

    Andrei Linde

    2015-04-02T23:59:59.000Z

    I describe a simple class of $\\alpha$-attractors, generalizing the single-field GL model of inflation in supergravity. The new class of models is defined for $0<\\alpha \\lesssim 1$, providing a good match to the present cosmological data. I also present a generalized version of these models which can describe not only inflation but also dark energy and supersymmetry breaking.

  16. HYSPEC : A CRYSTAL TIME OF FLIGHT HYBRID SPECTROMETER FOR THE SPALLATION NEUTRON SOURCE.

    SciTech Connect (OSTI)

    SHAPIRO,S.M.; ZALIZNYAK,I.A.

    2002-12-30T23:59:59.000Z

    This document lays out a proposal by the Instrument Development Team (IDT) composed of scientists from leading Universities and National Laboratories to design and build a conceptually new high-flux inelastic neutron spectrometer at the pulsed Spallation Neutron Source (SNS) at Oak Ridge. This instrument is intended to supply users of the SNS and scientific community, of which the IDT is an integral part, with a platform for ground-breaking investigations of the low-energy atomic-scale dynamical properties of crystalline solids. It is also planned that the proposed instrument will be equipped with a polarization analysis capability, therefore becoming the first polarized beam inelastic spectrometer in the SNS instrument suite, and the first successful polarized beam inelastic instrument at a pulsed spallation source worldwide. The proposed instrument is designed primarily for inelastic and elastic neutron spectroscopy of single crystals. In fact, the most informative neutron scattering studies of the dynamical properties of solids nearly always require single crystal samples, and they are almost invariably flux-limited. In addition, in measurements with polarization analysis the available flux is reduced through selection of the particular neutron polarization, which puts even more stringent limits on the feasibility of a particular experiment. To date, these investigations have mostly been carried out on crystal spectrometers at high-flux reactors, which usually employ focusing Bragg optics to concentrate the neutron beam on a typically small sample. Construction at Oak Ridge of the high-luminosity spallation neutron source, which will provide intense pulsed neutron beams with time-averaged fluxes equal to those at medium-flux reactors, opens entirely new opportunities for single crystal neutron spectroscopy. Drawing upon experience acquired during decades of studies with both crystal and time-of-flight (TOF) spectrometers, the IDT has developed a conceptual design for a focused-beam, hybrid time-of-flight instrument with a crystal monochromator for the SNS called HYSPEC (an acronym for hybrid spectrometer). The proposed instrument has a potential to collect data more than an order of magnitude faster than existing steady-source spectrometers over a wide range of energy transfer ({h_bar}{omega}) and momentum transfer (Q) space, and will transform the way that data in elastic and inelastic single-crystal spectroscopy are collected. HYSPEC is optimized to provide the highest neutron flux on sample in the thermal and epithermal neutron energy ranges at a good-to-moderate energy resolution. By providing a flux on sample several times higher than other inelastic instruments currently planned for the SNS, the proposed instrument will indeed allow unique ground-breaking measurements, and will ultimately make polarized beam studies at a pulsed spallation source a realistic possibility.

  17. New Crystal-Growth Methods for Producing Lattice-Matched Substrates for High-Temperature Superconductors

    SciTech Connect (OSTI)

    Boatner, L.A.

    2008-06-24T23:59:59.000Z

    This effort addressed the technical problem of identifying and growing, on a commercial scale, suitable single-crystal substrates for the subsequent deposition of epitaxial thin films of high temperature semiconductors such as GaN/AlN. The lack of suitable lattice-matched substrate materials was one of the major problem areas in the development of semiconducting devices for use at elevated temperatures as well as practical opto-electronic devices based on Al- and GaN technology. Such lattice-matched substrates are necessary in order to reduce or eliminate high concentrations of defects and dislocations in GaN/AlN and related epitaxial thin films. This effort concentrated, in particular, on the growth of single crystals of ZnO for substrate applications and it built on previous ORNL experience in the chemical vapor transport growth of large single crystals of zinc oxide. This combined expertise in the substrate growth area was further complemented by the ability of G. Eres and his collaborators to deposit thin films of GaN on the subject substrates and the overall ORNL capability for characterizing the quality of such films. The research effort consisted of research on the growth of two candidate substrate materials in conjunction with concurrent research on the growth and characterization of GaN films, i.e. the effort combined bulk crystal growth capabilities in the area of substrate production at both ORNL and the industrial partner, Commercial Crystal Growth Laboratories (CCL), Naples, Florida, with the novel thin-film deposition techniques previously developed in the ORNL SSD.

  18. A Complete Microfluidic Screening Platform for Rational Protein Crystallization

    E-Print Network [OSTI]

    Hansen, Carl L.

    A Complete Microfluidic Screening Platform for Rational Protein Crystallization Billy T. C. Lau integration, and low reagent consumption, microfluidic devices have emerged as viable technologies for protein crystallization. Current microfluidic crystallization technologies have focused on two separate strategies: one

  19. Li{sub 2}Si{sub 3}O{sub 7}: Crystal structure and Raman spectroscopy

    SciTech Connect (OSTI)

    Krueger, Hannes [Institute of Mineralogy and Petrography, University of Innsbruck, Innrain 52, 6020 Innsbruck (Austria)], E-mail: Hannes.Krueger@uibk.ac.at; Kahlenberg, Volker [Institute of Mineralogy and Petrography, University of Innsbruck, Innrain 52, 6020 Innsbruck (Austria); Kaindl, Reinhard [Christian-Doppler-Laboratory for Advanced Hard Coatings at the Institute of Mineralogy and Petrography, University of Innsbruck, 6020 Innsbruck (Austria)

    2007-03-15T23:59:59.000Z

    The crystal structure of metastable Li{sub 2}Si{sub 3}O{sub 7} was determined from single crystal X-ray diffraction data. The orthorhombic crystals were found to adopt space group Pmca with unit cell parameters of a=19.648(3)A, b=5.9969(8)A and c=4.8691(6)A. The content of the cell is Z=4. The obtained structural model was refined to a R-value of 0.035. The structure exhibits silicate sheets, which can be classified as {l_brace}uB,2,1{sub {approx}}{sup 2}{r_brace}[Si{sub 6}O{sub 14}] using the silicate nomenclature of Liebau. The layers are build up from zweier single chains running parallel to c. Raman spectra are presented and compared with other silicates. Furthermore, the structure is discussed versus Na{sub 2}Si{sub 3}O{sub 7}.

  20. Growth Of Oriented Crystals At Polymerized Membranes

    DOE Patents [OSTI]

    Charych, Deborah H. (Albany, CA), Berman, Amir (Ben-Shiva, IL)

    2000-01-25T23:59:59.000Z

    The present invention relates to methods and compositions for the growth and alignment of crystals at biopolymeric films. The methods and compositions of the present invention provide means to generate a variety of dense crystalline ceramic films, with totally aligned crystals, at low temperatures and pressures, suitable for use with polymer and plastic substrates.

  1. General recipe for designing photonic crystal cavities

    E-Print Network [OSTI]

    Vuckovic, Jelena

    . Yariv and P. Yeh, Optical Waves in Crystals (Wiley and Sons, 2003). 13. A. Badolato, K. Hennessy, M and links 1. S. Johnson, S. Fan, A. Mekis, and J. Joannopoulos, "Multipole-cancellation mechanism for high. Vuckovi´c, M. Loncar, H. Mabuchi, and A. Scherer, "Design of photonic crystal microcavities for cavity QED

  2. Ann. Geophysicae 14, 1192--1197 (1996) EGS --Springer-Verlag 1996 Pyramidal ice crystal scattering phase functions

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    tracing method for single hexagonal pyramidal ice crystals (such as solid and hollow bullets) randomly times since the beginning of this century, such as by Andrus (1915), Kimball (1915), Brush (1919), Leaf-tracing simulations for hexagonal hollow-ended column and bullet-rosette models, and con- cluded that the typical

  3. Increasing the Conversion Efficiency of Dye-Sensitized TiO2 Photoelectrochemical Cells by Coupling to Photonic Crystals

    E-Print Network [OSTI]

    The mechanism of enhancing the light harvesting efficiency of dye-sensitized TiO2 solar cells by coupling TiO2Increasing the Conversion Efficiency of Dye-Sensitized TiO2 Photoelectrochemical Cells by Coupling to conventional single-crystal solar cells. In this cell, an optically excited dye injects electrons

  4. Tuning the properties of complex transparent conducting oxides: Role of crystal symmetry, chemical composition, and carrier generation

    E-Print Network [OSTI]

    Medvedeva, Julia E.

