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Sample records for js rogers sr

  1. Recovery Act update from Sr. Advisor Matt Rogers-- End of Obligations

    Broader source: Energy.gov [DOE]

    Matt Rogers, Senior Advisor to the Secretary for Recovery Act Implementation, shares his thoughts as the Recovery Act reaches a critical milestone -- the end of the 2010 fiscal year and the last...

  2. Recovery Act update from Sr. Advisor Matt Rogers -- End of Obligations

    ScienceCinema (OSTI)

    Rogers, Matt

    2013-05-29

    Senior Advisor to the Secretary for Recovery Act Implementation Matt Rogers shares his thoughts as the Recovery Act reaches a critical milestone -- the end of the 2010 fiscal year and the last day to obligation contract and grant funding under the Recovery Act. For more information about the Recovery Act at the Department of Energy: http://www.energy.gov/recovery Follow the Department of Energy! http://facebook.com/energygov http://twitter.com/energy

  3. Roger M. Claycomb- Biography

    Broader source: Energy.gov [DOE]

    Roger Claycomb has more than 30 years of experience in the nuclear industry in both nuclear facility operations and oversight.

  4. Faces of Science: Roger Wiens

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

    Roger Wiens Faces of Science: Roger Wiens As a kid, Roger Wiens built model rockets and even a telescope. Today, Wiens fuels his passion for space by contributing to technology that is helping to explore Mars. March 4, 2015 Roger Wiens Roger Wiens, Space Contact Communications Office (505) 667-6700 SPACE Wiens' passion for space has no limits At nine years old, Roger Wiens built a telescope to sketch the features of Mars. Faces of Science: Roger Wiens 1:23 Faces of Science: Roger Wiens Forty

  5. Matt Rogers | Department of Energy

    Office of Environmental Management (EM)

    Matt Rogers About Us Matt Rogers - McKinsey & Company Photo of Matt Rogers Matt Rogers is a Director in McKinsey & Company's San Francisco Office. He is focused on the role technology and innovation play in restructuring markets, especially in energy and capital intensive industries. Matt recently rejoined McKinsey after serving as the Senior Advisor to the Secretary of Energy for Recovery Act Implementation. In this role, he had responsibility for managing the Department of Energy's

  6. Departure Roger Anthoine

    SciTech Connect (OSTI)

    2007-11-28

    Remerciements et discours du D.G. H.Schopper l'occasion du dpart de Roger Anthoine (attach de presse), qui travaillait dans la communication et quitte le Cern aprs 27 ans de service. Il gardait des relations avec des mdias internationaux et la presse locale; remise des cadeaux: album photo avec images des muss de Genve et un radio aviation; R.A. fait un rsum de ses activits et souvenirs et remercie ses collaborateurs

  7. Departure Roger Anthoine

    ScienceCinema (OSTI)

    None

    2011-04-25

    Remerciements et discours du D.G. H.Schopper à l'occasion du départ de Roger Anthoine (attaché de presse), qui travaillait dans la communication et quitte le Cern après 27 ans de service. Il gardait des relations avec des médias internationaux et la presse locale; remise des cadeaux: album photo avec images des musés de Genève et un radio aviation; R.A. fait un résumé de ses activités et souvenirs et remercie ses collaborateurs

  8. Faces of Science: Roger Wiens

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

    Roger Wiens March 4, 2015 Wiens' passion for space has no limits At nine years old, Roger Wiens built a telescope to sketch the features of Mars. 1:23 Faces of Science: Roger Wiens - 2 - Forty years later he returned to the Red Planet, this time as part of a team that invented ChemCam, a device aboard the rover Curiosity. Using a laser that packs the energy of a million light bulbs into a spot the size of a pinhead, ChemCam blasts pieces of Martian rock in search of elements like carbon and

  9. SR????

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

    29, and provide your name, organization and social security number for badging purposes. Fran can be reached at the telephone number or e-mail address listed above. SR-06-07 DOE...

  10. Jiangsu Jiasheng Photovoltaic Technology Co Ltd aka JS Solar...

    Open Energy Info (EERE)

    Jiasheng Photovoltaic Technology Co Ltd aka JS Solar Ltd Jump to: navigation, search Name: Jiangsu Jiasheng Photovoltaic Technology Co Ltd (aka JS Solar Ltd) Place: Jiangsu...

  11. J.S. 24 POWER TRANSMISSION AND DISTRIBUTION; VECTORS; ELECTRIC...

    Office of Scientific and Technical Information (OSTI)

    power and power factor of instantaneous phasors Hsu, J.S. 24 POWER TRANSMISSION AND DISTRIBUTION; VECTORS; ELECTRIC CURRENTS; ELECTRIC POTENTIAL; MONITORING; POWER SYSTEMS;...

  12. Buckley, J.S. 02 PETROLEUM; PETROLEUM; ENHANCED RECOVERY; ASPHALTENES...

    Office of Scientific and Technical Information (OSTI)

    Reservoir Wettability and its Effect on Oil Recovery. Buckley, J.S. 02 PETROLEUM; PETROLEUM; ENHANCED RECOVERY; ASPHALTENES; MINERALS; SURFACES; MICA; WETTABILITY We report on the...

  13. Matt Rogers on AES Energy Storage

    ScienceCinema (OSTI)

    Rogers, Matt

    2013-05-29

    The Department of Energy and AES Energy Storage recently agreed to a $17.1M conditional loan guarantee commitment. This project will develop the first battery-based energy storage system to provide a more stable and efficient electrical grid for New York State's high-voltage transmission network. Matt Rogers is the Senior Advisor to the Secretary for Recovery Act Implementation.

  14. Roger Seitz Savannah River National Laboratory

    Office of Environmental Management (EM)

    Practical Considerations for Development and Selection of Scenarios Roger Seitz Savannah River National Laboratory 3 June 2014 PA&RA Community of Practice SRNL-MS-2014-00076 2 PA&RA Community of Practice - 3 June 2014 Introduction ! Need set of cases to consider for quantitative assessments to evaluate effectiveness of disposal or remedial actions ! Emphasis on understanding roles and functions of "barriers" in context of system behavior rather than exact predictions

  15. The Honorable Harold Rogers The Honorable Daniel K. Inouye

    Office of Environmental Management (EM)

    Washington, DC 20585 (enter date here, centered) The Honorable Harold Rogers The Honorable Daniel K. Inouye Chairman, Committee on Appropriations Chairman, Committee on...

  16. VWA-0032- In the Matter of Roger W. Hardwick

    Broader source: Energy.gov [DOE]

    This Decision involves a complaint of reprisal filed by Roger W. Hardwick (also referred to as the Complainant) under the Department of Energy’s (DOE) Contractor Employee Protection Program, 10 C.F...

  17. VBA-0032- In the Matter of Roger H. Hardwick

    Broader source: Energy.gov [DOE]

    This Decision considers an Appeal of an Initial Agency Decision issued on July 6, 1999, on a complaint filed by Roger H. Hardwick (Hardwick or the complainant) under the Department of Energy (DOE)...

  18. SISGR-MuSR Investigations of Magnetic Semiconductors for Spintronics

    Office of Scientific and Technical Information (OSTI)

    Applications (Technical Report) | SciTech Connect Technical Report: SISGR-MuSR Investigations of Magnetic Semiconductors for Spintronics Applications Citation Details In-Document Search Title: SISGR-MuSR Investigations of Magnetic Semiconductors for Spintronics Applications Authors: Lichti, Roger Publication Date: 2014-03-27 OSTI Identifier: 1148701 Report Number(s): Final Report DOE Contract Number: SC0001769 Resource Type: Technical Report Research Org: Texas Tech University Sponsoring

  19. Punam Thakur*, Russell Hardy*, Roger Nelson** and Abraham Van Luik**

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

    19, 2015, Phoenix, Arizona, USA 1 The Role of Independent Monitoring in Maintaining Community Support through a Radiological Incident -A WIPP Case Study - 15107 Punam Thakur*, Russell Hardy*, Roger Nelson** and Abraham Van Luik** *Carlsbad Environmental Monitoring & Research Center, 1400 University Drive, Carlsbad, NM 88220, USA pthakur@cemrc.org ** US Department of Energy, Carlsbad Field Office, 4021 S. National Parks Highway, Carlsbad, NM 88220, USA ABSTRACT The Waste Isolation Pilot

  20. Microsoft PowerPoint - Session2_Rogers.pptx

    Gasoline and Diesel Fuel Update (EIA)

    mme search Program atural Gas Res International Gas Market Workshop International Gas Market Workshop European Gas Market Outlook European Gas Market Outlook Y STUDIES Na p p 23 rd August 2012 Howard V Rogers Director Natural Gas Programme E FOR ENERGY Director Natural Gas Programme Oxford Institute for Energy Studies ORD INSTITUT OXFO 1 mme Themes search Program Themes * European Price Transition from oil indexation to hub atural Gas Res pricing. * Europe and Asia LNG 'Tug of War' Y STUDIES Na

  1. Tribal Energy Program 2009 Annual Review - Roger Taylor

    Energy Savers [EERE]

    Energy Program 2009 Annual Review Roger Taylor November 16-20, 2009 National Renewable Energy Laboratory Innovation for Our Energy Future Major DOE National Laboratories Brookhaven Pacific Northwest Lawrence Berkeley Lawrence Livermore          INEL National Renewable Energy Laboratory Los Alamos Sandia Argonne Oak Ridge   Defense Program Labs  Office of Science Labs  Energy Efficiency and Renewable Energy Lab  Environmental Management Lab  Fossil

  2. Assistant Secretary Cathy Zoi and Senior Advisor Matt Rogers to Participate

    Office of Environmental Management (EM)

    in Platts Energy Reporter Roundtable | Department of Energy Cathy Zoi and Senior Advisor Matt Rogers to Participate in Platts Energy Reporter Roundtable Assistant Secretary Cathy Zoi and Senior Advisor Matt Rogers to Participate in Platts Energy Reporter Roundtable September 22, 2010 - 12:00am Addthis WASHINGTON -Thursday, September 23, 2010, Cathy Zoi, Assistant Secretary of Energy Efficiency and Renewable Energy and Matt Rogers, Senior Advisor to the Secretary of Energy, will participate

  3. LANL Researcher Roger Wiens Discusses ChemCam

    ScienceCinema (OSTI)

    Wiens, Roger

    2014-08-12

    Discussion of the ChemCam instrument on the Curiosity Rover that occurred during the NASA press conference prior to launch of the Mars Science Laboratory. The ChemCam instrument was developed by Los Alamos National Laboratory and the French Space Institute. Los Alamos National Laboratory researcher Roger Wiens discusses the instrument on this video. ChemCam uses a laser to "zap" features of the Martian landscape and then uses a spectrometer to gather information about the composition of the sample. ChemCam will help the Curiosity Rover determine whether Mars is or was habitable. The Rover is expected to touch down on the Red Planet on August 5, 2012.

  4. SR0305

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

    Hosts Public Workshops on Historical Preservation of SRS' Cold War Resources Flag Ribbon Art Aiken, SC - The Department of Energy's Savannah River Operations Office (DOE-SR) will...

  5. SR0014

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

    SC; November 30 - The Department of Energy (DOE) Savannah River Operations Office (SR) has published for public review and comment the Draft Environmental Impact Statement...

  6. SR0208

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

    , 2002 Media Contact: Julie Petersen (803) 725-2889 DOE-SR Announces Release Of SRS History Book Flag Ribbon Art Aiken, SC - Today the Department of Energy (DOE) Savannah River...

  7. SR0204

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

    2 Media Contact: Julie Petersen (803) 725-2889 Allison Named DOE-SR Acting Manager Flag Ribbon Art AIKEN, SC; July 1 - Assistant Secretary for Environmental Management Jessie H....

  8. SR9903

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

    22, 1999 Media Contact: Julie Petersen (803) 725-2889 DOE-SR To Prepare Supplemental Environmental Impact Statement On High-Level Waste System Alternatives Flag Ribbon Art AIKEN,...

  9. SR0606

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

    and transition. The draft RFP is available to interested parties on the DOE e-Commerce website: http:e-center.doe.gov and the DOE-SR acquisition website: http:...

  10. SR0703

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

    management services. The RFP is available to interested parties on the DOE e-Commerce website: http:e-center.doe.gov and the DOE-SR acquisition website: http:...

  11. SR0701?

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

    by April 30, 2007. The draft RFP is available to interested parties on the DOE e-Commerce website: http:e-center.doe.gov and the DOE-SR acquisition website: http:...

  12. DOE - Office of Legacy Management -- Rogers Iron Works Co - MO 10

    Office of Legacy Management (LM)

    Rogers Iron Works Co - MO 10 FUSRAP Considered Sites Site: ROGERS IRON WORKS CO. (MO.10 ) Elimination from consideration under FUSRAP Designated Name: Not Designated Alternate Name: Rogers Iron Co. MO.10-1 Location: Joplin , Missouri MO.10-1 Evaluation Year: 1990 MO.10-2 MO.10-3 Site Operations: Tested C-liner crushing methods. MO.10-1 Site Disposition: Eliminated - Potential for contamination considered remote based on limited quantities of material handled MO.10-3 MO.10-4 Radioactive Materials

  13. Science Showcase: George F. Smoot and Roger D. Kornberg | OSTI, US Dept of

    Office of Scientific and Technical Information (OSTI)

    Energy, Office of Scientific and Technical Information Science Showcase: George F. Smoot and Roger D. Kornberg Feature Archive George Smoot George F. Smoot won the 2006 Nobel Prize in Physics. George F. Smoot and Roger D. Kornberg have joined the growing list of Nobel Laureates associated with DOE. Smoot won the 2006 Nobel Prize in Physics for his work in blackbody and anisotropy of the cosmic microwave background radiation. Smoot is an astrophysicist at DOE's Lawrence Berkeley National Lab

  14. SR0008

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

    Wachenhut Receives Award Fee Flag Ribbon Art Note to Editors and News Directors The Department of Energy (DOE) has determined the performance award fee earned by Wackenhut Services, Incorporated, for the evaluation period October 1, 1999, through March 31, 2000. A copy of the letter announcing DOE's award fee determination can be obtained by calling (803) 725-2889. -DOE- SR-00-08

  15. SR0106

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

    31, 2001 Media Contact: Rick Ford (803) 725-2889 DOE Announces Wackenhut Services Inc. Award Fee Flag Ribbon Art Note To Editors and News Directors: The Department of Energy (DOE) has determined the performance award fee earned by Wackenhut Services, Incorporated, for the evaluation period October 1, 2000, through March 31, 2001. -DOE- SR-01-06

  16. SR0302

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

    8, 2003 Media Contact: Rick Ford (803) 725-2889 DOE Announces WSI Award Fee Flag Ribbon Art The Department of Energy (DOE) has determined the performance award fee earned by Wackenhut Services, Incorporated, for the evaluation period October 1, 2002, through March 31, 2003. The letter announcing DOE's award fee determination is available by calling (803)725-2889. -DOE- SR-03

  17. SR0009

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

    June 8, 2000 Media Contact: Rick Ford (803) 725-2889 WSRC Receives Award Fee Flag Ribbon Art Note to Editors and News Directors The Department of Energy (DOE) has determined the performance award fee earned by Westinghouse Savannah River Company for the evaluation period October 1, 1999, through March 31, 2000. To obatin a copy of the letter announcing DOE's award fee determination click here or call (803) 725-2889 -DOE- SR-00-08

  18. SR0015

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

    , 2000 Media Contact: Jim Giusti (803) 725-2889 WSRC Receives Award Fee Flag Ribbon Graphic Note to Editors and News Directors The Department of Energy (DOE) has determined the performance award fee earned by Westinghouse Savannah River Company for the evaluation period April 1, 2000, through September 30, 2000. To obatin a copy of the letter announcing DOE's award fee determination click here or call (803) 725-2889 -DOE- SR-00-15 | Back |

  19. SR0018

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

    Rick Ford (803) 725-2889 Wackenhut Receives Award Fee Flag Ribbon Graphic The Department of Energy (DOE) has determined the performance award fee earned by Wackenhut Services, Incorporated, for the evaluation period April 1, 2000, through September 30, 2000. To obatin a copy of the letter announcing DOE's award fee determination click here or call (803) 725-2889. -DOE- SR-00-18

  20. SR9805

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

    16, 1999 Media Contact: Rick Ford (803) 725-2889 WSCR Receives Award Fee Flag Ribbon Art The Department of Energy (DOE) has determined the performance award fees earned by Westinghouse Savannah River Company for the evaluation period October 1, 1998, through March 31, 1999. The letter announcing DOE's award fee determination is available by calling (803)725-2889. -DOE- SR-98-05

  1. SR9917

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

    6, 1999 Media Contact: Rick Ford (803) 725-2889 WSCR Receives Award Fee Flag Ribbon Art The Department of Energy (DOE) has determined the performance award fees earned by Westinghouse Savannah River Company for the evaluation period April 1, 1999, through September 30, 1999. The letter announcing DOE's award fee determination is available by calling (803)725-2889. -DOE- SR-99-17

  2. Charles Roger Alcock, 1996 | U.S. DOE Office of Science (SC)

    Office of Science (SC) Website

    Charles Roger Alcock, 1996 The Ernest Orlando Lawrence Award Lawrence Award Home Nomination & Selection Guidelines Award Laureates 2010's 2000's 1990's 1980's 1970's 1960's Ceremony The Life of Ernest Orlando Lawrence Contact Information The Ernest Orlando Lawrence Award U.S. Department of Energy SC-2/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-2411 E: Email Us 1990's Charles Roger Alcock, 1996 Print Text Size: A A A FeedbackShare Page For his scientific

  3. ROGER L. COPPLE ATTORNEY AT LAW FIRST NORTHERN PLAZA* P. O.

    Office of Legacy Management (LM)

    ROGER L. COPPLE ATTORNEY AT LAW FIRST NORTHERN PLAZA* P. O. Box 40 SANTA FE, NEW MEXICO 87501 (505) 982-4004 September 10, 1982 Professional Land Surveying 1404 Second Street Santa Fe, New Mexico 87501 ATTN: Gary Dawson Re: Bechtel National, Inc./United States Department of Energy - Contract No. DE-AC05-810R20722-FUSRAP Dear Mr. Dawson: As required by the terms of Purchase Contract No. 14501-01/04- PC-19 which involves the captioned contract I have prepared and en- close the following items:

  4. Micrometeorological data for energy-budget studies near Rogers Spring, Ash Meadows National Wildlife Refuge, Nye County, Nevada, 1994

    SciTech Connect (OSTI)

    Nichols, W.D.; Rapp, T.R.

    1996-05-01

    The data were collected at two sites near Rogers Spring for use in energy-budget studies beginning in 1994. The data collected at each site included net radiation, air temperature at two heights, dew- point temperature at two heights, windspeed at two heights, soil heat flux, and soil temperature in the interval between the land surface and the buried heat-flux plates.

  5. Delamere-JS

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

    Impact of Cloud Optical Properties on Longwave Radiation in the Arctic J. S. Delamere, E. J. Mlawer, and S. A. Clough Atmospheric and Environmental Research, Inc. Cambridge, Massachusetts K. H. Stamnes Stevens Institute of Technology Hoboken, New Jersey Introduction The surface energy budget of the Arctic is largely controlled by the net flow of solar and terrestrial radiation. Shortwave and longwave radiative fluxes are modulated by the surface properties, the vertical profiles of aerosols,

  6. John A. Rogers and Ralph G. Nuzzo Materials Research Laboratory, University of Illinois at Urbana-Champaign

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

    A. Rogers and Ralph G. Nuzzo Materials Research Laboratory, University of Illinois at Urbana-Champaign Luminescent Waveguide Concentrator Photovoltaics Achievement: We have developed composite luminescent concentrator photovoltaic system that embeds large scale, interconnected arrays of microscale silicon solar cells in thin matrix layers loaded with luminescent dopants. We have efficiently launched wavelength-downconverted photons that waveguide into the sides and bottom surfaces of the sparse

  7. SR0917.docx

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

    (803) 952-7697 Monday, August 10, 2009 james-r.giusti@srs.gov DOE Hosts Public Workshop On Energy Park Concept at the Savannah River Site Aiken, SC (Aug. 8) -- The Department of Energy's (DOE) Savannah River Operations Office (SR) will sponsor a four-hour workshop on the concept of an energy park at the Savannah River Site on August 18, 2009, at the North Augusta Municipal Center, 100 Georgia Avenue, in North Augusta, South Carolina. This initial workshop will feature brief presentations by

  8. 2010sr26.doc

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

    Thursday, September 2, 2010 james-r.giusti@srs.gov SRS Federal Employees Give to Area Food Bank Aiken, SC -- Representatives of the U.S. Department of Energy's Savannah River Operations Office (DOE-SR) at the Savannah River Site delivered the sixth and final truckload of food and non perishables to the Golden Harvest Food Bank today. The 335 federal employees at SRS donated 66,292 pounds of goods in just over 30 days to feed the needy in Georgia and South Carolina. If one does the math, the

  9. Sr:s I

    Office of Legacy Management (LM)

    Sr:s I ] t _ . DOE/EV-0005/43 AN L.OHS/H P.83.107 rL.06 - {03 / { b lii; t-. pr .S Fi ,i i!1 l';, ln ti V: iii li4 i.:l tf,i 'Jt ru' ,,\: :.5/ i i l t:' i:t s:l !3 E.\ il t; ,:; #; Fr.. li{ L-i ;i! ,tA 4 1.: $rg [ , ili k: ".,I k,, i,:. $ rji i:iii [".' ! . , F, iir il' ?:, 'i:' ir: *, Fr, }i.r |ir :y. ri FoRMERLYUTIL|ZEDMED/AEcS|TES REMEDIAL ACTION PROGRAM POST,REMEDIAL.AGTION RADIOLOGICAL SU RVEY OF KENT CH EMICAL LABORATORY THE UNIVERSITY OF CHICAGO CHICAGO, ILLINOIS MaY 1983 o c c

  10. SR-09-03.docx

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

    Recovery Act information for SRS can be found at http:www. srs.govrecovery. -DOE- SR-2009-03 New employees complete mandatory SRS general safety and security training at the...

  11. The J. Bennett Johnston Sr.

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

    J. Bennett Johnston Sr. Center for Advanced Microstructures and Devices (CAMD) EXCELLENCE IN SCIENCE AND ENGINEERING RESEARCH Overview LSU's Center for Advanced Microstructures and Devices (CAMD) provides researchers access to the only synchrotron light source in the southeastern United States. One of seven such facilities in the nation, more than 150 researchers, including LSU faculty, industrial users, local startup companies, and members of national research labs, use CAMD. It is also a key

  12. Remedial investigation work plan for Chestnut Ridge Operable Unit 4 (Rogers Quarry/Lower McCoy Branch) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect (OSTI)

    Not Available

    1993-09-01

    The Oak Ridge Y-12 Plant includes - 800 acres near the northeast comer of the reservation and adjacent to the city of Oak Ridge (Fig. 1-1). The plant is a manufacturing and developmental engineering facility that produced components for various nuclear weapons systems and provides engineering support to other Energy Systems facilities. More than 200 contaminated sites have been identified at the Y-12 Plant that resulted from past waste management practices. Many of the sites have operable units (OUs) based on priority and on investigative and remediation requirements. This Remedial Investigation RI work plan specifically addresses Chestnut Ridge OU 4. Chestnut Ridge OU 4 consists of Rogers Quarry and Lower McCoy Branch (MCB). Rogers Quarry, which is also known as Old Rogers Quarry or Bethel Valley Quarry was used for quarrying from the late 1940s or early 1950s until about 1960. Since that time, the quarry has been used for disposal of coal ash and materials from Y-12 production operations, including classified materials. Disposal of coal ash ended in July 1993. An RI is being conducted at this site in response to CERCLA regulations. The overall objectives of the RI are to collect data necessary to evaluate the nature and extent of contaminants of concern, support an Ecological Risk Assessment and a Human Health Risk Assessment, support the evaluation of remedial alternatives, and ultimately develop a Record of Decision for the site. The purpose of this work plan is to outline RI activities necessary to define the nature and extent of suspected contaminants at Chestnut Ridge OU 4. Potential migration pathways also will be investigated. Data collected during the RI will be used to evaluate the risk posed to human health and the environment by OU 4.

  13. SR-09-01 _SWPF_.doc

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

    using proven separation technologies of filtration and centrifugal contactors. -MORE- SR-08-01 Savannah River Operations Office SWPF CONSTRUCTION 2-2-2-2 After separation, the...

  14. SR????

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

    DOE Seeks Public Input on Scope of Environmental Review for the Global Nuclear Energy ... (PEIS) for the Presidents Global Nuclear Energy Partnership (GNEP) will be held on ...

  15. RADIOISOTOPE INVENTORY FOR TSPA-SR

    SciTech Connect (OSTI)

    C. Leigh; R. Rechard

    2001-01-30

    The total system performance assessment for site recommendation (TSPA-SR), on Yucca Mountain, as a site (if suitable) for disposal of radioactive waste, consists of several models. The Waste Form Degradation Model (i.e, source term) of the TSPA-SR, in turn, consists of several components. The Inventory Component, discussed here, defines the inventory of 26 radioisotopes for three representative waste categories: (1) commercial spent nuclear fuel (CSNF), (2) US Department of Energy (DOE) spent nuclear fuel (DSNF), and (3) high-level waste (HLW). These three categories are contained and disposed of in two types of waste packages (WPs)--CSNF WPs and co-disposal WPs, with the latter containing both DSNF and HLW. Three topics are summarized in this paper: first, the transport of radioisotopes evaluated in the past; second, the development of the inventory for the two WP types; and third, the selection of the most important radioisotopes to track in TSPA-SR.

  16. Role of SrMoO{sub 4} in Sr{sub 2}MgMoO{sub 6} synthesis

    SciTech Connect (OSTI)

    Vasala, S.; Yamauchi, H.; Karppinen, M.

    2011-05-15

    Here we investigate the elemental and phase compositions during the solid-state synthesis of the promising SOFC-anode material, Sr{sub 2}MgMoO{sub 6}, and demonstrate that molybdenum does not notably evaporate under the normal synthesis conditions with temperatures up to 1200 {sup o}C due to the formation of SrMoO{sub 4} as an intermediate product at low temperatures, below 600 {sup o}C. However, partial decomposition of the Sr{sub 2}MgMoO{sub 6} phase becomes evident at the higher temperatures ({approx}1500 {sup o}C). The effect of SrMoO{sub 4} on the electrical conductivity of Sr{sub 2}MgMoO{sub 6} is evaluated by preparing a series of Sr{sub 2}MgMoO{sub 6} samples with different amounts of additional SrMoO{sub 4}. Under the reducing operation conditions of an SOFC anode the insulating SrMoO{sub 4} phase is apparently reduced to the highly conductive SrMoO{sub 3} phase. Percolation takes place with 20-30 wt% of SrMoO{sub 4} in a Sr{sub 2}MgMoO{sub 6} matrix, with a notable increase in electrical conductivity after reduction. Conductivity values of 14, 60 and 160 S/cm are determined at 800 {sup o}C in 5% H{sub 2}/Ar for the Sr{sub 2}MgMoO{sub 6} samples with 30, 40 and 50 wt% of added SrMoO{sub 4}, respectively. -- Graphical abstract: SrMoO{sub 4} is formed at low temperatures during the synthesis of Sr{sub 2}MgMoO{sub 6}, which prevents the volatilization of Mo from typical precursor mixtures of this promising SOFC anode material. SrMoO{sub 4} is insulating and it is often found as an impurity in Sr{sub 2}MgMoO{sub 6} samples. It is however readily reduced to highly conducting SrMoO{sub 3}. Composites of Sr{sub 2}MgMoO{sub 6} and SrMoO{sub 3} show increased electrical conductivities compared to pure Sr{sub 2}MgMoO{sub 6} under the reductive operation conditions of an SOFC anode. Display Omitted Highlights: {yields} Sr{sub 2}MgMoO{sub 6} is a promising SOFC anode material. {yields} During the Sr{sub 2}MgMoO{sub 6} synthesis SrMoO{sub 4} is formed at low temperatures. {yields} Formation of SrMoO{sub 4} effectively prevents volatilization of Mo at high temperatures. {yields} Insulating SrMoO{sub 4} reduces to highly conductive SrMoO{sub 3} under SOFC-anode conditions. {yields} Composites of Sr{sub 2}MgMoO{sub 6} and SrMoO{sub 3} show high electrical conductivities.

  17. Fabrication of Sr silicate buffer layer on Si(100) substrate by pulsed laser deposition using a SrO target

    SciTech Connect (OSTI)

    Imanaka, Atsuhiro; Sasaki, Tsubasa; Hotta, Yasushi Satoh, Shin-ichi

    2014-09-01

    The authors fabricated 2??1 Sr-reconstructed Si(100) substrates using thin SrO layers, and used them to direct growth of crystalline perovskite oxide on Si. The SrO layers used to reconstruct the Si(100) substrates were grown by pulsed laser deposition from a SrO single crystal target, followed by postdeposition-annealing (PDA) of the SrO/Si(100) structure. In situ observations of reflective high-energy electron diffraction during PDA confirmed a 2??1 reconstruction of the Si surface and x-ray photoemission spectroscopy of the annealed samples confirmed the existence of Sr atoms in a silicate phase, which indicated that a 2??1 Sr-reconstructed Si surface was achieved. The optimal fabrication conditions were annealing at 720?C for 1?min and an equivalent SrO layer thickness (ML{sub eq}) of 2.5 ML{sub eq}. The temperature condition was very narrow, at 720??20?C, for an acceptable product. Subsequently, the authors demonstrated the growth of crystalline SrTiO{sub 3} films on the 2??1 Sr-reconstructed Si(100) surfaces.

  18. Carrier-Controlled Ferromagnetism in SrTiO3

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

    Moetakef, Pouya; Williams, James R.; Ouellette, Daniel G.; Kajdos, Adam P.; Goldhaber-Gordon, David; Allen, S. James; Stemmer, Susanne

    2012-06-27

    Magnetotransport and superconducting properties are investigated for uniformly La-doped SrTiO3 films and GdTiO3/SrTiO3 heterostructures, respectively. GdTiO3/SrTiO3 interfaces exhibit a high-density 2D electron gas on the SrTiO3 side of the interface, while, for the SrTiO3 films, carriers are provided by the dopant atoms. Both types of samples exhibit ferromagnetism at low temperatures, as evidenced by a hysteresis in the magnetoresistance. For the uniformly doped SrTiO3 films, the Curie temperature is found to increase with doping and to coexist with superconductivity for carrier concentrations on the high-density side of the superconducting dome. The Curie temperature of the GdTiO3/SrTiO3 heterostructures scales with themore » thickness of the SrTiO3 quantum well. The results are used to construct a stability diagram for the ferromagnetic and superconducting phases of SrTiO3.« less

  19. MHK Projects/SR 01 | Open Energy Information

    Open Energy Info (EERE)

    SR 01 < MHK Projects Jump to: navigation, search << Return to the MHK database homepage Loading map... "minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":5,"ty...

  20. Audit Report: OAS-SR-05-02 | Department of Energy

    Energy Savers [EERE]

    SR-05-02 Audit Report: OAS-SR-05-02 December 28, 2004 Review of Executive Protection Travel Not Available for Viewing More Documents & Publications Special Report: OAS-SR-04-01 Special Report: OAS-SR-05-03 Special Report: OAS-SR-05-01

  1. Microsoft Word - SR-2012-04.docx

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

    June 27, 2012 Bill Taylor, DOE, (803) 952-8564 bill.taylor@srs.gov Savannah River Site Federal Employees Volunteer for United Way Campaign Aiken, SC -- The Department of Energy's Savannah River Operations Office (DOE-SR) has selected two federal employee volunteers to assist the 2012 United Way Campaigns of the CSRA and Aiken. Jean Stump will work with the CSRA United Way Augusta office and Teressa Butler will work with the Aiken United Way office. The 2012 United Way campaign will run from

  2. Microsoft Word - sr-2013-08

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

    SAVANNAH RIVER OPERATIONS OFFICE AIKEN, SC 29802 NEWS MEDIA CONTACT: FOR IMMEDIATE RELEASE Amy Caver, DOE-SR, (803) 952-7213 August 15, 2013 amy.caver@srs.gov Dean Campbell, SRR, (803) 208-8270 dean.campbell@srs.gov GROUTING TO BEGIN TOMORROW ON TWO ADDITIONAL SRS WASTE TANKS AIKEN, S.C. (August 15, 2013) - Cement trucks hauling specially-formulated grout will once again be traversing the U.S. Department of Energy (DOE) Savannah River Site (SRS) as grouting activities on the next two underground

  3. Superconducting and magnetic properties of Sr?Ir?Sn??

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

    Biswas, P. K.; Wang, Kefeng; Amato, A.; Khasanov, R.; Luetkens, H.; Petrovic, C.; Cook, R. M.; Lees, M. R.; Morenzoni, E.

    2014-10-10

    Magnetization and muon spin relaxation or rotation (SR) measurements have been performed to study the superconducting and magnetic properties of Sr?Ir?Sn??. From magnetization measurements the lower and upper critical fields of Sr?Ir?Sn?? are found to be 81(1) Oe and 14.4(2) kOe, respectively. Zero-field SR data show no sign of any magnetic ordering or weak magnetism in Sr?Ir?Sn??. Transverse-field SR measurements in the vortex state provided the temperature dependence of the magnetic penetration depth ?. The dependence of ?? with temperature is consistent with the existence of single s-wave energy gap in the superconducting state of Sr?Ir?Sn?? with a gap valuemoreof 0.82(2) meV at absolute zero temperature. The magnetic penetration depth at zero temperature ?(0) is 291(3) nm. The ratio ?(0)/kBTc = 2.1(1) indicates that Sr?Ir?Sn?? should be considered as a strong-coupling superconductor.less

  4. Special Report: OAS-SR-04-01 | Department of Energy

    Energy Savers [EERE]

    4-01 Special Report: OAS-SR-04-01 July 22, 2004 Executive Protection and Scheduling and Advance Staff Travel in April 2004 Not Available for Viewing More Documents & Publications Audit Report: OAS-SR-05-02 Special Report: OAS-SR-05-03 Special Report: OAS-SR-05-01

  5. Special Report: OAS-SR-05-03 | Department of Energy

    Energy Savers [EERE]

    5-03 Special Report: OAS-SR-05-03 April 13, 2005 Review of Environmental Management Controls Not Available for Viewing More Documents & Publications Special Report: OAS-SR-04-01 Summary Special Report: OAS-SR-06-01 Audit Report: OAS-SR-05-02

  6. VBH-0083- In the Matter of S.R. Davis

    Broader source: Energy.gov [DOE]

    S.R. Davis (the Employee) filed a complaint against her former employer, Fluor Fernald, Inc. (the Contractor) under the Department of Energy (DOE) Contractor Employee Protection Program, 10 C.F.R....