    Tuning the properties of complex transparent conducting oxides: Role of crystal symmetry, chemical; revised manuscript received 24 February 2010; published 17 March 2010 The electronic properties of singleO3, , and -Ga2O3, rock salt and wurtzite ZnO, and layered InGaZnO4 reveals the role of the following

  5. Experimental phasing for structure determination using membrane-protein crystals grown by the lipid cubic phase method

    SciTech Connect (OSTI)

    Li, Dianfan; Pye, Valerie E.; Caffrey, Martin, E-mail: martin.caffrey@tcd.ie [Trinity College Dublin, Dublin (Ireland)

    2015-01-01T23:59:59.000Z

    Very little information is available in the literature concerning the experimental heavy-atom phasing of membrane-protein structures where the crystals have been grown using the lipid cubic phase (in meso) method. In this paper, pre-labelling, co-crystallization, soaking, site-specific mercury binding to genetically engineered single-cysteine mutants and selenomethionine labelling as applied to an integral membrane kinase crystallized in meso are described. An assay to assess cysteine accessibility for mercury labelling of membrane proteins is introduced. Despite the marked increase in the number of membrane-protein structures solved using crystals grown by the lipid cubic phase or in meso method, only ten have been determined by SAD/MAD. This is likely to be a consequence of the technical difficulties associated with handling proteins and crystals in the sticky and viscous hosting mesophase that is usually incubated in glass sandwich plates for the purposes of crystallization. Here, a four-year campaign aimed at phasing the in meso structure of the integral membrane diacylglycerol kinase (DgkA) from Escherichia coli is reported. Heavy-atom labelling of this small hydrophobic enzyme was attempted by pre-labelling, co-crystallization, soaking, site-specific mercury binding to genetically engineered single-cysteine mutants and selenomethionine incorporation. Strategies and techniques for special handling are reported, as well as the typical results and the lessons learned for each of these approaches. In addition, an assay to assess the accessibility of cysteine residues in membrane proteins for mercury labelling is introduced. The various techniques and strategies described will provide a valuable reference for future experimental phasing of membrane proteins where crystals are grown by the lipid cubic phase method.

  6. Liquid crystal device and method thereof

    DOE Patents [OSTI]

    Shiyanovskii, Sergij V; Gu, Mingxia; Lavrentovich, Oleg D

    2012-10-23T23:59:59.000Z

    The invention provides a liquid crystal device and method thereof. Subsequent to applying a first electrical voltage on a liquid crystal to induce a reorientation of the liquid crystal, a second electrical voltage with proper polarity is applied on the liquid crystal to assist the relaxation of the reorientation that was induced by the first electrical voltage. The "switch-off" phase of the liquid crystal can therefore be accelerated or temporally shortened, and the device can exhibit better performance such as fast response to on/off signals. The invention can be widely used LCD, LC shutter, LC lens, spatial light modulator, telecommunication device, tunable filter, beam steering device, and electrically driven LC device, among others.

  7. Enhanced spontaneous emission from nanodiamond colour centres on opal photonic crystal

    E-Print Network [OSTI]

    Faraz A Inam; Torsten Gaebel; Carlo Bradac; Luke Stewart; Michael J Withford; Judith M Dawes; James R Rabeau; Michael J Steel

    2011-02-02T23:59:59.000Z

    Colour centres in diamond are promising candidates as a platform for quantum technologies and biomedical imaging based on spins and/or photons. Controlling the emission properties of colour centres in diamond is a key requirement for developing efficient single photon sources with high collection efficiency. A number of groups have produced enhancement in the emission rate over narrow wavelength ranges by coupling single emitters in nanodiamond crystals to resonant electromagnetic structures. Here we characterise in detail the spontaneous emission rates of nitrogen-vacancy centres positioned in various locations on a structured substrate. We show an average factor of 1.5 enhancement of the total emission rate when nanodiamonds are on an opal photonic crystal surface, and observe changes in the lifetime distribution. We present a model to explain these observations and associate the lifetime properties with dipole orientation and polarization effects.

  8. Analysis of Crystal Lattice Deformation by Ion Channeling. |...

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

    Crystal Lattice Deformation by Ion Channeling. Analysis of Crystal Lattice Deformation by Ion Channeling. Abstract: A model of dislocations has been developed for the use in Monte...

  9. Microfluidic systems for continuous crystallization of small organic molecules

    E-Print Network [OSTI]

    Sultana, Mahmooda

    2010-01-01T23:59:59.000Z

    This thesis presents one of the first demonstrations of continuous crystallization in microfluidic devices, and illustrates their use for various applications related to crystallization of small organic molecules. ...

  10. antiferroelectric liquid crystals: Topics by E-print Network

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

    of phases in antiferroelectric liquid crystals Condensed Matter (arXiv) Summary: The free energy of antiferroelectric liquid crystal which takes into account polar order...

  11. antiferroelectric liquid crystal: Topics by E-print Network

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

    of phases in antiferroelectric liquid crystals Condensed Matter (arXiv) Summary: The free energy of antiferroelectric liquid crystal which takes into account polar order...

  12. Single rotor turbine engine

    DOE Patents [OSTI]

    Platts, David A. (Los Alamos, NM)

    2002-01-01T23:59:59.000Z

    There has been invented a turbine engine with a single rotor which cools the engine, functions as a radial compressor, pushes air through the engine to the ignition point, and acts as an axial turbine for powering the compressor. The invention engine is designed to use a simple scheme of conventional passage shapes to provide both a radial and axial flow pattern through the single rotor, thereby allowing the radial intake air flow to cool the turbine blades and turbine exhaust gases in an axial flow to be used for energy transfer. In an alternative embodiment, an electric generator is incorporated in the engine to specifically adapt the invention for power generation. Magnets are embedded in the exhaust face of the single rotor proximate to a ring of stationary magnetic cores with windings to provide for the generation of electricity. In this alternative embodiment, the turbine is a radial inflow turbine rather than an axial turbine as used in the first embodiment. Radial inflow passages of conventional design are interleaved with radial compressor passages to allow the intake air to cool the turbine blades.

  13. Corrosion of Partially Crystallized Glasses

    SciTech Connect (OSTI)

    Hrma, Pavel R.; Riley, Brian J.; Vienna, John D.

    2002-05-21T23:59:59.000Z

    Using existing data on corrosion of partially crystallized, simulated, high-level waste glasses, coefficients were introduced to evaluate the cumulative influence of secondary effects, such as residual stresses or concentration gradients on product consistency test response. As compared to predictions based solely on residual glass composition effects, the results showed that cristobalite, eucryptite, and nepheline had a higher-than-predicted impact on glass corrosion, while the effects of baddeleyite, hematite, calcium-zirconium silicate, and zircon were close to those predicted. The effects of acmite and lithium silicate were opposite to those expected based on their compositions. The analysis revealed important limitations of the databases currently available. Better understanding of corrosion phenomena will require quantitative composition data, microscopic characterization of pristine and corroded surfaces, and long-term tests with glass coupons or monoliths.

  14. Ammothermal Growth of Gan Substrates For Leds: High-Pressure Ammonothermal Process for Bulk Gallium Nitride Crystal Growth for Energy Efficient Commercially Competitive Lighting

    SciTech Connect (OSTI)

    None

    2011-01-01T23:59:59.000Z

    Broad Funding Opportunity Announcement Project: The new GaN crystal growth method is adapted from that used to grow quartz crystals, which are very inexpensive and represent the second-largest market for single crystals for electronic applications (after silicon). More extreme conditions are required to grow GaN crystals and therefore a new type of chemical growth chamber was invented that is suitable for large-scale manufacturing. A new process was developed that grows GaN crystals at a rate that is more than double that of current processes. The new technology will enable GaN substrates with best-in-world quality at lowest-in-world prices, which in turn will enable new generations of white LEDs, lasers for full-color displays, and high-performance power electronics.

  15. Influence of the defect structure of {gamma}-La{sub 2(1-x)}Nd{sub 2x}S{sub 3} crystals on their spectroscopic properties

    SciTech Connect (OSTI)

    Mamedov, A. A., E-mail: tedd33@mail.ru [National Academy of Sciences of Azerbaijan, Institute of Physics (Azerbaijan)

    2010-04-15T23:59:59.000Z

    The photoluminescence and Raman scattering of undoped {gamma}-Ln{sub 2}S{sub 3} single crystals (Ln is a rare earth ion) and the decay kinetics of the {sup 4}F{sub 3/2} level of Nd ions in these crystals have been investigated. The distortion of the decay curve of the Nd {sup 4}F{sub 3/2} level upon excitation by light with {lambda} = 0.53 {mu}m is explained.

  16. Synthesis and X-ray crystal structure determination of N-p-methylphenyl-4-benzoyl-3,4-diphenyl-2-azetidinone

    SciTech Connect (OSTI)

    Kabak, Mehmet, E-mail: kabak@eng.ankara.edu.tr [University of Ankara, Department of Engineering Physics, Faculty of Engineering (Turkey); Senoez, Huelya [Hacettepe University, Faculty of Sciences, Department of Chemistry (Turkey); Elmali, Ayhan [University of Ankara, Department of Engineering Physics, Faculty of Engineering (Turkey); Adar, Vildan [Hacettepe University, Faculty of Sciences, Department of Chemistry (Turkey); Svoboda, Ingrid [Darmstadt University of Technology, Institute of Material Science (Germany); Dusek, Michal; Fejfarova, Karla [Institute of Physics (Czech Republic)

    2010-12-15T23:59:59.000Z

    The title compound, C{sub 29}H{sub 23}NO{sub 2}, has been characterized by single-crystal X-ray diffraction at two different temperatures (303 K and 120 K) and wavelengths (MoK{sub {alpha}} and CuK{sub {alpha}}). The non-centrosymmetric hexagonal crystal structure contains four-membered planar {beta}-lactam ring with an unusually long C-C bond. The {beta}-lactam ring is almost planar.

  17. Seed crystals with improved properties for melt processing superconductors for practical applications

    DOE Patents [OSTI]

    Veal, B.W.; Paulikas, A.; Balachandran, U.; Zhong, W.

    1997-03-18T23:59:59.000Z

    A method of fabricating bulk superconducting material is disclosed including RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} comprising heating compressed powder oxides and/or carbonates of R and Ba and Cu present in mole ratios to form RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} in physical contact with an oxide single crystal seed to a temperature sufficient to form a liquid phase in the RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} while maintaining the single crystal seed solid to grow the superconducting material and thereafter cooling to provide a material including RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. R is a rare earth or Y or La and the single crystal seed has a lattice mismatch with RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} of less than about 2% at the growth temperature. The starting material may be such that the final product contains a minor amount of R{sub 2}BaCuO{sub 5}.

  18. Seed crystals with improved properties for melt processing superconductors for practical applications

    DOE Patents [OSTI]

    Veal, Boyd W. (Downers Grove, IL); Paulikas, Arvydas (Downers Grove, IL); Balachandran, Uthamalingam (Hinsdale, IL); Zhong, Wei (Chicago, IL)

    1997-01-01T23:59:59.000Z

    A method of fabricating bulk superconducting material including RBa.sub.2 Cu.sub.3 O.sub.7-.delta. comprising heating compressed powder oxides and/or carbonates of R and Ba and Cu present in mole ratios to form RBa.sub.2 Cu.sub.3 O.sub.7-.delta. in physical contact with an oxide single crystal seed to a temperature sufficient to form a liquid phase in the RBa.sub.2 Cu.sub.3 O.sub.7-.delta. while maintaining the single crystal seed solid to grow the superconducting material and thereafter cooling to provide a material including RBa.sub.2 Cu.sub.3 O.sub.7-.delta.. R is a rare earth or Y or La and the single crystal seed has a lattice mismatch with RBa.sub.2 Cu.sub.3 O.sub.7-.delta. of less than about 2% at the growth temperature. The starting material may be such that the final product contains a minor amount of R.sub.2 BaCuO.sub.5.

  19. Computational Study and Analysis of Structural Imperfections in 1D and 2D Photonic Crystals

    SciTech Connect (OSTI)

    K.R. Maskaly

    2005-06-01T23:59:59.000Z

    Dielectric reflectors that are periodic in one or two dimensions, also known as 1D and 2D photonic crystals, have been widely studied for many potential applications due to the presence of wavelength-tunable photonic bandgaps. However, the unique optical behavior of photonic crystals is based on theoretical models of perfect analogues. Little is known about the practical effects of dielectric imperfections on their technologically useful optical properties. In order to address this issue, a finite-difference time-domain (FDTD) code is employed to study the effect of three specific dielectric imperfections in 1D and 2D photonic crystals. The first imperfection investigated is dielectric interfacial roughness in quarter-wave tuned 1D photonic crystals at normal incidence. This study reveals that the reflectivity of some roughened photonic crystal configurations can change up to 50% at the center of the bandgap for RMS roughness values around 20% of the characteristic periodicity of the crystal. However, this reflectivity change can be mitigated by increasing the index contrast and/or the number of bilayers in the crystal. In order to explain these results, the homogenization approximation, which is usually applied to single rough surfaces, is applied to the quarter-wave stacks. The results of the homogenization approximation match the FDTD results extremely well, suggesting that the main role of the roughness features is to grade the refractive index profile of the interfaces in the photonic crystal rather than diffusely scatter the incoming light. This result also implies that the amount of incoherent reflection from the roughened quarterwave stacks is extremely small. This is confirmed through direct extraction of the amount of incoherent power from the FDTD calculations. Further FDTD studies are done on the entire normal incidence bandgap of roughened 1D photonic crystals. These results reveal a narrowing and red-shifting of the normal incidence bandgap with increasing RMS roughness. Again, the homogenization approximation is able to predict these results. The problem of surface scratches on 1D photonic crystals is also addressed. Although the reflectivity decreases are lower in this study, up to a 15% change in reflectivity is observed in certain scratched photonic crystal structures. However, this reflectivity change can be significantly decreased by adding a low index protective coating to the surface of the photonic crystal. Again, application of homogenization theory to these structures confirms its predictive power for this type of imperfection as well. Additionally, the problem of a circular pores in 2D photonic crystals is investigated, showing that almost a 50% change in reflectivity can occur for some structures. Furthermore, this study reveals trends that are consistent with the 1D simulations: parameter changes that increase the absolute reflectivity of the photonic crystal will also increase its tolerance to structural imperfections. Finally, experimental reflectance spectra from roughened 1D photonic crystals are compared to the results predicted computationally in this thesis. Both the computed and experimental spectra correlate favorably, validating the findings presented herein.

  20. A short working distance multiple crystal x-ray spectrometer

    SciTech Connect (OSTI)

    Dickinson, B.; Seidler, G. T.; Webb, Z. W.; Bradley, J. A.; Nagle, K. P. [Department of Physics, University of Washington, Seattle, Washington 98195 (United States); Heald, S. M. [Advanced Photon Source, Argonne National Laboratories, Argonne, Illinois 60439 (United States); Gordon, R. A. [Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6 (Canada); Chou, I. M. [U.S. Geological Survey, Reston, Virginia 20192 (United States)

    2008-12-15T23:59:59.000Z

    For x-ray spot sizes of a few tens of microns or smaller, a millimeter-sized flat analyzer crystal placed {approx}1 cm from the sample will exhibit high energy resolution while subtending a collection solid angle comparable to that of a typical spherically bent crystal analyzer (SBCA) at much larger working distances. Based on this observation and a nonfocusing geometry for the analyzer optic, we have constructed and tested a short working distance (SWD) multicrystal x-ray spectrometer. This prototype instrument has a maximum effective collection solid angle of 0.14 sr, comparable to that of 17 SBCA at 1 m working distance. We find good agreement with prior work for measurements of the Mn K{beta} x-ray emission and resonant inelastic x-ray scattering for MnO, and also for measurements of the x-ray absorption near-edge structure for Dy metal using L{alpha}{sub 2} partial-fluorescence yield detection. We discuss future applications at third- and fourth-generation light sources. For concentrated samples, the extremely large collection angle of SWD spectrometers will permit collection of high-resolution x-ray emission spectra with a single pulse of the Linac Coherent Light Source. The range of applications of SWD spectrometers and traditional multi-SBCA instruments has some overlap, but also is significantly complementary.

  1. Multilayers and Crystal for a Multi-bandpass Monochromator

    SciTech Connect (OSTI)

    Feng, Renfei [Canadian Light Source, Saskatoon, Canada; Platonov, Yuriy [Rigaku Innovative Technologies, Inc., Auburn Hills, Michigan; Broadway, David [Rigaku Innovative Technologies, Inc., Auburn Hills, Michigan; Ice, Gene E [ORNL; Gerson, Andrea [University of South Australia; McIntyre, Stewart [University of Western Ontario, The

    2008-01-01T23:59:59.000Z

    VESPERS beamline is a hard X-ray microprobe beamline dedicated to micro-diffraction and micro-fluorescence analysis at the Canadian Light Source; it requires multi-bandpass X-ray beams for different types of samples and experiments. A specially designed double crystal/multilayer monochromator was built for this purpose with three different bandpasses: 0.01%, 1.6% and 10%. The diffraction elements used for the monochromator have a triple-stripe design using Si(111) crystal as a single substrate with two differing stripes of Mo/B4C multilayers deposited thereon. The uncovered Si(111) section provides a 0.01% bandpass, while the periodic and depth-graded Mo/B4C multilayers provide 1.6% and 10% bandpasses, respectively. This paper outlines the requirements and specifications of the diffracting elements as well as the design, deposition and optimization of the multilayers. The performance of the deposited multilayer structures has been tested using Cu-Ka radiation line with a Huber diffractometer.