  7. VBA-0083- In the Matter of S.R. Davis

    Broader source: Energy.gov [DOE]

    This Decision considers an Appeal of an Initial Agency Decision (IAD) issued on April 21, 2004, involving a complaint filed by S.R. Davis (also referred to as the Complainant) under the Department...

  8. Rb-Sr Geochronologic Investigation Of Precambrian Samples From...

    Open Energy Info (EERE)

    Rb-Sr Geochronologic Investigation Of Precambrian Samples From Deep Geothermal Drill Holes, Fenton Hill, New Mexico Jump to: navigation, search OpenEI Reference LibraryAdd to...

  9. VWA-0024- In the Matter of Russell P. Marler, Sr.

    Broader source: Energy.gov [DOE]

    This Decision involves a complaint filed by Russell P. Marler, Sr. (Marler or “the complainant”) under the Department of Energy (DOE) Contractor Employee Protection Program, codified at 10 C.F.R....

  10. Jie Gao > Sr. Electrochemist - Spectrum Brands > Center Alumni...

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

    Jie Gao Sr. Electrochemist - Spectrum Brands jiegaocn@gmail.com Jie was a former member of the Abrua Group as a postdoc. In May 2015, he joined Spectrum Brands as an...

  11. SR-08-03 _LEU Shipments_.doc

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

    uranium, but the agreement with TVA is proposed to continue to provide a disposition path for LEU solution produced by the DOE Enriched Uranium Disposition Project. -DOE- SR-08-03...

  12. Summary Special Report: OAS-SR-06-01 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Special Report: OAS-SR-06-01 Summary Special Report: OAS-SR-06-01 October 7, 2005 Management of the Clean Cities Conference PDF icon Summary Special Report: OAS-SR-06-01 More Documents & Publications Special Report: OAS-SR-05-03 Special Report: OAS-SR-05-01 Special Report: OAS-M-07-05

  13. Optical and structural stability of blue SrO:Eu{sup 2+} phosphor

    SciTech Connect (OSTI)

    Komatsu, Keiji; Nakamura, Atsushi; Ohshio, Shigeo; Toda, Ikumi; Muramatsu, Hiroyuki; Saitoh, Hidetoshi

    2013-08-15

    Chemical stability of 6-coodinated SrO is a fundamental problem when this is used for various applications. In this study, optical and chemical stabilities of 8-coordinated SrO:Eu{sup 2+} phosphor were investigated. SrO:Eu{sup 2+} phosphor was synthesized from thermal treatment of SrO:Eu powder located on a single crystalline MgO at 1500 C under reduction atmosphere. Obtained 8-coordinated SrO:Eu{sup 2+} phosphor exhibit strong blue luminescence and chemical stability in distilled water for 3 days. Our findings prove that obtained 8-coordinated SrO:Eu{sup 2+} possesses relative optical and chemical stabilities in water. - Graphical abstract: Obtained 8-coordinated SrO:Eu{sup 2+} phosphor exhibit strong blue luminescence in distilled water. Highlights: We investigated optical and chemical stabilities of 8-coordinated SrO:Eu{sup 2+} phosphor in water. Obtained 8-coordinated SrO:Eu{sup 2+} phosphor exhibit strong blue luminescence and chemical stability in distilled water for 3 days. We found that the 8-coodrodinated SrO crystal structure changed to SrCO{sub 3} crystal structure after the 5 days immersion. The obtained SrO:Eu{sup 2+} phosphor possesses high chemical stability under water, compared with commercial (6-coordinated) SrO.

  14. Phase stability of the SrMn O 3 hexagonal perovskite system at...

    Office of Scientific and Technical Information (OSTI)

    Phase stability of the SrMn O 3 hexagonal perovskite system at high pressure and temperature Title: Phase stability of the SrMn O 3 hexagonal perovskite system at highpressure and ...

  15. Special Inquiry: OAS-SR-11-01 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    SR-11-01 Special Inquiry: OAS-SR-11-01 May 18, 2011 Allegations Regarding Western Area Power Administration's Desert Southwest Reigon The U.S. Office of Special Counsel requested...

  16. Synthesis of BiPbSrCaCuO superconductor

    DOE Patents [OSTI]

    Hults, William L.; Kubat-Martin, Kimberly A.; Salazar, Kenneth V.; Phillips, David S.; Peterson, Dean E.

    1994-01-01

    A process and a precursor composition for preparing a lead-doped bismuth-strontium-calcium-copper oxide superconductor of the formula Bi.sub.a Pb.sub.b Sr.sub.c Ca.sub.d Cu.sub.e O.sub.f wherein a is from about 1.7 to about 1.9, b is from about 0.3 to about 0.45, c is from about 1.6 to about 2.2, d is from about 1.6 to about 2.2, e is from about 2.97 to about 3.2 and f is 10.+-.z by reacting a mixture of Bi.sub.4 Sr.sub.3 Ca.sub.3 Cu.sub.4 O.sub.16.+-.z, an alkaline earth metal cuprate, e.g., Sr.sub.9 Ca.sub.5 Cu.sub.24 O.sub.41, and an alkaline earth metal plumbate, e.g., Ca.sub.2-x Sr.sub.x PbO.sub.4 wherein x is about 0.5, is disclosed.

  17. Synthesis of BiPbSrCaCuO superconductor

    DOE Patents [OSTI]

    Hults, W.L.; Kubat-Martin, K.A.; Salazar, K.V.; Phillips, D.S.; Peterson, D.E.

    1994-04-05

    A process and a precursor composition for preparing a lead-doped bismuth-strontium-calcium-copper oxide superconductor of the formula Bi[sub a]Pb[sub b]Sr[sub c]Ca[sub d]Cu[sub e]O[sub f] wherein a is from about 1.7 to about 1.9, b is from about 0.3 to about 0.45, c is from about 1.6 to about 2.2, d is from about 1.6 to about 2.2, e is from about 2.97 to about 3.2 and f is 10[+-]z by reacting a mixture of Bi[sub 4]Sr[sub 3]Ca[sub 3]Cu[sub 4]O[sub 16[+-]z], an alkaline earth metal cuprate, e.g., Sr[sub 9]Ca[sub 5]Cu[sub 24]O[sub 41], and an alkaline earth metal plumbate, e.g., Ca[sub 2[minus]x]Sr[sub x]PbO[sub 4] wherein x is about 0.5, is disclosed.

  18. Microsoft Word - OAS-SR-10-04 - WEB VERSION

    Office of Environmental Management (EM)

    OFFICIAL USE ONLY OFFICIAL USE ONLY eeOFF Special Inquiry U.S. Department of Energy Office of Inspector General Office of Audit Services Review of Allegations Regarding Hiring and Contracting in the Office of Energy Efficiency and Renewable Energy OAS-SR-10-04 September 2010 Department of Energy Washington, DC 20585 September 22, 2010 MEMORANDUM FOR THE SECRETARY FROM: Gregory H. Friedman Inspector General SUBJECT: INFORMATION: Special Inquiry: "Review of Allegations Regarding Hiring and

  19. Octonary resistance states in La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Octonary resistance states in La0.7Sr0.3MnO3BaTiO3La0.7Sr0.3MnO3 multiferroic tunnel junctions Citation Details In-Document Search This content will become ...

  20. Transverse thermoelectric effect in La{sub 0.67}Sr{sub 0.33}MnO{sub 3}|SrRuO{sub 3} superlattices

    SciTech Connect (OSTI)

    Shiomi, Y.; Handa, Y.; Kikkawa, T.; Saitoh, E.

    2015-06-08

    Transverse thermoelectric effects in response to an out-of-plane heat current have been studied in an external magnetic field for ferromagnetic superlattices consisting of La{sub 0.67}Sr{sub 0.33}MnO{sub 3} and SrRuO{sub 3} layers. The superlattices were fabricated on SrTiO{sub 3} substrates by pulsed laser deposition. We found that the sign of the transverse thermoelectric voltage for the superlattices is opposite to that for La{sub 0.67}Sr{sub 0.33}MnO{sub 3} and SrRuO{sub 3} single layers at 200?K, implying an important role of spin Seebeck effects inside the superlattices. At 10?K, the magnetothermoelectric curves shift from the zero field due to an antiferromagnetic coupling between layers in the superlattices.

  1. Matt Rogers on AES Energy Storage

    Broader source: Energy.gov [DOE]

    The Department of Energy and AES Energy Storage recently agreed to a $17.1M conditional loan guarantee commitment. This project will develop the first battery-based energy storage system to provide...

  2. THE FEDERAL ENERGY ADMINISTRATION By Roger Anders

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    of Energy Office of Management Office of the Executive ... Office, a short-term organization created to coordinate ... because the Wall Street Journal raised questions about ...

  3. Revised calibration of the Sm:SrB{sub 4}O{sub 7} pressure sensor...

    Office of Scientific and Technical Information (OSTI)

    The pressure-induced shift of Sm:SrBsub 4Osub 7 fluorescence was calibrated in a ... CORRECTIONS; DOPED MATERIALS; FLUORESCENCE; HELIUM; PRESSURE DEPENDENCE; PRESSURE ...

  4. Accessing a growth window for SrVO3 thin films (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    Accessing a growth window for SrVO3 thin films Citation Details In-Document Search This ... Department of Materials Science and Engineering, Pennsylvania State University, University ...

  5. Role of the interface on radiation damage in the SrTiO{sub 3...

    Office of Scientific and Technical Information (OSTI)

    SrTiOsub 3 (STO) thin films grown on a single crystal ... 87545 (United States) Materials Science and Technology Division, ... TITANATES; SUBSTRATES; THIN FILMS; TRANSMISSION ...

  6. Sr. Business Analyst - Supply Chain Mgmt. (Term Position) | Princeton

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

    Plasma Physics Lab Sr. Business Analyst - Supply Chain Mgmt. (Term Position) Department: Business Operations Supervisor(s): Jaclyn Pursell Staff: AM 5 Requisition Number: 1500993 Princeton Plasma Physics Lab (PPPL) is seeking to hire an experienced Business Analyst (BA) to work on the implementation of PeopleSoft 9.2. The BA will be the liaison between the functional area lead and the implementation project team, and will set the direction/vision for PeopleSoft Purchasing, eProcurement,

  7. Magnetic Ordering in Sr3YCo4O10+x

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

    Kishida, Takayoshi; Kapetanakis, Myron D.; Yan, Jiaqiang; Sales, Brian C.; Pantelides, Sokrates T.; Pennycook, Stephen J.; Chisholm, Matthew F.

    2016-01-28

    Transition-metal oxides often exhibit complex magnetic behavior due to the strong interplay between atomic-structure, electronic and magnetic degrees of freedom. Cobaltates, especially, exhibit complex behavior because of cobalt’s ability to adopt various valence and spin state configurations. The case of the oxygen-deficient perovskite Sr3YCo4O10+x (SYCO) has gained considerable attention because of persisting uncertainties about its structure and the origin of the observed room temperature ferromagnetism. Here we report a combined investigation of SYCO using aberration-corrected scanning transmission electron microscopy and density functional theory calculations.

  8. Special Inquiry: OAS-SR-07-01 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    07-01 Special Inquiry: OAS-SR-07-01 November 27, 2006 Selected Controls over Classified Information at the Los Alamos National Laboratory Not Available for Viewing More Documents & Publications Special Inquiry: SI-11-27 Special Inquiry: OAS-SR-10-04 Audit Report: IG-0880

  9. Resistance switching in epitaxial SrCoO{sub x} thin films

    SciTech Connect (OSTI)

    Tambunan, Octolia T.; Parwanta, Kadek J.; Acharya, Susant K.; Lee, Bo Wha; Jung, Chang Uk; Kim, Yeon Soo; Park, Bae Ho; Jeong, Huiseong; Park, Ji-Yong; Cho, Myung Rae; Park, Yun Daniel; Choi, Woo Seok; Kim, Dong-Wook; Jin, Hyunwoo; Lee, Suyoun; Song, Seul Ji; Kang, Sung-Jin; Kim, Miyoung; Hwang, Cheol Seong

    2014-08-11

    We observed bipolar switching behavior from an epitaxial strontium cobaltite film grown on a SrTiO{sub 3} (001) substrate. The crystal structure of strontium cobaltite has been known to undergo topotactic phase transformation between two distinct phases: insulating brownmillerite (SrCoO{sub 2.5}) and conducting perovskite (SrCoO{sub 3??}) depending on the oxygen content. The currentvoltage characteristics of the strontium cobaltite film showed that it could have a reversible insulator-to-metal transition triggered by electrical bias voltage. We propose that the resistance switching in the SrCoO{sub x} thin film could be related to the topotactic phase transformation and the peculiar structure of SrCoO{sub 2.5}.

  10. Epitaxial Cr on n-SrTiO3(001)An ideal Ohmic contact

    SciTech Connect (OSTI)

    Capan, Cigdem; Sun, Guangyuan; Bowden, Mark E.; Chambers, Scott A.

    2012-01-30

    Epitaxial Cr metallizations grown on n-SrTiO3(001) by molecular beam epitaxy are shown to result in an ordered interface with Cr bound to O in the terminal TiO2 layer, no reduction of the SrTiO3, and a near-perfect Ohmic contact. Cr/n-SrTiO3(001) thus constitutes an ideal interface between a pure metal and wide gap oxide in which interface redox chemistry does not occur, and the Fermi level remains unpinned.

  11. Epitaxial Cr on n-SrTiO{sub 3}(001) - An ideal Ohmic contact

    SciTech Connect (OSTI)

    Capan, C.; Sun, G. Y.; Bowden, M. E.; Chambers, S. A.

    2012-01-30

    Epitaxial Cr metallizations grown on n-SrTiO{sub 3}(001) by molecular beam epitaxy are shown to result in an ordered interface with Cr bound to O in the terminal TiO{sub 2} layer, no reduction of the SrTiO{sub 3}, and a near-perfect Ohmic contact. Cr/n-SrTiO{sub 3}(001) thus constitutes an ideal interface between a pure metal and wide gap oxide in which interface redox chemistry does not occur, and the Fermi level remains unpinned.

  12. DOE-SR Makes a Difference Through Donation to Educational Center |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy DOE-SR Makes a Difference Through Donation to Educational Center DOE-SR Makes a Difference Through Donation to Educational Center February 24, 2011 - 12:00pm Addthis Media Contact Amy Caver, DOE (803) 952-7697 amy.caver@srs.gov Aiken, SC -- The Department of Energy-Savannah River Operations Office (DOE-SR) is making a real impact to increase learning resources for an educational nonprofit organization through its Computers for Learning (CFL) program. Just recently,

  13. Structure symmetry determination and magnetic evolution in Sr2Ir1-xRhxO4

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | DOE PAGES Structure symmetry determination and magnetic evolution in Sr2Ir1-xRhxO4 This content will become publicly available on November 23, 2016 « Prev Next » Title: Structure symmetry determination and magnetic evolution in Sr2Ir1-xRhxO4 We use single-crystal neutron diffraction to determine the crystal structure symmetry and to study the magnetic evolution in the rhodium doped iridates Sr2Ir1-xRhxO4 (0 ≤ x ≤ 0.16). Throughout this doping range, the crystal

  14. Thickness-dependent coherent phonon frequency in ultrathin FeSe/SrTiO3

    Office of Scientific and Technical Information (OSTI)

    films (Journal Article) | SciTech Connect Thickness-dependent coherent phonon frequency in ultrathin FeSe/SrTiO3 films Citation Details In-Document Search Title: Thickness-dependent coherent phonon frequency in ultrathin FeSe/SrTiO3 films Ultrathin FeSe films grown on SrTiO3 substrates are a recent milestone in atomic material engineering due to their important role in understanding unconventional superconductivity in Fe-based materials. By using femtosecond time- and angle-resolved

  15. Structure symmetry determination and magnetic evolution in Sr2Ir1...

    Office of Scientific and Technical Information (OSTI)

    evolution in Sr2Ir1-xRhxO4 This content will become publicly available on November 23, 2016 Prev Next Title: Structure symmetry determination and magnetic evolution in ...

  16. FIA-16-0018- In the Matter of Wayne C. Brunsilius, Sr.

    Broader source: Energy.gov [DOE]

    On February 16, 2016, OHA denied a FOIA Appeal filed by Wayne C. Brunsilius, Sr. (Appellant) of a determination issued by the Office of Legacy Management (OLM).  In the Appeal, the Appellant...

  17. Role of polaron hopping in leakage current behavior of a SrTiO...

    Office of Scientific and Technical Information (OSTI)

    m thickness for SrTiOsub 3 layer, and a temperature of 150 C. The applied voltage resulted in the migration of ionic defects (oxygen vacancies) from anode towards cathode. ...

  18. X-ray absorption near-edge spectra of overdoped La 2 - x Sr x...

    Office of Scientific and Technical Information (OSTI)

    X-ray absorption near-edge spectra of overdoped La 2 - x Sr x CuO 4 high- T c superconductors Citation Details In-Document Search Title: X-ray absorption near-edge spectra of...

  19. Special Report: OAS-SR-10-03 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    3 Special Report: OAS-SR-10-03 September 14, 2010 Department's Freedom of Information Act Request Process The Freedom of Information Act (FOIA or the Act) (5 U.S.C. 552) specifies...

  20. Special Report: OAS-SR-05-01 | Department of Energy

    Office of Environmental Management (EM)

    05-01 Special Report: OAS-SR-05-01 October 1, 2004 Department's Process of Responding to a Congressional Information Request Not Available for Viewing More Documents & Publications...

  1. Tuning the metal-insulator crossover and magnetism in SrRuO3...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Tuning the metal-insulator crossover and magnetism in SrRuO3 by ionic gating Citation Details In-Document Search Title: Tuning the metal-insulator crossover and ...

  2. Unconventional Switching Behavior in La0.7Sr0.3MnO3/La0.7Sr0.3CoO3

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

    Exchange-spring Bilayer | Stanford Synchrotron Radiation Lightsource Unconventional Switching Behavior in La0.7Sr0.3MnO3/La0.7Sr0.3CoO3 Exchange-spring Bilayer Monday, March 30, 2015 Interfacial magnetic interactions between ferromagnetic/antiferromagnetic (FM/AFM) and FM/FM materials play a key role in numerous magnetic technologies such as high performance permanent magnets and magnetic read heads. High performance permanent magnets with large coercivity and high magnetization can be

  3. Phase stability of the SrMn O 3 hexagonal perovskite system at high

    Office of Scientific and Technical Information (OSTI)

    pressure and temperature (Journal Article) | DOE PAGES Publisher's Accepted Manuscript: Phase stability of the SrMn O 3 hexagonal perovskite system at high pressure and temperature Title: Phase stability of the SrMn O 3 hexagonal perovskite system at high pressure and temperature Authors: Nielsen, Morten Bormann ; Ceresoli, Davide ; Parisiades, Paraskevas ; Prakapenka, Vitali B. ; Yu, Tony ; Wang, Yanbin ; Bremholm, Martin Publication Date: 2014-12-01 OSTI Identifier: 1180602 Grant/Contract

  4. Phase stability of the SrMn O 3 hexagonal perovskite system at high

    Office of Scientific and Technical Information (OSTI)

    pressure and temperature (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Phase stability of the SrMn O 3 hexagonal perovskite system at high pressure and temperature Citation Details In-Document Search Title: Phase stability of the SrMn O 3 hexagonal perovskite system at high pressure and temperature Authors: Nielsen, Morten Bormann ; Ceresoli, Davide ; Parisiades, Paraskevas ; Prakapenka, Vitali B. ; Yu, Tony ; Wang, Yanbin ; Bremholm, Martin Publication

  5. Special Inquiry: INS-SR-13-02 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    INS-SR-13-02 Special Inquiry: INS-SR-13-02 April 15, 2013 Alleged Mismanagement of the Department of Energy's Executive Protection Operations The Office of Special Operations (Special Operations) has primary responsibility for the protection and evacuation of the Secretary of Energy and other executive personnel as designated by the Secretary. Special Operations, a part of the Office of Health, Safety and Security (HSS), employs special agents charged with managing executive protection

  6. Special Report: OIG-SR-16-01 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    OIG-SR-16-01 Special Report: OIG-SR-16-01 November 16, 2015 Management Challenges at the Department of Energy - Fiscal Year 2016 The Office of Inspector General annually identifies what it considers the Department of Energy's most significant management challenges. The overall goal is to focus attention on significant issues in order to enhance the effectiveness of programs and operations. While the fiscal year (FY) 2016 challenge areas remain largely consistent with those in previous years,

  7. Enhanced Superconducting Gaps in Trilayer High-Temperature Bi (2) Sr (2) Ca

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

    (2) Cu (3) O (10+delta) Cuprate Superconductor (Journal Article) | SciTech Connect Enhanced Superconducting Gaps in Trilayer High-Temperature Bi (2) Sr (2) Ca (2) Cu (3) O (10+delta) Cuprate Superconductor Citation Details In-Document Search Title: Enhanced Superconducting Gaps in Trilayer High-Temperature Bi (2) Sr (2) Ca (2) Cu (3) O (10+delta) Cuprate Superconductor Authors: Ideta, S ; Takashima, K. ; Hashimoto, M. ; Yoshida, T. ; Fujimori, A. ; Anzai, H. ; Fujita, T. ; Nakashima, Y. ;

  8. Special Inquiry: INS-SR-13-01 | Department of Energy

    Energy Savers [EERE]

    Special Inquiry: INS-SR-13-01 Special Inquiry: INS-SR-13-01 January 31, 2013 Alleged Wasteful Spending Regarding International Travel for the Department of Energy's Deputy Secretary The Department of Energy's Deputy Secretary represents the U.S. Government, the Department and the Secretary in many high-level international and ministerial meetings. In this role, the Deputy Secretary is authorized executive protection while on international travel for security purposes, to reduce the risk of harm

  9. Audit Special Inquiry: OAS-SR-10-04 | Department of Energy

    Energy Savers [EERE]

    Inquiry: OAS-SR-10-04 Audit Special Inquiry: OAS-SR-10-04 September 22, 2010 Special Inquiry: Review of Allegations Regarding Hiring and Contracting in the Office of Energy Efficiency and Renewable Energy In April 2010, the Office of Inspector General (OIG) began receiving allegations concerning hiring and contracting practices within the Office of Energy Efficiency and Renewable Energy (EERE). These allegations included: 1. Improprieties in the hiring of a contract employee to a senior Federal

  10. Special Review: OAI-SR-16-01 | Department of Energy

    Energy Savers [EERE]

    OAI-SR-16-01 Special Review: OAI-SR-16-01 February 18, 2016 Allegations Regarding the Sandia National Laboratories Mixed Waste Landfill Since December 2014, the Office of Inspector General has received multiple allegations and information regarding human health and environmental protection issues due to the waste stored in the Sandia National Laboratories (SNL) Mixed Waste Landfill (MWL). For example, it was alleged that the inventory of the MWL was not complete and that contaminants from the

  11. The effect of replacement of Sr by Ca on the structural and luminescence properties of the red-emitting Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} LED conversion phosphor

    SciTech Connect (OSTI)

    Li, Y.Q.; With, G. de; Hintzen, H.T.

    2008-03-15

    The influence of the replacement of Sr by Ca on structural and luminescence properties of Eu{sup 2+}-doped Sr{sub 2}Si{sub 5}N{sub 8} is reported. The Rietveld refinement of the powder X-ray diffraction data shows that the Ca{sup 2+} ion preferentially occupies the larger Sr site in Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}. Although the excitation spectrum is hardly modified, the position of the emission band of Eu{sup 2+} can be tailored through partial replacement of Sr by Ca in Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, resulting in red-emission shifting from 620 to 643 nm. Furthermore, (Sr, Ca){sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} shows high potential as a conversion phosphor for white-light LED applications due to similar absorption, conversion efficiency and thermal quenching behaviour for 465 nm excitation after the introduction of the Ca ion. - Graphical abstract: The temperature dependence of the luminescence efficiency of M{sub 1.9}Eu{sub 0.1}Si{sub 5}N{sub 8} (M=Ca, Sr, Ba) and Sr{sub 1.3}Ca{sub 0.6}Eu{sub 0.1}Si{sub 5}N{sub 8} ({lambda}{sub exc}=465 nm)

  12. X-ray nano-diffraction study of Sr intermetallic phase during solidification of Al-Si hypoeutectic alloy

    SciTech Connect (OSTI)

    Manickaraj, Jeyakumar; Gorny, Anton; Shankar, Sumanth, E-mail: shankar@mcmaster.ca [Light Metal Casting Research Centre (LMCRC), Department of Mechanical Engineering, McMaster University, 1280 Main Street W, Hamilton, Ontario L8S 4L7 (Canada); Cai, Zhonghou [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)

    2014-02-17

    The evolution of strontium (Sr) containing intermetallic phase in the eutectic reaction of Sr-modified Al-Si hypoeutectic alloy was studied with high energy synchrotron beam source for nano-diffraction experiments and x-ray fluorescence elemental mapping. Contrary to popular belief, Sr does not seem to interfere with the Twin Plane Re-entrant Edge (TPRE) growth mechanism of eutectic Si, but evolves as the Al{sub 2}Si{sub 2}Sr phase during the eutectic reaction at the boundary between the eutectic Si and Al grains.

  13. Direct imaging of LaAlO{sub 3}/SrTiO{sub 3} nanostructures using...

    Office of Scientific and Technical Information (OSTI)

    Direct imaging of LaAlOsub 3SrTiOsub 3 nanostructures using piezoresponse force ... (United States) Department of Materials Science and Engineering, University of ...

  14. Influence of rare earth doping on thermoelectric properties of SrTiO{sub 3} ceramics

    SciTech Connect (OSTI)

    Liu, J. Wang, C. L.; Li, Y.; Su, W. B.; Zhu, Y. H.; Li, J. C.; Mei, L. M.

    2013-12-14

    Thermoelectric properties of SrTiO{sub 3} ceramics, doped with different rare earth elements, were investigated in this work. It's found that the ionic radius of doping elements plays an important role on thermoelectric properties: SrTiO{sub 3} ceramics doped with large rare earth ions (such as La, Nd, and Sm) exhibit large power factors, and those doped with small ions (such as Gd, Dy, Er, and Y) exhibit low thermal conductivities. Therefore, a simple approach for enhancing the thermoelectric performance of SrTiO{sub 3} ceramics is proposed: mainly doped with large ions to obtain a large power factor and, simultaneously, slightly co-doped with small ions to obtain a low thermal conductivity. Based on this rule, Sr{sub 0.8}La{sub 0.18}Yb{sub 0.02}TiO{sub 3} ceramics were prepared, whose ZT value at 1?023?K reaches 0.31, increasing by a factor of 19% compared with the single-doped counterpart Sr{sub 0.8}La{sub 0.2}TiO{sub 3} (ZT?=?0.26)

  15. DOE Spent Nuclear Fuel Information in Support of TSPA-SR

    SciTech Connect (OSTI)

    H. H. Loo

    1999-08-01

    The Department of Energy (DOE) Office of Civilian Radioactive Waste Management (RW) has started the recommendation (SR) effort to show that Yucca Mountain could be selected as the first geologic repository for spent nuclear fuel (SNF) and high-level waste. One component of the site recommendation will be a total system performance assessment (TSPA), based on the design concept and the scientific data and analysis available, describing the repository's probable behavior relative to the overall system performance standards. Thus, all the data collected from the Exploratory Studies Facilities to-date have been incorporated into the latest TSPA model. To ensure that the DOE-owned SNF continues to be acceptable for disposal in the repository, it will be included in the TSPA-SR evaluation. A number of parameters are needed in the TSPA-SR models to predict the performance of the DOE-owned SNF materials placed into the potential repository. This report documents all of the basis and/or derivation for each of these parameters. A number of properties were not readily available at the time the TSPA-SR data were requested. Thus, expert judgement and opinion were used to determine a best property value. The performance of the DOE-owned SNF will be published as part of the TSPA-SR report.

  16. Amphoteric doping of praseodymium Pr3+ in SrTiO3 grain boundaries

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

    Yang, H.; Lee, H. S.; Kotula, P. G.; Sato, Y.; Ikuhara, Y.; Browning, N. D.

    2015-03-26

    Charge Compensation in rare-earth Praseodymium (Pr3+) doped SrTiO3 plays an important role in determining the overall photoluminescence properties of the system. Here, the Pr3+ doping behavior in SrTiO3 grain boundaries (GBs) is analyzed using aberration corrected scanning transmission electron microscopy (STEM). The presence of Pr3+ induces structure variations and changes the statistical prevalence of GB structures. In contrast to the assumption that Pr3+ substitutes for A site as expected in the bulk, Pr3+ is found to substitute both Sr and Ti sites inside GBs with the highest concentration in the Ti sites. As a result, this amphoteric doping behavior inmore »the boundary plane is further confirmed by first principles theoretical calculations.« less

  17. Amphoteric doping of praseodymium Pr3+ in SrTiO3 grain boundaries

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

    Yang, H.; Lee, H. S.; Kotula, P. G.; Sato, Y.; Ikuhara, Y.; Browning, N. D.

    2015-03-26

    Charge Compensation in rare-earth Praseodymium (Pr3+) doped SrTiO3 plays an important role in determining the overall photoluminescence properties of the system. Here, the Pr3+ doping behavior in SrTiO3 grain boundaries (GBs) is analyzed using aberration corrected scanning transmission electron microscopy (STEM). The presence of Pr3+ induces structure variations and changes the statistical prevalence of GB structures. In contrast to the assumption that Pr3+ substitutes for A site as expected in the bulk, Pr3+ is found to substitute both Sr and Ti sites inside GBs with the highest concentration in the Ti sites. As a result, this amphoteric doping behavior inmore » the boundary plane is further confirmed by first principles theoretical calculations.« less

  18. Highly conducting SrMoO{sub 3} thin films for microwave applications

    SciTech Connect (OSTI)

    Radetinac, Aldin Mani, Arzhang; Ziegler, Jrgen; Alff, Lambert; Komissinskiy, Philipp; Melnyk, Sergiy; Nikfalazar, Mohammad; Zheng, Yuliang; Jakoby, Rolf

    2014-09-15

    We have measured the microwave resistance of highly conducting perovskite oxide SrMoO{sub 3} thin film coplanar waveguides. The epitaxial SrMoO{sub 3} thin films were grown by pulsed laser deposition and showed low mosaicity and smooth surfaces with a root mean square roughness below 0.3?nm. Layer-by-layer growth could be achieved for film thicknesses up to 400?nm as monitored by reflection high-energy electron diffraction and confirmed by X-ray diffraction. We obtained a constant microwave resistivity of 29???cm between 0.1 and 20?GHz by refining the frequency dependence of the transmission coefficients. Our result shows that SrMoO{sub 3} is a viable candidate as a highly conducting electrode material for all-oxide microwave electronic devices.

  19. Photoinduced changes of the chemical potential in superconducting Bi 2 Sr 2

    Office of Scientific and Technical Information (OSTI)

    CaCu 2 O 8 + δ (Journal Article) | SciTech Connect Photoinduced changes of the chemical potential in superconducting Bi 2 Sr 2 CaCu 2 O 8 + δ Citation Details In-Document Search This content will become publicly available on October 11, 2016 Title: Photoinduced changes of the chemical potential in superconducting Bi 2 Sr 2 CaCu 2 O 8 + δ Authors: Miller, Tristan L. ; Smallwood, Christopher L. ; Zhang, Wentao ; Eisaki, Hiroshi ; Orenstein, Joseph ; Lanzara, Alessandra Publication Date:

  20. HIPed Tailored Ceramic Waste Forms for the Immobilization of Cs, Sr and Tc

    Office of Scientific and Technical Information (OSTI)

    (Conference) | SciTech Connect Conference: HIPed Tailored Ceramic Waste Forms for the Immobilization of Cs, Sr and Tc Citation Details In-Document Search Title: HIPed Tailored Ceramic Waste Forms for the Immobilization of Cs, Sr and Tc × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and Technical Information (OSTI) and is provided as a public service. Visit OSTI to utilize additional information

  1. FIA-13-0051 - In the Matter of DeShonne E. Massey Sr. | Department of

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Energy 1 - In the Matter of DeShonne E. Massey Sr. FIA-13-0051 - In the Matter of DeShonne E. Massey Sr. On August 14, 2013, the Office of Hearings and Appeals (OHA) issued a decision granting, in part, an appeal (Appeal) from a Freedom of Information Act (FOIA) determination issued by the Office of Information Resources (OIR). The Appellant filed a FOIA request seeking copies of any and all records related to a named OHA employee's use of flexiplace or telecommuting during her entire tenure

  2. Role of polaron hopping in leakage current behavior of a SrTiO{sub 3}

    Office of Scientific and Technical Information (OSTI)

    single crystal (Journal Article) | SciTech Connect Role of polaron hopping in leakage current behavior of a SrTiO{sub 3} single crystal Citation Details In-Document Search Title: Role of polaron hopping in leakage current behavior of a SrTiO{sub 3} single crystal We studied the ionic/electronic transport and resistance degradation behavior of dielectric oxides by solving the electrochemical transport equations. Here, we took into account the non-periodical boundary conditions for the

  3. Tuning the metal-insulator crossover and magnetism in SrRuO3 by ionic

    Office of Scientific and Technical Information (OSTI)

    gating (Journal Article) | SciTech Connect Journal Article: Tuning the metal-insulator crossover and magnetism in SrRuO3 by ionic gating Citation Details In-Document Search Title: Tuning the metal-insulator crossover and magnetism in SrRuO3 by ionic gating Reversible control of charge transport and magnetic properties without degradation is a key for device applications of transition metal oxides. Chemical doping during the growth of transition metal oxides can result in large changes in

  4. Synthesis of highly phase pure (Bi, Pb)-Sr-Ca-Cu-O superconductor

    DOE Patents [OSTI]

    Dorris, Stephen E. (La Grange Park, IL); Poeppel, Roger B. (Glen Ellyn, IL); Prorok, Barton C. (Harrisville, PA); Lanagan, Michael T. (Woodridge, IL); Maroni, Victor A. (Naperville, IL)

    1994-01-01

    An article and method of manufacture of (Bi,Pb)-Sr-Ca-Cu-O superconductor. The superconductor is manufactured by preparing a first powdered mixture of bismuth oxide, lead oxide, strontium carbonate, calcium carbonate and copper oxide. A second powdered mixture is then prepared of strontium carbonate, calcium carbonate and copper oxide. The mixtures are calcined separately with the two mixtures then combined. The resulting combined mixture is then subjected to a powder in tube deformation and thermal processing to produce a substantially phase pure (Bi,Pb)-Sr-Ca-Cu-O superconductor.

  5. Synthesis of highly phase pure (Bi, Pb)-Sr-Ca-Cu-O superconductor

    DOE Patents [OSTI]

    Dorris, S.E.; Poeppel, R.B.; Prorok, B.C.; Lanagan, M.T.; Maroni, V.A.

    1994-10-11

    An article and method of manufacture of (Bi,Pb)-Sr-Ca-Cu-O superconductor are disclosed. The superconductor is manufactured by preparing a first powdered mixture of bismuth oxide, lead oxide, strontium carbonate, calcium carbonate and copper oxide. A second powdered mixture is then prepared of strontium carbonate, calcium carbonate and copper oxide. The mixtures are calcined separately with the two mixtures then combined. The resulting combined mixture is then subjected to a powder in tube deformation and thermal processing to produce a substantially phase pure (Bi,Pb)-Sr-Ca-Cu-O superconductor. 5 figs.

  6. Tunable synthesis of TiO{sub 2}/SrO core/shell nanowire arrays with enhanced photocatalytic activity

    SciTech Connect (OSTI)

    Wang, Wenqi; Yang, Jie; Gong, Yingpeng; Hong, Hanlie

    2013-01-15

    Graphical abstract: TiO{sub 2} nanowires with tunable SrO shell layer are easily fabricated. The core/shell structure can enhance the photocatalytic activity of TiO{sub 2} nanowires and restrict the recombination of the electrons/holes. Display Omitted Highlights: ? A facile method to fabricate TiO{sub 2}/SrO core-shell nanowire array is reported. ? The thickness of SrO shell layer can be tunable by adjusting the dipping time. ? TiO{sub 2}/SrO core/shell nanowires shows enhanced photocatalytic activity. -- Abstract: We report a simple method to fabricate well-aligned TiO{sub 2}/SrO core/shell nanowire arrays. The core/shell structure is confirmed to have crystalline TiO{sub 2} nanowires core and amorphous SrO shell layer. The shell is composed of SrO with tunable thickness. Photocatalytic activity measurement shows that TiO{sub 2}/SrO core/shell nanowire arrays outperform uncovered TiO{sub 2} nanowires. Such core/shell nanowire arrays have potential applications for photovoltaic devices and as high performance photocatalyst.

  7. Interfacial dislocations in (111) oriented (Ba0.7Sr0.3)TiO3 films on SrTiO3 single crystal

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

    Shen, Xuan; Yamada, Tomoaki; Lin, Ruoqian; Kamo, Takafumi; Funakubo, Hiroshi; Wu, Di; Xin, Huolin L.; Su, Dong

    2015-10-08

    In this study, we have investigated the interfacial structure of epitaxial (Ba,Sr)TiO3 films grown on (111)-oriented SrTiO3 single-crystal substrates using transmission electron microscopy (TEM) techniques. Compared with the (100) epitaxial perovskite films, we observe dominant dislocation half-loop with Burgers vectors of a<110> comprised of a misfit dislocation along <112>, and threading dislocations along <110> or <100>. The misfit dislocation with Burgers vector of a <110> can dissociate into two ½ a <110> partial dislocations and one stacking fault. We found the dislocation reactions occur not only between misfit dislocations, but also between threading dislocations. Via three-dimensional electron tomography, we retrievedmore » the configurations of the threading dislocation reactions. The reactions between threading dislocations lead to a more efficient strain relaxation than do the misfit dislocations alone in the near-interface region of the (111)-oriented (Ba0.7Sr0.3)TiO3 films.« less

  8. High antiferromagnetic transition temperature of a honeycomb compound SrRu2O6

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

    Tian, Wei; Svoboda, Chris; Ochi, M.; Matsuda, M.; Cao, Huibo; Cheng, J. -G.; Sales, B. C.; Mandrus, D.; Arita, R.; Trivedi, Nandini; et al

    2015-09-14

    We study the high-temperature magnetic order in a quasi-two-dimensional honeycomb compound SrRu2O6 by measuring magnetization and neutron powder diffraction with both polarized and unpolarized neutrons. SrRu2O6 crystallizes into the hexagonal lead antimonate (PbSb2O6, space group P31m) structure with layers of edge-sharing RuO6 octahedra separated by Sr2+ ions. SrRu2O6 is found to order at TN = 565 K with Ru moments coupled antiferromagnetically both in plane and out of plane. The magnetic moment is 1.30(2) μB/Ru at room temperature and is along the crystallographic c axis in the G-type magnetic structure. We perform density functional calculations with constrained random-phase approximation (RPA)more » to obtain the electronic structure and effective intra- and interorbital interaction parameters. The projected density of states shows strong hybridization between Ru 4d and O 2p. By downfolding to the target t2g bands we extract the effective magnetic Hamiltonian and perform Monte Carlo simulations to determine the transition temperature as a function of interand intraplane couplings. We find a weak interplane coupling, 3% of the strong intraplane coupling, permits three-dimensional magnetic order at the observed TN .« less

  9. Synthesis and Structure Determination of Ferromagnetic Semiconductors LaAMnSnO6 (A = Sr Ba)

    SciTech Connect (OSTI)

    T Yang; T Perkisas; J Hadermann; M Croft; A Ignatov; M Greenblatt

    2011-12-31

    LaAMnSnO{sub 6} (A = Sr, Ba) have been synthesized by high temperature solid-state reactions under dynamic 1% H{sub 2}/Ar flow. Rietveld refinements on room temperature powder X-ray diffraction data indicate that LaSrMnSnO{sub 6} crystallizes in the GdFeO{sub 3}-structure, with space group Pnma and, combined with transmission electron microscopy, LaBaMnSnO{sub 6} in Imma. Both space groups are common in disordered double-perovskites. The Mn{sup 3+} and Sn{sup 4+} ions whose valence states were confirmed by X-ray absorption spectroscopy, are completely disordered over the B-sites and the BO{sub 6} octahedra are slightly distorted. LaAMnSnO{sub 6} are ferromagnetic semiconductors with a T{sub C} = 83 K for the Sr- and 66 K for the Ba-compound. The title compounds, together with the previously reported LaCaMnSnO{sub 6} provide an interesting example of progression from Pnma to Imma as the tolerance factor increases. An analysis of the relationship between space group and tolerance factor for the series LaAMnMO{sub 6} (A = Ca, Sr, Ba; M = Sn, Ru) provides a better understanding of the symmetry determination for double perovskites.

  10. Enhanced irreversibility by crystal defects in the Bi-Sr-Ca-Cu-O system

    SciTech Connect (OSTI)

    Salem-Sugui, S. Jr.; Shi, Donglu; McFarland, S.E.

    1991-04-01

    We measured magnetic irreversibility, H*(T), in liquid-quenched Bi-Sr-Ca-Cu-O samples with various microstructures at high applied field (up to 7 T). We found that H*(T) is considerably increased in the Bi{sub 2}Sr{sub 2}Ca{sub 3}Cu{sub 4}O{sub x} (2234) sample with a large amount of crystal defects, including severe lattice distortion and calcium and copper rich precipitates. We argue that the lattice distortion may affect the degree of anisotropy and the Josephson coupling between the Cu-O layers, which in turn enhance the irreversibility in the Bi-Sr-Ca-Cu-O system. A critical current density, J{sub c}, of 8 {times} 10{sup 4} A/cm{sup 2} at 8 kG and 40 K was obtained in the 2234 sample with many defects, while the J{sub c} dropped significantly at the same temperature and field in the near stoichiometry Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (2223) sample with a uniform microstructure.

  11. Preparation of Bi-Sr-Ca-Cu-O superconductors from oxide-glass precursors

    DOE Patents [OSTI]

    Hinks, David G. (Lemont, IL); Capone, II, Donald W. (Northbridge, MA)

    1992-01-01

    A superconductor and precursor therefor from oxide mixtures of Ca, Sr, Bi and Cu. Glass precursors quenched to elevated temperatures result in glass free of crystalline precipitates having enhanced mechanical properties. Superconductors are formed from the glass precursors by heating in the presence of oxygen to a temperature below the melting point of the glass.

  12. Graphic presentation of quarterly /sup 90/Sr fallout data, 1954-1982

    SciTech Connect (OSTI)

    Larsen, R.J.

    1984-01-01

    This report graphically presents all of the precipitation and /sup 90/Sr deposition data for all stations operated as part of the Environmental Measurements Laboratory's (EML) global fallout program since the initiation of the program in 1954. 3 references, 179 figures.

  13. Revised calibration of the Sm:SrB{sub 4}O{sub 7} pressure sensor using the

    Office of Scientific and Technical Information (OSTI)

    Sm-doped yttrium-aluminum garnet primary pressure scale (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Revised calibration of the Sm:SrB{sub 4}O{sub 7} pressure sensor using the Sm-doped yttrium-aluminum garnet primary pressure scale Citation Details In-Document Search Title: Revised calibration of the Sm:SrB{sub 4}O{sub 7} pressure sensor using the Sm-doped yttrium-aluminum garnet primary pressure scale The pressure-induced shift of Sm:SrB{sub 4}O{sub 7}

  14. Crystal structure of Sr{sub 3}Ir{sub 2}O{sub 7} investigated by

    Office of Scientific and Technical Information (OSTI)

    transmission electron microscopy (Journal Article) | SciTech Connect structure of Sr{sub 3}Ir{sub 2}O{sub 7} investigated by transmission electron microscopy Citation Details In-Document Search Title: Crystal structure of Sr{sub 3}Ir{sub 2}O{sub 7} investigated by transmission electron microscopy We report on the crystallographic structure of the layered perovskite iridate Sr{sub 3}Ir{sub 2}O{sub 7}, investigated using transmission electron microscopy. The space group was found to be Bbcb

  15. Direct imaging of LaAlO{sub 3}/SrTiO{sub 3} nanostructures using

    Office of Scientific and Technical Information (OSTI)

    piezoresponse force microscopy (Journal Article) | SciTech Connect Direct imaging of LaAlO{sub 3}/SrTiO{sub 3} nanostructures using piezoresponse force microscopy Citation Details In-Document Search Title: Direct imaging of LaAlO{sub 3}/SrTiO{sub 3} nanostructures using piezoresponse force microscopy The interface between LaAlO{sub 3} and TiO{sub 2}-terminated SrTiO{sub 3} can be switched between metastable conductive and insulating states using a conductive atomic force microscope probe.

  16. Electric field effects in graphene/LaAlO{sub 3}/SrTiO{sub 3}

    Office of Scientific and Technical Information (OSTI)

    heterostructures and nanostructures (Journal Article) | SciTech Connect Electric field effects in graphene/LaAlO{sub 3}/SrTiO{sub 3} heterostructures and nanostructures Citation Details In-Document Search Title: Electric field effects in graphene/LaAlO{sub 3}/SrTiO{sub 3} heterostructures and nanostructures We report the development and characterization of graphene/LaAlO{sub 3}/SrTiO{sub 3} heterostructures. Complex-oxide heterostructures are created by pulsed laser deposition and are

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

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

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

    2013-07-01

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

  18. Octonary resistance states in La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3

    Office of Scientific and Technical Information (OSTI)

    multiferroic tunnel junctions (Journal Article) | SciTech Connect Journal Article: Octonary resistance states in La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 multiferroic tunnel junctions Citation Details In-Document Search This content will become publicly available on October 6, 2016 Title: Octonary resistance states in La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 multiferroic tunnel junctions General drawbacks of current electronic/spintronic devices are high power consumption and low density storage. A

  19. Revealing the atomic and electronic structure of a SrTiO{sub 3}/LaNiO{sub 3}/SrTiO{sub 3} heterostructure interface

    SciTech Connect (OSTI)

    Zhang, Zaoli; Soltan, S.; Schmid, H.; Habermeier, H.-U.; Keimer, B.; Kaiser, U.

    2014-03-14

    The atomic structures of SrTiO{sub 3} (STO)/LaNiO{sub 3} (LNO)/STO heterostructure interfaces were investigated by spherical aberration-corrected (C{sub S}) (scanning) transmission electron microscopy. Atomic displacement and lattice distortion measurements and electron energy loss spectroscopy (EELS) were used to quantitatively analyze the distortion of the interfacial octahedra and the bond length at the interfaces. Combined with high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy analyses, two distinct interfacial atomic terminating layers are unambiguously determined. Ensuing quantitative HRTEM measurements revealed that the Ni-O bond length in the interfacial octahedral is elongated at the bottom interface (NiO{sub 2}-SrO). Atomic displacement shows structural relaxation effects when crossing the interfaces and lattice distortions across the interface is more pronounced in LNO than in STO. The Ti/O atomic ratio, La and Ti relative atomic ratio as derived by EELS quantification indicate non-stoichiometric composition at the interfaces. Distinct fine structures of Ti-L{sub 2,3} edge and O-K edge at the bottom and top interfaces are observed. By comparison, we are able to estimate Ti valency at both interfaces. Combining the structural distortions and Ti valency, the polar discontinuity and charge transfer at the interfaces are discussed.

  20. Oxygen vacancies at the surface of SrTiO{sub 3} thin films

    SciTech Connect (OSTI)

    Silva, Alexandre R.; Dalpian, Gustavo M.

    2014-01-21

    The two-dimensional electron gas (2DEG) observed at the surface of oxide thin films and at the interface between two oxides has been widely discussed, but the mechanism responsible for this behavior is still not well understood. In this work, we study the properties of the SrTiO{sub 3} (001) surface and show that defects are necessary in order to explain this 2DEG. We study the properties of oxygen vacancies at the TiO{sub 2} and SrO terminated surface, and conclude they can explain the metallic behavior experimentally observed. There is a strong tendency for these vacancies to be localized at the surface, where the formation energy is less than 2.92?eV.

  1. Electronic and magnetic properties of epitaxial perovskite SrCrO3(001)

    SciTech Connect (OSTI)

    Zhang, Hongliang; Du, Yingge; Sushko, Petr; Bowden, Mark E.; Shutthanandan, V.; Qiao, Liang; Cao, Guixin; Gai, Zheng; Sallis, Shawn; Piper, L.F.J.; Chambers, Scott A.

    2015-06-24

    We have investigated the intrinsic properties of SrCrO3 epitaxial thin films synthesized by molecular beam epitaxy. We find compelling evidence that SrCrO3 is a correlated metal. X-ray photoemission valence band and O K-edge x-ray absorption spectra indicate a strongly hybridized Cr3d-O2p state crossing the Fermi level, leading to metallic behavior. Comparison between valence band spectra near the Fermi level and the densities of states calculated using density functional theory (DFT) also suggests the presence of coherent and incoherent states and points to a strong electron-electron correlation effects. The magnetic susceptibility can be described by Pauli paramagnetism at temperatures above 100 K, but reveals antiferromagnetic behavior at lower temperatures resulting from orbital ordering as suggested by Ortega-San-Martin et al. [Phys. Rev. Lett. 99, 255701 (2007)].

  2. Dielectric relaxation and conduction in SrTiO{sub 3} thin films under dc bias

    SciTech Connect (OSTI)

    Ang, Chen; Yu, Zhi; Cross, L. E.; Guo, Ruyan; Bhalla, A. S.

    2001-08-06

    The dielectric and conduction behavior of SrTiO{sub 3} thin films deposited on a SrTiO{sub 3} single-crystal substrate is studied. Without dc bias, an obvious dielectric 'defect mode' in the dielectric loss is observed in the temperature range of {approx}100--200 K; however, no noticeable corresponding dielectric constant peak is observed. By applying a high dc bias ({>=}40 kV/cm), a dielectric constant peak with frequency dispersion appears in the same temperature range, the dielectric loss is increased, and simultaneously high dc conduction is observed. The induced dielectric constant peak is related to dc conduction and attributed to the coupling effect of the mobile carriers with the dielectric defect mode. {copyright} 2001 American Institute of Physics.

  3. Thickness-dependent metal-insulator transition in epitaxial SrRuO? ultrathin films

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

    Shen, Xuan; Qiu, Xiangbiao; Su, Dong; Zhou, Shengqiang; Li., Aidong; Wu, Di

    2015-01-06

    Transport characteristics of ultrathin SrRuO? films, deposited epitaxially on TiO?-terminated SrTiO? (001) single-crystal substrates, were studied as a function of film thickness. Evolution from a metallic to an insulating behavior is observed as the film thickness decreases from 20 to 4 unit cells. In films thicker than 4 unit cells, the transport behavior obeys the Drude low temperature conductivity with quantum corrections, which can be attributed to weak localization. Fitting the data with 2-dimensional localization model indicates that electron-phonon collisions are the main inelastic relaxation mechanism. In the film of 4 unit cells in thickness, the transport behavior follows variablemorerange hopping model, indicating a strongly localized state. Magnetoresistance measurements reveal a likely magnetic anisotropy with the magnetic easy axis along the out-of-plane direction.less

  4. Defects and persistent conductivity in SrTiO{sub 3}

    SciTech Connect (OSTI)

    McCluskey, Matthew D.; Tarun, Marianne C.

    2014-02-21

    Strontium titanate (SrTiO{sub 3}) is often used as a substrate for oxide thin films such as high-temperature superconductors. It has the perovskite structure and an indirect band gap of 3.25 eV. Our prior work showed that hydrogen impurities form a defect complex that contains two hydrogen atoms. The complex was tentatively attributed to a passivated strontium vacancy. Alternatively, it could be a partially passivated titanium vacancy. In order to create titanium vacancies, we annealed samples in an evacuated ampoule with SrO powder. These samples show unexpected behavior. After illuminating with sub-gap light, the free-electron concentration increases significantly. After the light is turned off, the high conductivity persists at room temperature. We attribute persistent photoconductivity (PPC) to the excitation of an electron from a vacancy into the conduction band, with a low recapture rate.

  5. Effective activation energy in the Bi-Sr-Ca-Cu-O systems

    SciTech Connect (OSTI)

    Sengupta, S.; Shi, D.; Wang, Z.; Smith, M.; McGinn, P.J.

    1992-08-01

    Magnetic relaxation in the Bi-Sr-Ca-Cu-O systems has been investigated in a wide temperature regime. Previously reported studies of the effective activation energy, U, have been controversial in terms of temperature and field dependence of the critical current density, j{sub c}. We have considered the temperature dependence of j{sub c} and constructed the U-j (or M) curves for the Bi-Sr-Ca-Cu-O system. We found that at a constant driving force and temperature, U is considerably higher for 2245 samples than for 2223 samples. This enhancement can be attributed to the flux pinning from finely dispersed calcium- and copper- rich precipitates.

  6. Effective activation energy in the Bi-Sr-Ca-Cu-O systems

    SciTech Connect (OSTI)

    Sengupta, S.; Shi, D.; Wang, Z.; Smith, M. ); McGinn, P.J. . Dept. of Electrical Engineering)

    1992-08-01

    Magnetic relaxation in the Bi-Sr-Ca-Cu-O systems has been investigated in a wide temperature regime. Previously reported studies of the effective activation energy, U, have been controversial in terms of temperature and field dependence of the critical current density, j[sub c]. We have considered the temperature dependence of j[sub c] and constructed the U-j (or M) curves for the Bi-Sr-Ca-Cu-O system. We found that at a constant driving force and temperature, U is considerably higher for 2245 samples than for 2223 samples. This enhancement can be attributed to the flux pinning from finely dispersed calcium- and copper- rich precipitates.

  7. Thickness-dependent metal-insulator transition in epitaxial SrRuO3 ultrathin films

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

    Shen, Xuan; Qiu, Xiangbiao; Su, Dong; Zhou, Shengqiang; Li, Aidong; Wu, Di

    2015-01-06

    Transport characteristics of ultrathin SrRuO₃ films, deposited epitaxially on TiO₂-terminated SrTiO₃ (001) single-crystal substrates, were studied as a function of film thickness. Evolution from a metallic to an insulating behavior is observed as the film thickness decreases from 20 to 4 unit cells. In films thicker than 4 unit cells, the transport behavior obeys the Drude low temperature conductivity with quantum corrections, which can be attributed to weak localization. Fitting the data with 2-dimensional localization model indicates that electron-phonon collisions are the main inelastic relaxation mechanism. In the film of 4 unit cells in thickness, the transport behavior follows variablemore » range hopping model, indicating a strongly localized state. As a result, magnetoresistance measurements reveal a likely magnetic anisotropy with the magnetic easy axis along the out-of-plane direction.« less

  8. Upper limit on spontaneous supercurrents in Sr2RuO4

    SciTech Connect (OSTI)

    Chung, Suk Bum

    2010-04-05

    It is widely believed that the perovskite Sr{sub 2}RuO{sub 4} is an unconventional superconductor with broken time reversal symmetry. It has been predicted that superconductors with broken time reversal symmetry should have spontaneously generated supercurrents at edges and domain walls. We have done careful imaging of the magnetic fields above Sr{sub 2}RuO{sub 4} single crystals using scanning Hall bar and SQUID microscopies, and see no evidence for such spontaneously generated supercurrents. We use the results from our magnetic imaging to place upper limits on the spontaneously generated supercurrents at edges and domain walls as a function of domain size. For a single domain, this upper limit is below the predicted signal by two orders of magnitude. We speculate on the causes and implications of the lack of large spontaneous supercurrents in this very interesting superconducting system.

  9. Electronic phase diagram of epitaxial La{sub 1?x}Sr{sub x}FeO{sub 3} films

    SciTech Connect (OSTI)

    Xie, Y. J.; Scafetta, M. D.; Moon, E. J.; Krick, A. L.; Sichel-Tissot, R. J.; May, S. J.

    2014-08-11

    The electronic phase diagram of epitaxial La{sub 1?x}Sr{sub x}FeO{sub 3} films is presented. The films were grown on SrTiO{sub 3} using molecular beam epitaxy with post-growth annealing to minimize oxygen vacancies. Insulating behavior is observed from x?=?00.9, with metallic conduction only present for x?=?1.0. While the La-rich compounds exhibit polaron conduction over all temperatures measured, the Sr-rich films exhibit an electronic phase transition within the compositional window of x?=?0.490.9 as revealed by temperature-dependent resistivity measurements. The transition temperatures are found to decrease with increasing Sr content. The constructed phase diagram is discussed in the context of other 3d e{sub g} perovskite systems including manganites and cobaltites.

  10. Photoconductivity and Non-Exponential Relaxation at Insulating LaAlO3/SrTiO3 Interfaces

    SciTech Connect (OSTI)

    Kim, Minu; Bell, C.; Hikita, Y.; Kozuka, Y.; Kim, B.G.; Hwang, H.Y.

    2012-08-17

    LaAlO{sub 3} is grown on SrO terminated (100) SrTiO{sub 3}, and (110) SrTiO{sub 3}, producing insulating heterointerfaces without light. Photocurrent spectroscopy at low temperatures reveals a broad distribution of interface states between 2 eV and 2.7 eV at both interfaces, with a higher density in the (110) case concomitant with relatively shallow traps. The photocurrent relaxation can be well fitted by a stretched exponential form, confirming energetically distributed electron traps. Photo-carrier lifetimes are larger than a few hundred seconds for optical excitation approaching the SrTiO{sub 3} band-gap energy, providing the opportunity to study transient light-induced properties at low temperatures.

  11. Spin-dependent transport across Co/LaAlO{sub 3}/SrTiO{sub 3} heterojunctions

    SciTech Connect (OSTI)

    Swartz, Adrian G.; Harashima, Satoshi; Xie, Yanwu; Kim, Bongju; Hwang, Harold Y.; Lu, Di; Bell, Christopher; Hikita, Yasuyuki

    2014-07-21

    The conducting interface formed between LaAlO{sub 3} and SrTiO{sub 3} exhibits high electron mobility, tunable carrier densities, and is theoretically predicted to have long spin lifetimes. Thus, the LaAlO{sub 3}/SrTiO{sub 3} heterostructure is a promising system for the transportation of spin information. We have investigated spin-dependent transport across Co/LaAlO{sub 3}/SrTiO{sub 3} heterostructures using an all electrical three terminal geometry and observed Lorentzian magnetoresistance typically associated with Hanle spin dephasing. However, such a picture fails to explain all the experimentally observed behavior. Further, experiments with spin-unpolarized Au/LaAlO{sub 3}/SrTiO{sub 3} heterojunctions support an alternative scenario involving current modulation by spin-dependent transport through defect states in the LaAlO{sub 3} barrier.

  12. Alleged Mismanagement of the Department of Energy's Executive Protection Operations, INS-SR-13-02

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Special Inquiry Alleged Mismanagement of the Department of Energy's Executive Protection Operations INS-SR-13-02 April 2013 Department of Energy Washington, DC 20585 April 15, 2013 MEMORANDUM FOR THE SECRETARY FROM: Gregory H. Friedman Inspector General SUBJECT: INFORMATION: Special Inquiry on "Alleged Mismanagement of the Department of Energy's Executive Protection Operations" BACKGROUND The Office of Special Operations (Special Operations) has primary responsibility for the

  13. Special Report: OAS-SR-10-02 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    2 Special Report: OAS-SR-10-02 July 29, 2010 Resolution of Questioned, Unresolved and Potentially Unallowable Costs Incurred in Support of the YuccaMountain Project The Nuclear Waste Policy Act Amendments of 1987 designated Yucca Mountain in Southwestern Nevada as the site for a national geologic repository for high-level nuclear waste. The Department of Energy assigned management of the program to the Office of Civilian Nuclear Waste Management (OCRWM). Bechtel SAIC Company, LLC (BSC) was the

  14. Precise Measurement of Strontium-82 Radioactivity in the Sr-Rb PET

    Office of Science (SC) Website

    Generator | U.S. DOE Office of Science (SC) Precise Measurement of Strontium-82 Radioactivity in the Sr-Rb PET Generator Nuclear Physics (NP) NP Home About Research Facilities Science Highlights Benefits of NP Applications of Nuclear Science Applications of Nuclear Science Archives Small Business Innovation / Technology Transfer Funding Opportunities Nuclear Science Advisory Committee (NSAC) Community Resources Contact Information Nuclear Physics U.S. Department of Energy SC-26/Germantown

  15. Thermodynamic Instability at the Stoichiometric LaAlO3/SrTiO3(001) Interface

    SciTech Connect (OSTI)

    Qiao, Liang; Droubay, Timothy C.; Shutthanandan, V.; Zhu, Zihua; Sushko, P. V.; Chambers, Scott A.

    2010-08-11

    Fully stoichiometric epitaxial LaAlO3 grown on the TiO2-terminated SrTiO3(001) by off-axis pulsed laser deposition is shown to exhibit strong La-Sr cation intermixing. This result is predicted by classical and quantum mechanical calculations of the relative stabilities of abrupt and intermixed states. The extensive cation intermixing has a marked impact on the electronic properties of the interface.

  16. On the photo and thermally stimulated luminescence properties of U doped SrBPO{sub 5}

    SciTech Connect (OSTI)

    Kumar, Mithlesh Mohapatra, M.; Natarajan, V.

    2014-12-15

    Highlights: Synthesis of SrBPO{sub 5}:U phosphor by solid state route. Confirmed the stabilization of uranium as UO{sub 2}{sup 2+}. Evaluation of order of kinetics and trap parameters of the system. ESR-TSL correlation of the observed glow peak. Probable mechanism proposed for the TSL glow peak. - Abstract: Un-doped and uranium doped SrBPO{sub 5} samples were synthesized using solid-state reaction route and investigated for their photo and luminescence properties. Photoluminescence (PL) spectrum of uranium doped sample showed five peaks at 502, 524, 547, 569 and 597 nm. The average frequency of symmetric stretching of O=U=O in the ground electronic state was found to be about 757 cm{sup ?1}. PL decay time measurements on the system confirmed the stabilization of uranium as UO{sub 2}{sup 2+} in the matrix. Thermally stimulated luminescence (TSL) measurements carried out on gamma irradiated SrBPO{sub 5}:U sample showed a glow peak at 390 K, whose spectral characteristics was found to be typical of UO{sub 2}{sup 2+}. The trap parameters were evaluated using different heating rate method. Room temperature EPR data suggested the formation of borate and oxygen based radical centers in the gamma-irradiated sample. Detailed EPR-TSL correlation studies confirmed the destruction of the oxygen radical to be responsible for the observed glow peak.

  17. Temperature dependence of anisotropic magnetoresistance in antiferromagnetic Sr{sub 2}IrO{sub 4}

    SciTech Connect (OSTI)

    Wang, C.; Seinige, H.; Tsoi, M.; Cao, G.; Zhou, J.-S.; Goodenough, J. B.

    2015-05-07

    Temperature-dependent magnetotransport properties of the antiferromagnetic semiconductor Sr{sub 2}IrO{sub 4} are investigated with point-contact devices. The point-contact technique allows to probe very small volumes and, therefore, to look for electronic transport on a microscopic scale. Point-contact measurements with single crystals of Sr{sub 2}IrO{sub 4} were intended to see whether the additional local resistance associated with a small contact area between a sharpened Cu tip and the antiferromagnet shows magnetoresistance (MR) such as that seen in bulk crystals. Point-contact measurements at liquid nitrogen temperature revealed large MRs (up to 28%) for modest magnetic fields (250 mT) applied within an IrO{sub 2} (ab) plane with angular dependence showing a crossover from four-fold to two-fold symmetry with an increasing magnetic field. Point contact measurement exhibits distinctive anisotropic magnetoresistance (AMR) in comparison to a bulk experiment, imposing intriguing questions about the mechanism of AMR in this material. Temperature-dependent MR measurements show that the MR falls to zero at the Neel temperature, but the temperature dependence of the MR ratio differs qualitatively from that of the resistivity. This AMR study helps to unveil the entanglement between electronic transport and magnetism in Sr{sub 2}IrO{sub 4} while the observed magnetoresistive phenomena can be potentially used to sense the antiferromagnetic order parameter in spintronic applications.

  18. New insulating antiferromagnetic quaternary iridates MLa10Ir4O24 (M=Sr, Ba)

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

    Zhao, Qingbiao; Han, Fei; Stoumpos, Constantinos C.; Han, Tian -Heng; Li, Hao; Mitchell, J. F.

    2015-07-01

    Recently, oxides of Ir4+ have received renewed attention in the condensed matter physics community, as it has been reported that certain iridates have a strongly spin-orbital coupled (SOC) electronic state, Jeff = ½, that defines the electronic and magnetic properties. The canonical example is the Ruddlesden-Popper compound Sr2IrO4, which has been suggested as a potential route to a new class of high temperature superconductor due to the formal analogy between Jeff = ½ and the S = ½ state of the cuprate superconductors. The quest for other iridium oxides that present tests of the underlying SOC physics is underway. Inmore » this spirit, here we report the synthesis and physical properties of two new quaternary tetravalent iridates, MLa10Ir4O24 (M = Sr, Ba). The crystal structure of both compounds features isolated IrO6 octahedra in which the electronic configuration of Ir is d5. As a result, both compounds order antiferromagnetically despite the lack of obvious superexchange pathways, and resistivity measurement shows that SrLa10Ir4O24 is an insulator.« less

  19. Characteristics of conductive SrRuO{sub 3} thin films with different microstructures

    SciTech Connect (OSTI)

    Jia, Q.X.; Chu, F.; Adams, C.D.; Wu, X.D.; Hawley, M.; Cho, J.H.; Findikoglu, A.T.; Foltyn, S.R.; Smith, J.L.; Mitchell, T.E.

    1996-09-01

    Conductive SrRuO{sub 3} thin films were epitaxially grown on (100) LaAlO{sub 3} substrates by pulsed laser deposition over a temperature range from 650{degree}C to 825{degree}C. Well-textured films exhibiting a strong orientation relationship to the underlying substrate could be obtained at a deposition temperature as low as 450{degree}C. The degree of crystallinity of the films improved with increasing deposition temperature as confirmed by x-ray diffraction, transmission electron microscopy, and scanning tunneling microscopy. Scanning electron microscopy revealed no particulates on the film surface. The resistivity of the SrRuO{sub 3} thin films was found to be a strong function of the crystallinity of the film and hence the substrate temperature during film deposition. A residual resistivity ratio (RRR={rho}{sub 300K}/{rho}{sub 4.2K}) of more than 8 was obtained for the SrRuO{sub 3} thin films deposited under optimized processing conditions. {copyright} {ital 1996 Materials Research Society.}

  20. Superconducting and magnetic properties of Sr3Ir4Sn13

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

    Biswas, P. K.; Amato, A.; Khasanov, R.; Luetkens, H.; Wang, Kefeng; Petrovic, C.; Cook, R. M.; Lees, M. R.; Morenzoni, E.