  2. Novel photonic crystal cavities and related structures.

    SciTech Connect (OSTI)

    Luk, Ting Shan

    2007-11-01T23:59:59.000Z

    The key accomplishment of this project is to achieve a much more in-depth understanding of the thermal emission physics of metallic photonic crystal through theoretical modeling and experimental measurements. An improved transfer matrix technique was developed to enable incorporation of complex dielectric function. Together with microscopic theory describing emitter radiative and non-radiative relaxation dynamics, a non-equilibrium thermal emission model is developed. Finally, experimental methodology was developed to measure absolute emissivity of photonic crystal at high temperatures with accuracy of +/-2%. Accurate emissivity measurements allow us to validate the procedure to treat the effect of the photonic crystal substrate.

  3. Cold neutron scattering in imperfect deuterium crystals

    E-Print Network [OSTI]

    Andrzej Adamczak

    2010-12-10T23:59:59.000Z

    The differential cross sections for cold neutron scattering in mosaic deuterium crystals have been calculated for various target temperatures. The theoretical results are compared with the recent experimental data for the neutron wavelengths $\\lambda\\approx$~1--9~\\AA. It is shown that the structures of observed Bragg peaks can be explained by the mosaic spread of about $3^{\\circ}$ and contributions from a~limited number of crystal orientations. Such a~crystal structure should be also taken into account in ultracold neutron upscattering due to the coherent phonon annihilation in solid deuterium.

  4. Shearing Flows in Liquid Crystal Models

    E-Print Network [OSTI]

    Dorn, Timothy

    2012-05-31T23:59:59.000Z

    . The director field is the realization of local averaging to de- scribe the natural state in a nematic liquid crystal, Figure 1.1. For any natural alignment of the liquid crystal, n?, one prescribes that W (n?,?n?) = 0. Since the director field is used... derivative of h by the formula D Dt h(t,x) = ?h? t +(u · ~?)h. The acceleration is of the liquid crystal material through the point x is given by a(t,x) = Du Dt . Following the classical approach one assumes that for every open subset Wt ??, trav- eling along...

  5. Crystal growth under external electric fields

    SciTech Connect (OSTI)

    Uda, Satoshi; Koizumi, Haruhiko; Nozawa, Jun; Fujiwara, Kozo [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

    2014-10-06T23:59:59.000Z

    This is a review article concerning the crystal growth under external electric fields that has been studied in our lab for the past 10 years. An external field is applied electrostatically either through an electrically insulating phase or a direct injection of an electric current to the solid-interface-liquid. The former changes the chemical potential of both solid and liquid and controls the phase relationship while the latter modifies the transport and partitioning of ionic solutes in the oxide melt during crystallization and changes the solute distribution in the crystal.

  6. NMR and NQR parameters of ethanol crystal

    E-Print Network [OSTI]

    Milinkovic, M

    2012-01-01T23:59:59.000Z

    Electric field gradients and chemical shielding tensors of the stable monoclinic crystal phase of ethanol are computed. The projector-augmented wave (PAW) and gauge-including projector-augmented wave (GIPAW) models in the periodic plane-wave density functional theory are used. The crystal data from X-ray measurements, as well as the structures where either all atomic, or only hydrogen atom positions are optimized in the density functional theory are analyzed. These structural models are also studied by including the semi-empirical Van der Waals correction to the density functional theory. Infrared spectra of these five crystal models are calculated.

  7. Visualizing kinetic pathways of homogeneous nucleation in colloidal crystallization

    E-Print Network [OSTI]

    Peng Tan; Ning Xu; Lei Xu

    2014-12-18T23:59:59.000Z

    When a system undergoes a transition from a liquid to a solid phase, it passes through multiple intermediate structures before reaching the final state. However, our knowledge on the exact pathways of this process is limited, mainly due to the difficulty of realizing direct observations. Here, we experimentally study the evolution of symmetry and density for various colloidal systems during liquid-to-solid phase transitions, and visualize kinetic pathways with single-particle resolution. We observe the formation of relatively-ordered precursor structures with different symmetries, which then convert into metastable solids. During this conversion, two major cross-symmetry pathways always occur, regardless of the final state and the interaction potential. In addition, we find a broad decoupling of density variation and symmetry development, and discover that nucleation rarely starts from the densest regions. These findings hold for all our samples, suggesting the possibility of finding a unified picture for the complex crystallization kinetics in colloidal systems.

  8. Quasiresonant Excitation of InP/InGaP Quantum Dots Using Second Harmonic Generated in a Photonic Crystal Cavity

    E-Print Network [OSTI]

    Buckley, Sonia; Hatami, Fariba; Vuckovic, Jelena

    2012-01-01T23:59:59.000Z

    Indistinguishable single photons are necessary for quantum information processing applications. Resonant or quasiresonant excitation of single quantum dots provides greater single photon indistinguishability than incoherent pumping, but is also more challenging experimentally. Here, we demonstrate high signal to noise quasiresonant excitation of InP/InGaP quantum dots. The excitation is provided via second harmonic generated from a telecommunications wavelength laser resonant with the fundamental mode of a photonic crystal cavity, fabricated at twice the quantum dot transition wavelength. The second harmonic is generated using the \\chi(2) nonlinearity of the InGaP material matrix.

  9. Quasiresonant Excitation of InP/InGaP Quantum Dots Using Second Harmonic Generated in a Photonic Crystal Cavity

    E-Print Network [OSTI]

    Sonia Buckley; Kelley Rivoire; Fariba Hatami; Jelena Vuckovic

    2012-10-03T23:59:59.000Z

    Indistinguishable single photons are necessary for quantum information processing applications. Resonant or quasiresonant excitation of single quantum dots provides greater single photon indistinguishability than incoherent pumping, but is also more challenging experimentally. Here, we demonstrate high signal to noise quasiresonant excitation of InP/InGaP quantum dots. The excitation is provided via second harmonic generated from a telecommunications wavelength laser resonant with the fundamental mode of a photonic crystal cavity, fabricated at twice the quantum dot transition wavelength. The second harmonic is generated using the \\chi(2) nonlinearity of the InGaP material matrix.

  10. 7 Å Resolution in Protein 2-Dimentional-Crystal X-Ray Diffraction at Linac Coherent Light Source

    SciTech Connect (OSTI)

    Pedrini, Bill; Tsai, Ching-Ju; Capitani, Guido; Padeste, Celestino; Hunter, Mark; Zatsepin, Nadia A.; Barty, Anton; Benner, Henry; Boutet, Sebastien; Feld, Geoffrey K.; Hau-Riege, Stefan; Kirian, Rick; Kupitz, Christopher; Messerschmidt, Marc; Ogren, John I.; Pardini, Tommaso; Segelke, Brent; Williams, Garth J.; Spence , John C.; Abela, Rafael; Coleman, Matthew A.; Evans, James E.; Schertler, Gebhard; Frank, Matthias; Li, Xiao-Dan

    2014-06-09T23:59:59.000Z

    Membrane proteins arranged as two-dimensional (2D) crystals in the lipid en- vironment provide close-to-physiological structural information, which is essential for understanding the molecular mechanisms of protein function. X-ray diffraction from individual 2D crystals did not represent a suitable investigation tool because of radiation damage. The recent availability of ultrashort pulses from X-ray Free Electron Lasers (X-FELs) has now provided a mean to outrun the damage. Here we report on measurements performed at the LCLS X-FEL on bacteriorhodopsin 2D crystals mounted on a solid support and kept at room temperature. By merg- ing data from about a dozen of single crystal diffraction images, we unambiguously identified the diffraction peaks to a resolution of 7 °A, thus improving the observable resolution with respect to that achievable from a single pattern alone. This indicates that a larger dataset will allow for reliable quantification of peak intensities, and in turn a corresponding increase of resolution. The presented results pave the way to further X-FEL studies on 2D crystals, which may include pump-probe experiments at subpicosecond time resolution.

  11. Membrane Protein Crystallization in Lipidic Mesophases. Hosting Lipid Effects on the Crystallization and Structure of a Transmembrane Peptide

    SciTech Connect (OSTI)

    Hfer, Nicole; Aragao, David; Lyons, Joseph A.; Caffrey, Martin (Trinity)

    2011-09-28T23:59:59.000Z

    Gramicidin is an apolar pentadecapeptide antibiotic consisting of alternating d- and l-amino acids. It functions, in part, by creating pores in membranes of susceptible cells rendering them leaky to monovalent cations. The peptide should be able to traverse the host membrane either as a double-stranded, intertwined double helix (DSDH) or as a head-to-head single-stranded helix (HHSH). Current structure models are based on macromolecular X-ray crystallography (MX) and nuclear magnetic resonance (NMR). However, the HHSH form has only been observed by NMR. The shape and size of the different gramicidin conformations differ. We speculated therefore that reconstituting it into a lipidic mesophase with bilayers of different microstructures would preferentially stabilize one form over the other. By using such mesophases for in meso crystallogenesis, the expectation was that at least one would generate crystals of gramicidin in the HHSH form for structure determination by MX. This was tested using commercial and in-house synthesized lipids that support in meso crystallogenesis. Lipid acyl chain lengths were varied from 14 to 18 carbons to provide mesophases with a range of bilayer thicknesses. Unexpectedly, all lipids produced high-quality, structure-grade crystals with gramicidin only in the DSDH conformation.