    2014-10-10

    In this research, magnetization and muon spin relaxation or rotation (µSR) measurements have been performed to study the superconducting and magnetic properties of Sr₃Ir₄Sn₁₃. From magnetization measurements the lower and upper critical fields of Sr₃Ir₄Sn₁₃ are found to be 81(1) Oe and 14.4(2) kOe, respectively. Zero-field µSR data show no sign of any magnetic ordering or weak magnetism in Sr₃Ir₄Sn₁₃. Transverse-field µSR measurements in the vortex state provided the temperature dependence of the magnetic penetration depth λ. The dependence of λ⁻² with temperature is consistent with the existence of single s-wave energy gap in the superconducting state of Sr₃Ir₄Sn₁₃ withmore » a gap value of 0.82(2) meV at absolute zero temperature. The magnetic penetration depth at zero temperature λ(0) is 291(3) nm. The ratio Δ(0)/kBTc = 2.1(1) indicates that Sr₃Ir₄Sn₁₃ should be considered as a strong-coupling superconductor.« less

  1. 110K Bi-Sr-Ca-Cu-O superconductor oxide and method for making same

    DOE Patents [OSTI]

    Veal, B.W.; Downey, J.W.; Lam, D.J.; Paulikas, A.P.

    1992-12-22

    A superconductor is disclosed consisting of a sufficiently pure phase of the oxides of Bi, Sr, Ca, and Cu to exhibit a resistive zero near 110K resulting from the process of forming a mixture of Bi[sub 2]O[sub 3], SrCO[sub 3], CaCO[sub 3] and CuO into a particulate compact wherein the atom ratios are Bi[sub 2], Sr[sub 1.2-2.2], Ca[sub 1.8-2.4], Cu[sub 3]. Thereafter, heating the particulate compact rapidly in the presence of oxygen to an elevated temperature near the melting point of the oxides to form a sintered compact, and then maintaining the sintered compact at the elevated temperature for a prolonged period of time. The sintered compact is cooled and reground. Thereafter, the reground particulate material is compacted and heated in the presence of oxygen to an elevated temperature near the melting point of the oxide and maintained at the elevated temperature for a time sufficient to provide a sufficiently pure phase to exhibit a resistive zero near 110K. 7 figs.

  2. 110K Bi-Sr-Ca-Cu-O superconductor oxide and method for making same

    DOE Patents [OSTI]

    Veal, Boyd W.; Downey, John W.; Lam, Daniel J.; Paulikas, Arvydas P.

    1992-01-01

    A superconductor consisting of a sufficiently pure phase of the oxides of Bi, Sr, Ca, and Cu to exhibit a resistive zero near 110K resulting from the process of forming a mixture of Bi.sub.2 O.sub.3, SrCO.sub.3, CaCO.sub.3 and CuO into aparticulate compact wherein the atom ratios are Bi.sub.2, Sr.sub.1.2-2.2, Ca.sub.1.8-2.4, Cu.sub.3. Thereafter, heating the particulate compact rapidly in the presence of oxygen to an elevated temperature near the melting point of the oxides to form a sintered compact, and then maintaining the sintered compact at the elevated temperature for a prolonged period of time. The sintered compact is cooled and reground. Thereafter, the reground particulate material is compacted and heated in the presence of oxygen to an elevated temperature near the melting point of the oxide and maintained at the elevated temperature for a time sufficient to provide a sufficiently pure phase to exhibit a resistive zero near 110K.

  3. Structural evolution of epitaxial SrCoOx films near topotactic phase transition

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

    Jeen, Hyoung Jeen; Lee, Ho Nyung

    2015-12-18

    Control of oxygen stoichiometry in complex oxides via topotactic phase transition is an interesting avenue to not only modifying the physical properties, but utilizing in many energy technologies, such as energy storage and catalysts. However, detailed structural evolution in the close proximity of the topotactic phase transition in multivalent oxides has not been much studied. In this work, we used strontium cobaltites (SrCoOx) epitaxially grown by pulsed laser epitaxy (PLE) as a model system to study the oxidation-driven evolution of the structure, electronic, and magnetic properties. We grew coherently strained SrCoO2.5thin films and performed post-annealing at various temperatures for topotacticmore » conversion into the perovskite phase (SrCoO3-δ). We clearly observed significant changes in electronic transport, magnetism, and microstructure near the critical temperature for the topotactic transformation from the brownmillerite to the perovskite phase. Furthermore, the overall crystallinity was well maintained without much structural degradation, indicating that topotactic phase control can be a useful tool to control the physical properties repeatedly via redox reactions.« less

  4. Optically pumped cerium-doped LiSrAlF{sub 6} and LiCaAlF{sub 6}

    DOE Patents [OSTI]

    Marshall, C.D.; Payne, S.A.; Krupke, W.F.

    1996-05-14

    Ce{sup 3+}-doped LiSrAlF{sub 6} crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF{sub 6} with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF{sub 6} type of chemical formula, e.g. Ce-doped LiCaAlF{sub 6} and LiSrGaF{sub 6}, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator. 10 figs.

  5. Optically pumped cerium-doped LiSrAlF.sub.6 and LiCaAlF.sub.6

    DOE Patents [OSTI]

    Marshall, Christopher D. (Livermore, CA); Payne, Stephen A. (Castro Valley, CA); Krupke, William F. (Pleasanton, CA)

    1996-01-01

    Ce.sup.3+ -doped LiSrAlF.sub.6 crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF.sub.6 with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF.sub.6 type of chemical formula, e.g. Ce-doped LiCaAlF.sub.6 and LiSrGaF.sub.6, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator.

  6. High temperature crystal structures and superionic properties of SrCl{sub 2}, SrBr{sub 2}, BaCl{sub 2} and BaBr{sub 2}

    SciTech Connect (OSTI)

    Hull, Stephen; Norberg, Stefan T.; Ahmed, Istaq; Eriksson, Sten G.; Mohn, Chris E.

    2011-11-15

    The structural properties of the binary alkaline-earth halides SrCl{sub 2}, SrBr{sub 2}, BaCl{sub 2} and BaBr{sub 2} have been investigated from ambient temperature up to close to their melting points, using the neutron powder diffraction technique. Fluorite-structured SrCl{sub 2} undergoes a gradual transition to a superionic phase at 900-1100 K, characterised by an increasing concentration of anion Frenkel defects. At a temperature of 920(3) K, the tetragonal phase of SrBr{sub 2} undergoes a first-order transition to a cubic fluorite phase. This high temperature phase shows the presence of extensive disorder within the anion sublattice, which differs from that found in superionic SrCl{sub 2}. BaCl{sub 2} and BaBr{sub 2} both adopt the cotunnite crystal structure under ambient conditions. BaCl{sub 2} undergoes a first-order structural transition at 917(5) K to a disordered fluorite-structured phase. The relationship between the (disordered) crystal structures and the ionic conductivity behaviour is discussed and the influence of the size of the mobile anion on the superionic behaviour is explored. - Graphical abstract: Anomalous behaviour of the lattice expansion of SrCl{sub 2} at temperatures of {approx}1000 K is associated with the gradual transition to a superionic phase, whilst SrBr{sub 2} undergoes a first-order structural transition ({beta}{yields}{alpha}) to a fluorite-structured superionic phase at 920(3) K. Highlights: > Anomalous behaviour of the lattice expansion of SrCl{sub 2} occurs at temperatures {approx}1000 K. > Crystal structure of {beta}-SrBr{sub 2} is described in detail. > On heating, SrBr{sub 2} and BaCl{sub 2} transform to a fluorite-structured superionic phase. > Temperature dependence of the BaCl{sub 2} and BaBr{sub 2} structures is presented. > Nature of the superionic phases within the alkaline-earth halides is discussed.

  7. Stanislav Golubov, and Roger Stoller - Materials Science and...

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

    other defects where they recombine and become trapped. In the absence of an applied stress, dislocations present in the lattice preferentially absorb the defects, causing them...

  8. Roger D. Kornberg Polymerase, DNA, RNA, and Transcription

    Office of Scientific and Technical Information (OSTI)

    also helps explain how the process sometimes goes awry, leading to birth defects, cancer and other diseases.' - Edited excerpt from 2006 Nobel Prize in Chemistry Resources ...

  9. Paul V. Braun and John A. Rogers Materials Research Laboratory...

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

    potential for unique designs which enhance light-matter interaction in unexpected ways. September 2011 Research Highlight E. Nelson, et al., Nature Materials 10, 676-681 (2011)...

  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)

    2008-04-21

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

  11. Pressure-induced collapsed-tetragonal phase in SrCo2As2

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

    Jayasekara, W. T.; Kaluarachchi, U. S.; Ueland, B. G.; Pandey, Abhishek; Lee, Y. B.; Taufour, V.; Sapkota, A.; Kothapalli, K.; Sangeetha, N. S.; Fabbris, G.; et al

    2015-12-08

    We present high-energy x-ray diffraction data under applied pressures up to p = 29GPa, neutron diffraction measurements up to p = 1.1GPa, and electrical resistance measurements up to p = 5.9GPa, on SrCo2As2. Our x-ray diffraction data demonstrate that there is a first-order transition between the tetragonal (T) and collapsed-tetragonal (cT) phases, with an onset above approximately 6 GPa at T = 7K. The pressure for the onset of the cT phase and the range of coexistence between the T and cT phases appears to be nearly temperature independent. The compressibility along the a axis is the same for themore » T and cT phases, whereas, along the c axis, the cT phase is significantly stiffer, which may be due to the formation of an As-As bond in the cT phase. Our resistivity measurements found no evidence of superconductivity in SrCo2As2 for p ≤ 5.9 GPa and T ≥ 1.8 K. The resistivity data also show signatures consistent with a pressure-induced phase transition for p ≳ 5.5 GPa. Single-crystal neutron diffraction measurements performed up to 1.1 GPa in the T phase found no evidence of stripe-type or A-type antiferromagnetic ordering down to 10 K. Spin-polarized total-energy calculations demonstrate that the cT phase is the stable phase at high pressure with a ca ratio of 2.54. As a result, these calculations indicate that the cT phase of SrCo2As2 should manifest either A-type antiferromagnetic or ferromagnetic order.« less

  12. La??xSrxCuO? superconductor nanowire devices

    SciTech Connect (OSTI)

    Litombe, N. E.; Bollinger, A. T.; Hoffman, J. E.; Bozovic, I.

    2014-07-02

    La??xSrxCuO? nanowire devices have been fabricated and characterized using electrical transport measurements. Nanowires with widths down to 80 nm are patterned using high-resolution electron beam lithography. However, the narrowest nanowires show incomplete superconducting transitions with some residual resistance at T = 4 K. Here, we report on refinement of the fabrication process to achieve narrower nanowire devices with complete superconducting transitions, opening the path to the study of novel physics arising from dimension-limited superconductivity on the nanoscale.

  13. Projected shell model study of neutron-rich deformed isotopes of Sr and Zr

    SciTech Connect (OSTI)

    Verma, Sonia; Dar, Parvaiz Ahmad; Devi, Rani [Department of Physics and Electronics, University of Jammu, Jammu-180006 (India)

    2008-02-15

    The projected shell model (PSM) study of {sup 98-102}Sr and {sup 100-104}Zr nuclei is carried out. The reliability of the ground-state wave function is checked by reproducing yrast spectra and electromagnetic properties. The mechanism for the onset of sudden and large deformation at N=60 is worked out. The present piece of research work has unified the two different, or conflicting, early explanations for the onset of deformation at N=60 by the spherical shell model and mean-field theory.

  14. Pulse shaping using nonlinear dielectric SrTiO{sub 3}

    SciTech Connect (OSTI)

    Findikoglu, A.T.; Reagor, D.W.; Rasmussen, K.O.; Bishop, A.R.; Gronbech-Jensen, N.; Jia, Q.X.; Fan, Y.; Kwon, C.

    1999-03-01

    We have studied electromagnetic pulse shaping in coplanar waveguide delay lines made from superconducting YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} electrodes on nonlinear dielectric SrTiO{sub 3} single-crystal substrates. The delay lines exhibited bias- and temperature-dependent nonlinearity and dispersion, with associated pulse-shaping effects. At low temperatures and under certain bias conditions, the interplay of dispersion and nonlinearity has led to stable and compact wave forms, reminiscent of microwave solitons. {copyright} {ital 1999 American Institute of Physics.}

  15. Flux pinning by precipitates in the Bi-Sr-Ca-Cu-O system

    DOE Patents [OSTI]

    Shi, Donglu (Chicago, IL)

    1992-01-01

    A fundamental pinning mechanism has been identified in the Bi-Sr-Ca-Cu-O system. The pinning strength has been greatly increased by the introduction of calcium- and copper-rich precipitates into the sample matrix. The calcium and copper are supersaturated in the system by complete melting, and the fine calcium and copper particles precipitated during subsequent crystallization anneal to obtain the superconducting phases. The intragrain critical current density has been increased from the order of 10.sup.5 A/cm.sup.2 to 10.sup.7 A/cm.sup.2 at 5 T.

  16. Bi-Sr-Ca-Cu-O surface studied by means of scanning tunnelling microscope

    SciTech Connect (OSTI)

    Witek, A.; Dabkowski, A.; Rauluszkiewicz, J.

    1989-03-10

    Surface topography of the high-T/sub c/ superconductor BiSrCaCu/sub 2/O/sub x/ has been investigated by means of scanning tunnelling microscope. The measurements were performed on the natural surface of ceramics material in air at room temperature. It can be deduced from the surface images, that bulk orthorhombic crystal structure extends to the surface. The surface seems to be uniform metallic in character and not drastically contaminated. Regular steps observed on the surface correspond to the dimension of the unit cell in z direction or its multiples.

  17. Special Report: OAS-SR-10-01 | Department of Energy

    Energy Savers [EERE]

    10-01 Special Report: OAS-SR-10-01 July 21, 2010 Need for Enhanced Surveillance During the Yucca Mountain Project Shut Down The Nuclear Waste Policy Act Amendments of 1987 (Act) designated Yucca Mountain in Southwestern Nevada as the site for a national geologic repository for high-level nuclear waste, primarily the waste generated by U.S. commercial nuclear plants. The Department of Energy (Department) assigned management of the program to the Office of Civilian Nuclear Waste Management (OCRWM)

  18. Target and orbit feedback simulations of a muSR beamline at BNL

    SciTech Connect (OSTI)

    MacKay, W. W.; Fischer, W.; Blaskiewicz, M.; Pile, P.

    2015-05-03

    Well-polarized positive surface muons are a tool to measure the magnetic properties of materials since the precession rate of the spin can be determined from the observation of the positron directions when the muons decay. The use of the AGS complex at BNL has been explored for a muSR facility previously. Here we report simulations of a beamline with a target inside a solenoidal field, and of an orbit feed-back system with single muon beam positioning monitors based on technology available today

  19. Action spectroscopy of SrCl{sup +} using an integrated ion trap time-of-flight mass spectrometer

    SciTech Connect (OSTI)

    Puri, Prateek Schowalter, Steven J.; Hudson, Eric R.; Kotochigova, Svetlana; Petrov, Alexander

    2014-07-07

    The photodissociation cross-section of SrCl{sup +} is measured in the spectral range of 36?00046?000 cm{sup ?1} using a modular time-of-flight mass spectrometer (TOF-MS). By irradiating a sample of trapped SrCl{sup +} molecular ions with a pulsed dye laser, X{sup 1}?{sup +} state molecular ions are electronically excited to the repulsive wall of the A{sup 1}? state, resulting in dissociation. Using the TOF-MS, the product fragments are detected and the photodissociation cross-section is determined for a broad range of photon energies. Detailed ab initio calculations of the SrCl{sup +} molecular potentials and spectroscopic constants are also performed and are found to be in good agreement with experiment. The spectroscopic constants for SrCl{sup +} are also compared to those of another alkaline earth halogen, BaCl{sup +}, in order to highlight structural differences between the two molecular ions. This work represents the first spectroscopy and ab initio calculations of SrCl{sup +}.

  20. SR0304

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

    NNSA Official Recognize Rapid Completion Of Key Tritium Processing Components Flag Ribbon Art AIKEN, S.C. (June 12)- Dr. Everet Beckner, Deputy Administrator for Defense Programs,...

  1. SR0005

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

    Program (EMSP) National Workshop in Atlanta, GA on April 24-27 at the Westin Peachtree Plaza. Hosted by DOE's Office of Environmental Management, Office of Science, Idaho...

  2. SR0006

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

    Program (EMSP) National Workshop in Atlanta, GA on April 25-27 at the Westin Peachtree Plaza. Hosted by DOE's Office of Environmental Management and Office of Science, Idaho...

  3. SR0111

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

    (803) 725-2889 Dept. Of Energy Kicks Off Its 2001 Combined Federal Campaign Flag Ribbon Art AIKEN, SC - DOE employees at SRS begin their 2001 CFC with an Opening Program...

  4. SR0207

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

    30, 2002 Media Contact: Julie Petersen (803) 725-2889 Notice To Editors: DOE Releases SRS History Book Flag Ribbon Art WHO: U.S. Department of Energy (DOE) Savannah River...

  5. SR0011

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

    the 50th Anniversary of the Savannah River Site. Secretary Richardson will be joined by Gen. John Gordon, Administrator of the National Nuclear Security Administration; Dr....

  6. SR0002

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

    2000. Following his visit to SRS facilities and a first-hand look at security functions, Gen. Habiger will meet with media representatives. General Habiger will be available for...

  7. SR0007

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

    Restoration Technology End User Conference on June 6-8 at the Sheraton Augusta Hotel, in Augusta, Georgia. The principal purposes of the conference are to share cleanup...

  8. SR0010

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

    Planning and Preparedness." The workshop will be held at the Radisson Riverfront Hotel. Mayor Bob Young, Augusta-Richmond County, will open the workshop. Reporters are...

  9. SR0101

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

    8, 2001 Media Contact: Bill Taylor (803) 725-2889 Savannah River Site's Martin Luther King, Jr., Day Observance Flag Ribbon Art Media organizations are invited to attend and cover...

  10. SR9909

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

    separate Site ceremony, Westinghouse Savannah River Company was awarded MERIT status for continuous improvement in the area of employee safety and health. WSRC is the single...

  11. SR0601

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

    S.C. -- A joint National Nuclear Security Administration and Office of Environmental Management nonproliferation program at the Savannah River Site (SRS) completed its 200th...

  12. SR0604

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

    DOE Safely Reaches DNFSB Stabilization Milestone AIKEN, S.C., (October 5, 2006) The Department of Energy announced today that it reached a major safety milestone in nuclear...

  13. SR0804

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

    5, 2004 Media Contact: Jim Giusti (803) 952-7697 SRS Resumes All Classified Electronic Media Work Following Stand-Down Flag Ribbon Art Aiken, S.C. -The Department of Energy's (DOE)...

  14. SR0303

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

    (803) 725-2889 Environmental Conference To Showcase Cleanup Technologies Flag Ribbon Art AIKEN, S.C., June 2 -- Approximately 200 professionals from across the United States...

  15. SR9916

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

    Bill Taylor (803) 725-2889 SRS Seeks Public Input On Updated Strategic Plan Flag Ribbon Art Aiken, SC (Dec. 15, 1999)--The Department of Energy's Savannah River Site today...

  16. SR0605

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

    5, 2006) The Department of Energy (DOE) announced today the safe disposal of 20,000 drums of transuranic waste previously stored at its Savannah River Site (SRS) with a recent...

  17. SR0104

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

    New Mexico, left the Site shortly after noon today. This shipment, which consists of 42 drums of transuranic waste, is the first of at least four SRS shipments to WIPP planned for...

  18. SR0706

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

    Year for his dedication and high achievement to encourage small business participation in Fiscal Year 2006. Winners of DOEs 2006 Secretarial Small Business Awards were presented...

  19. SR9807

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

    4, 1999 Media Contact: Bill Taylor (803) 725-2889 DOE Teams with State on Dedication and Management of 10,000 Acre Crackerneck Wildlife Management Area and Ecological Reserve Flag...

  20. SR9910

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

    2, 1999 Media Contact: Bill Taylor (803) 725-2889 Wackenhut Receives Award Fee Flag Ribbon Art Note to Editors and News Directors The Department of Energy (DOE) has determined the...

  1. SR0107

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

    4, 2001 Media Contact: Bill Taylor (803) 725-2889 DOE & DOL Hold Public Meetings For Energy Employees Occupational Illness Compensation Program At Flag Ribbon Art Aiken SC (June...

  2. SR9901

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

    6, 1999 Media Contact: Bill Taylor (803) 725-2889 DOE Renews SRS Security Contract With Wackenhut Services Inc. Flag Ribbon Art Aiken, SC - The Department of Energy (DOE) has...

  3. SR0017

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

    Bill Taylor (803) 725-2889 Media Availability For Dr. David Michaels, Assistant Secretary for Environment, Safety and Health Flag Ribbon Graphic Note to Editors and News Directors...

  4. SR9806

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

    3, 1999 Media Contact: Bill Taylor (803) 725-2889 Note To Editors Flag Ribbon Art SECRETARY RICHARDSON TO VISIT SAVANNAH RIVER SITE ON JUNE 24, 1999 WHO: Secretary of Energy Bill...

  5. SR0016

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

    5, 2000 Media Contact: Bill Taylor (803) 725-2889 DOE Meeting To Focus On New Compensation Program For Work-Related Illness Effecting SRS Employees Flag Ribbon Graphic Aiken, SC -...

  6. SR0003

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

    4, 2000 Media Contact: Bill Taylor (803) 725-2889 DOE To Present Savannah River Site's Upcoming Fiscal Year 2001 Budget Flag Ribbon Art Aiken, SC -- The public is invited to view...

  7. SR0201

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

    February 5, 2001 Media Contact: Bill Taylor (803) 725-2889 SRS Environmental Management FY2003 Budget and Top-To-Bottom Review Presented At Friday Meeting Flag Ribbon Art The...

  8. SR0001

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

    Area, at 4:45 p.m., January 13. Media members will not need to be badged for access. Please contact Bill Taylor of the DOE Office of External Affairs at 725-2889 with any...

  9. SR0301

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

    January 31, 2003 Media Contact: Bill Taylor (803) 725-2889 Helicopters to Conduct Equipment Tests Over Savannah River Site During February Flag Ribbon Art U.S. Government...

  10. SR0110

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

    4, 2001 Media Contact: Bill Taylor (803) 725-2889 Energy Employees Compensation Center To Open In North Augusta, SC Flag Ribbon Art Aiken SC (July 24) -- A resource center where...

  11. SR0012

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

    July 31, 2000 Media Contact: Rick Ford (803) 725-2889 "Melt And Dilute" Selected To Treat DOE's Spent Nuclear Fuel At Savannah River Flag Ribbon Art Technology Supports Administration's Non-Proliferation Commitments The Department of Energy has selected a new technology to manage the majority of spent fuel being received at the Department of Energy's (DOE) Savannah River Site (SRS), near Aiken, S.C. "I've given the green light to the SRS workforce to put the melt and dilute

  12. SR0103

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

    7, 2001 Media Contact: James Giusti (803) 725-2889 Note to Editors and News Directors Flag Ribbon Art On May 8, media representatives are invited to observe the first shipment of transuranic, or TRU, waste leave the Savannah Rive Site (SRS) for the Waste Isolation Plant (WIPP), located in Carlsbad, NM. A truck, loaded with the TRUPACT-II shipping containers, will pass through the Site’s Jackson Barricade (Barricade #1) en route to I-20 at about 12:15 p.m. Media representatives planning to view

  13. SR0108

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

    8, 2001 Media Contact: Jim Giusti (803) 725-2889 DOE Announces Plans For Offsite Treatment & Disposal of SRS Waste Flag Ribbon Art Aiken, SC -- The Department of Energy (DOE) has published an Amended Record of Decision (ROD) to the Savannah River Site (SRS) Waste Management Environmental Impact Statement (DOE/EIS-0217). This ROD modifies earlier decisions concerning the treatment and disposal of low-level radioactive waste (LLW) and mixed hazardous and low-level radioactive waste (MLLW) at

  14. SR0501

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

    14, 2005 Media Contact: James Giusti (803) 952-7697 End State Vision at Savannah River Site Made Public Flag Ribbon Art Aiken, S.C. - The Department of Energy's Savannah River Operations Office issued the draft Savannah River Site (SRS) End State Vision Document for review and comment on Wednesday (March 9, 2005). The SRS End State Vision Document is a concise guide to current conditions at SRS and the conditions the Department plans to achieve through the Site's Environmental Management (EM)

  15. SR0608

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

    30, 2006 Media Contact: James Giusti (803) 952-7697 Assistant Secretary for Environmental Management Marks SRS Achieving First Area Closure AIKEN, S.C., – With the completion of remediation work at the U.S. Department of Energy (DOE) Savannah River Site’s (SRS) T Area, SRS has achieved its first area closure, transforming a former industrial area into a grassy hill. T Area is the first area at SRS closed under an “area closure” concept endorsed by the U.S. Environmental Protection Agency and

  16. SR9908

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

    9, 1999 Media Contact: Rick Ford (803) 725-2889 Notice To News Editors and News Directors Flag Ribbon Art WHO: On July 13, Dr. David Michaels, Assistant Secretary for Environment, Safety and Health for the Department of Energy (DOE), will present awards to two Savannah River Site (SRS) contractors, Wackenhut Services, Inc. (WSI) and Westinghouse Savannah River Company (WSRC) for significant achievements in DOE's Voluntary Protection Program (VPP). The Department initiated its VPP in January 1994

  17. SR9911

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

    6, 1999 Media Contact: Rick Ford (803) 725-2889 Note To Editors and News Directors Flag Ribbon Art The following is a statement by Greg Rudy, Manager of the Savannah River Operations Office, on the election of Ambrose Schwallie to the position of Executive Vice President of Morrison Knudsen Corporation and his promotion to President and Chief Executive Officer of the Westinghouse Government Services Group. "Ambrose successfully led the Site through some of its most challenging and uncertain

  18. SR9914

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

    1, 1999 Media Contact: Bill Taylor (803) 725-2889 SRS Vehicles Begin Era Of Alternative Fuels Flag Ribbon Art Aiken S.C. (Sept. 28, 1999) - The Savannah River Site (SRS) began a new era of alternative fuel use today when special ethanol fuel became available in two 10,000 gallon fuel storage tanks that went into operation in the A and H areas. The E85 ethanol fuel, a mixture of 85 percent ethanol and 15 percent unleaded gasoline, will allow a new fleet of alternative fuel vehicles (AFV's) to

  19. SR0004

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

    5, 1999 Media Contact: James R. Giusti (803) 725-2889 DOE Releases Accident Investigation Report On FB-Line Workers' Plutonium Intake Flag Ribbon Art Aiken, SC - The Department of...

  20. SR9912

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

    17, 1999 Media Contact: Bill Taylor (803) 725-2889 DOE Security Czar To Visit SRS August 18, 1999 Flag Ribbon Art General Eugene Habiger (USAF Ret.), the Department of Energy's...

  1. SR9913

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

    Contact: Jim Giusti (803) 725-2889 DOE Initiates Investigation Into FB Line Worker Contamination Flag Ribbon Art Aiken, SC - The Department of Energy's Savannah River Operations...

  2. SR9902

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

    Monday, February 1, 1999. A satellite downlink will be available at: Satellite: TelStar 5 Location: 97 deg. West Latitude Transponder: 17 Frequency: C-Band 4040 MHz Polarization:...

  3. SR0705

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

    June 13, 2007 Media Contact: James Giusti (803) 952-7697 james-r.giusti@srs.gov SRS CONSTRUCTS New Clean Energy Efficient Steam plant under Energy Savings Performance Contract ...

  4. SR0112

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

    News Release Logo For Immediate Release October 18, 2001 Media Contact: Julie Petersen (803) 725-2889 DOE ANNOUNCES RECORD OF DECISION ON SRS SALT WASTE PROCESSING ALTERNATIVES...

  5. SR0603

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

    July 10, 2006 Media Contact: Julie Petersen (803) 952-7697 Startup of Second Nuclear Waste Storage Facility at the Savannah River Site DOE Managed Small Business Contract Safely...

  6. SR0203

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

    31, 2002 Media Contact: Julie Petersen (803) 725-2889 DOE Announces Availability Of Final EIS On SRS High-Level Waste Tank Closures Flag Ribbon Art AIKEN, SC; May 31 - The...

  7. SR0708

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

    272007 Media Contact: Julie Petersen (803) 952-7697 julie.petersen@srs.gov DOE AUTHORIZES CONSTRUCTION START OF SALT WASTE PROCESSING FACILITY AT SRS Aiken , SC - Today the U.S....

  8. SR0205

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

    19, 2002 Media Contact: Julie Petersen (803) 725-2889 DOE Announces Record Of Decision On SRS High-Level Waste Tank Closure Flag Ribbon Art AIKEN, SC -- The U.S. Department of...

  9. SR0206

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

    17, 2002 Media Contact: Julie Petersen (803) 725-2889 DOE Announces Conceptual Design Contracts For SRS Salt Waste Processing Facility Flag Ribbon Art Aiken, SC - Today the...

  10. SR0109

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

    0, 2001 Media Contact: Julie Petersen (803) 725-2889 DOE ANNOUNCES AVAILABILITY OF FINAL SUPPLEMENTAL EIS AND IDENTIFIES PREFERRED SALT PROCESSING ALTERNATIVE Flag Ribbon Art...

  11. SR0704

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

    3, 2004 Media Contact: Julie Petersen (803) 952-7697 Media Advisory: Media Day On SRS Accelerated Cleanup Flag Ribbon Art NOTE TO EDITORS AND NEWS DIRECTORS: AIKEN, S.C. (July 13,...

  12. SR0105

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

    4, 2001 Media Contact: Julie Petersen (803) 725-2889 Doe Announces Availability Of Draft RFP On Salt Waste Processing Facility Flag Ribbon Art Aiken, SC; May 24, 2001 -- Today the...

  13. SR0102

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

    30, 2001 Media Contact: Julie Petersen (803) 725-2889 DOE Annouces Availability of Draf SEIS On Salt PRocessing Alternatives Flag Ribbon Art Aiken, SC -- Today the Department of...

  14. SR0209

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

    4, 2002 Media Contact: Bill Taylor (803) 725-2889 DOENNSA to Host Modern Pit Facility Media Availability Flag Ribbon Art U. S. Department of Energy National Nuclear Security...

  15. SR0704

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

    Farrow Nancy H. Fenstermacher Ed Petty Jeffrey Wallace Ray William Wabbersen George Milton Widener David L. Allen Kids Bronze Awardees (50-74 hours) Jolene Long Katherine Long...

  16. SR0113?

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

    the conceptual design of a Salt Waste Processing Facility based on the Caustic Side Solvent Extraction technology. After conceptual design, DOE will select one of these EPC...

  17. SR0013

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

    ResourcesEqual Employment Opportunity Best Practices" Award from the Federal Personnel Management Institute (FPMI). The award is presented annually by FPMI to a single Federal...

  18. SR0505

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

    Once the MOX fuel has been irradiated, the plutonium can no longer be readily used for nuclear weapons. Established by Congress in 2000, NNSA is a semi-autonomous agency within the ...

  19. SR0503

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

    Once the MOX fuel has been irradiated, the plutonium can no longer be readily used for nuclear weapons. Established by Congress in 2000, NNSA is a semi-autonomous agency within the ...

  20. SR9904

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

    this important milestone in the Energy Department's work to permanently dispose of defense-generated transuranic waste left from the research and production of nuclear weapons. ...

  1. Spin orientations of the spin-half Ir4+ ions in Sr3NiIrO6, Sr2IrO4 and Na2IrO3: Density functional, perturbation theory and Madelung potential analyses

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

    Gordon, Elijah E.; Xiang, Hongjun; Koehler, Jurgen; Whangbo, Myung -Hwan

    2016-03-01

    The spins of the low-spin Ir4+ (S = 1/2, d5) ions at the octahedral sites of the oxides Sr3NiIrO6, Sr2IrO4 and Na2IrO3 exhibit preferred orientations with respect to their IrO6 octahedra. We evaluated the magnetic anisotropies of these S = 1/2 ions on the basis of DFT calculations including spin-orbit coupling (SOC), and probed their origin by performing perturbation theory analyses with SOC as perturbation within the LS coupling scheme. The observed spin orientations of Sr3NiIrO6 and Sr2IrO4 are correctly predicted by DFT calculations, and are accounted for by the perturbation theory analysis. As for the spin orientation of Na2IrO3,more » both experimental studies and DFT calculations have not been unequivocal. Our analysis reveals that the Ir4+ spin orientation of Na2IrO3 should have nonzero components along the c- and a-axes directions. The spin orientations determined by DFT calculations are sensitive to the accuracy of the crystal structures employed, which is explained by perturbation theory analyses when interactions between adjacent Ir4+ ions are taken into consideration. There are indications implying that the 5d electrons of Na2IrO3 are less strongly localized compared with those of Sr3NiIrO6 and Sr2IrO4. This implication was confirmed by showing that the Madelung potentials of the Ir4+ ions are less negative in Na2IrO3 than in Sr3NiIrO6, Sr2IrO4. Most transition-metal S = 1/2 ions do have magnetic anisotropies because the SOC induces interactions among their crystal-field split d-states, and the associated mixing of the states modifies only the orbital parts of the states. This finding cannot be mimicked by a spin Hamiltonian because this model Hamiltonian lacks the orbital degree of freedom, thereby leading to the spin-half syndrome. As a result, the spin-orbital entanglement for the 5d spin-half ions Ir4+ is not as strong as has been assumed lately.« less

  2. Electric field effects in graphene/LaAlO{sub 3}/SrTiO{sub 3} heterostructures and nanostructures

    SciTech Connect (OSTI)

    Huang, Mengchen; Jnawali, Giriraj; Hsu, Jen-Feng; Dhingra, Shonali; Bi, Feng; Chen, Lu; DUrso, Brian; Irvin, Patrick; Levy, Jeremy; Lee, Hyungwoo; Ryu, Sangwoo; Eom, Chang-Beom; Ghahari, Fereshte; Ravichandran, Jayakanth; Kim, Philip

    2015-06-01

    We report the development and characterization of graphene/LaAlO{sub 3}/SrTiO{sub 3} heterostructures. Complex-oxide heterostructures are created by pulsed laser deposition and are integrated with graphene using both mechanical exfoliation and transfer from chemical-vapor deposition on ultraflat copper substrates. Nanoscale control of the metal-insulator transition at the LaAlO{sub 3}/SrTiO{sub 3} interface, achieved using conductive atomic force microscope lithography, is demonstrated to be possible through the graphene layer. LaAlO{sub 3}/SrTiO{sub 3}-based electric field effects using a graphene top gate are also demonstrated. The ability to create functional field-effect devices provides the potential of graphene-complex-oxide heterostructures for scientific and technological advancement.

  3. Optical absorption in epitaxial La{sub 1-x}Sr{sub x}FeO{sub 3} thin films

    SciTech Connect (OSTI)

    Scafetta, M D.; Xie, Y. J.; Torres, M.; Spanier, J. E.; May, S. J.

    2013-02-25

    We report the dependence of optical absorption on Sr concentration in La{sub 1-x}Sr{sub x}FeO{sub 3} (LSFO) (x{<=}0.4) perovskite thin films. Strained epitaxial films were deposited on SrTiO{sub 3} substrates using oxide molecular beam epitaxy. We find systematic changes in the optical absorption spectra with increasing x including a red-shift of transition energies and the increasing presence of a lower energy transition within the fundamental gap of pure LaFeO{sub 3}. These results serve as a demonstration of the complex manner in which absorption spectra can be altered in complex oxides via heterovalent A-site substitution.

  4. Selective Separation of Cs and Sr from LiCl-Based Salt for Electrochemical Processing of Oxide Spent Nuclear Fuel

    SciTech Connect (OSTI)

    P Sachdev

    2008-07-01

    Electrochemical processing technology is currently being used for the treatment of metallic spent fuel from the Experimental Breeder Reactor-II at Idaho National Laboratory. The treatment of oxide-based spent nuclear fuel via electrochemical processing is possible provided there is a front-end oxide reduction step. During this reduction process, certain fission products, including Cs and Sr, partition into the salt phase and form chlorides. Both solid state and molten LiCl-zeolite-A ion exchange tests were conducted for selectively removing Cs and Sr from LiCl-based salt. The solid-state tests produced in excess of 99% removal of Cs and Sr. The molten state tests failed due to phase transformation of the zeolite structure when in contact with the molten LiCl salt.

  5. Electrostatic carrier doping of GdTiO{sub 3}/SrTiO{sub 3} interfaces

    SciTech Connect (OSTI)

    Moetakef, Pouya; Cain, Tyler A.; Zhang, Jack Y.; Janotti, Anderson; Van de Walle, Chris G.; Stemmer, Susanne; Ouellette, Daniel G.; Allen, S. James; Klenov, Dmitri O.; Rajan, Siddharth

    2011-12-05

    Heterostructures and superlattices consisting of a prototype Mott insulator, GdTiO{sub 3}, and the band insulator SrTiO{sub 3} are grown by molecular beam epitaxy and show intrinsic electronic reconstruction, approximately 1/2 electron per surface unit cell at each GdTiO{sub 3}/SrTiO{sub 3} interface. The sheet carrier densities in all structures containing more than one unit cell of SrTiO{sub 3} are independent of layer thicknesses and growth sequences, indicating that the mobile carriers are in a high concentration, two-dimensional electron gas bound to the interface. These carrier densities closely meet the electrostatic requirements for compensating the fixed charge at these polar interfaces. Based on the experimental results, insights into interfacial band alignments, charge distribution, and the influence of different electrostatic boundary conditions are obtained.

  6. Tracking chemical changes in a live cell: Biomedical applications of SR-FTIR spectromicroscopy

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

    Holman, Hoi-Ying N.; Martin, Michael C.; McKinney, Wayne R.

    2003-01-01

    Synchrotron radiation-based Fourier transform infrared (SR-FTIR) spectromicroscopy is a newly emerging bioanalytical and imaging tool. This unique technique provides mid-infrared (IR) spectra, hence chemical information, with high signal-to-noise at spatial resolutions as fine as 3 to 10 microns. Thus it enables researchers to locate, identify, and track specific chemical events within an individual living mammalian cell. Mid-IR photons are too low in energy (0.05-0.5 eV) to either break bonds or to cause ionization. In this review, we show that the synchrotron IR beam has no detectable effects on the short- and long-term viability, reproductive integrity, cell-cycle progression, and mitochondrial metabolismmore » in living human cells, and produces only minimal sample heating (<0.5°C). We will then present several examples demonstrating the application potentials of SR-FTIR spectromicroscopy in biomedical research. These will include monitoring living cells progressing through the cell cycle, including death, and cells reacting to dilute concentrations of toxins.« less

  7. Theoretical study of cubic Rashba effect at SrTiO3 (001) surfaces

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

    Shanavas, Kavungal Veedu

    2016-01-11

    The origin of Rashba spin splitting in the two-dimensional electron gas at the (001) surface of SrTiO3 is studied using first-principles calculations and tight-binding model. Calculations of oxygen vacancies under virtual crystal approximation reveal a two-dimensional electron-gas subband structure similar to polar materials, consistent with observations on SrTiO3. Our studies also confirm that k dependence of the spin splitting is predominantly cubic in the surface Tit2g states, even though structural relaxations diminish the effect in dxy bands. A tight-binding model, explicitly including Tid and Op states as well as next-nearest-neighbor interactions, is derived to understand the first-principles results. Effective RashbamoreHamiltonians for the surface bands are derived using quasidegenerate perturbation theory and scenarios in which linear k contribution may be suppressed are discussed. Furthermore, the cubic terms in the Hamiltonian are found to be different from the model derived using k ? p theory, leading to different pseudospin symmetry in the Brillouin zone.less

  8. Interacting factors and cellular localization of SR protein-specific kinase Dsk1

    SciTech Connect (OSTI)

    Tang, Zhaohua; Luca, Maria; Taggart-Murphy, Laura; Portillio, Jessica; Chang, Cathey; Guven, Ayse; Lin, Ren-Jang; Murray, Johanne; Carr, Antony

    2012-10-01

    Schizosaccharomyces pombe Dsk1 is an SR protein-specific kinase (SRPK), whose homologs have been identified in every eukaryotic organism examined. Although discovered as a mitotic regulator with protein kinase activity toward SR splicing factors, it remains largely unknown about what and how Dsk1 contributes to cell cycle and pre-mRNA splicing. In this study, we investigated the Dsk1 function by determining interacting factors and cellular localization of the kinase. Consistent with its reported functions, we found that pre-mRNA processing and cell cycle factors are prominent among the proteins co-purified with Dsk1. The identification of these factors led us to find Rsd1 as a novel Dsk1 substrate, as well as the involvement of Dsk1 in cellular distribution of poly(A){sup +} RNA. In agreement with its role in nuclear events, we also found that Dsk1 is mainly localized in the nucleus during G{sub 2} phase and at mitosis. Furthermore, we revealed the oscillation of Dsk1 protein in a cell cycle-dependent manner. This paper marks the first comprehensive analysis of in vivo Dsk1-associated proteins in fission yeast. Our results reflect the conserved role of SRPK family in eukaryotic organisms, and provide information about how Dsk1 functions in pre-mRNA processing and cell-division cycle.

  9. Quasiparticle dynamics across the full Brillouin zone of Bi2Sr2CaCu2O8+δ

    Office of Scientific and Technical Information (OSTI)

    traced with ultrafast time and angle-resolved photoemission spectroscopy (Journal Article) | SciTech Connect Quasiparticle dynamics across the full Brillouin zone of Bi2Sr2CaCu2O8+δ traced with ultrafast time and angle-resolved photoemission spectroscopy Citation Details In-Document Search Title: Quasiparticle dynamics across the full Brillouin zone of Bi2Sr2CaCu2O8+δ traced with ultrafast time and angle-resolved photoemission spectroscopy A hallmark in the cuprate family of

  10. Anomalous Transport in Sketched Nanostructures at the LaAlO3/SrTiO3

    Office of Scientific and Technical Information (OSTI)

    Interface (Journal Article) | SciTech Connect Anomalous Transport in Sketched Nanostructures at the LaAlO3/SrTiO3 Interface Citation Details In-Document Search Title: Anomalous Transport in Sketched Nanostructures at the LaAlO3/SrTiO3 Interface Authors: Cheng, Guanglei ; Veazey, Joshua P. ; Irvin, Patrick ; Cen, Cheng ; Bogorin, Daniela F. ; Bi, Feng ; Huang, Mengchen ; Lu, Shicheng ; Bark, Chung-Wung ; Ryu, Sangwoo ; Cho, Kwang-Hwan ; Eom, Chang-Beom ; Levy, Jeremy Publication Date:

  11. Growth of epitaxial (Sr,Ba){sub n+1}Ru{sub n}O{sub 3n+1} films

    SciTech Connect (OSTI)

    Schlom, D.G.; Knapp, S.B.; Wozniak, S. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering] [and others

    1997-12-01

    We have grown epitaxial (Sr,Ba) (n+1)Ru(n)O(3n+1) films, n = 1, 2, and infinity, by pulsed laser deposition (PLD) and controlled their orientation by choosing appropriate substrates. The growth conditions yielding phase pure films have been mapped out. Resistivity versus temperature measurements show that both a and c axis films of Sr2RuO4 are metallic, but not superconducting. The latter is probably due to the presence of low-level impurities that are difficult to avoid given the target preparation process involved in growing these films by PLD.

  12. Strain relaxation in epitaxial SrRuO{sub 3} thin films on LaAlO{sub 3} substrates

    SciTech Connect (OSTI)

    Gao, M.; Du, H.; Dai, C.; Lin, Y.; Ma, C. R.; Liu, M.; Collins, G.; Zhang, Y. M.; Chen, C. L.

    2013-09-30

    Strain relaxation behavior of epitaxial SrRuO{sub 3} thin films on (001) LaAlO{sub 3} substrates was investigated using high resolution X-ray diffraction. Lattice distortion and dislocation densities were systematically studied with samples under different growth conditions. Reciprocal space maps reveal different strain relaxation behavior in SrRuO{sub 3} thin films grown at different temperatures. Two kinds of strain relaxation mechanisms were proposed to understand the growth dynamics, including the evolution of threading dislocations and the tilt of crystalline planes.

  13. Direct real space observation of magneto-electronic inhomogeneity in ultra-thin film La{sub 0.5}Sr{sub 0.5}CoO{sub 3??} on SrTiO{sub 3}(001)

    SciTech Connect (OSTI)

    Kelly, S.; Galli, F.; Aarts, J. E-mail: aarts@physics.leidenuniv.nl; Bose, Shameek; Sharma, M.; Leighton, C. E-mail: aarts@physics.leidenuniv.nl

    2014-09-15

    Recent magnetotransport and neutron scattering measurements implicate interfacial magneto-electronic phase separation as the origin of the degradation in transport and magnetism in ultra-thin film La{sub 1?x}Sr{sub x}CoO{sub 3} on SrTiO{sub 3}(001). Here, using low temperature scanning tunneling microscopy and spectroscopy the first direct, real space observation of this nanoscopic electronic inhomogeneity is provided. Films of thickness 12.4?nm (32 unit cells) are found to exhibit spatially uniform conductance, in stark contrast to 4.7?nm (12 unit cell) films that display rich variations in conductance, and thus local density of states. The electronic heterogeneity occurs across a hierarchy of length scales (550?nm), with complex correlations with both topography and applied magnetic fields. These results thus provide a direct observation of magneto-electronic inhomogeneity in SrTiO{sub 3}(001)/La{sub 0.5}Sr{sub 0.5}CoO{sub 3} at thicknesses below 67?nm, in good agreement with less direct techniques.

  14. Reversible nano-structuring of SrCrO3-? through oxidization and reduction at low temperatures

    SciTech Connect (OSTI)

    Zhang, Hongliang; Sushko, Petr; Colby, Robert J.; Du, Yingge; Bowden, Mark E.; Chambers, Scott A.

    2014-08-18

    Oxygen vacancies are often present in complex oxides as point defects and their effect on the electronic properties of the oxides is typically uniform and isotropic. Exploiting oxygen deficiency in order to generate controllably, novel structures and functional properties remains a challenging goal. We show that epitaxial strontium chromite films can be transformed, reversibly and at low temperature, from the cubic metallic perovskite SrCrO3-? to the rhombohedral semiconducting SrCrO2.8. Oxygen vacancies aggregate and give rise to ordered arrays of {111}-oriented SrO2 planes interleaved between layers of tetrahedrally-coordinated Cr4+ and separated by ~1 nm. First-principle calculations provide insight into the origin of the stability of such nanostructures and, consistent with the experimental data, predict that the barrier for oxide ion diffusion along these quasi-2D nanostructures is ~5 times lower than that in the cubic SrCrO3-? a property of considerable importance in, for example, solid oxide fuel cells.

  15. 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

    2013-07-01

    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)

  16. Resistive switching characteristics of polycrystalline SrTiO{sub 3} films

    SciTech Connect (OSTI)

    Jong Choi, Hyung; Won Park, Suk; Deok Han, Gwon; Hyung Shim, Joon; Na, Junhong; Kim, Gyu-Tae

    2014-06-16

    Strontium titanate (STO) thin films 90?nm in thickness were grown on a Pt substrate through atomic layer deposition (ALD). The as-deposited ALD STO grown with an ALD cycle ratio of 1:1 (Sr:Ti) was in an amorphous phase, and annealing at 800?C in air crystallized the films into the perovskite phase. This phase change was confirmed by x-ray diffraction and transmission electron microscopy. The as-deposited ALD STO exhibited no discernible switching mechanism, whereas unipolar switching behavior was reproducibly observed with a high resistance ratio (10{sup 8}10{sup 9}) and strict separation of the set/reset voltages and currents in the annealed ALD STO. Mechanisms for charge transport in both the low- and high-resistance states and for resistive switching in the annealed ALD STO are also proposed.

  17. Target and orbit feedback simulations of a muSR beam line at BNL

    SciTech Connect (OSTI)

    MacKay, W.; Blaskiewicz, M.; Fischer, W.; Pile, P.

    2015-07-28

    Well-polarized positive surface muons are a tool to measure the magnetic properties of materials since the precession rate of the spin can be determined from the observation of the positron directions when the muons decay. For a dc beam an ideal µSR flux for surface µ+ should be about 40 kHz/mm2. In this report we show how this flux could be achieved in a beam line using the AGS complex at BNL for a source of protons. We also determined that an orbit feedback system with a pair of thin silicon position monitors and kickers would miss the desired flux by at least an order of magnitude, even with perfect time resolution and no multiple scattering.

  18. Fabrication of Sr- and Co-doped lanthanum chromite interconnectors for SOFC

    SciTech Connect (OSTI)

    Setz, L.F.G. [Departamento de Engenharia de Materiais, Universidade Federal de Sao Carlos - DEMa/UFSCar (Brazil) [Departamento de Engenharia de Materiais, Universidade Federal de Sao Carlos - DEMa/UFSCar (Brazil); Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN (Brazil); Santacruz, I. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain)] [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain); Colomer, M.T., E-mail: tcolomer@icv.csic.es [Instituto de Ceramica y Vidrio, ICV (CSIC), 28049 Madrid (Spain); Mello-Castanho, S.R.H. [Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN (Brazil)] [Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN (Brazil); Moreno, R. [Instituto de Ceramica y Vidrio, ICV (CSIC), 28049 Madrid (Spain)] [Instituto de Ceramica y Vidrio, ICV (CSIC), 28049 Madrid (Spain)

    2011-07-15

    Graphical abstract: FESEM micrographs of the fresh fracture surfaces for the La{sub 0.80}Sr{sub 0.20}Cr{sub 0.92}Co{sub 0.08}O{sub 3} sintered specimens cast from optimised suspensions with 13.5, 15 and 17.5 vol.% solids loading. Aqueous suspensions were prepared using ammonium polyacrylate (PAA) as dispersant and tetramethylammonium hydroxide (TMAH) to assure a basic pH and providing stabilization. Sintering of the green discs was performed in air at 1600 {sup o}C for 4 h. Highlights: {yields} Optimum casting slips were achieved with 3 wt.% of ammonium polyacrylate and 1 wt.% of tetramethylammonium hydroxide. -- Abstract: Many studies have been performed dealing with the processing conditions of electrodes and electrolytes in solid oxide fuel cells (SOFCs). However, the processing of the interconnector material has received less attention. Lanthanum chromite (LaCrO{sub 3}) is probably the most studied material as SOFCs interconnector. This paper deals with the rheology and casting behaviour of lanthanum chromite based materials to produce interconnectors for SOFCs. A powder with the composition La{sub 0.80}Sr{sub 0.20}Cr{sub 0.92}Co{sub 0.08}O{sub 3} was obtained by combustion synthesis. Aqueous suspensions were prepared to solids loading ranging from 8 to 17.5 vol.%, using ammonium polyacrylate (PAA) as dispersant and tetramethylammonium hydroxide (TMAH) to assure a basic pH and providing stabilization. The influence of the additives concentrations and suspension ball milling time were studied. Suspensions prepared with 24 h ball milling, with 3 wt.% and 1 wt.% of PAA and TMAH, respectively, yielded the best conditions for successful slip casting. Sintering of the green discs was performed in air at 1600 {sup o}C for 4 h leading to relatively dense materials.

  19. (JS)_BL13 schedule S02-S03FY15HO3FINAL.xlsx

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

    16 17 18 19 20 21 22 Day Shift 6:00 3996 B Sandberg 3996 B Sandberg 3996 B Sandberg 3996 A Sandberg 3996 A Sandberg 3996 A Sandberg 3996 A Sandberg 3 0 4 Night Shift 18:00 8055 B Ogasawara 80055 B Ogasawara 8055 B Ogasawara 3996 B Sandberg 3996 B Sandberg 3996 A Sandberg 3996 A Sandberg 2 3 2 Feb 23 24 25 26 27 28 1 Day Shift 6:00 AP AP 4247 B Graves 4247 B Graves 4247 B Graves 4247 B Graves 4247 B Graves 5 0 0 Night Shift 18:00 AP AP 4180 C Li 4180 C Li 4180 C Li 4238 A Savikhin 4238 A Savikhin

  20. (JS)_BL13 schedule S02-S03FY15HO3FINAL.xlsx

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

    A Ogassawara 8855 A Ogassawara 3 3 0 Apr 6 7 8 9 10 11 12 Day Shift 6:00 AP AP 4281 A Cho 4281 A Cho 4281 A Cho 4281 A Cho 8073 A Ohldag 1 4 0 Night Shift 18:00 AP AP 4281 A Cho...

  1. Hyperfine structure of {sup 87,89}Sr 5s4d{sup 3}D-5snf transitions in collinear fast beam RIMS

    SciTech Connect (OSTI)

    Bushaw, B. A.; Kluge, H.-J.; Lantzsch, J.; Schwalbach, R.; Schwarz, M.; Stenner, J.; Stevens, H.; Wendt, K.; Zimmer, K.

    1995-04-01

    The title transition, with n=20, 23, and 32 were measured for stable {sup 87}Sr and the observed hfs was interpreted and strong hyperfine mixing of all four terms {sup 1}F3 and {sup 3}F2,3,4 in the upper configuration. The results of the analysis were used to predict the hfs for the radioactive isotope {sup 89}Sr. Measurement were then performed on samples containing 10{sup 9} atoms {sup 89}Sr. The positions and intensities of the hfs components selected for study were found to agree well with the predicted values.

  2. Structure and optical properties of a noncentrosymmetric borate RbSr{sub 4}(BO{sub 3}){sub 3}

    SciTech Connect (OSTI)

    Xia, M.J.; Li, R.K.

    2013-01-15

    A new noncentrosymmetric borate, RbSr{sub 4}(BO{sub 3}){sub 3} (abbreviated as RSBO), has been grown from Rb{sub 2}O--B{sub 2}O{sub 3}--RbF flux and its crystal structure was determined by single crystal x-ray diffraction. It crystallizes in space group Ama2 with cell parameters of a=11.128(10) A, b=12.155(15) A, c=6.952(7) A, Z=4. The basic structural units are isolated planar BO{sub 3} groups. Second harmonic generation (SHG) test of the title compound by the Kurtz-Perry method shows that RSBO can be phase matchable with an effective SHG coefficient about two-thirds as large as that of KH{sub 2}PO{sub 4} (KDP). Finally, based on the anionic group approximation, the optical properties of the title compound are compared with those of the structure-related apatite-like compounds with the formula 'A{sub 5}(TO{sub n}){sub 3}X'. - Graphical abstract: RbSr{sub 4}(BO{sub 3}){sub 3} and some other borate NLO compounds, namely Ca{sub 5}(BO{sub 3}){sub 3}F RCa{sub 4}(BO{sub 3}){sub 3}O (R=Y or Gd) and Na{sub 3}La{sub 2}(BO{sub 3}){sub 3} can be viewed as the derivatives of apatite. They have similar formula composed of five cations and three anion groups (we call them 5/3 structures). The detailed SHG coefficients and optical properties of the apatite-like NLO crystals were compared and summarized. Highlights: Black-Right-Pointing-Pointer A new noncentrosymmetric borate RbSr{sub 4}(BO{sub 3}){sub 3} was grown from flux. Black-Right-Pointing-Pointer The RbSr{sub 4}(BO{sub 3}){sub 3} can be viewed as a derivative of the apatite-like structure. Black-Right-Pointing-Pointer The structure and its relationship to the optical properties of RbSr{sub 4}(BO{sub 3}){sub 3} are compared with other NLO crystals with apatite-like structures. Black-Right-Pointing-Pointer The basic structural units are the planar BO{sub 3} groups in the structure. Black-Right-Pointing-Pointer Second harmonic generation (SHG) test shows that RbSr{sub 4}(BO{sub 3}){sub 3} can be phase matchable with an effective SHG coefficient about two-thirds as large as that of KH{sub 2}PO{sub 4}.

  3. Interfacial dislocations in (111) oriented (Ba0.7Sr0.3)TiO3 films on SrTiO3 single crystal

    SciTech Connect (OSTI)

    Shen, Xuan; Yamada, Tomoaki; Lin, Ruoqian; Kamo, Takafumi; Funakubo, Hiroshi; Wu, Di; Xin, Huolin L.; Su, Dong

    2015-10-08

    In this study, we have investigated the interfacial structure of epitaxial (Ba,Sr)TiO3 films grown on (111)-oriented SrTiO3 single-crystal substrates using transmission electron microscopy (TEM) techniques. Compared with the (100) epitaxial perovskite films, we observe dominant dislocation half-loop with Burgers vectors of a<110> comprised of a misfit dislocation along <112>, and threading dislocations along <110> or <100>. The misfit dislocation with Burgers vector of a <110> can dissociate into two a <110> partial dislocations and one stacking fault. We found the dislocation reactions occur not only between misfit dislocations, but also between threading dislocations. Via three-dimensional electron tomography, we retrieved the configurations of the threading dislocation reactions. The reactions between threading dislocations lead to a more efficient strain relaxation than do the misfit dislocations alone in the near-interface region of the (111)-oriented (Ba0.7Sr0.3)TiO3 films.

  4. Thickness-dependent metal-insulator transition in epitaxial SrRuO3 ultrathin films

    SciTech Connect (OSTI)

    Shen, Xuan; Qiu, Xiangbiao; Su, Dong; Zhou, Shengqiang; Li, Aidong; Wu, Di

    2015-01-06

    Transport characteristics of ultrathin SrRuO? films, deposited epitaxially on TiO?-terminated SrTiO? (001) single-crystal substrates, were studied as a function of film thickness. Evolution from a metallic to an insulating behavior is observed as the film thickness decreases from 20 to 4 unit cells. In films thicker than 4 unit cells, the transport behavior obeys the Drude low temperature conductivity with quantum corrections, which can be attributed to weak localization. Fitting the data with 2-dimensional localization model indicates that electron-phonon collisions are the main inelastic relaxation mechanism. In the film of 4 unit cells in thickness, the transport behavior follows variable range hopping model, indicating a strongly localized state. As a result, magnetoresistance measurements reveal a likely magnetic anisotropy with the magnetic easy axis along the out-of-plane direction.

  5. Magnetic, dielectric, and magnetoelectric properties in Sr{sub 2}CoGe{sub 2}O{sub 7}

    SciTech Connect (OSTI)

    Song, Y. Q.; Li, Q.; Zhou, W. P.; Cao, Q. Q.; Wang, D. H. Du, Y. W.; Zhang, Z. M.; Xu, Q. Y.

    2015-05-07

    We investigate the magnetoelectric effect in Sr{sub 2}CoGe{sub 2}O{sub 7}, which has a two-dimensional magnetic interaction between Co ions in the ab plane. This compound shows a weak magnetism and field-induced magnetic transition below the temperature of 7?K. It does not exhibit electric polarization under zero magnetic field. However, by applying an external magnetic field, the electric polarization is induced around its Nel temperature and increases with increasing magnetic field. The induced electric polarization in Sr{sub 2}CoGe{sub 2}O{sub 7} is almost two orders of magnitude smaller than that of Ba{sub 2}CoGe{sub 2}O{sub 7}. This result suggests that the different ionic radius of the strontium and the barium anion plays a key role in determining the property of electric polarization. The origins of electric polarization and magnetoelectric effect are discussed.

  6. Structural instability of the CoO4 tetrahedral chain in SrCoO3-δ thin films

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

    Glamazda, A.; Choi, Kwang-yong; Lemmens, P.; Choi, Woo Seok; Jeen, Hyoungjeen; Meyer, Tricia L.; Lee, Ho Nyung

    2015-08-31

    Raman scattering experiments together with detailed lattice dynamic calculations are performed to elucidate crystallographic and electronic peculiarities of SrCoO3-δ films. We observe that the 85 cm-1 phonon mode involving the rotation of a CoO4 tetrahedron undergoes a hardening by 21 cm-1 when the temperature is decreased. In addition, new phonon modes appear at 651.5 and 697.6 cm-1 . The latter modes are attributed to the Jahn-Teller activated modes. Upon cooling from room temperature, all phonons exhibit an exponential-like increase of intensity with a characteristic energy of about 103–107 K. We attribute this phenomenon to an instability of the CoO4 tetrahedralmore » chain structure, which constitutes a key ingredient to understand the electronic and structural properties of the brownmillerite SrCoO2.5.« less

  7. Total energy study of the microscopic structure and electronic properties of tetragonal perovskite SrTiO{sub 3}

    SciTech Connect (OSTI)

    Rubio-Ponce, A.; Olgun, D.

    2014-05-15

    To study the structural and electronic properties of cubic perovskite SrTiO{sub 3} and its stress-induced tetragonal phase, we have performed total energy calculations and studied the effect of oxygen vacancies on the electronic properties of tetragonal perovskite SrTiO{sub 3}. The method used was the relativistic full-potential linearized augmented plane wave (FLAPW) method. To obtain the geometry that minimizes the total energy, we relaxed the internal atomic sites of the tetragonal cell. As a result of this procedure, we have found that the titanium atoms move toward the plane of the vacancy by 0.03 , and the apical oxygen atoms move to the same plane by approximately 0.14 . These results are discussed in comparison with experimental data.

  8. Phase transitions in double perovskite Sr{sub 2}ScSbO{sub 6}: An Ab-initio study

    SciTech Connect (OSTI)

    Ray, Rajyavardhan; Kumar, Uday; Sinha, T. P.

    2014-04-24

    First Principles study of the electronic properties of recently synthesized double perovskite Sr{sub 2}ScSbO{sub 6} have been performed using density functional theory. With increasing temperature, the Sr compound undergoes three structural phase transitions at 400K, 550K and 650K approximately, leading to the following sequence of phases: P21/n ? I2/m ? I4/m ? Fm-3m. Starting from the monoclinic phase P21/n at room temperature, resulting from the Sc/Sb ordering, the electronic structure for the tetragonal I4/m at 613K and cubic Fm-3m for T?660K has been studied in terms of the density of states and band-structure. Presence of large band gap, both direct and indirect, has been reported and analyzed.

  9. Disorder from order among anisotropic next-nearest-neighbor Ising spin chains in SrHo2O4

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

    Wen, J. -J.; Tian, W.; Garlea, V. O.; Koohpayeh, S. M.; McQueen, T. M.; Li, H. -F.; Yan, J. -Q.; Rodriguez-Rivera, J. A.; Vaknin, D.; Broholm, C. L.

    2015-02-26

    In this study, we describe why Ising spin chains with competing interactions in SrHo2O4 segregate into ordered and disordered ensembles at low temperatures (T). Using elastic neutron scattering, magnetization, and specific heat measurements, the two distinct spin chains are inferred to have Néel (↑↓↑↓) and double-Néel (↑↑↓↓) ground states, respectively. Below TN = 0.68(2)K, the Néel chains develop three-dimensional long range order (LRO), which arrests further thermal equilibration of the double-Néel chains so they remain in a disordered incommensurate state for T below TS = 0.52(2)K. SrHo2O4 distills an important feature of incommensurate low dimensional magnetism: kinetically trapped topological defectsmore » in a quasi–d–dimensional spin system can preclude order in d + 1 dimensions.« less

  10. ASSESSMENT OF 90SR AND 137CS PENETRATION INTO REINFORCED CONCRETE (EXTENT OF 'DEEPENING') UNDER NATURAL ATMOSPHERIC CONDITIONS

    SciTech Connect (OSTI)

    Farfan, E.; Jannik, T.

    2011-10-01

    When assessing the feasibility of remediation following the detonation of a radiological dispersion device or improvised nuclear device in a large city, several issues should be considered including the levels and characteristics of the radioactive contamination, the availability of resources required for decontamination, and the planned future use of the city's structures and buildings. Currently, little is known about radionuclide penetration into construction materials in an urban environment. Knowledge in this area would be useful when considering costs of a thorough decontamination of buildings, artificial structures, and roads in an affected urban environment. Pripyat, a city substantially contaminated by the Chernobyl Nuclear Power Plant accident in April 1986, may provide some answers. The main objective of this study was to assess the depth of {sup 90}Sr and {sup 137}Cs penetration into reinforced concrete structures in a highly contaminated urban environment under natural weather conditions. Thirteen reinforced concrete core samples were obtained from external surfaces of a contaminated building in Pripyat. The concrete cores were drilled to obtain sample layers of 0-5, 5-10, 10-15, 15-20, 20-30, 30-40, and 40-50 mm. Both {sup 90}Sr and {sup 137}Cs were detected in the entire 0-50 mm profile of the reinforced cores sampled. In most of the cores, over 90% of the total {sup 137}Cs inventory and 70% of the total {sup 90}Sr inventory was found in the first 0-5 mm layer of the reinforced concrete. {sup 90}Sr had penetrated markedly deeper into the reinforced concrete structures than {sup 137}Cs.

  11. High antiferromagnetic transition temperature of a honeycomb compound SrRu2O6

    SciTech Connect (OSTI)

    Tian, Wei; Svoboda, Chris; Ochi, M.; Matsuda, M.; Cao, Huibo; Cheng, J. -G.; Sales, B. C.; Mandrus, D.; Arita, R.; Trivedi, Nandini; Yan, Jiaqiang

    2015-09-14

    We study the high-temperature magnetic order in a quasi-two-dimensional honeycomb compound SrRu2O6 by measuring magnetization and neutron powder diffraction with both polarized and unpolarized neutrons. SrRu2O6 crystallizes into the hexagonal lead antimonate (PbSb2O6, space group P31m) structure with layers of edge-sharing RuO6 octahedra separated by Sr2+ ions. SrRu2O6 is found to order at TN = 565 K with Ru moments coupled antiferromagnetically both in plane and out of plane. The magnetic moment is 1.30(2) ?B/Ru at room temperature and is along the crystallographic c axis in the G-type magnetic structure. We perform density functional calculations with constrained random-phase approximation (RPA) to obtain the electronic structure and effective intra- and interorbital interaction parameters. The projected density of states shows strong hybridization between Ru 4d and O 2p. By downfolding to the target t2g bands we extract the effective magnetic Hamiltonian and perform Monte Carlo simulations to determine the transition temperature as a function of interand intraplane couplings. We find a weak interplane coupling, 3% of the strong intraplane coupling, permits three-dimensional magnetic order at the observed TN .

  12. Photoluminescence performance of thulium doped Li{sub 4}SrCa(SiO{sub 4}){sub 2} under irradiation of ultraviolet and vacuum ultraviolet lights

    SciTech Connect (OSTI)

    Wang, Zhaofeng; Li, Yezhou; Liu, Xiong; Wei, Xingmin; Chen, Yueling; Zhou, Fei; Wang, Yuhua

    2014-11-15

    Highlights: A novel blue-emitting phosphor Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} was reported. Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} exhibited excellent thermal and irradiation stability. Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} was found to possess high color purity. - Abstract: In this work, we synthesized Tm{sup 3+} doped Li{sub 4}SrCa(SiO{sub 4}){sub 2} phosphors and investigated their photoluminescence properties under the excitation of ultraviolet and vacuum ultraviolet lights. The crystal structure analysis and variation of cell parameters confirm that Tm{sup 3+} ions have been successfully doped in the structure of Li{sub 4}SrCa(SiO{sub 4}){sub 2} host by occupying the sites of Ca{sup 2+} with the coordination number of 6. The luminescence results suggest that Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} is a good blue-emitting phosphor when excited by ultraviolet and vacuum ultraviolet irradiations. In addition, it is observed that there is nearly no degradation for Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} after undergoing thermal and irradiation treatments. Possible mechanisms for the luminescence processes are proposed on the basis of the discussion of excitation and emission spectra. In particular, the emission color of Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} by excitation of 147 and 172 nm irradiations is very close to the standard blue color, suggesting that it could be potentially applied in plasma display panels and mercury-free fluorescence lamps.