  12. Changes in mobility of plastic crystal ethanol during its transformation into the monoclinic crystal state

    SciTech Connect (OSTI)

    Sanz, Alejandro, E-mail: alejandro.sanz@csic.es; Nogales, Aurora; Ezquerra, Tiberio A. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain)] [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain); Puente-Orench, Inés [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France) [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France); Instituto de Ciencia de Materiales de Aragón, ICMA-CSIC, Pedro Cerbuna 12, 50009 Zaragoza (Spain); Jiménez-Ruiz, Mónica [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France)] [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France)

    2014-02-07T23:59:59.000Z

    Transformation of deuterated ethanol from the plastic crystal phase into the monoclinic one is investigated by means of a singular setup combining simultaneously dielectric spectroscopy with neutron diffraction. We postulate that a dynamic transition from plastic crystal to supercooled liquid-like configuration through a deep reorganization of the hydrogen-bonding network must take place as a previous step of the crystallization process. Once these precursor regions are formed, subsequent crystalline nucleation and growth develop with time.

  13. Semiconductor liquid crystal composition and methods for making the same

    DOE Patents [OSTI]

    Alivisatos, A. Paul; Li, Liang-shi

    2005-04-26T23:59:59.000Z

    Semiconductor liquid crystal compositions and methods for making such compositions are disclosed. One embodiment of the invention is directed to a liquid crystal composition including a solvent and semiconductor particles in the solvent. The solvent and the semiconductor particles are in an effective amount in the liquid crystal composition to form a liquid crystal phase.

  14. Characterizing heralded single-photon sources with imperfect measurement devices

    E-Print Network [OSTI]

    M. Razavi; I. Söllner; E. Bocquillon; C. Couteau; R. Laflamme; G. Weihs

    2009-09-12T23:59:59.000Z

    Any characterization of a single-photon source is not complete without specifying its second-order degree of coherence, i.e., its $g^{(2)}$ function. An accurate measurement of such coherence functions commonly requires high-precision single-photon detectors, in whose absence, only time-averaged measurements are possible. It is not clear, however, how the resulting time-averaged quantities can be used to properly characterize the source. In this paper, we investigate this issue for a heralded source of single photons that relies on continuous-wave parametric down-conversion. By accounting for major shortcomings of the source and the detectors--i.e., the multiple-photon emissions of the source, the time resolution of photodetectors, and our chosen width of coincidence window--our theory enables us to infer the true source properties from imperfect measurements. Our theoretical results are corroborated by an experimental demonstration using a PPKTP crystal pumped by a blue laser, that results in a single-photon generation rate about 1.2 millions per second per milliwatt of pump power. This work takes an important step toward the standardization of such heralded single-photon sources.

  15. Styrene Purification and Recovery Using Freeze Crystallization

    E-Print Network [OSTI]

    Heist, J. A.; Wrobel, P. J.

    Lab tests have demonstrated the ability to separate styrene from ABS and SAN plastics wastes by cooling the waste until the styrene begins to crystallize. The same process that recovers styrene from these wastes can be used to purify styrene...

  16. Nanoparticle-chiral nematic liquid crystal composites

    E-Print Network [OSTI]

    Payne, Jeffrey C. (Jeffrey Christopher), 1981-

    2006-01-01T23:59:59.000Z

    The advancement of the fabrication of a one-dimensional photonic crystal without time-reversal and space-inversion symmetries was pursued. Theoretical studies predict that such a system would exhibit unusual optical ...

  17. Thermophysical parameters of the LBO crystal

    SciTech Connect (OSTI)

    Grechin, Sergei G [Scientific-Research Institute of Radioelectronics and Laser Technology at the N.E. Bauman Moscow State Technical University, Moscow (Russian Federation); Zuev, A V; Fokin, A S [All-Russian Scientific Research Institute of Aviation Materials, Moscow (Russian Federation); Kokh, Aleksandr E [V.S.Sobolev Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Moiseev, N V; Popov, Petr A; Sidorov, Aleksei A [Acad. I. G. Petrovskii Bryansk State University, Bryansk (Russian Federation)

    2010-08-27T23:59:59.000Z

    The thermophysical parameters (linear thermal expansion coefficients, thermal conductivities, and heat capacity) of the lithium triborate (LBO) crystal are measured and compared with previously published data. (nonlinear-optics phenomena)

  18. Crystallization of carbon tetrachloride in confined geometries

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Crystallization of carbon tetrachloride in confined geometries Adil Meziane1 , Jean-Pierre E 40 71 08 #12;2 Abstract The thermal behaviour of carbon tetrachloride confined in silica gels

  19. The Crystal Method: Asteroseismology of BPM 37093

    E-Print Network [OSTI]

    T. S. Metcalfe; M. H. Montgomery; A. Kanaan

    2004-08-19T23:59:59.000Z

    More than 40 years have passed since Ed Salpeter and others predicted that the carbon/oxygen cores of the coolest white dwarf stars in our Galaxy will theoretically crystallize. This effect has a dramatic impact on the calculated ages of cool white dwarfs, but until recently we have had no way of testing the theory. In 1992, pulsations were discovered in the massive potentially crystallized white dwarf BPM 37093, and in 1999 the theoretical effects of crystallization on the pulsation modes were determined. Observations from two Whole Earth Telescope campaigns in 1998 and 1999, combined with a new model-fitting method using a genetic algorithm, are now giving us the first glimpse inside of a crystallized star.

  20. Imaging with Spherically Bent Crystals or Reflectors

    SciTech Connect (OSTI)

    Bitter, M; Hill, K W; Scott, S; Ince-Cushman, A; Reinke, M; Podpaly, Y; Rice, J E; Beiersdorfer, P

    2010-06-01T23:59:59.000Z

    This paper consists of two parts: Part I describes the working principle of a recently developed x-ray imaging crystal spectrometer, where the astigmatism of spherically bent crystals is being used with advantage to record spatially resolved spectra of highly charged ions for Doppler measurements of the ion-temperature and toroidal plasmarotation- velocity profiles in tokamak plasmas. This type of spectrometer was thoroughly tested on NSTX and Alcator C-Mod, and its concept was recently adopted for the design of the ITER crystal spectrometers. Part II describes imaging schemes, where the astigmatism has been eliminated by the use of matched pairs of spherically bent crystals or reflectors. These imaging schemes are applicable over a wide range of the electromagnetic radiation, which includes microwaves, visible light, EUV radiation, and x-rays. Potential applications with EUV radiation and x-rays are the diagnosis of laserproduced plasmas, imaging of biological samples with synchrotron radiation, and lithography.

  1. Enhancement of crystal homogeneity of protein crystals under application of an external alternating current electric field

    SciTech Connect (OSTI)

    Koizumi, H.; Uda, S.; Fujiwara, K.; Nozawa, J. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577 (Japan); Tachibana, M. [Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, 236-0027 (Japan); Kojima, K. [Department of Education, Yokohama Soei University, 1 Miho-tyou, Midori-ku, Yokohama, 226-0015 (Japan)

    2014-10-06T23:59:59.000Z

    X-ray diffraction rocking-curve measurements were performed on tetragonal hen egg white (HEW) lysozyme crystals grown with and without the application of an external alternating current (AC) electric field. The crystal quality was assessed by the full width at half maximum (FWHM) value for each rocking curve. For two-dimensional maps of the FWHMs measured on the 440 and the 12 12 0 reflection, the crystal homogeneity was improved under application of an external electric field at 1 MHz, compared with that without. In particular, the significant improvement of the crystal homogeneity was observed for the 12 12 0 reflection.

  2. Method for reducing energy losses in laser crystals

    DOE Patents [OSTI]

    Atherton, L.J.; DeYoreo, J.J.; Roberts, D.H.

    1992-03-24T23:59:59.000Z

    A process for reducing energy losses in crystals is disclosed which comprises: a. heating a crystal to a temperature sufficiently high as to cause dissolution of microscopic inclusions into the crystal, thereby converting said inclusions into point-defects, and b. maintaining said crystal at a given temperature for a period of time sufficient to cause said point-defects to diffuse out of said crystal. Also disclosed are crystals treated by the process, and lasers utilizing the crystals as a source of light. 12 figs.