  13. IDENTIFICATION OF AN {sup 84}Sr-DEPLETED CARRIER IN PRIMITIVE METEORITES AND IMPLICATIONS FOR THERMAL PROCESSING IN THE SOLAR PROTOPLANETARY DISK

    SciTech Connect (OSTI)

    Paton, Chad; Schiller, Martin; Bizzarro, Martin E-mail: schiller@snm.ku.dk

    2013-02-01

    The existence of correlated nucleosynthetic heterogeneities in solar system reservoirs is now well demonstrated for numerous nuclides. However, it has proven difficult to discriminate between the two disparate processes that can explain such correlated variability: incomplete mixing of presolar material or secondary processing of a well-mixed disk. Using stepwise acid-leaching of the Ivuna CI-chondrite, we show that unlike other nuclides such as {sup 54}Cr and {sup 50}Ti, Sr-isotope variability is the result of a carrier depleted in {sup 84}Sr. The carrier is most likely presolar SiC, which is known to have both high Sr-concentrations relative to solar abundances and extremely depleted {sup 84}Sr compositions. Thus, variability in {sup 84}Sr in meteorites and their components can be attributed to varying contributions from presolar SiC. The observed {sup 84}Sr excesses in calcium-aluminum refractory inclusions (CAIs) suggest their formation from an SiC-free gaseous reservoir, whereas the {sup 84}Sr depletions present in differentiated meteorites require their formation from material with an increased concentration of SiC relative to CI chondrites. The presence of a positive correlation between {sup 84}Sr and {sup 54}Cr, despite being hosted in carriers of negative and positive anomalies, respectively, is not compatible with incomplete mixing of presolar material but instead suggests that the solar system's nucleosynthetic heterogeneity reflects selective thermal processing of dust. Based on vaporization experiments of SiC under nebular conditions, the lack of SiC material in the CAI-forming gas inferred from our data requires that the duration of thermal processing of dust resulting in the vaporization of CAI precursors was extremely short-lived, possibly lasting only hours to days.

  14. The radiation chemistry of Cs-7SB, a solvent modifier used in Cs and Sr extraction

    SciTech Connect (OSTI)

    Mincher, B.J.; Martin, L.R.; Elias, G.; Mezyk, S.P.

    2008-07-01

    The solvent modifier 1-(2,2,3,3-tetrafluoro-propoxy)-3-(4-sec-butylphenoxy)-2-propanol, (Cs- 7SB) is used in conjunction with calixarenes and crown ethers dissolved in alkane diluents for the extraction of Cs and Sr from highly radioactive solutions. Its purpose is to solvate the ligands and the resulting ligand-metal complexes in the organic phase. Given this role, and its relatively high concentration in the formulations used for solvent extraction, radiolytic degradation of Cs-7SB might decrease the extraction efficiency of these elements as the solvent accumulates absorbed radiation dose. This work presents the results of studies of Cs-7SB using post-radiolysis gas chromatography with electron-capture detection and solvent-extraction distribution-ratio measurements. Also presented is the kinetic analysis of the bimolecular rate constant for the modifier's reaction with nitrogen trioxide and nitrogen dioxide radicals, major radiolytically-produced radical species in irradiated aqueous nitric acid. Although Cs-7SB was found to undergo reactions with nitrogen-centered radicals, little decrease in extraction efficiency was found. It is concluded the modifier, always present at concentrations much higher than the ligands, acts as a radical scavenger, protecting ligands from radiolytic attack. (authors)

  15. Structural and optical study of ? BIMEVOX; ME: Ba{sup 2+} and Sr{sup 2+}

    SciTech Connect (OSTI)

    Gupta, Sakshi Singh, K.

    2015-05-15

    Bismuth oxide based compounds, such as Bi{sub 4}V{sub 2}O{sub 11-?} (BIVOX), exhibit Aurivillus type of interleaving arrangement of (Bi{sub 2}O{sub 2}){sup 2+} and (VO{sub 3}?{sub 0.5}){sup 2-} (?: oxygen vacancies). Bi{sub 4}V{sub 2}O{sub 11-?,} is known to have three kinds of temperature dependent interconvertible polymorphs ? (monoclinic), ? (orthorhombic) and ? (tetragonal). Out of all the three phases, the ? phase is highly disordered and hence, is the most conductive one which can be stabilized by proper lower valence cation (ME) doping at V site. Bi{sub 4}V{sub 1.90}ME{sub 0.20}O{sub 11-?} (ME: Ba{sup 2+} and Sr{sup 2+}) were prepared via splat quenching technique. The required compositions were melted at 1250 C in an electric furnace. The as quenched samples were sintered at 800 C for 12 hours (h). The formed phases were analyzed using X-ray diffraction on quenched and sintered samples, the peak at 32{sup } is found to be singlet in all the samples which confirms the presence of ?-phase. Hence, the stabilization of ?-phase with tetragonal structure was found to have taken place with doping and quenching. These samples are also studied by FT-IR and UV/vis spectroscopy to investigate the effect of dopants on structure and band gaps respectively.

  16. Optical Ramsey spectroscopy of a single trapped {sup 88}Sr{sup +} ion

    SciTech Connect (OSTI)

    Letchumanan, V. [National Physical Laboratory, Teddington, Middlesex TW11 0LW (United Kingdom); Department of Physics, Imperial College London, South Kensington Campus, London SW7 2BW (United Kingdom); Gill, P.; Sinclair, A.G. [National Physical Laboratory, Teddington, Middlesex TW11 0LW (United Kingdom); Riis, E. [Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2004-09-01

    Coherent optical spectroscopy has been performed on the narrow 5s {sup 2}S{sub 1/2}-4d {sup 2}D{sub 5/2} quadrupole transition in a single Doppler-cooled and trapped {sup 88}Sr{sup +} ion. High-contrast optical Ramsey spectra have been observed with fringe visibilities up to {approx}90%. The visibility decreased as the free precession period was increased, and was limited by the interrogation laser's coherence. The effect of varying the relative phase of the second Ramsey pulse was investigated. By measuring the difference in excitation probability on reversing a 90 deg. relative phase shift between the two Ramsey pulses, we have demonstrated Ramsey's anti-symmetric line shape in the optical domain. A significant advantage of this line shape is the zero crossing at line center and the independence of this center frequency on drifts in signal amplitude. This optical Ramsey line shape is suitable for stabilizing a local oscillator to an atomic reference transition in an optical frequency standard. All observed optical Ramsey signals are well described by a model using the optical Bloch equations.

  17. Carrier density independent scattering rate in SrTiO₃-based electron liquids

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

    Mikheev, Evgeny; Raghavan, Santosh; Zhang, Jack Y.; Marshall, Patrick B.; Kajdos, Adam P.; Balents, Leon; Stemmer, Susanne

    2016-02-10

    We examine the carrier density dependence of the scattering rate in two- and three-dimensional electron liquids in SrTiO3 in the regime where it scales with Tn (T is the temperature and n ≤ 2) in the cases when it is varied by electrostatic control and chemical doping, respectively. It is shown that the scattering rate is independent of the carrier density. This is contrary to the expectations from Landau Fermi liquid theory, where the scattering rate scales inversely with the Fermi energy (EF). We discuss that the behavior is very similar to systems traditionally identified as non-Fermi liquids (n

  18. Magnetism and Metal-Insulator Transition in Oxygen Deficient SrTiO3

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

    Lopez-Bezanilla, Alejandro; Ganesh, Panchapakesan; Littlewood, Peter B.

    2015-09-08

    First-principles calculations to study the electronic and magnetic properties of bulk, oxygen-deficient SrTiO3 (STO) under different doping conditions and densities have been conducted. The appearance of magnetism in oxygen-deficient STO is not determined solely by the presence of a single oxygen vacancy but by the density of free carriers and the relative proximity of the vacant sites. We find that while an isolated vacancy behaves as a nonmagnetic double donor, manipulation of the doping conditions allows the stability of a single-donor state, with emergent local moments coupled ferromagnetically by carriers in the conduction band. Strong local lattice distortions enhance themore » binding of this state. The energy of the in-gap local moment can be further tuned by orthorhombic strain. Consequently we find that the free-carrier density and strain are fundamental components to obtaining trapped spin-polarized electrons in oxygen-deficient STO, which may have important implications in the design of optical devices.« less

  19. Carrier density independent scattering rate in SrTiO3-based electron liquids

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

    Mikheev, Evgeny; Raghavan, Santosh; Zhang, Jack Y.; Marshall, Patrick B.; Kajdos, Adam P.; Balents, Leon; Stemmer, Susanne

    2016-02-10

    We examine the carrier density dependence of the scattering rate in two- and three-dimensional electron liquids in SrTiO3 in the regime where it scales with Tn (T is the temperature and n ≤ 2) in the cases when it is varied by electrostatic control and chemical doping, respectively. It is shown that the scattering rate is independent of the carrier density. This is contrary to the expectations from Landau Fermi liquid theory, where the scattering rate scales inversely with the Fermi energy (EF). We discuss that the behavior is very similar to systems traditionally identified as non-Fermi liquids (n

  20. Characterization and Application of Superlig 620 Solid Phase Extraction Resin for Automated Process Monitoring of 90Sr

    SciTech Connect (OSTI)

    Devol, Timothy A.; Clements, John P.; Farawila, Anne F.; O'Hara, Matthew J.; Egorov, Oleg; Grate, Jay W.

    2009-11-30

    Characterization of SuperLig 620 solid phase extraction resin was performed in order to develop an automated on-line process monitor for 90Sr. The main focus was on strontium separation from barium, with the goal of developing an automated separation process for 90Sr in high-level wastes. High-level waste contains significant 137Cs activity, of which 137mBa is of great concern as an interference to the quantification of strontium. In addition barium, yttrium and plutonium were studied as potential interferences to strontium uptake and detection. A number of complexants were studied in a series of batch Kd experiments, as SuperLig 620 was not previously known to elute strontium in typical mineral acids. The optimal separation was found using a 2M nitric acid load solution with a strontium elution step of ~0.49M ammonium citrate and a barium elution step of ~1.8M ammonium citrate. 90Sr quantification of Hanford high-level tank waste was performed on a sequential injection analysis microfluidics system coupled to a flow-cell detector. The results of the on-line procedure are compared to standard radiochemical techniques in this paper.

  1. Band alignment in visible-light photo-active CoO/SrTiO{sub 3} (001) heterostructures

    SciTech Connect (OSTI)

    Seo, Hosung; Demkov, Alexander A.

    2014-12-28

    Epitaxial oxide heterostructures are of fundamental interest in a number of problems ranging from oxide electronics to model catalysts. The epitaxial CoO/SrTiO{sub 3} (001) heterostructure on Si(001) has been recently studied as a model oxide catalyst for water splitting under visible light irradiation (Ngo et al., J. Appl. Phys. 114, 084901 (2013)). We use density functional theory to investigate the valence band offset at the CoO/SrTiO{sub 3} (001) interface. We examine the mechanism of charge transfer and dielectric screening at the interface and demonstrate that charge transfer is mediated by the metal-induced gap states in SrTiO{sub 3}, while the dielectric screening at the interface is largely governed by the ionic polarization of under-coordinated oxygen. Based on this finding, we argue that strain relaxation in CoO plays a critical role in determining the band offset. We find that the offsets of 1.361.10?eV, calculated in the Schottky-limit are in excellent agreement with the experimental value of 1.20?eV. In addition, we investigate the effect of the Hubbard correction, applied on the Co 3d states, on the dipole layer and potential shift at the interface.

  2. Interstaple Dithiol Cross-Linking in Au(25)(SR)(18) Nanomolecules: A Combined Mass Spectrometric and Computational Study

    SciTech Connect (OSTI)

    Jiang, Deen; Dass, Amala; Tschumper, Gregory; Mattern, Daniell; Van Dornshuld, Eric; Kota, Rajesh; Jupally, Vijay

    2011-01-01

    A systematic study of cross-linking chemistry of the Au{sub 25}(SR){sub 18} nanomolecule by dithiols of varying chain length, HS-(CH2)n-SH where n = 2, 3, 4, 5, and 6, is presented here. Monothiolated Au{sub 25} has six [RSAuSRAuSR] staple motifs on its surface, and MALDI mass spectrometry data of the ligand exchanged clusters show that propane (C3) and butane (C4) dithiols have ideal chain lengths for interstaple cross-linking and that up to six C3 or C4 dithiols can be facilely exchanged onto the cluster surface. Propanedithiol predominately exchanges with two monothiols at a time, making cross-linking bridges, while butanedithiol can exchange with either one or two monothiols at a time. The extent of cross-linking can be controlled by the Au{sub 25}(SR){sub 18} to dithiol ratio, the reaction time of ligand exchange, or the addition of a hydrophobic tail to the dithiol. MALDI MS suggests that during ethane (C2) dithiol exchange, two ethanedithiols become connected by a disulfide bond; this result is supported by density functional theory (DFT) prediction of the optimal chain length for the intrastaple coupling. Both optical absorption spectroscopy and DFT computations show that the electronic structure of the Au{sub 25} nanomolecule retains its main features after exchange of up to eight monothiol ligands.

  3. Inter-staple Dithiol Crosslinking in Au25(SR)18 Nanomolecules: A Combined Mass Spectrometric and Computational Study

    SciTech Connect (OSTI)

    Dass, Amala; Jiang, Deen; Jupally, Vijay; Kota, Rajesh; Mattern, Daniell; Tschumper, Gregory; Van Dornshuld, Eric

    2011-01-01

    A systematic study of cross-linking chemistry of the Au{sub 25}(SR){sub 18} nanomolecule by dithiols of varying chain length, HS-(CH{sub 2}){sub n}-SH where n = 2, 3, 4, 5, and 6, is presented here. Monothiolated Au{sub 25} has six [RSAuSRAuSR] staple motifs on its surface, and MALDI mass spectrometry data of the ligand exchanged clusters show that propane (C3) and butane (C4) dithiols have ideal chain lengths for interstaple cross-linking and that up to six C3 or C4 dithiols can be facilely exchanged onto the cluster surface. Propanedithiol predominately exchanges with two monothiols at a time, making cross-linking bridges, while butanedithiol can exchange with either one or two monothiols at a time. The extent of cross-linking can be controlled by the Au{sub 25}(SR){sub 18} to dithiol ratio, the reaction time of ligand exchange, or the addition of a hydrophobic tail to the dithiol. MALDI MS suggests that during ethane (C2) dithiol exchange, two ethanedithiols become connected by a disulfide bond; this result is supported by density functional theory (DFT) prediction of the optimal chain length for the intrastaple coupling. Both optical absorption spectroscopy and DFT computations show that the electronic structure of the Au{sub 25} nanomolecule retains its main features after exchange of up to eight monothiol ligands.

  4. Spin-orbit tuned metal-insulator transitions in single-crystal Sr?Ir1xRhxO? (0?x?1)

    SciTech Connect (OSTI)

    Qi, T. F.; Korneta, O. B.; Li, L.; Butrouna, K.; Cao, V. S.; Wan, Xiangang; Schlottmann, P.; Kaul, R. K.; Cao, G.

    2012-09-06

    Sr?IrO? is a magnetic insulator driven by spin-orbit interaction (SOI) whereas the isoelectronic and isostructural Sr?RhO? is a paramagnetic metal. The contrasting ground states have been shown to result from the critical role of the strong SOI in the iridate. Our investigation of structural, transport, magnetic, and thermal properties reveals that substituting 4d Rh?? (4d?) ions for 5d Ir?? (5d?) ions in Sr?IrO? directly reduces the SOI and rebalances the competing energies so profoundly that it generates a rich phase diagram for Sr?Ir1xRhxO? featuring two major effects: (1) Light Rh doping (0 ? x ? 0.16) prompts a simultaneous and precipitous drop in both the electrical resistivity and the magnetic ordering temperature TC, which is suppressed to zero at x = 0.16 from 240 K at x = 0. (2) However, with heavier Rh doping [0.24 < x < 0.85 (0.05)] disorder scattering leads to localized states and a return to an insulating state with spin frustration and exotic magnetic behavior that only disappears near x = 1. The intricacy of Sr?Ir1xRhxO? is further highlighted by comparison with Sr?Ir1xRuxO? where Ru?? (4d?) drives a direct crossover from the insulating to metallic states.

  5. Synthesis, Crystal and Electronic Structures of the Pnictides AE3TrPn3 (AE = Sr, Ba; Tr = Al, Ga; Pn = P, As)

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

    Stoyko, Stanislav; Voss, Leonard; He, Hua; Bobev, Svilen

    2015-09-24

    New ternary arsenides AE3TrAs3 (AE = Sr, Ba; Tr = Al, Ga) and their phosphide analogs Sr3GaP3 and Ba3AlP3 have been prepared by reactions of the respective elements at high temperatures. Single-crystal X-ray diffraction studies reveal that Sr3AlAs3 and Ba3AlAs3 adopt the Ba3AlSb3-type structure (Pearson symbol oC56, space group Cmce, Z = 8). This structure is also realized for Sr3GaP3 and Ba3AlP3. Likewise, the compounds Sr3GaAs3 and Ba3GaAs3 crystallize with the Ba3GaSb3-type structure (Pearson symbol oP56, space group Pnma, Z = 8). Both structures are made up of isolated pairs of edge-shared AlPn4 and GaPn4 tetrahedra (Pn = pnictogen, i.e.,more » P or As), separated by the alkaline-earth Sr2+ and Ba2+ cations. In both cases, there are no homoatomic bonds, hence, regardless of the slightly different atomic arrangements, both structures can be rationalized as valence-precise [AE2+]3[Tr3+][Pn3-]3, or rather [AE2+]6[Tr2Pn6]12-, i.e., as Zintl phases.« less

  6. WE-D-BRE-01: A Sr-90 Irradiation Device for the Study of Cutaneous Radiation Injury

    SciTech Connect (OSTI)

    Dorand, JE; Bourland, JD; Burnett, LR; Tytell, M

    2014-06-15

    Purpose: To determine dosimetric character for a custom-built Sr-90 beta irradiator designed for the study of Cutaneous Radiation Injury (CRI) in a porcine animal model. In the event of a radiological accident or terrorist event, Sr-90, a fission by-product, will likely be produced. CRI is a main concern due to the low energy and superficial penetration in tissue of beta particles from Sr-90. Seven 100 mCi plaque Sr-90 radiation sources within a custom-built irradiation device create a 40 mm diameter region of radiation-induced skin injury as part of a larger project to study the efficacy of a topical keratin-based product in CRI healing. Methods: A custom-built mobile irradiation device was designed and implemented for in vivo irradiations. Gafchromic EBT3 radiochromic film and a PTW Markus chamber type 23343 were utilized for dosimetric characterization of the beta fluence at the surface produced by this device. Films were used to assess 2-dimensional dose distribution and percent depth dose characteristics of the radiation field. Ion chamber measurements provided dose rate data within the field. Results: The radiation field produced by the irradiation device is homogeneous with high uniformity (?5%) and symmetry (?3%) with a steep dose fall-off with depth from the surface. Dose rates were determined to be 3.8 Gy/min and 3.3 Gy/min for film and ion chamber measurements, respectively. A dose rate of 3.4 Gy/min was used to calculate irradiation times for in vivo irradiations. Conclusion: The custom-built irradiation device enables the use of seven Sr-90 beta sources in an array to deliver a 40 mm diameter area of homogeneous skin dose with a dose rate that is useful for research purposes and clinically relevant for the induction of CRI. Doses of 36 and 42 Gy successfully produce Grade III CRI and are used in the study of the efficacy of KeraStat. This project has been funded in whole or in part with Federal funds from the Biomedical Advanced Research and Development Authority, Office of the Assistant Secretary for Preparedness and Response, Office of the Secretary, Department of Health and Human Services, under Contract No. HHSO100201200007C.

  7. Structural, electronic and magnetic properties of the series of double perovskites (Ca,Sr){sub 2?x}La{sub x}FeIrO{sub 6}

    SciTech Connect (OSTI)

    Bufaial, L.; Adriano, C.; Lora-Serrano, R.; Duque, J.G.S.; Mendona-Ferreira, L.; Rojas-Ayala, C.; Baggio-Saitovitch, E.; Bittar, E.M.; Pagliuso, P.G.

    2014-04-01

    Polycrystalline samples of the series of double perovskites Sr{sub 2?x}La{sub x}FeIrO{sub 6} were synthesized. Their structural, electronic and magnetic properties were investigated by X-ray powder diffraction, Mssbauer spectroscopy, magnetic susceptibility, heat capacity and electrical resistivity experiments. The compounds crystallize in a monoclinic structure and were fitted in space group P2{sub 1}/n, with a significant degree of Fe/Ir cationic disorder. As in Ca{sub 2?x}La{sub x}FeIrO{sub 6} the Sr-based system seems to evolve from an antiferromagnetic ground state for the end members (x=0.0 and x=2.0) to a ferrimagnetic order in the intermediate regions (x?1). Since Mssbauer spectra indicate that Fe valence remains 3+ with doping, this tendency of change in the nature of the microscopic interaction could be attributed to Ir valence changes, induced by La{sup 3+} electrical doping. Upon comparing both Ca and Sr series, Sr{sub 2?x}La{sub x}FeIrO{sub 6} is more structurally homogenous and presents higher magnetization and transition temperatures. Magnetic susceptibility measurements at high temperatures on Sr{sub 1.2}La{sub 0.8}FeIrO{sub 6} indicate a very high ferrimagnetic Curie temperature T{sub C}?700K. For the Sr{sub 2}FeIrO{sub 6} compound, electrical resistivity experiments under applied pressure suggest that this material might be a Mott insulator. - Graphical abstract: The Weiss constant as a function of La doping for the (Ca,Sr){sub 2?x}La{sub x}FeIrO{sub 6} series, indicating changes in FeIr magnetic coupling on both families. - Highlights: The double perovskite series (Ca,Sr){sub 2?x}La{sub x}FeIrO{sub 6} were synthesized. Changes in the Fe-Ir magnetic coupling due to La doping on both series. Evidence of high T{sub C} on Sr{sub 1.2}La{sub 0.8}FeIrO{sub 6}. Indication of Mott insulator behavior on Sr{sub 2}FeIrO{sub 6}.

  8. Crystal structure and magnetic properties and Zn substitution effects on the spin-chain compound Sr{sub 3}Co{sub 2}O{sub 6}

    SciTech Connect (OSTI)

    Wang, Xia [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba Ibaraki 305-0044 (Japan); Department of Chemistry, Graduate School of Science, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); Guo, Yanfeng, E-mail: Yangfeng.Guo@physics.ox.ac.uk [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba Ibaraki 305-0044 (Japan); Sun, Ying [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba Ibaraki 305-0044 (Japan); Tsujimoto, Yoshihiro [Materials Processing Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba Ibaraki 305-0047 (Japan); Matsushita, Yoshitaka [Materials Analysis Station, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba Ibaraki 305-0047 (Japan); Yamaura, Kazunari, E-mail: yamaura.kazunari@nims.go.jp [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba Ibaraki 305-0044 (Japan); Department of Chemistry, Graduate School of Science, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan)

    2013-08-15

    The effects of substituting Co on the spin-chain compound Sr{sub 3}Co{sub 2}O{sub 6} with Zn were investigated by synchrotron X-ray diffraction, magnetic susceptibility, isothermal magnetization, and specific heat measurements. To the best of our knowledge, this is the first report to describe the successful substitution of Co in Sr{sub 3}Co{sub 2}O{sub 6} with Zn. The substitution was carried out by a method involving high pressures and temperatures to obtain Sr{sub 3}CoZnO{sub 6}, which crystalized into a K{sub 4}CdCl{sub 6}-derived rhombohedral structure with a space group of R-3c, similar to the host compound. With the Zn substitution, the Ising-type magnetic anisotropy of the host compound remarkably reduced; the newly formed Sr{sub 3}CoZnO{sub 6} became magnetically isotropic with Heisenberg-type characteristics. This could probably be ascribed to the establishment of a different interaction pathway, Co{sup 4+}(S=1/2)OZn{sup 2+}(S=0)OCo{sup 4+}(S=1/2). Details of the magnetic properties of Zn substituted Sr{sub 3}Co{sub 2}O{sub 6} were reported. - Graphical abstract: Crystal structure of the spin-chain compound Sr{sub 3}CoZnO{sub 6} synthesized at 6 GPa. Zn atoms preferably occupy the trigonal prism sites rather than the octahedral sites. As a result, the compound is much magnetically isotropic. Highlights: Effects of substituting Co with Zn on spin-chain magnetism of Sr{sub 3}Co{sub 2}O{sub 6} were studied. High-pressure synthesis resulted in a solid solution of Sr{sub 3}CoZnO{sub 6}. Sr{sub 3}CoZnO{sub 6} showed more isotropic magnetism than the host Sr{sub 3}Co{sub 2}O{sub 6}.

  9. Overall Photocatalytic Water Splitting with NiOx-SrTiO3 A Revised Mechanism

    SciTech Connect (OSTI)

    Townsend, Troy K.; Browning, Nigel D.; Osterloh, Frank

    2012-11-01

    NiOx (0 < x < 1) modified SrTiO3 (STO) is one of the best studied photocatalyst for overall water splitting under UV light. The established mechanism for this and many other NiOx containing catalysts assumes water oxidation to occur at the early transition metal oxide and water reduction at NiOx. Here we show that NiOx-STO is more likely a three component Ni-STO-NiO catalyst, in which STO absorbs the light, Ni reduces protons, and NiO oxidizes water. This interpretation is based on systematic H2/O2 evolution tests of appropriately varied catalyst compositions using oxidized, chemically and photochemically added nickel and NiO nanoparticle cocatalysts. Surface photovoltage (SPV) measurements reveal that Ni(0) serves as an electron trap (site for water reduction) and that NiO serves as a hole trap (site for water oxidation). Electrochemical measurements show that the overpotential for water oxidation correlates with NiO content, whereas the water reduction overpotential depends on Ni content. Photodeposition experiments with NiCl2 and H2PtCl6 on NiO-STO show that electrons are available on the STO surface, not on the NiO particles. Based on photoelectrochemistry, both NiO and Ni particles suppress the Fermi level in STO, but the effect of this shift on catalytic activity is not clear. Overall, the results suggest a revised role for NiO in NiOx-STO and in many other nickel-containing water splitting systems, including NiOx-La:KTaO3, and many layered perovskites.

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

    SciTech Connect (OSTI)

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

    2013-01-01

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

  11. High temperature-induced phase transitions in Sr{sub 2}GdRuO{sub 6} complex perovskite

    SciTech Connect (OSTI)

    Triana, C.A.; Corredor, L.T.; Landinez Tellez, D.A.; Roa-Rojas, J.

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Crystal structure, thermal expansion and phase transitions at high-temperature of Sr{sub 2}GdRuO{sub 6} perovskite has been investigated. Black-Right-Pointing-Pointer X-ray diffraction pattern at 298 K of Sr{sub 2}GdRuO{sub 6} corresponds to monoclinic perovskite-type structure with P2{sub 1}/n space group. Black-Right-Pointing-Pointer Evolution of X-ray diffraction patterns at high-temperature shows that the Sr{sub 2}GdRuO{sub 6} perovskite suffers two-phase transitions. Black-Right-Pointing-Pointer At 573 K the X-ray diffraction pattern of Sr{sub 2}GdRuO{sub 6} corresponds to monoclinic perovskite-type structure with I2/m space group. Black-Right-Pointing-Pointer At 1273 K the Sr{sub 2}GdRuO{sub 6} perovskite suffers a complete phase-transition from monoclinic I2/m (no. 12) to tetragonal I4/m (no. 87). -- Abstract: The crystal structure behavior of the Sr{sub 2}GdRuO{sub 6} complex perovskite at high-temperature has been investigated over a wide temperature range between 298 K {<=} T {<=} 1273 K. Measurements of X-ray diffraction at room-temperature and Rietveld analysis of the experimental patterns show that this compound crystallizes in a monoclinic perovskite-like structure, which belongs to the P2{sub 1}/n (no. 14) space group and 1:1 ordered arrangement of Ru{sup 5+} and Gd{sup 3+} cations over the six-coordinate M sites. Experimental lattice parameters were obtained to be a =5.8103(5) Angstrom-Sign , b =5.8234(1) Angstrom-Sign , c =8.2193(9) Angstrom-Sign , V = 278.11(2) Angstrom-Sign {sup 3} and angle {beta} = 90.310(5) Degree-Sign . The high-temperature analysis shows the occurrence of two-phase transitions on this material. First, at 573 K it adopts a monoclinic perovskite-type structure with I2/m (no. 12) space group with lattice parameters a = 5.8275(6) Angstrom-Sign , b = 5.8326(3) Angstrom-Sign , c = 8.2449(2) Angstrom-Sign , V = 280.31(3) Angstrom-Sign {sup 3} and angle {beta} = 90.251(3) Degree-Sign . Close to 1273 K it undergoes a complete phase-transition from monoclinic I2/m (no. 12) to tetragonal I4/m (no. 87), with lattice parameters a = 5.8726(1) Angstrom-Sign , c = 8.3051(4) Angstrom-Sign , V = 286.39(8) Angstrom-Sign {sup 3} and angle {beta} = 90.0 Degree-Sign . The high-temperature phase transition from monoclinic I2/m (no. 12) to tetragonal I4/m (no. 87) is characterized by strongly anisotropic displacements of the anions.

  12. (Sr,Ba)(Si,Ge){sub 2} for thin-film solar-cell applications: First-principles study

    SciTech Connect (OSTI)

    Kumar, Mukesh E-mail: mkgarg79@gmail.com; Umezawa, Naoto; Imai, Motoharu

    2014-05-28

    In order to meet the increasing demand for electric power generation from solar energy conversion, the development of efficient light absorber materials has been awaited. To this end, the electronic and optical properties of advanced alkaline-earth-metals disilicides and digermanides (SrSi{sub 2}, BaSi{sub 2}, SrGe{sub 2}, and BaGe{sub 2}) are studied by means of the density functional theory using HSE06 exchange-correlation energy functional. Our calculations show that all these orthorhombic structured compounds have fundamental indirect band gaps in the range E{sub g} ? 0.891.25 eV, which is suitable for solar cell applications. The estimated lattice parameters and band gaps are in good agreement with experiments. Our calculations show that the electronic band structures of all four compounds are very similar except in the vicinity of the ?-point. The valence band of these compounds is made up by Si(Ge)-p states, whereas the conduction band is composed of Sr(Ba)-d states. Their band alignments are carefully determined by estimating the work function of each compound using slab model. The optical properties are discussed in terms of the complex dielectric function ?(?)?=??{sub 1}(?)?+?i?{sub 2}(?). The static and high-frequency dielectric constants are calculated, taking into account the ionic contribution. The absorption coefficient ?(?) demonstrates that a low energy dispersion of the conduction band, which results in a flat conduction band minimum, leads to large optical activity in these compounds. Therefore, alkaline-earth-metals disilicides and digermanides possess great potential as light absorbers for applications in thin-film solar cell technologies.

  13. Comparative Gamma Spectroscopy with SrI2(Eu), GYGAG(Ce) and Bi-loaded Plastic Scintillators

    SciTech Connect (OSTI)

    Cherepy, N J

    2010-11-19

    We are developing new scintillator materials that offer potential for high resolution gamma ray spectroscopy at low cost. Single crystal SrI{sub 2}(Eu) offers {approx}3% resolution at 662 keV, in sizes of {approx}1 in{sup 3}. We have developed ceramics processing technology allowing us to achieve cubic inch scale transparent ceramic scintillators offering gamma spectroscopy performance superior to NaI(Tl). We fabricated a bismuth-loaded plastic scintillator that demonstrates energy resolution of {approx}8% at 662 keV in small sizes. Gamma ray spectroscopy can be used to identify the presence of weak radioactive sources within natural background. The ability to discriminate close-lying spectral lines is strongly dependent upon the energy resolution of the detector. In addition to excellent energy resolution, large volume detectors are needed to acquire sufficient events, for example, to identify a radioactive anomaly moving past a detector. We have employed a 'directed search' methodology for identifying potential scintillator materials candidates, resulting in the discovery of Europium-doped Strontium Iodide, SrI{sub 2}(Eu), Cerium-doped Gadolinium Garnet, GYGAG(Ce), and Bismuth-loaded Polymers. These scintillators possess very low self-radioactivity, offer energy resolution of 3-8% at 662 keV, and have potential to be grown cost-effectively to sizes similar to the most widely deployed gamma spectroscopy scintillator, Thallium-doped Sodium Iodide, NaI(Tl). In this study, gamma ray spectra of a variety of sources, were obtained employing SrI{sub 2}(Eu), GYGAG(Ce), Bi-loaded polymers, LaBr{sub 3}(Ce), and NaI(Tl). The effects of detector size, energy resolution, and background radioactivity (including self-radioactivity) on the ability to distinguish weak sources is quantified, based on a simple model, and qualitatively compared to laboratory data.

  14. Manipulation of subsurface carbon nanoparticles in Bi?Sr?CaCu?O8+? using a scanning tunneling microscope

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

    Stollenwerk, A. J.; Gu, G.; Hurley, N.; Beck, B.; Spurgeon, K.; Kidd, T. E.

    2015-03-01

    We present evidence that subsurface carbon nanoparticles in Bi?Sr?CaCu?O8+? can be manipulated with nanometer precision using a scanning tunneling microscope. High resolution images indicate that most of the carbon particles remain subsurface after transport observable as a local increase in height as the particle pushes up on the surface. Tunneling spectra in the vicinity of these protrusions exhibit semiconducting characteristics with a band gap of approximately 1.8 eV, indicating that the incorporation of carbon locally alters the electronic properties near the surface.

  15. High-Tc superconductivity at the interface between the CaCuO2 and SrTiO3 insulating oxides

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

    Di Castro, D.; Cantoni, C.; Ridolfi, F.; Aruta, C.; Tebano, A.; Yang, N.; Balestrino, G.

    2015-09-28

    At interfaces between complex oxides it is possible to generate electronic systems with unusual electronic properties, which are not present in the isolated oxides. One important example is the appearance of superconductivity at the interface between insulating oxides, although, until now, with very low Tc. We report the occurrence of high Tc superconductivity in the bilayer CaCuO2/SrTiO3, where both the constituent oxides are insulating. In order to obtain a superconducting state, the CaCuO2/SrTiO3 interface must be realized between the Ca plane of CaCuO2 and the TiO2 plane of SrTiO3. Only in this case can oxygen ions be incorporated in themore » interface Ca plane, acting as apical oxygen for Cu and providing holes to the CuO2 planes. In addition, a detailed hole doping spatial profile can be obtained by scanning transmission electron microscopy and electron-energy-loss spectroscopy at the O K edge, clearly showing that the (super)conductivity is confined to about 1–2 CaCuO2 unit cells close to the interface with SrTiO3. The results obtained for the CaCuO2/SrTiO3 interface can be extended to multilayered high Tc cuprates, contributing to explaining the dependence of Tc on the number of CuO2 planes in these systems.« less

  16. A first-principles study of Pt thin films on SrTiO{sub 3}(100): Support effects on CO adsorption

    SciTech Connect (OSTI)

    Yuk, Simuck F.; Asthagiri, Aravind

    2015-03-28

    Density functional theory was used to study CO adsorption on thin Pt metal films supported on SrO- and TiO{sub 2}-terminated SrTiO{sub 3}(100) surfaces. Regardless of substrate-termination, significant enhancement in CO binding occurred on the Pt monolayer compared to the bulk Pt(100) surface. We also observed CO-coverage dependent shifting of Pt atoms, influenced by the nature of underlying oxide atoms. These oxide-induced effects become negligible after depositing more than 2 monolayers of Pt. Evaluating the electronic structures of oxide-supported Pt showed that the interaction of filled Pt d{sub xz+yz} and empty Pt d{sub z{sup 2}} states with CO molecular orbitals can be directly related to CO adsorption on the Pt/SrTiO{sub 3}(100) surface. A hybrid d-band model is able to capture the CO adsorption trends for systems that do not show large lateral distortion except for the case of Pt adsorbed above the Sr atom on the SrO-termination. For this case, charge transfer from adjacent Pt atoms leads to a large filled d{sub z{sup 2}} peak below the Fermi level that weakens the Pt–CO σ bonding due to Pauli repulsion.

  17. Interfacial mode coupling as the origin of the enhancement of Tc in FeSe films on SrTiO3

    SciTech Connect (OSTI)

    Lee, J. J.; Schmitt, F. T.; Moore, R. G.; Johnston, S.; Cui, Y. -T.; Li, W.; Yi, M.; Liu, Z. K.; Hashimoto, M.; Zhang, Y.; Lu, D. H.; Devereaux, T. P.; Lee, D. -H.; Shen, Z. -X.; /SIMES, Stanford /SLAC /Stanford U., Geballe Lab.

    2014-11-12

    Films of iron selenide (FeSe) one unit cell thick grown on strontium titanate (SrTiO3 or STO) substrates have recently shown superconducting energy gaps opening at temperatures close to the boiling point of liquid nitrogen (77 K), which is a record for the iron-based superconductors. The gap opening temperature usually sets the superconducting transition temperature Tc, as the gap signals the formation of Cooper pairs, the bound electron states responsible for superconductivity. To understand why Cooper pairs form at such high temperatures, we examine the role of the SrTiO3 substrate. Here we report high-resolution angle-resolved photoemission spectroscopy results that reveal an unexpected characteristic of the single-unit-cell FeSe/SrTiO3 system: shake-off bands suggesting the presence of bosonic modes, most probably oxygen optical phonons in SrTiO3, which couple to the FeSe electrons with only a small momentum transfer. Such interfacial coupling assists superconductivity in most channels, including those mediated by spin fluctuations. Our calculations suggest that this coupling is responsible for raising the superconducting gap opening temperature in single-unit-cell FeSe/SrTiO3.

  18. First principle calculations of effective exchange integrals: Comparison between SR (BS) and MR computational results

    SciTech Connect (OSTI)

    Yamaguchi, Kizashi; Nishihara, Satomichi; Saito, Toru; Yamanaka, Shusuke; Kitagawa, Yasutaka; Kawakami, Takashi; Yamada, Satoru; Isobe, Hiroshi; Okumura, Mitsutaka

    2015-01-22

    First principle calculations of effective exchange integrals (J) in the Heisenberg model for diradical species were performed by both symmetry-adapted (SA) multi-reference (MR) and broken-symmetry (BS) single reference (SR) methods. Mukherjee-type (Mk) state specific (SS) MR coupled-cluster (CC) calculations by the use of natural orbital (NO) references of ROHF, UHF, UDFT and CASSCF solutions were carried out to elucidate J values for di- and poly-radical species. Spin-unrestricted Hartree Fock (UHF) based coupled-cluster (CC) computations were also performed to these species. Comparison between UHF-NO(UNO)-MkMRCC and BS UHF-CC computational results indicated that spin-contamination of UHF-CC solutions still remains at the SD level. In order to eliminate the spin contamination, approximate spin-projection (AP) scheme was applied for UCC, and the AP procedure indeed corrected the error to yield good agreement with MkMRCC in energy. The CC double with spin-unrestricted Brueckner's orbital (UBD) was furthermore employed for these species, showing that spin-contamination involved in UHF solutions is largely suppressed, and therefore AP scheme for UBCCD removed easily the rest of spin-contamination. We also performed spin-unrestricted pure- and hybrid-density functional theory (UDFT) calculations of diradical and polyradical species. Three different computational schemes for total spin angular momentums were examined for the AP correction of the hybrid (H) UDFT. HUDFT calculations followed by AP, HUDFT(AP), yielded the S-T gaps that were qualitatively in good agreement with those of MkMRCCSD, UHF-CC(AP) and UB-CC(AP). Thus a systematic comparison among MkMRCCSD, UCC(AP) UBD(AP) and UDFT(AP) was performed concerning with the first principle calculations of J values in di- and poly-radical species. It was found that BS (AP) methods reproduce MkMRCCSD results, indicating their applicability to large exchange coupled systems.

  19. Band alignment of epitaxial SrTiO3 thin films with (LaAlO3)0.3-(Sr2AlTaO6)0.7 (001)

    SciTech Connect (OSTI)

    Comes, Ryan B.; Xu, Peng; Jalan, Bharat; Chambers, Scott A.

    2015-09-28

    SrTiO3 (STO) epitaxial thin films and heterostructures are of considerable interest due to the wide range of functionalities they exhibit. The alloy perovskite (LaAlO3)0.3-(Sr2AlTaO6)0.7 (LSAT) is commonly used as a substrate for these material structures due to its structural compatibility. However, surprisingly little is known about the electronic properties of the STO/LSAT interface despite its potentially important role in affecting the overall electronic structure of system. We examine the band alignment of STO/LSAT heterostructures using x-ray photoelectron spectroscopy for epitaxial STO films deposited using two different molecular beam epitaxy approaches. We find that the valence band offset ranges from +0.2(1) eV to -0.2(1) eV depending on surface conditions for the film and substrate. From these results we extract a conduction band offset from -2.4(1) eV to -2.8(1) eV, indicating that the conduction band edge is more deeply bound in STO and that LSAT will not act as a sink or trap for electrons in the supported film or multilayer.

  20. Resistive switching in ultra-thin La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrRuO{sub 3} superlattices

    SciTech Connect (OSTI)

    Jammalamadaka, S. Narayana; Vanacken, Johan; Moshchalkov, V. V.

    2014-07-21

    Superlattices may play an important role in next generation electronic and spintronic devices if the key-challenge of the reading and writing data can be solved. This challenge emerges from the coupling of low dimensional individual layers with macroscopic world. Here, we report the study of the resistive switching characteristics of a hybrid structure made out of a superlattice with ultrathin layers of two ferromagnetic metallic oxides, La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) and SrRuO{sub 3} (SRO). Bipolar resistive switching memory effects are measured on these LSMO/SRO superlattices, and the observed switching is explainable by ohmic and space charge-limited conduction laws. It is evident from the endurance characteristics that the on/off memory window of the cell is greater than 14, which indicates that this cell can reliably distinguish the stored information between high and low resistance states. The findings may pave a way to the construction of devices based on nonvolatile resistive memory effects.

  1. Octonary resistance states in La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 multiferroic tunnel junctions

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

    Yue -Wei Yin; Tao, Jing; Huang, Wei -Chuan; Liu, Yu -Kuai; Yang, Sheng -Wei; Dong, Si -Ning; Zhu, Yi -Mei; Li, Qi; Li, Xiao -Guang

    2015-10-06

    General drawbacks of current electronic/spintronic devices are high power consumption and low density storage. A multiferroic tunnel junction (MFTJ), employing a ferroelectric barrier layer sandwiched between two ferromagnetic layers, presents four resistance states in a single device and therefore provides an alternative way to achieve high density memories. Here, an MFTJ device with eight nonvolatile resistance states by further integrating the design of noncollinear magnetization alignments between the ferromagnetic layers is demonstrated. Through the angle-resolved tunneling magnetoresistance investigations on La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 junctions, it is found that, besides collinear parallel/antiparallel magnetic configurations, the MFTJ shows at least two other stable noncollinear (45°more » and 90°) magnetic configurations. As a result, combining the tunneling electroresistance effect caused by the ferroelectricity reversal of the BaTiO3 barrier, an octonary memory device is obtained, representing potential applications in high density nonvolatile storage in the future.« less

  2. Interfacial charge-mediated non-volatile magnetoelectric coupling in Co0.3Fe0.7/Ba0.6Sr0.4TiO3/Nb:SrTiO3 multiferroic heterostructures

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

    Zhou, Ziyao; Howe, Brandon M.; Liu, Ming; Nan, Tianxiang; Chen, Xing; Mahalingam, Krishnamurthy; Sun, Nian X.; Brown, Gail J.

    2015-01-13

    The central challenge in realizing non-volatile, E-field manipulation of magnetism lies in finding an energy efficient means to switch between the distinct magnetic states in a stable and reversible manner. In this work, we demonstrate using electrical polarization-induced charge screening to change the ground state of magnetic ordering in order to non-volatilely tune magnetic properties in ultra-thin Co0.3Fe0.7/Ba0.6Sr0.4TiO3/Nb:SrTiO3 (001) multiferroic heterostructures. A robust, voltage-induced, non-volatile manipulation of out-of-plane magnetic anisotropy up to 40 Oe is demonstrated and confirmed by ferromagnetic resonance measurements. This discovery provides a framework for realizing charge-sensitive order parameter tuning in ultra-thin multiferroic heterostructures, demonstrating great potentialmore » for delivering compact, lightweight, reconfigurable, and energy-efficient electronic devices.« less

  3. Soil concentration, vertical distribution and inventory of plutonium, [sup 241]Am, [sup 90]Sr and [sup 137]Cs in the Marche Region of Central Italy

    SciTech Connect (OSTI)

    Jia, G.; Testa, C.; Desideri, D.; Guerra, F.; Meli, M.A.; Roselli, C. . Inst. of General Chemistry); Belli, M.E. )

    1999-07-01

    Soil concentrations of [sup 239+240]Pu, [sup 238]Pu, [sup 241]Am, [sup 90]Sr, and [sup 137]Cs are investigated in the Marche Region of Central Italy. Mean values in uncultivated soils are 3.5--8 times higher than the corresponding values in cultivated soils. Radionuclide inventories and ratios are consistent with values reported by the United nations Scientific Committee on the Effect of Atomic Radiation for this latitude. This suggests that radiocontamination in this region is mainly due to atmospheric deposition of nuclear weapon test fallout. The vertical distribution of these radionuclides is also studied. The results show that, with the exception of [sup 90]Sr, more than 90% of these radionuclides are contained in the first 20 cm of soil and that mobility follows the order [sup 90]Sr > [sup 241]Am > [sup 239+240]Pu, [sup 238]Pu > [sup 137]Cs.

  4. Epitaxial growth, structure, and intermixing at the LaAlO{sub 3}/SrTiO{sub 3} interface as the film stoichiometry is varied

    SciTech Connect (OSTI)

    Qiao, L.; Droubay, T. C.; Kaspar, T. C.; Chambers, S. A.; Varga, T.; Bowden, M. E.; Shutthanandan, V.; Zhu, Z.

    2011-02-15

    LaAlO{sub 3} epitaxial films with La:Al cation ratios ranging from 0.9 to 1.2 were grown on TiO{sub 2}-terminated SrTiO{sub 3} (001) substrates by off-axis pulsed laser deposition. Although all films are epitaxial, rocking curve measurements show that the crystallographic quality degrades with increasing La:Al ratio. Films with La:Al ratios of 0.9, 1.0, and 1.1 were coherently strained to the substrate. However, the out-of-plane lattice parameter increases over this range, revealing a decrease in film tetragonality. Although all film surfaces exhibit hydroxylation, the extent of hydroxylation is greater for the La-rich films. Rutherford backscattering spectrometry reveals that La from the film diffuses deeply into the SrTiO{sub 3} substrate and secondary-ion-mass spectroscopy shows unambiguous Sr outdiffusion into the films.

  5. Giant Magneto-Resistance in Epitaxial (La0.7Sr0.3MnO3)0.5: (ZnO)0.5

    Office of Scientific and Technical Information (OSTI)

    Nanocomposites (Technical Report) | SciTech Connect Technical Report: Giant Magneto-Resistance in Epitaxial (La0.7Sr0.3MnO3)0.5: (ZnO)0.5 Nanocomposites Citation Details In-Document Search Title: Giant Magneto-Resistance in Epitaxial (La0.7Sr0.3MnO3)0.5: (ZnO)0.5 Nanocomposites A great deal of research has been carried out in oxide material systems. Among them, ZnO and La0.7Sr0.3MnO3 (LSMO) are of particular interest due to their superb optical properties and colossal magneto-resistive

  6. Structural Comparison of n-type and p-type LaAlO3/SrTiO3 Interfaces

    SciTech Connect (OSTI)

    Bell, Christopher

    2011-08-19

    Using a surface x-ray diffraction technique, we investigated the atomic structure of two types of interfaces between LaAlO{sub 3} and SrTiO{sub 3}, that is, p-type (SrO/AlO{sub 2}) and n-type (TiO{sub 2}/LaO) interfaces. Our results demonstrate that the SrTiO{sub 3} in the sample with the n-type interface has a large polarized region, while that with the p-type interface has a limited polarized region. In addition, the atomic intermixing was observed to extend deeper into STO substrate at the n-type interface than at the p-type. These differences result in different degrees of band bending, which likely contributes to the striking difference in electrical conductivity between the two types of interfaces.

  7. Hysteretic electrical transport in BaTiO{sub 3}/Ba{sub 1?x}Sr{sub x}TiO{sub 3}/Ge heterostructures

    SciTech Connect (OSTI)

    Ngai, J. H.; Kumah, D. P.; Walker, F. J.; Ahn, C. H.

    2014-02-10

    We present electrical transport measurements of heterostructures comprised of BaTiO{sub 3} and Ba{sub 1?x}Sr{sub x}TiO{sub 3} epitaxially grown on Ge. Sr alloying imparts compressive strain to the BaTiO{sub 3}, which enables the thermal expansion mismatch between BaTiO{sub 3} and Ge to be overcome to achieve c-axis oriented growth. The conduction bands of BaTiO{sub 3} and Ba{sub 1?x}Sr{sub x}TiO{sub 3} are nearly aligned with the conduction band of Ge, which facilitates electron transport. Electrical transport measurements through the dielectric stack exhibit rectifying behavior and hysteresis, where the latter is consistent with ferroelectric switching.

  8. Epitaxial YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}/Sr{sub 2}RuO{sub 4} heterostructures

    SciTech Connect (OSTI)

    Schlom, D.G.; Merritt, B.A.; Madhavan, S. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering] [and others

    1997-09-01

    The anisotropic oxide superconductors YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} and Sr{sub 2}RuO{sub 4} have been epitaxially combined in various ways (c-axis on c-axis, c-axis on a-axis, and a-axis on a-axis) though the use of appropriate substrates. Phase-pure a-axis oriented or c-axis oriented epitaxial Sr{sub 2}RuO{sub 4} films were grown by pulsed laser deposition. YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} films were then grown on both orientations of Sr{sub 2}RuO{sub 4} films and the resulting epitaxy was characterized.

  9. Polarization-dependent infrared reflectivity study of Sr???Ca????Cu??O?? under pressure: Charge dynamics, charge distribution, and anisotropy

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

    Frank, S.; Huecker, M.; Huber, A.; Ammerahl, U.; Kuntscher, C. A.

    2014-12-18

    We present a polarization-dependent infrared reflectivity study of the spin-ladder compound Sr???Ca????Cu??O?? under pressure. The optical response is strongly anisotropic, with the highest reflectivity along the ladders/chains (E?c) revealing a metallic character. For the polarization direction perpendicular to the ladder plane, an insulating behavior is observed. With increasing pressure the optical conductivity for E?c shows a strong increase, which is most pronounced below 2000cm?. According to the spectral weight analysis of the E?c optical conductivity the hole concentration in the ladders increases with increasing pressure and tends to saturate at high pressure. At ~7.5 GPa the number of holes permoreCu atom in the ladders has increased by ??=0.09(0.01), and the Cu valence in the ladders has reached the value +2.33. The optical data suggest that Sr???Ca????Cu??O?? remains electronically highly anisotropic up to high pressure, also at low temperatures.less

  10. Polarization-dependent infrared reflectivity study of Sr???Ca????Cu??O?? under pressure: Charge dynamics, charge distribution, and anisotropy

    SciTech Connect (OSTI)

    Frank, S.; Huecker, M.; Huber, A.; Ammerahl, U.; Kuntscher, C. A.

    2014-12-18

    We present a polarization-dependent infrared reflectivity study of the spin-ladder compound Sr???Ca????Cu??O?? under pressure. The optical response is strongly anisotropic, with the highest reflectivity along the ladders/chains (E?c) revealing a metallic character. For the polarization direction perpendicular to the ladder plane, an insulating behavior is observed. With increasing pressure the optical conductivity for E?c shows a strong increase, which is most pronounced below 2000cm?. According to the spectral weight analysis of the E?c optical conductivity the hole concentration in the ladders increases with increasing pressure and tends to saturate at high pressure. At ~7.5 GPa the number of holes per Cu atom in the ladders has increased by ??=0.09(0.01), and the Cu valence in the ladders has reached the value +2.33. The optical data suggest that Sr???Ca????Cu??O?? remains electronically highly anisotropic up to high pressure, also at low temperatures.

  11. Tunable bilayer two-dimensional electron gas in LaAlO{sub 3}/SrTiO{sub 3} superlattices

    SciTech Connect (OSTI)

    Ma, H. J. Harsan E-mail: phyarian@nus.edu.sg; Annadi, A.; Zeng, S. W.; Ariando E-mail: phyarian@nus.edu.sg; Huang, Z.; L, W. M.; Wong, L. M.; Wang, S. J.; Venkatesan, T.

    2014-07-07

    We report magnetotransport properties of double heterointerfaces in LaAlO{sub 3}/SrTiO{sub 3}/LaAlO{sub 3}/SrTiO{sub 3}(001) (LAO/STO/LAO/STO). A strong nonlinearity in the Hall resistivity is found when the temperature is below 80?K. This effect is attributed to multichannel conduction of interfacial charges generated in double heterostructures of LAO/STO where two-dimensional electron gas (2DEG) is produced. The multichannel conduction is confirmed by back gating modulation of Hall effect. Our result suggests the possibility to achieve coupled bilayer 2DEG layers in LAO/STO superlattices.

  12. Electric field effects on spin accumulation in Nb-doped SrTiO{sub 3} using tunable spin injection contacts at room temperature

    SciTech Connect (OSTI)

    Kamerbeek, A. M.; Vries, E. K. de; Wees, B. J. van; Banerjee, T.; Dankert, A.; Dash, S. P.

    2014-05-26

    We report on features in charge transport and spin injection in an oxide semiconductor, Nb-doped SrTiO{sub 3}. This is demonstrated using electrically tunable spin injection contacts which exploit the large electric field at the interface and its interplay with the relative permittivity of the semiconductor. We realize spin accumulation in Nb-doped SrTiO{sub 3} which displays a unique dependence of the spin lifetime with bias polarity. These findings suggest a strong influence of the interface electric field on the charge transport as well as on spin accumulation unlike in conventional semiconductors and opens up promising avenues in oxide spintronics.

  13. Strain-relaxation and critical thickness of epitaxial La1.85Sr0.15CuO4 films

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

    Meyer, Tricia L; Jiang, Lu; Park, Sungkyun; Egami, Takeshi; Lee, Ho Nyung

    2015-12-08

    We report the thickness-dependent strain-relaxation behavior and the associated impacts upon the superconductivity in epitaxial La1.85Sr0.15CuO4 films grown on different substrates, which provide a range of strain. We have found that the critical thickness for the onset of superconductivity in La1.85Sr0.15CuO4 films is associated with the finite thickness effect and epitaxial strain. In particular, thin films with tensile strain greater than ~0.25% revealed no superconductivity. We attribute this phenomenon to the inherent formation of oxygen vacancies that can be minimized via strain relaxation.

  14. Superconducting and magnetic properties of Sr3Ir4Sn13

    SciTech Connect (OSTI)

    Biswas, P. K.; Amato, A.; Khasanov, R.; Luetkens, H.; Wang, Kefeng; Petrovic, C.; Cook, R. M.; Lees, M. R.; Morenzoni, E.

    2014-10-10

    In this research, magnetization and muon spin relaxation or rotation (SR) measurements have been performed to study the superconducting and magnetic properties of Sr?Ir?Sn??. From magnetization measurements the lower and upper critical fields of Sr?Ir?Sn?? are found to be 81(1) Oe and 14.4(2) kOe, respectively. Zero-field SR data show no sign of any magnetic ordering or weak magnetism in Sr?Ir?Sn??. Transverse-field SR measurements in the vortex state provided the temperature dependence of the magnetic penetration depth ?. The dependence of ?? with temperature is consistent with the existence of single s-wave energy gap in the superconducting state of Sr?Ir?Sn?? with a gap value of 0.82(2) meV at absolute zero temperature. The magnetic penetration depth at zero temperature ?(0) is 291(3) nm. The ratio ?(0)/kBTc = 2.1(1) indicates that Sr?Ir?Sn?? should be considered as a strong-coupling superconductor.

  15. Coexistence of antiferromagnetic and ferromagnetic spin correlations in SrCo2As2 revealed by 59Co and 75As NMR

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

    Wiecki, P.; Ogloblichev, V.; Pandey, Abhishek; Johnston, D. C.; Furukawa, Y.

    2015-06-15

    In nonsuperconducting, metallic paramagnetic SrCo2As2, inelastic neutron scattering measurements have revealed strong stripe-type q=(π,0) antiferromagnetic (AFM) spin correlations. Using nuclear magnetic resonance (NMR) measurements on 59Co and 75As nuclei, we demonstrate that stronger ferromagnetic (FM) spin correlations coexist in SrCo2As2. Our NMR data are consistent with density functional theory (DFT) calculations which show enhancements at both q=(π,0) and the in-plane FM q=0 wave vectors in static magnetic susceptibility χ(q). We suggest that the strong FM fluctuations prevent superconductivity in SrCo2As2, despite the presence of stripe-type AFM fluctuations. Since DFT calculations have consistently revealed similar enhancements of the χ(q) at bothmore »q=(π,0) and q=0 in the iron-based superconductors and parent compounds, our observation of FM correlations in SrCo2As2 calls for detailed studies of FM correlations in the iron-based superconductors.« less

  16. Epitaxial growth, structure and intermixing at the LaAlO3/SrTiO3 interface as the film stoichiometry is varied

    SciTech Connect (OSTI)

    Qiao, Liang; Droubay, Timothy C.; Varga, Tamas; Bowden, Mark E.; Shutthanandan, V.; Zhu, Zihua; Kaspar, Tiffany C.; Chambers, Scott A.

    2011-02-11

    LaAlO3 epitaxial films with La:Al cation ratios ranging from 0.9 to 1.2 were grown on TiO2-terminated SrTiO3 (001) substrates by off-axis pulsed laser deposition. Although all films are epitaxial, rocking curve and Kiessig fringe oscillation measurements show that the crystallographic quality degrades with increasing La:Al ratio. Films with La:Al ratios of 0.9, 1.0, and 1.1 were coherently strained to the substrate. However, the out-of-plane lattice parameter increases over this range, revealing a decrease in film tetragonality. Although all film surfaces exhibit hydroxylation, the extent of hydroxylation is greater for the La-rich films. Rutherford backscattering spectrometry reveals that La from the film diffuses deeply into the SrTiO3 substrate and secondary ion mass spectroscopy shows unambiguous Sr outdiffusion into the films. Intermixing, which is generally not investigated in studies of the LaAlO3/SrTiO3 interface, may have important implications for the mechanism of electrical conductivity.

  17. Sr-isotopic composition of marbles from the Puerto Galera area (Mindoro, Philippines): additional evidence for a Paleozoic age of a metamorphic complex in the Philippine island arc

    SciTech Connect (OSTI)

    Knittel, U.; Daniels, U.

    1987-02-01

    The Sr-isotopic composition of marbles from the Puerto Galera area (Mindoro, Philippines) is compatible with either a Tertiary or a Paleozoic age. The former is considered as unlikely because nonmetamorphic sediments of that age overlie the metamorphic complex. This implies that the metamorphic complex does not represent the basement of the Philippine arc but is an accreted terrane.

  18. Coexistence of antiferromagnetic and ferromagnetic spin correlations in SrCo2As2 revealed by Co59 and As75 NMR

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

    Wiecki, P.; Ogloblichev, V.; Pandey, Abhishek; Johnston, D. C.; Furukawa, Y.

    2015-06-15

    In nonsuperconducting, metallic paramagnetic SrCo2As2, inelastic neutron scattering measurements have revealed strong stripe-type q=(?,0) antiferromagnetic (AFM) spin correlations. Using nuclear magnetic resonance (NMR) measurements on 59Co and 75Asnuclei, we demonstrate that stronger ferromagnetic (FM) spin correlations coexist in SrCo2As2. Our NMR data are consistent with density functional theory (DFT) calculations which show enhancements at both q=(?,0) and the in-plane FM q=0 wave vectors in static magnetic susceptibility ?(q). We suggest that the strong FM fluctuations prevent superconductivity in SrCo2As2, despite the presence of stripe-type AFM fluctuations. Since DFT calculations have consistently revealed similar enhancements of the ?(q) at both q=(?,0)moreand q=0 in the iron-based superconductors and parent compounds, our observation of FM correlations in SrCo2As2 calls for detailed studies of FM correlations in the iron-based superconductors.less

  19. REMOVAL OF TECHNETIUM 99 FROM THE EFFLUENT TREATMENT FACILITY (ETF) BASIN 44 USING PUROLITE A-530E & REILLEX HPQ & SYBRON IONAC SR-7 ION EXCHANGE RESINS

    SciTech Connect (OSTI)

    DUNCAN JB

    2004-10-29

    This report documents the laboratory testing and analyses as directed under the test plan, RPP-20407. The overall goal of this task was to evaluate and compare candidate anion exchange resins for their capacity to remove Technetium-99 from Basin 44 Reverse Osmosis reject stream. The candidate resins evaluated were Purolite A-530E, Reillex HPQ, and Sybron IONAC SR-7.

  20. Octahedral rotations in strained LaAlO{sub 3}/SrTiO{sub 3} (001) heterostructures

    SciTech Connect (OSTI)

    Fister, T. T.; Hruszkewycz, S. O.; Proffit, D. L.; Eastman, J. A.; Fuoss, P. H.; Baldo, P. M.; Fong, D. D.; Zhou, H.; Luo, Z.; Seo, S. S. A.; Lee, H. N.

    2014-02-01

    Many complex oxides display an array of structural instabilities often tied to altered electronic behavior. For oxide heterostructures, several different interfacial effects can dramatically change the nature of these instabilities. Here, we investigate LaAlO{sub 3}/SrTiO{sub 3} (001) heterostructures using synchrotron x-ray scattering. We find that when cooling from high temperature, LaAlO{sub 3} transforms from the Pm3{sup }m to the Imma phase due to strain. Furthermore, the first 4 unit cells of the film adjacent to the substrate exhibit a gradient in rotation angle that can couple with polar displacements in films thinner than that necessary for 2D electron gas formation.

  1. The radiation chemistry of CCD-PEG, a solvent-extraction process for Cs and Sr from dissolved nuclear fuel

    SciTech Connect (OSTI)

    Mincher, B.J.; Herbst, R.S.; Tillotson, R.D.; Mezyk, S.P.

    2008-07-01

    Cobalt dicarbollide and polyethylene glycol in phenyl-trifluoromethyl sulfone (HCCD/PEG in FS- 13) is currently under consideration for use in the process-scale selective extraction of fission- product cesium and strontium from dissolved nuclear fuel. This solvent will be exposed to high radiation doses during use and has not been adequately investigated for radiation stability. Here, HCCD/PEG was y-irradiated to various absorbed doses, to a maximum of 432 kGy, using {sup 60}Co. Irradiations were performed for the neat organic phase and also for the organic phase in contact with 1 M-nitric acid mixed by air sparging. Post-irradiation solvent-extraction measurements showed that Cs distribution ratios were unaffected; however, Sr extraction efficiency decreased with absorbed dose under both conditions and was greater when in contact with the aqueous phase. Stripping performance was not affected. A mechanism, initiated by direct radiolysis of the sulfone diluent, is proposed. (authors)

  2. LaCrO{sub 3} heteroepitaxy on SrTiO{sub 3}(001) by molecular beam epitaxy

    SciTech Connect (OSTI)

    Qiao, L.; Droubay, T. C.; Bowden, M. E.; Shutthanandan, V.; Kaspar, T. C.; Chambers, S. A.

    2011-08-08

    Stoichiometric, epitaxial LaCrO{sub 3} films have been grown on SrTiO{sub 3}(001) by molecular beam epitaxy using O{sub 2} as the oxidant. Films grew in a layer-by-layer fashion, giving rise to coherently strained, structurally excellent films and surfaces which preserve the step-terrace structure of the substrate. The critical thickness is in excess of 500 A. Cr(III) near the surface is easily oxidized to Cr(V) upon exposure to atomic oxygen and reduction back to Cr(III) is readily achieved by vacuum annealing, resulting in tunability of the charge state at the B-site cation.

  3. Understanding the mechanism of conductivity at the LaAlO3/SrTiO3(001) interface

    SciTech Connect (OSTI)

    Chambers, Scott A.

    2011-07-01

    The observation of conductivity at (001)-oriented interfaces of the two band insulators LaAlO3 and SrTiO3 is both fascinating and potentially useful for next-generation electronics. The reigning paradigm to explain the conductivity phenomenon is an electronic reconstruction resulting from the instability created by forming an interface of polar and nonpolar perovskites, leading to the formation of a two-dimensional electron gas. However, the complexities introduced by the strong tendency of the cations to mix across the interface also manifest themselves in the electronic structure, and this mixing gives rise to other ways for the interface to stabilize and become conductive. In this Prospective, arguments for and against these two explanations are explored and strategies for resolving the issue are suggested.

  4. LaCrO3 heteroepitaxy on SrTiO3(001) by molecular beam epitaxy

    SciTech Connect (OSTI)

    Qiao, Liang; Droubay, Timothy C.; Bowden, Mark E.; Shutthanandan, V.; Kaspar, Tiffany C.; Chambers, Scott A.

    2011-08-09

    Stoichiometric, epitaxial LaCrO3 films have been grown on TiO2-terminated SrTiO3(001) substrates by molecular beam epitaxy using O2 as the oxidant. Film growth occurred in a layer-by-layer fashion, giving rise to structurally excellent films and surfaces which preserve the step-terrace structure of the substrate. The critical thickness is in excess of 500 . Near-surface Cr(III) is highly susceptible to further oxidation to Cr(V), leading to the formation of a disordered phase upon exposure to atomic oxygen. Recovery of the original epitaxial LaCrO3 phase is readily achieved by vacuum annealing.

  5. Tunable and adaptive bandpass filter using a nonlinear dielectric thin film of SrTiO{sub 3}

    SciTech Connect (OSTI)

    Findikoglu, A.T.; Jia, Q.X.; Wu, X.D.; Chen, G.J.; Venkatesan, T.; Reagor, D.W.

    1996-03-01

    We have prepared an electrically tunable and adaptive 3-pole half-wave bandpass coplanar waveguide filter incorporating a 1.2-{mu}m-thick paraelectric SrTiO{sub 3} bottom layer and a 0.4-{mu}m-thick superconducting YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} top electrode layer on a LaAlO{sub 3} substrate. By applying a separate bias voltage on each pole and also on each coupling capacitance of the device at 4 and 76 K, the filter response is not only fine tuned to achieve symmetric and optimized filter characteristics with less than 2{percent} bandwidth centered around 2.5 GHz, but also broadband tuned to shift the passband by more than 15{percent}. {copyright} {ital 1996 American Institute of Physics.}

  6. Heterojunction band offsets and dipole formation at BaTiO{sub 3}/SrTiO{sub 3} interfaces

    SciTech Connect (OSTI)

    Balaz, Snjezana; Zeng, Zhaoquan; Brillson, Leonard J.; Department of Physics, The Ohio State University, 191 West Woodruff, Columbus, Ohio 43210

    2013-11-14

    We used a complement of photoemission and cathodoluminescence techniques to measure formation of the BaTiO{sub 3} (BTO) on SrTiO{sub 3} (STO) heterojunction band offset grown monolayer by monolayer by molecular beam epitaxy. X-ray photoemission spectroscopy (XPS) provided core level and valence band edge energies to monitor the valence band offset in-situ as the first few crystalline BTO monolayers formed on the STO substrate. Ultraviolet photoemission spectroscopy (UPS) measured Fermi level positions within the band gap, work functions, and ionization potentials of the growing BTO film. Depth-resolved cathodoluminescence spectroscopy measured energies and densities of interface states at the buried heterojunction. Kraut-based XPS heterojunction band offsets provided evidence for STO/BTO heterojunction linearity, i.e., commutativity and transitivity. In contrast, UPS and XPS revealed a large dipole associated either with local charge transfer or strain-induced polarization within the BTO epilayer.