  3. Demixing cascades in cluster crystals

    E-Print Network [OSTI]

    Nigel B. Wilding; Peter Sollich

    2014-07-14T23:59:59.000Z

    In a cluster crystal, each lattice site is occupied by multiple soft-core particles. As the number density is increased at zero temperature, a `cascade' of isostructural phase transitions can occur between states whose site occupancy differs by unity. For low but finite temperature, each of these transitions terminates in a critical point. Using tailored Monte Carlo simulation techniques we have studied such demixing cascades in systems of soft particles interacting via potentials of the generalized exponential form $u(r)=\\epsilon\\exp[-(r/\\sigma)^n]$. We have estimated the critical parameters of the first few transitions in the cascade as a function of the softness parameter $n$. The critical temperature and pressure exhibit non-monotonic behaviour as $n$ is varied, although the critical chemical potential remains monotonic. The trends for the pressure and chemical potential are confirmed by cell model calculations at zero temperature. As $n\\to 2^+$, all the transitions that we have observed are preempted by melting although we cannot rule out that clustering transitions survive at high density.

  4. Photonic Crystal Laser-Driven Accelerator Structures

    SciTech Connect (OSTI)

    Cowan, B.; /SLAC

    2005-09-19T23:59:59.000Z

    We discuss simulated photonic crystal structure designs for laser-driven particle acceleration, focusing on three-dimensional planar structures based on the so-called ''woodpile'' lattice. We demonstrate guiding of a speed-of-light accelerating mode by a defect in the photonic crystal lattice and discuss the properties of this mode. We also discuss particle beam dynamics in the structure, presenting a novel method for focusing the beam. In addition we describe some potential coupling methods for the structure.

  5. Liquid crystal variable retarders in atomic scattering

    SciTech Connect (OSTI)

    Furst, J.E.; Yu, D.H.; Hayes, P.A.; DSouza, C.M.; Williams, J.F. [Physics Department, Centre for Atomic, Molecular, and Surface Physics, The University of Western Australia, Nedlands. WA. 6907 (Australia)] [Physics Department, Centre for Atomic, Molecular, and Surface Physics, The University of Western Australia, Nedlands. WA. 6907 (Australia)

    1996-11-01T23:59:59.000Z

    The applications of liquid crystal variable retarders in the production of spin-polarized electrons and in the determination of the polarization of optical radiation from atoms excited by polarized electrons are discussed. The advantages of using liquid crystal variable retarders in the measurement of Stokes parameters are insensitivity to the incident photon direction, large transmission diameter, variable retardation over large wavelength range without mechanical movement, and {ital in} {ital situ} calibration. {copyright} {ital 1996 American Institute of Physics.}

  6. Photonic crystal fiber injected with Fe{sub 3}O{sub 4} nanofluid for magnetic field detection

    SciTech Connect (OSTI)

    Thakur, Harneet V.; Nalawade, Sandipan M.; Gupta, Swati [Photonics Group, Department of Applied Physics, Defence Institute of Advanced Technology, Girinagar, Pune 411 025 (India); Kitture, Rohini [Department of Electronic-Science, Fergusson College, Pune 411 004 (India); Kale, S. N. [Nanotechnology Group, Department of Applied Physics, Defence Institute of Advanced Technology, Girinagar, Pune 411 025 (India)

    2011-10-17T23:59:59.000Z

    We report a magnetic field sensor having advantages of both photonic crystal fiber and optofluidics, combining them on a single platform by infiltrating small amount of Fe{sub 3}O{sub 4} magnetic optofluid/nanofluid in cladding holes of polarization-maintaining photonic crystal fiber. We demonstrated that magnetic field of few mT can be easily and very well detected with higher sensitivity of 242 pm/mT. The change in the birefringence values has been correlated to the response of nanofluid to applied field.

  7. Measurement of Coupling PDC photon sources with single-mode and multimode optical fibers

    E-Print Network [OSTI]

    Stefania Castelletto; Ivo Pietro Degiovanni; Alan Migdall; Valentina Schettini; Michael Ware

    2004-08-03T23:59:59.000Z

    We investigate the coupling efficiency of parametric downconversion light (PDC) into single and multi-mode optical fibers as a function of the pump beam diameter, crystal length and walk-off. We outline two different theoretical models for the preparation and collection of either single-mode or multi-mode PDC light (defined by, for instance, multi-mode fibers or apertures, corresponding to bucket detection). Moreover, we define the mode-matching collection efficiency, important for realizing a single-photon source based on PDC output into a well-defined single spatial mode. We also define a multimode collection efficiency that is useful for single-photon detector calibration applications.

  8. Measurement of Coupling PDC photon sources with single-mode and multimode optical fibers

    E-Print Network [OSTI]

    Castelletto, S; Migdal, A; Schettini, V; Ware, M; Castelletto, Stefania; Degiovanni, Ivo Pietro; Migdall, Alan; Schettini, Valentina; Ware, Michael

    2004-01-01T23:59:59.000Z

    We investigate the coupling efficiency of parametric downconversion light (PDC) into single and multi-mode optical fibers as a function of the pump beam diameter, crystal length and walk-off. We outline two different theoretical models for the preparation and collection of either single-mode or multi-mode PDC light (defined by, for instance, multi-mode fibers or apertures, corresponding to bucket detection). Moreover, we define the mode-matching collection efficiency, important for realizing a single-photon source based on PDC output into a well-defined single spatial mode. We also define a multimode collection efficiency that is useful for single-photon detector calibration applications.

  9. Storage of up-converted telecom photons in a doped crystal

    E-Print Network [OSTI]

    Nicolas Maring; Kutlu Kutluer; Joachim Cohen; Matteo Cristiani; Margherita Mazzera; Patrick M. Ledingham; Hugues de Riedmatten

    2014-10-01T23:59:59.000Z

    We report on an experiment that demonstrates the frequency up-conversion of telecommunication wavelength single-photon-level pulses to be resonant with a $\\mathrm{Pr}^{3+}$:$\\mathrm{Y}_2\\mathrm{Si}\\mathrm{O}_5$ crystal. We convert the telecom photons at $1570\\,\\mathrm{nm}$ to $606\\,\\mathrm{nm}$ using a periodically-poled potassium titanyl phosphate nonlinear waveguide. The maximum device efficiency (which includes all optical loss) is inferred to be $\\eta_{\\mathrm{dev}}^{\\mathrm{max}} = 22 \\pm 1\\,%$ (internal efficiency $\\eta_{\\mathrm{int}} = 75\\pm8\\,%$) with a signal to noise ratio exceeding 1 for single-photon-level pulses with durations of up to 560$\\,$ns. The converted light is then stored in the crystal using the atomic frequency comb scheme with storage and retrieval efficiencies exceeding $\\eta_{\\mathrm{AFC}} = 20\\,%$ for predetermined storage times of up to $5\\,\\mu\\mathrm{s}$. The retrieved light is time delayed from the noisy conversion process allowing us to measure a signal to noise ratio exceeding 100 with telecom single-photon-level inputs. These results represent the first demonstration of single-photon-level optical storage interfaced with frequency up-conversion.

  10. Single beam write and/or replay of spatial heterodyne holograms

    DOE Patents [OSTI]

    Thomas, Clarence E. (Knoxville, TN); Hanson, Gregory R. (Clinton, TN)

    2007-11-20T23:59:59.000Z

    A method of writing a spatially heterodyne hologram having spatially heterodyne fringes includes: passing a single write beam through a spatial light modulator that digitally modulates said single write beam; and focusing the single write beam at a focal plane of a lens to impose a holographic diffraction grating pattern on the photorefractive crystal, the holographic diffraction grating pattern including the spatially heterodyne hologram having spatially heterodyne fringes, wherein only said single write beam is incident on said photorefractive crystal without a reference beam. A method of replaying a spatially heterodyne hologram having spatially heterodyne fringes at a replay angle includes: illuminating a photorefractive crystal having a holographic diffraction grating with a beam from a laser at an illumination angle, the holographic diffraction grating pattern including the spatially heterodyne hologram having spatially heterodyne fringes, wherein a difference between said illumination angle and said replay angle defines a diffraction angle .alpha. that is a function of a plane wave mathematically added to original object wave phase and amplitude data of said spatially heterodyne hologram having spatially heterodyne fringes.

  11. 5, 80558090, 2005 Single particle

    E-Print Network [OSTI]

    Boyer, Edmond

    with Energy-Dispersive X-ray Anal- ysis (EDX). Samples were collected onboard the British Met Office Hercules ­ Published: 5 September 2005 Correspondence to: A. C. Targino (admir@misu.su.se) © 2005 Author(s). This work crystal residual particles collected over Scandinavia during the INTACC (INTeraction of Aerosol and Cold

  12. Surface Energy,Surface Energy, Surface Tension & Shape of CrystalsSurface Tension & Shape of Crystals

    E-Print Network [OSTI]

    Subramaniam, Anandh

    Surface Energy,Surface Energy, Surface Tension & Shape of CrystalsSurface Tension & Shape of shapes of crystals are important: (i) growth shape and (ii) equilibrium shape Surface/interface energy surfaces. The joining of two phases creates an interface. (Two orientations of the same crystalline phase

  13. Single-crystal elasticity of fayalite to 12 GPa Sergio Speziale1

    E-Print Network [OSTI]

    Duffy, Thomas S.

    , Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA Received 4 May 2004; revised constants of a natural Fe-rich olivine (Fe0.94Mn0.06)2SiO4 were determined by Brillouin scattering to 12

  14. The effects of solution parameters on the structure of polyethylene single crystals

    E-Print Network [OSTI]

    Ashburn, Donald George

    1964-01-01T23:59:59.000Z

    ~ 24 ~ 301 (1957) ~ 2? A~ Keller ~ Phil? Nag? 2? 1171 (1957) ~ 3? H?D? Keith and F?J ~ Padden, Jr? ~ J ~ Polymer Sci. ~ Q? 123 (1959) ~ 4? D?C? Baseett and Ai Keller, Phil. Nag' ~ g? 1553 (1962). ~ D ~ H? Renecker and P, H, Qeil, J, kppl...?R. Swan and W& Helglsch? J. Appl. Phys, , +I? 1906 (1960) ~ 10 D, C Bassett, F?C, Frank, and A Keller, Phil. Na;;. , 8, 1739 (1963)? 11, D?C. Bassett, F?C? Frank? and A? Keller? Phil? Nag ~ 8? 1753 (1963 ) . 12, D?C Bassett? A Keller, and ST Nitsuhashi...

  15. Amplification of cylindrically polarized laser beams in single crystal fiber amplifiers

    E-Print Network [OSTI]

    Boyer, Edmond

    Balembois,2 Patrick Georges,2 and Marwan Abdou Ahmed1 1 Institut für Strahlwerkzeuge, Universität Stuttgart. Michalowski, M. Abdou Ahmed, V. Onuseit, V. Rominger, M. Kraus, and T. Graf, "Effects of Radial and Tangential:YAG thin-disk laser with high efficiency," Opt. Express 19(6), 5093­5104 (2011). 11. M. Abdou Ahmed, M

  16. Calorimeter for adsorption energies of larger molecules on single crystal surfaces

    E-Print Network [OSTI]

    Campbell, Charles T.

    , Hyeran Ihm, David E. Moilanen, and Charles T. Campbell Department of Chemistry, Box 351700, University a pair- wise bond additivity model.9,10 While Ge et al.,9 Brown et al.,10,11 and Kose et al.12,13 has

  17. Growth and electrochromic properties of single-crystal V2O5 nanorod arrays

    E-Print Network [OSTI]

    Cao, Guozhong

    -13 cm2 /s 5,6 and the electrical conductivity of V2O5 10-2 ­10-3 S/cm 7,8 are both small and, thusO5 gel into deionized water.18 V2O5 nanorod arrays have been grown inside polycarbonate templates

  18. A measurement of the temperature dependence of the absorption edge of single crystals, using polarized light

    E-Print Network [OSTI]

    Dunham, Robert Latham

    1964-01-01T23:59:59.000Z

    . For comparison, the value of the shift in germanium is 3. 9 X 10 eV/'C. Yiork on photoconductivity at Hebrew University stimulated some optical research at the same university, involving absorption, specular reflectivity, and thermoluminescence measurements... QUARTZ / WINDOW FIG. I. DEWAR FLASK 23 50. S83 ELECTRONIC T UBE DIV ISION OF DUMONT LABORATORIES I O. I- W LIl t' I- V) Z tlJ V) I. O S-I GOOO 9000 WAVELENGTH-ANGSTROMS FIG. 2. SPECTRAL IAESPONSE 12000 1. 5 TEMPEPATURE 'K FIG. B...

  19. Integration of single-crystal devices with flexible substrates using conductive adhesive layers

    E-Print Network [OSTI]

    Doran, Christopher Kyle Gregory

    2011-01-01T23:59:59.000Z

    Journal of Microelectromechanical Systems. 12, 256 (2003).in fabricating microelectromechanical systems. 1.1: Current

  20. Waste Heat Energy Harvesting Using Olsen Cycle on PZN-5.5PT Single Crystals

    E-Print Network [OSTI]

    McKinley, Ian Meeker; Kandilian, Razmig; Pilon, Laurent

    2012-01-01T23:59:59.000Z

    1 µ m thick Au 0.68 Pd 0.32 electrode. (a) (b) Displacement,1 µ m thick Au 0.68 Pd 0.32 electrodes having ? =16,951 kg/m

  1. Pore space percolation in sea ice single crystals D. J. Pringle,1,2

    E-Print Network [OSTI]

    Golden, Kenneth M.

    from 2 to 12% and we found arrays of near-parallel intracrystalline brine layers whose connectivity threshold in the brine microstructure of sea ice. In previous works this critical behavior has been inferred at higher brine volumes by the formation of thin necks between the brine layers. We relate these results

  2. Temperature-dependent Urbach tail measurements of lutetium aluminum garnet single crystals

    E-Print Network [OSTI]

    Liberman, Vladimir

    Lutetium aluminum garnet (LuAG) is the most promising candidate for a high-index lens material for use in microlithographic imaging lenses. In the deep ultraviolet spectral range the transmission of high-purity LuAG was ...

  3. Temperature gradient transport growth of potassium tantalate niobate, KTa??xNbxO?, single crystals

    E-Print Network [OSTI]

    Goeking, Kent Wayne

    1987-01-01T23:59:59.000Z

    temperature and Curie point ill KTN compositional analysis . 29 . 30 Ix LIST OF FIGURES FIGURE Page Cubic perovskite structure - paraelectric phase. Tetragonal distorted perovskite structure - ferroelectric phase. . . 3 Ferroelectric polarization vs..., this material was found to display ferroelectric behavior. Unlike early ferroelectrics, BaTIOs had a simple cubic centrosymmetric perovskite structure that allowed extensive investigation into the mechanics of ferroelectricity. Following this discovery...

  4. Irradiated cubic single crystal SiC as a high temperature sensor Alex A. Volinsky

    E-Print Network [OSTI]

    Volinsky, Alex A.

    flux on the order of 21020 neutrons/cm2 at 0.18 MeV causes over 3% volume lattice expansion. Radiation-ray diffractometry, and heat-transfer. 3 irradiation interacts with SiC primarily by scattering off nuclei, an event, which, in turn, will complicate lattice parameter measurements. Neutron ly imparts energy and momentum

  5. Understanding and development of combined acoustic and magnetic actuation of Ni?MnGa single crystals

    E-Print Network [OSTI]

    Techapiesancharoenkij, Ratchatee, 1979-

    2007-01-01T23:59:59.000Z

    Ni-Mn-Ga based ferromagnetic shape memory alloys (FSMAs) have emerged as a promising new class of active materials capable of producing a large (several %) magnetic-field-induced strain (MFIS). FSMAs still have several ...

  6. The Fabrication of an Inverter using Rubrene Single Crystal Organic Transistors

    E-Print Network [OSTI]

    understanding of the technology, leading to higher quality advanced applications. The Inverter Circuit Good Bad, Sendai, Japan Conclusions and Future Work: Fabrication of the Inverter: Characterization of Devices: Acknowledgements: I would like to thank Rice University's NanoJapan Program, which was generously funded by a grant

  7. Scintillation characteristics of undoped and Cu+-doped Li2B4O7 single crystals

    E-Print Network [OSTI]

    Kobayashi, Masaaki; Senguttuvan, Nachimuthu

    2015-01-01T23:59:59.000Z

    Scintillation characteristics of undoped and Cu+-doped lithium tetraborate Li2B4O7 (LTB) were studied including optical transmittance, photoluminescence, radioluminescence for X- and gamma-rays, alpha/gamma ratio, and decay kinetics. The total time-integrated LYs in undoped and Cu+-doped LTB for X-rays are ~600 and ~760 ph/MeV (photons/MeV), respectively. The decay kinetics in undoped and Cu+-doped LTB are similar to each other. Typical decay spectra for pulsed X-rays can be fitted with four exponentials: for fast (t1~0.8 ns, t2~25-50 ns), medium (t3~300-400 ns), and slow (t4~20-30 ms) components. The slow component occupies about 60% of the total LY, while the fast ones less than 10%. The 10-90% rise time was 163 ps. The alpha/gamma ratio was 0.18 for external 241Am alpha-rays. The obtained increase in LY due to Cu+ doping remains modest. The Cu+-induced emission contains both fast and slow components, requiring further studies of the emission mechanism to explain the fast component.

  8. Scintillation characteristics of undoped and Cu+-doped Li2B4O7 single crystals

    E-Print Network [OSTI]

    Masaaki Kobayashi; Mitsuru Ishii; Nachimuthu Senguttuvan

    2015-03-12T23:59:59.000Z

    Scintillation characteristics of undoped and Cu+-doped lithium tetraborate Li2B4O7 (LTB) were studied including optical transmittance, photoluminescence, radioluminescence for X- and gamma-rays, alpha/gamma ratio, and decay kinetics. The total time-integrated LYs in undoped and Cu+-doped LTB for X-rays are ~600 and ~760 ph/MeV (photons/MeV), respectively. The decay kinetics in undoped and Cu+-doped LTB are similar to each other. Typical decay spectra for pulsed X-rays can be fitted with four exponentials: for fast (t1~0.8 ns, t2~25-50 ns), medium (t3~300-400 ns), and slow (t4~20-30 ms) components. The slow component occupies about 60% of the total LY, while the fast ones less than 10%. The 10-90% rise time was 163 ps. The alpha/gamma ratio was 0.18 for external 241Am alpha-rays. The obtained increase in LY due to Cu+ doping remains modest. The Cu+-induced emission contains both fast and slow components, requiring further studies of the emission mechanism to explain the fast component.

  9. Dielectric characterization of single crystal tourmaline as a function of temperature and frequency

    E-Print Network [OSTI]

    Webb, Perry Vernon

    1983-01-01T23:59:59.000Z

    of tourmaline and lithium tantalate used in this research. I also wish to express my thanks to Dr. Yellapu Anjaneyulu for his help in the design of the furnace chamber and his interest in this work. For help in modifying the temperature controller, I am... for Impedance measurements . . 17 8 Real Permittivity vs. Temperature of Lithium Tantalate . 18 9 Real Permittivity vs. Temperature of Tourmaline 10 Real Permittivity vs. Frequency of Tourmaline 11 Conductivity vs. Temperature of Tourmaline . 12...

  10. EXPERIMENTAL VERIFICATION OF INTERNAL FRICTION AT GHZ FREQUENCIES IN DOPED SINGLE-CRYSTAL SILICON

    E-Print Network [OSTI]

    Afshari, Ehsan

    losses into account. Recent work in MEMS resonators has started to utilize some of the electrical of the energy loss in a resonator, also has similar limits that arise from practical implementation, including Eugene Hwang and Sunil A. Bhave OxideMEMS Lab, School of Electrical and Computer Engineering, Cornell

  11. Detection of single-ion spectra by Coulomb-crystal heating

    SciTech Connect (OSTI)

    Clark, Craig R.; Goeders, James E.; Dodia, Yatis K.; Viteri, C. Ricardo; Brown, Kenneth R. [Schools of Chemistry and Biochemistry Computational Science and Engineering and Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2010-04-15T23:59:59.000Z

    The coupled motion of ions in a radiofrequency trap has been used to connect the frequency-dependent laser-induced heating of a sympathetically cooled spectroscopy ion with changes in the fluorescence of a laser-cooled control ion. This technique, sympathetic heating spectroscopy, is demonstrated using two isotopes of calcium. In the experiment, a few scattered photons from the spectroscopy ion are transformed into a large deviation from the steady-state fluorescence of the control ion. This allows us to detect an optical transition where the number of scattered photons is below our fluorescence detection limit. Possible applications of the technique to molecular ion spectroscopy are briefly discussed.

  12. (Fundamental electron transfer processes at the single crystal semiconductor/liquid interface)

    SciTech Connect (OSTI)

    Lewis, N.S.

    1991-01-01T23:59:59.000Z

    The last year's work has focused on several aspects of the fundamental chemistry and physics semiconductor/liquid junction behavior. These projects have been directed primarily towards GaAs/liquid contacts, because GaAs/liquid systems provide high energy conversion efficiencies and offer an opportunity to gain mechanistic understanding of the factors that are important to control in an efficient photoelectrochemical energy conversion system.

  13. [Fundamental electron transfer processes at the single crystal semiconductor/liquid interface]. Progress report

    SciTech Connect (OSTI)

    Lewis, N.S.

    1991-12-31T23:59:59.000Z

    The last year`s work has focused on several aspects of the fundamental chemistry and physics semiconductor/liquid junction behavior. These projects have been directed primarily towards GaAs/liquid contacts, because GaAs/liquid systems provide high energy conversion efficiencies and offer an opportunity to gain mechanistic understanding of the factors that are important to control in an efficient photoelectrochemical energy conversion system.

  14. Nanoscale Anisotropic Plastic Deformation in Single Crystal Aragonite C. Kearney,1

    E-Print Network [OSTI]

    of calcium carbonate, CaCO3) is a mineral ubiquitous in natural systems includ- ing living organisms [1-to-aragonite transition and the development of the CaCO3 phase diagram [10]. Although the mechanical behavior of aragonite is a rhombohedral form of CaCO3 and olivine [14], which, like aragonite, has an orthorhom- bic structure

  15. Correlation between number of ferroelectric variants and coercive field of lead ziconate titanate single crystals

    E-Print Network [OSTI]

    Chen, Long-Qing

    Understanding the magnitude of coercive fields, the external electric field that results in zero net field is defined as the magnitude of an external electric field, which results in zero net polarization Alamos, New Mexico 87545 and Department of Materials Science and Engineering, Penn State University

  16. Sm^Nd dating of spatially controlled domains of garnet single crystals: a new method of

    E-Print Network [OSTI]

    Ganguly, Jibamitra

    a peak metamorphic P^T condition of 8 þ 1 kbar, 820 þ 30C [Spear and Parrish, J. Petrol. 37 (1996) 733 of multiple geochronological systems [Spear and Parrish, J. Petrol. 37 (1996) 733^ 765], a cooling rate of V15

  17. MAGNON SCATTERING OF SLOW NEUTRONS ON A PYRRHOTITE SINGLE CRYSTAL By ADAM WANIC,

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    of Nuclear Physics, Cracow, Poland. Institute of Nuclear Sciences " Boris Kidric ", Vinca, Yugoslavia (1 spectrometer installed at the TVRS reactor in Vinca. The energy analysis together with the diffraction method were applied and are described. The results are interpreted in the frame of spin wave theory. A spin

  18. Photochemical Grafting of Organic Alkenes to Single-Crystal TiO2...

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

    Surfaces: A Mechanistic Study. Abstract: The UV-induced photochemical grafting of terminal alkenes has emerged as a versatile way to form molecular layers on semiconductor...

  19. High temperature solution growth of pseudobrookite, Fe?TiO?, single crystals

    E-Print Network [OSTI]

    Baird, Bobbie Ann

    1986-01-01T23:59:59.000Z

    if one were to consider an induction furnace, a constraint is faced in crucible materials. Crucibles of very high melting temperature such as platinum or iridium are quite costly. In order to lower the temperature at which the material becomes liquid.... J. M. . Principles of Induction Melting . American Foundrymen's Society, Inc. . Des Plaines, Illinois, 1977. Taylor. R. W. , Liquidus temperatures in the system FeO-FesOs-TiOs. J. of Arn. Cer. Soc. , 46, 276-279, 1963. Wanklyn, B. M. , Two new...

  20. Paramagnetic Spin Correlations in CaFe2As2 Single Crystals

    SciTech Connect (OSTI)

    Omar Diallo, Souleymane [ORNL; Pratt, Daniel [Ames Laboratory and Iowa State University; Fernandes, Rafael [Ames Laboratory and Iowa State University; Tian, Wei [Ames Laboratory and Iowa State University; Zarestky, J. L. [Ames Laboratory and Iowa State University; Lumsden, Mark D [ORNL; Perring, T. G. [ISIS Facility, Rutherford Appleton Laboratory; Broholm, C. [Johns Hopkins University; Ni, Ni [Ames Laboratory and Iowa State University; Budko, S L [Ames Laboratory and Iowa State University; Canfield, Paul [Ames Laboratory and Iowa State University; Li, Haifeng [Ames Laboratory and Iowa State University; Vaknin, D [Ames Laboratory and Iowa State University; Kreyssig, A. [Ames Laboratory and Iowa State University; Goldman, A. I. [Ames Laboratory and Iowa State University; Mcqueeney, R J [Ames Laboratory and Iowa State University

    2010-01-01T23:59:59.000Z

    Magnetic correlations in the paramagnetic phase of CaFe2As2(TN=172 K) have been examined by means of inelastic neutron scattering from 180 K ( 1.05TN) up to 300 K (1.8TN). Despite the first-order nature of the magnetic ordering, strong but short-ranged antiferromagnetic (AFM) correlations are clearly observed. These correlations, which consist of quasielastic scattering centered at the wave vector QAFM of the low-temperature AFM structure, are observed up to the highest measured temperature of 300 K and at high energy transfer ( >60 meV). The L dependence of the scattering implies rather weak interlayer coupling in the tetragonal c direction corresponding to nearly two-dimensional fluctuations in the (ab) plane. The spin correlation lengths within the Fe layer are found to be anisotropic, consistent with underlying fluctuations of the AFM stripe structure. Similar to the cobalt-doped superconducting BaFe2As2 compounds, these experimental features can be adequately reproduced by a scattering model that describes short-ranged and anisotropic spin correlations with overdamped dynamics.