  7. Radiochemical procedures for analysis of Pu, Am, Cs and Sr in water, soil, sediments and biota samples

    SciTech Connect (OSTI)

    Wong, K.M.; Jokela, T.A.; Noshkin, V.E.

    1994-02-01

    The Environmental Radioactivity Analysis Laboratory (ERAL) was established as an analytical facility. The primary function of ERAL is to provide fast and accurate radiological data of environmental samples. Over the years, many radiochemical procedures have been developed by the staffs of ERAL. As result, we have found that our procedures exist in many different formats and in many different notebooks, documents and files. Therefore, in order to provide for more complete and orderly documentation of the radiochemical procedures that are being used by ERAL, we have decided to standardize the format and compile them into a series of reports. This first report covers procedures we have developed and are using for the radiochemical analysis of Pu, Am, Cs, and Sr in various matrices. Additional analytical procedures and/or revisions for other elements will be reported as they become available through continuation of these compilation efforts.

  8. Magnetic order and electronic structure of 5d3 double perovskite Sr2ScOsO6

    SciTech Connect (OSTI)

    Calder, Stuart A; Morrow, Ryan; Taylor, Alice E; Lumsden, Mark D; Woodward, Patrick; Christianson, Andrew D; Singh, David J

    2015-01-01

    The magnetic susceptibility, crystal and magnetic structures, and electronic structure of double perovskite Sr2ScOsO6 are reported. Using both neutron and x-ray powder diffraction we find that the crystal structure is monoclinic P21/n from 3.5 to 300 K. Magnetization measurements indicate an antiferromagnetic transition at TN=92 K, one of the highest transition temperatures of any double perovskite hosting only one magnetic ion. Type I antiferromagnetic order is determined by neutron powder diffraction, with an Os moment of only 1.6(1) muB, close to half the spin-only value for a crystal field split 5d electron state with t2g^3 ground state. Density functional calculations show that this reduction is largely the result of strong Os-O hybridization, with spin-orbit coupling responsible for only a ~0.1 muB reduction in the moment.

  9. Strong Energy-momentum Dispersion of Phonon Dressed Carriers in the Lightly Doped Band Insulator SrTiO3

    SciTech Connect (OSTI)

    Meevasana, Warawat

    2010-05-26

    Much progress has been made recently in the study of the effects of electron-phonon (el-ph) coupling in doped insulators using angle resolved photoemission (ARPES), yielding evidence for the dominant role of el-ph interactions in underdoped cuprates. As these studies have been limited to doped Mott insulators, the important question arises how this compares with doped band insulators where similar el-ph couplings should be at work. The archetypical case is the perovskite SrTiO{sub 3} (STO), well known for its giant dielectric constant of 10000 at low temperature, exceeding that of La{sub 2}CuO{sub 4} by a factor of 500. Based on this fact, it has been suggested that doped STO should be the archetypical bipolaron superconductor. Here we report an ARPES study from high-quality surfaces of lightly doped SrTiO{sub 3}. Comparing to lightly doped Mott insulators, we find the signatures of only moderate electron-phonon coupling: a dispersion anomaly associated with the low frequency optical phonon with a {lambda}{prime} {approx} 0.3 and an overall bandwidth renormalization suggesting an overall {lambda}{prime} {approx} 0.7 coming from the higher frequency phonons. Further, we find no clear signatures of the large pseudogap or small polaron phenomena. These findings demonstrate that a large dielectric constant itself is not a good indicator of el-ph coupling and highlight the unusually strong effects of the el-ph coupling in doped Mott insulators.

  10. Neutron diffraction study of the crystal structure and structural phase transition of La{sub 0.7}Ca{sub 0.3-x}Sr{sub x}CrO{sub 3} (0<=x<=0.3)

    SciTech Connect (OSTI)

    Omoto, Kazuki; Norberg, Stefan T.; Hull, Steve; Aoto, Akimitsu; Hashimoto, Takuya

    2010-02-15

    The crystal structure of the La{sub 0.7}Ca{sub 0.3-x}Sr{sub x}CrO{sub 3} series, including the compositional and temperature dependence of the structural parameters, has been studied by variable temperature neutron diffraction measurements. The extent of the distortions from the ideal cubic perovskite structure has been evaluated quantitatively using the average bond lengths and the mean volumes of the [CrO{sub 6}] octahedron and [(La/Ca/Sr)O{sub 12}] polyhedron, and has been shown to decrease with increase of Sr content or temperature. At the structural phase transition from the orthorhombic (Pnma) structure to the rhombohedral (R3-barc) one, the volume of the [CrO{sub 6}] octahedron decreases whereas that of the [(La/Ca/Sr)O{sub 12}] polyhedron shows little difference, resulting in an overall decrease in the level of distortion. The change in the degree of distortion at the phase transition decreases with increase of Sr content, in agreement with the smaller variation of the enthalpy and volume for the specimens with higher Sr content. - Graphical abstract: Temperature dependence of parameter, PHI, representing the extent of distortion from the ideal cubic perovskite structure, for La{sub 0.7}Ca{sub 0.3}CrO{sub 3} (diamonds) and La{sub 0.7}Ca{sub 0.15}Sr{sub 0.15}CrO{sub 3} (circles) calculated from neutron diffraction patterns.

  11. Controlled peak wavelength shift of Ca{sub 1-} {sub x} Sr {sub x} (S {sub y} Se{sub 1-} {sub y} ):Eu{sup 2+} phosphor for LED application

    SciTech Connect (OSTI)

    Nazarov, Mihail . E-mail: nazarov.mihail@samsung.com; Yoon, Chulsoo

    2006-08-15

    The highly efficient red-orange-yellow-emitting phosphor (Ca{sub 1-} {sub x} Sr {sub x} )(S{sub 1-} {sub y} Se {sub y} ):Eu{sup 2+} in combination with commercial green phosphor SrGa{sub 2}S{sub 4}:Eu{sup 2+} and blue LED are proposed for a three-band white LED. The luminescence mechanism and optimization parameters are discussed on the basis of proposed peak wavelength diagram. - Graphical abstract: 'Peak wavelength diagram for (Ca{sub 1-} {sub x} Sr {sub x} )(S{sub 1-} {sub y} Se {sub y} ):Eu{sup 2+}'.

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

    SciTech Connect (OSTI)

    Pandey, Abhishek; Quirinale, D. G.; Jayasekara, W.; Sapkota, A.; Kim, M. G.; Dhaka, R. S.; Lee, Y.; Heitmann, T. W.; Stephens, P. W.; Ogloblichev, V.; Kreyssig, A.; McQueeney, R. J.; Goldman, A. I.; Kaminski, Adam; Harmon, B. N.; Furukawa, Y.; Johnston, D. C.

    2013-07-01

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

  13. Disorder from order among anisotropic next-nearest-neighbor Ising spin chains in SrHo2O4

    SciTech Connect (OSTI)

    Wen, J. -J.; Tian, W.; Garlea, V. O.; Koohpayeh, S. M.; McQueen, T. M.; Li, H. -F.; Yan, J. -Q.; Rodriguez-Rivera, J. A.; Vaknin, D.; Broholm, C. L.

    2015-02-26

    In this study, we describe why Ising spin chains with competing interactions in SrHo2O4 segregate into ordered and disordered ensembles at low temperatures (T). Using elastic neutron scattering, magnetization, and specific heat measurements, the two distinct spin chains are inferred to have Nel (????) and double-Nel (????) ground states, respectively. Below TN = 0.68(2)K, the Nel chains develop three-dimensional long range order (LRO), which arrests further thermal equilibration of the double-Nel chains so they remain in a disordered incommensurate state for T below TS = 0.52(2)K. SrHo2O4 distills an important feature of incommensurate low dimensional magnetism: kinetically trapped topological defects in a quasiddimensional spin system can preclude order in d + 1 dimensions.

  14. Left-handed properties of manganite-perovskites La{sub 1-x}Sr{sub x}MnO{sub 3} at various dopant concentrations

    SciTech Connect (OSTI)

    Belozorov, D. P.; Girich, A. A.; Tarapov, S. I.; Pogorily, A. M.; Tovstolytkin, A. I.; Belous, A. G.; Solopan, S. A.

    2014-03-15

    The experimental study of Double Negative (DNG) state of electromagnetic wave propagating in lanthanum manganite-perovskites doped with strontium La{sub 1-x}Sr{sub x}MnO{sub 3} is provided firstly below individual Curie temperatures (in ferromagnetic metal state (FM) for La{sub 1-x}Sr{sub x}MnO{sub 3}). Various dopant concentrations are considered for ceramic specimens: x = 0.15;??0.225;??0.3;??0.45;??0.6. It is shown that dependence of the DNG-peak intensity on dopant concentration is sharply non-monotone with maximum at the dopant concentrations x = 0.225 0.3. This behaviour follows the change of Curie temperature with increase of dopant concentration in such substances. The obtained dependence of DNG peak intensity supports the opinion concerning the role of disorder in highly doped manganite-perovskite magnetic ceramics under study.

  15. Enhance D. C. resistivity of Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} ceramic by acceptor (Mn) doping

    SciTech Connect (OSTI)

    Sharma, Hakikat Arya, G. S.; Pramar, Kusum; Negi, N. S.

    2015-05-15

    In the present work, we prepared Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Mn (2 and 3 at % on Ti site) doped Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} ceramic by sol- gel method. The samples were characterized by X-ray diffraction (XRD). The XRD patterns reveled that Mn ions did not change the perovskite structure of BST (70/30). The dielectric measurements proved that dielectric constant decreased with Mn doping. The dc resistivity was studied by using I-V measurements. The dc resistivity of the BST increased with Mn doping, which suppressed the leakage current.

  16. Band Alignment, Built-In Potential, and the Absence of Conductivity at the LaCrO3/SrTiO3(001) Heterojunction

    SciTech Connect (OSTI)

    Chambers, Scott A.; Qiao, Liang; Droubay, Timothy C.; Kaspar, Tiffany C.; Arey, Bruce W.; Sushko, P. V.

    2011-11-07

    MBE-grown LaCrO3/SrTiO3(001) exhibits a staggered band alignment with valence and conduction band offsets of 2.45(6) and 0.8(1) eV, respectively. Core-level XPS peak broadening is consistent with no band bending in the SrTiO3 and a gradient of ~200 meV per unit cell in the LaCrO3. This gradient is adequate to trigger an electronic reconstruction, and the attendant transfer of charge from film to substrate, to alleviate the polarity mismatch. However, the interface is insulating because charge redistribution within the CrO2 layers occurs rather than electronic reconstruction to screen the field.

  17. Abnormal thermal conductivity in tetragonal tungsten bronze Ba{sub 6−x}Sr{sub x}Nb{sub 10}O{sub 30}

    SciTech Connect (OSTI)

    Kolodiazhnyi, T. Sakurai, H.; Vasylkiv, O.; Borodianska, H.; Mozharivskyj, Y.

    2014-03-17

    Ba{sub 6−x}Sr{sub x}Nb{sub 10}O{sub 30} solid solution with 0 ≤ x ≤ 6 crystallizes in centrosymmetric tetragonal “tungsten bronze” structure (space group P4/mbm). We report on the x dependence of thermal conductivity of polycrystalline samples measured in the 2–400 K temperature interval. Substitution of Sr for Ba brings about a significant decrease in thermal conductivity at x ≥ 3 accompanied by development of a low-temperature (T ≈ 10–30 K) “plateau” region reminiscent of a glass-like compounds. We explain this behaviour based on a size-driven site occupancy and atomic displacement parameters associated with an alkaline earth atomic positions in the title compounds.

  18. Anomalous temperature dependence in valence band spectra: A resonant photoemission study of layered perovskite Sr{sub 2}CoO{sub 4}

    SciTech Connect (OSTI)

    Pandey, Pankaj K.; Choudhary, R. J. Phase, D. M.

    2014-05-05

    Valence band spectra (VBS) and its modification across Curie temperature (T{sub C}) of Sr{sub 2}CoO{sub 4} thin film are studied using resonant photoemission spectroscopy. It is found that VBS mainly consists of hybridized states of Co-3d t{sub 2g}e{sub g} and O-2p; however, Co-3d e{sub g} states show its prominence only in the ferromagnetic temperature regime. Below T{sub C}, spectral weight transfer takes place anomalously from high binding energy (B.E.) region to low B.E. region, signifying the enhanced intermediate or low spin state Co{sup 4+} ions. It is suggested that spin-lattice coupling and many-body effects in Sr{sub 2}CoO{sub 4} derived from the strong electron correlations lead to such temperature dependence of VBS.

  19. Structural instability of the CoO4 tetrahedral chain in SrCoO3-? thin films

    SciTech Connect (OSTI)

    Glamazda, A.; Choi, Kwang-yong; Lemmens, P.; Choi, Woo Seok; Jeen, Hyoungjeen; Meyer, Tricia L.; Lee, Ho Nyung

    2015-08-31

    Raman scattering experiments together with detailed lattice dynamic calculations are performed to elucidate crystallographic and electronic peculiarities of SrCoO3-? films. We observe that the 85 cm-1 phonon mode involving the rotation of a CoO4 tetrahedron undergoes a hardening by 21 cm-1 when the temperature is decreased. In addition, new phonon modes appear at 651.5 and 697.6 cm-1 . The latter modes are attributed to the Jahn-Teller activated modes. Upon cooling from room temperature, all phonons exhibit an exponential-like increase of intensity with a characteristic energy of about 103107 K. We attribute this phenomenon to an instability of the CoO4 tetrahedral chain structure, which constitutes a key ingredient to understand the electronic and structural properties of the brownmillerite SrCoO2.5.

  20. Electric field and temperature dependence of dielectric permittivity in strontium titanate investigated by a photoemission study on Pt/SrTiO{sub 3}:Nb junctions

    SciTech Connect (OSTI)

    Hirose, Sakyo; Okushi, Hideyo; Yoshikawa, Hideki; Adachi, Yutaka; Ohsawa, Takeo; Haneda, Hajime; Ueda, Shigenori; Ando, Akira; Ohashi, Naoki

    2015-05-11

    Schottky junctions made from platinum and niobium-doped strontium titanate (SrTiO{sub 3}:Nb) were investigated by hard X-ray photoemission (HXPES) and through a band bending behavior simulation using a phenomenological model, which assumes a decrease in dielectric constant due to an electric field. Thus, we confirmed that the observed HXPES spectra at relatively high temperatures, e.g., >250?K, were well simulated using this phenomenological model. In contrast, it was inferred that the model was not appropriate for junction behavior at lower temperatures, e.g., <150?K. Therefore, a reconstruction of the phenomenological model is necessary to adequately explain the dielectric properties of SrTiO{sub 3}.

  1. Zn2+ and Sr2+ Adsorption at the TiO2 (110)-Electrolyte Interface: Influence of Ionic Strength, Coverage, and Anions

    SciTech Connect (OSTI)

    Zhang,Z.; Fenter, P.; Cheng, L.; Sturchio, N.; Bedzyk, M.; Machesky, M.; Anovitz, L.; Wesolowski, D.

    2006-01-01

    The X-ray standing wave technique was used to probe the sensitivity of Zn{sup 2+} and Sr{sup 2+} ion adsorption to changes in both the adsorbed ion coverage and the background electrolyte species and concentrations at the rutile ({alpha}-TiO{sub 2}) (110)-aqueous interface. Measurements were made with various background electrolytes (NaCl, NaTr, RbCl, NaBr) at concentrations as high as 1 m. The results demonstrate that Zn{sub 2+} and Sr{sub 2+} reside primarily in the condensed layer and that the ion heights above the Ti-O surface plane are insensitive to ionic strength and the choice of background electrolyte (with <0.1 Angstroms changes over the full compositional range). The lack of any specific anion coadsorption upon probing with Br{sup -}, coupled with the insensitivity of Zn{sup 2+} and Sr{sup 2+} cation heights to changes in the background electrolyte, implies that anions do not play a significant role in the adsorption of these divalent metal ions to the rutile (110) surface. Absolute ion coverage measurements for Zn{sup 2+} and Sr{sup 2+} show a maximum Stern-layer coverage of {approx}0.5 monolayer, with no significant variation in height as a function of Stern-layer coverage. These observations are discussed in the context of Gouy-Chapman-Stern models of the electrical double layer developed from macroscopic sorption and pH-titration studies of rutile powder suspensions. Direct comparison between these experimental observations and the MUltiSIte Complexation (MUSIC) model predictions of cation surface coverage as a function of ionic strength revealed good agreement between measured and predicted surface coverages with no adjustable parameters.

  2. Comparative studies of dipole polarizabilities in Sr{sup +}, Ba{sup +}, and Ra{sup +} and their applications to optical clocks

    SciTech Connect (OSTI)

    Sahoo, B. K.; Timmermans, R. G. E.; Das, B. P.; Mukherjee, D.

    2009-12-15

    Static dipole polarizabilities are calculated in the ground and metastable states of Sr{sup +}, Ba{sup +} and Ra{sup +} using the relativistic coupled-cluster method. Trends of the electron correlation effects are investigated in these atomic ions. We also estimate the Stark and black-body radiation shifts from these results for these systems for the transitions proposed for the optical frequency standards and compare them with available experimental data.

  3. Structure and magnetic interactions in the solid solution Ba{sub 3?x}Sr{sub x}Cr{sub 2}O{sub 8}

    SciTech Connect (OSTI)

    Grundmann, Henrik; Schilling, Andreas; Marjerrison, Casey A.; Dabkowska, Hanna A.; Gaulin, Bruce D.

    2013-09-01

    Highlights: We describe for the first time the preparation of single- and polycrystalline members of the solid solution Ba{sub 3?x}Sr{sub x}Cr{sub 2}O{sub 8}. We report on the structural changes in the solid solution at room temperature depending on the stoichiometry. We describe the peculiar change of the magnetic behavior in the solid solution with the stoichiometry. - Abstract: Solid solutions of the magnetic insulators Ba{sub 3}Cr{sub 2}O{sub 8} and Sr{sub 3}Cr{sub 2}O{sub 8} (Ba{sub 3?x}Sr{sub x}Cr{sub 2}O{sub 8}) have been prepared in polycrystalline form for the first time. Single crystalline material was obtained using a mirror image floating zone technique. X-ray diffraction data taken at room temperature indicate that the space group of Ba{sub 3?x}Sr{sub x}Cr{sub 2}O{sub 8} remains unchanged for all values of x, while the cell parameters depend on the chemical composition, as expected. Magnetization data, measured from 300 K down to 2 K, suggest that the interaction constant J{sub d} within the Cr{sup 5+} dimers varies in a peculiar way as a function of x, starting at J{sub d} = 25 K for x = 0, then first slightly dropping to J{sub d} = 18 K for x ? 0.75, before reaching J{sub d} = 62 K for x = 3.

  4. Syntheses and characterization of energetic compounds constructed from alkaline earth metal cations (Sr and Ba) and 1,2-bis(tetrazol-5-yl)ethane

    SciTech Connect (OSTI)

    Xia Zhengqiang; Chen Sanping; Wei Qing; Qiao Chengfang

    2011-07-15

    Two new energetic compounds, [M(BTE)(H{sub 2}O){sub 5}]{sub n} (M=Sr(1), Ba(2)) [H{sub 2}BTE=1,2-bis(tetrazol-5-yl)ethane], have been hydrothermally synthesized and structurally characterized. Single-crystal X-ray diffraction analyses reveal that they are isomorphous and exhibit 2D (4,4) net framework, generated by 4-connected Sr{sub 2}(H{sub 2}O){sub 10}/Ba{sub 2}(H{sub 2}O){sub 10} SBUs linked up by two independent binding modes of H{sub 2}BTE, and the resulting 2D structure is interconnected by hydrogen-bond and strong face to face {pi}-{pi} stacking interactions between two tetrazole rings to lead to a 3D supramolecular architecture. DSC measurements show that they have significant catalytic effects on thermal decomposition of ammonium perchlorate. Moreover, the photoluminescence properties, thermogravimetric analyses, and flame colors of the as-prepared compounds are also investigated in this paper. - Graphical abstract: Two novel 2D isomorphous alkaline earth metal complexes were assembled by 4-connected Sr{sub 2}(H{sub 2}O){sub 10}/Ba{sub 2}(H{sub 2}O){sub 10} SBUs and two independent binding modes of H{sub 2}BTE ligands, and the catalytic performances toward thermal decomposition of ammonium perchlorate and photoluminescent properties of them were investigated. Highlights: > Two novel alkaline earth energetic coordination polymers have been prepared.{yields} Both structures are layered based on 4-connected Sr{sub 2}(H{sub 2}O){sub 10}/Ba{sub 2}(H{sub 2}O){sub 10} SBUs and two distinct H{sub 2}BTE coordination modes.{yields} The dehydrated products of the compounds possess good thermostability and significant catalytic effects on thermal decomposition of AP.

  5. Blue light emitting SrSn(OH){sub 6} nano-rods doped with lanthanide ions (Eu{sup 3+}, Tb{sup 3+} and Dy{sup 3+})

    SciTech Connect (OSTI)

    Patel, D.K.; Nuwad, J.; Rajeswari, B.; Vishwanadh, B.; Sudarsan, V.; Vatsa, R.K.; Kadam, R.M.; Pillai, C.G.S.; Kulshreshtha, S.K.

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ? Room temperature synthesis of blue light emitting SrSn(OH){sub 6} nano-rods. ? Blue light emission originates from the recombination of self trapped excitons. ? There exists energy transfer from host to lanthanide ions in SrSn(OH){sub 6}:Ln nano-rods. ? Solubility of Eu{sup 3+} ions in SrSn(OH){sub 6} nano-rods is around 1.5 at%. -- Abstract: Blue light emitting SrSn(OH){sub 6} nano-rods were prepared in aqueous medium at room temperature. Presence of lanthanide ions in reaction medium during synthesis of nano-rods, leads to significant changes in the morphology of the nano-rods. Based on luminescence studies emission in the blue region from SrSn(OH){sub 6} nano-rods has been attributed to radiative recombination of self trapped excitons in the lattice. SrSn(OH){sub 6} nano-rods were doped with lanthanide ions like Eu{sup 3+}, Tb{sup 3+} and Dy{sup 3+} and their luminescence studies revealed that there exists energy transfer from host to lanthanide ions. From the luminescence studies on Eu{sup 3+} doped samples, it is confirmed that up to 1.5 at%, Eu{sup 3+} ions get incorporated at Sr{sup 2+} site in SrSn(OH){sub 6} lattice and beyond which a separate Eu{sup 3+} containing phase is formed. Part of the europium ions also exists as Eu{sup 2+} species in the lattice as confirmed by electron paramagnetic resonance (EPR) studies.

  6. Tuning the metal-insulator crossover and magnetism in SrRuO3 by ionic gating

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

    Yi, Hee Taek; Gao, Bin; Xie, Wei; Cheong, Sang -Wook; Podzorov, Vitaly

    2014-10-13

    Reversible control of charge transport and magnetic properties without degradation is a key for device applications of transition metal oxides. Chemical doping during the growth of transition metal oxides can result in large changes in physical properties, but in most of the cases irreversibility is an inevitable constraint. We report a reversible control of charge transport, metal-insulator crossover and magnetism in field-effect devices based on ionically gated archetypal oxide system - SrRuO3. In these thin-film devices, the metal-insulator crossover temperature and the onset of magnetoresistance can be continuously and reversibly tuned in the range 90–250 K and 70–100 K, respectively,more » by application of a small gate voltage. We infer that a reversible diffusion of oxygen ions in the oxide lattice dominates the response of these materials to the gate electric field. These findings provide critical insights into both the understanding of ionically gated oxides and the development of novel applications.« less

  7. Spin and orbital Ti magnetism at LaMnO3/SrTiO3 interfaces

    SciTech Connect (OSTI)

    Garcial-Barriocanal, J; Cezar, J. C.; Bruno, F. Y.; Thakur, P.; Brookes, N. B.; Utfeld, C.; Riviera-Calzada, A.; Giblin, S. R.; Taylor, J. W.; Duffy, J. A.; Dugdale, S. B.; Nakamura, T.; Kodama, K.; Leon, C.; Okamoto, Satoshi; Santamaria, J.

    2010-01-01

    In systems with strong electron-lattice coupling, such as manganites, orbital degeneracy is lifted, what causes a null expectation value of the orbital moment. Magnetic structure is thus determined by spin-spin superexchange. In titanates, however, with much smaller Jahn-Teller distortions, orbital degeneracy might allow non-zero values of the orbital magnetic moment. Accordingly, novel forms of ferromagnetic superexchange interaction unique to t2g electrons systems have been theoretically predicted, although their experimental observation has remained elusive. Here we report a new kind of Ti3+ ferromagnetism at LaMnO3/SrTiO3 epitaxial interfaces. It results from charge transfer to the empty conduction band of the titanate and has spin and orbital contributions evidencing the role played by orbital degeneracy. The possibility of tuning magnetic alignment (ferromagnetic or antiferromagnetic) of Ti and Mn moments by structural parameters is demonstrated. This result will provide important clues for the understanding of the effects of orbital degeneracy in superexchange coupling.

  8. Unintentional F doping of SrTiO3(001) etched in HF acid-structure and electronic properties

    SciTech Connect (OSTI)

    Chambers, Scott A.; Droubay, Timothy C.; Capan, Cigdem; Sun, Guangyuan

    2012-02-01

    We show that the HF acid etch commonly used to prepare SrTiO3(001) for heteroepitaxial growth of complex oxides results in a non-negligible level of F doping within the terminal surface layer of TiO2. Using a combination of x-ray photoelectron spectroscopy and scanned angle x-ray photoelectron diffraction, we determine that on average ~ 13% of the O anions in the surface layer are replaced by F, but that F does not occupy O sites in deeper layers. Despite this perturbation to the surface, the Fermi level remains unpinned, and the surface-state density, which determines the amount of band bending, is driven by factors other than F doping. The presence of F at the STO surface is expected to result in lower electron mobilities at complex oxide heterojunctions involving STO substrates because of impurity scattering. Unintentional F doping can be substantially reduced by replacing the HF-etch step with a boil in deionized water, which in conjunction with an oxygen tube furnace anneal, leaves the surface flat and TiO2 terminated.

  9. Tunable electronic structure in dilute magnetic semiconductor Sr{sub 3}SnO/c-YSZ/Si (001) epitaxial heterostructures

    SciTech Connect (OSTI)

    Lee, Y. F.; Narayan, J.; Schwartz, J.

    2014-10-28

    We report a systematic study of the structural, physical, and chemical properties of epitaxial thin films of emerging dilute magnetic semiconductor (DMS) Sr{sub 3}SnO (SSO) integrated with Si (100) prepared by various post-growth annealing treatments. The transport properties of these films are primarily governed by oxygen vacancies and the results are explained with the variable-range hopping model. The increased oxygen vacancy concentration generated by post-growth vacuum annealing results in a shorter hopping distance and reduced hopping energy and Coulomb gap, leading to lower resistivity; oxygen annealing shows the opposite effects. The work function ranges from 4.54 to 4.02 eV and shows a negative linear relationship with oxygen vacancy concentration, accompanied by a 0.42 eV shift in the surface Fermi level. The transport and ultraviolet photoelectron spectroscopy probes agree quantitatively on measurement of the resistivity and surface electronic structure. The results provide a direct and consistent explanation that the property changes in the bulk and at the surface are primarily attributed to oxygen vacancies, which are believed to be the carriers in the SSO thin films. The ability to manipulate the work function and oxygen vacancy concentration in epitaxial DMS SSO thin films offers great potential for the development of spintronic devices.

  10. Geometry-dependent penetration fields in superconducting Bi2Sr2CaCu2O8+? platelets

    SciTech Connect (OSTI)

    By: Curran, P. J.; Clem, J. R.; Bending, S. J.; Tsuchiya, Y.; Tamegai, T.

    2010-10-01

    Magneto-optical imaging has been used to study vortex penetration into regular polygon-shaped Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} platelets with various geometries (disks, pentagons, squares, and triangles) but known fixed areas. In all cases we observe an exponential dependence of the field of first penetration, H{sub p}, on temperature, consistent with a dominant Bean-Livingston barrier for pancake vortices at our measurement temperatures (45-80 K). However, the penetration field consistently decreases with decreasing degree of sample symmetry, in stark contrast to conventional estimates of demagnetization factors using equivalent ellipsoids based on inscribed circles, which predict the reverse trend. Surprisingly, this observation does not appear to have been reported in the literature before. We demonstrate empirically that estimates using equivalent ellipsoids based on circumscribed circles predict the correct qualitative experimental trend in H{sub p}. Our work has important implications for the estimation of appropriate effective demagnetization factors for flux penetration into arbitrarily shaped superconducting bodies.

  11. Geometry-dependent penetration fields of superconducting Bi2Sr2CaCu2O8+? platelets

    SciTech Connect (OSTI)

    Curran, P. J.; Clem, J. R.; Bending, S. J.; Tsuchiya, Y.; Tamegai, T.

    2010-10-01

    Magneto-optical imaging has been used to study vortex penetration into regular polygon-shaped Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} platelets with various geometries (disks, pentagons, squares, and triangles) but known fixed areas. In all cases we observe an exponential dependence of the field of first penetration, H{sub p}, on temperature, consistent with a dominant Bean-Livingston barrier for pancake vortices at our measurement temperatures (45-80 K). However, the penetration field consistently decreases with decreasing degree of sample symmetry, in stark contrast to conventional estimates of demagnetization factors using equivalent ellipsoids based on inscribed circles, which predict the reverse trend. Surprisingly, this observation does not appear to have been reported in the literature before. We demonstrate empirically that estimates using equivalent ellipsoids based on circumscribed circles predict the correct qualitative experimental trend in Hp. Our work has important implications for the estimation of appropriate effective demagnetization factors for flux penetration into arbitrarily shaped superconducting bodies.

  12. Built-in and Induced Polarization Across LaAlO3/SrTiO3 Heterojunctions

    SciTech Connect (OSTI)

    Guneeta, Singh-Bhalla

    2011-08-15

    Ionic crystals terminated at oppositely charged polar surfaces are inherently unstable and expected to undergo surface reconstructions to maintain electrostatic stability. Essentially, an electric field that arises between oppositely charged atomic planes gives rise to a built-in potential that diverges with thickness. Here we present evidence of such a built-in potential across polar LaAlO{sub 3} thin films grown on SrTiO{sub 3} substrates, a system well known for the electron gas that forms at the interface. By performing tunneling measurements between the electron gas and metallic electrodes on LaAlO{sub 3} we measure a built-in electric field across LaAlO{sub 3} of 80.1 meV/{angstrom}. Additionally, capacitance measurements reveal the presence of an induced dipole moment across the heterostructure. We forsee use of the ionic built-in potential as an additional tuning parameter in both existing and novel device architectures, especially as atomic control of oxide interfaces gains widespread momentum.

  13. Stoichiometry dependence of potential screening at La ( 1 - δ ) Al ( 1 + δ ) O 3 / SrTiO 3 interfaces

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

    Weiland, Conan; Sterbinsky, George E.; Rumaiz, Abdul K.; Hellberg, C. Stephen; Woicik, Joseph C.; Zhu, Shaobo; Schlom, Darrell G.

    2015-04-03

    Hard x-ray photoelectron spectroscopy (HAXPES) and variable kinetic energy x-ray photoelectron spectroscopy (VKE-XPS) analyses have been performed on ten-unit-cell-thick La(1-δ)Al(1+δ)O₃ films, with La:Al ratios of 1.1, 1.0, and 0.9, deposited on SrTiO₃. Only Al-rich films are known to have a conductive interface. VKE-XPS, coupled with maximum entropy analysis, shows significant differences in the compositional depth profile among the Al-rich, La-rich, and stoichiometric films: significant La enrichment at the interface is observed in the La-rich and stoichiometric films, while the Al-rich film shows little to no intermixing. Additionally, the La-rich and stoichiometric films show a high concentration of Al at themore »surface, which is not observed in the Al-rich film. HAXPES valence band (VB) analysis shows a broadening of the VB for the Al-rich sample relative to the stoichiometric and La-rich samples. This broadening is consistent with an electric field across the Al-rich film. These results are consistent with a defect-driven electronic reconstruction.« less

  14. Cation mixing, band offsets and electric fields at LaAlO3/SrTiO3(001) heterojunctions with variable La:Al atom ratio

    SciTech Connect (OSTI)

    Qiao, Liang; Droubay, Timothy C.; Kaspar, Tiffany C.; Sushko, P. V.; Chambers, Scott A.

    2011-08-01

    Interfacial intermixing and electronic structure were investigated at thin (35 unit cells.), epitaxial La1 ? xAl1 + xO3/SrTiO3(001) heterojunctions for x = 0 and 0.05. Angle-resolved X-ray photoelectron spectroscopy reveals rather extensive cation intermixing for all films, independent of composition. The valence band offset for the nominally stoichiometric (x = 0) film is 0.16 0.10 eV, with the valence band maximum of SrTiO3 being deeper in binding energy than that of LaAlO3. Similar values are obtained for x = 0.05. There is no measurable band bending in either the LaAlO3 or the SrTiO3 near the interface. These results are at odds with first principles theoretical predictions based on perfect stoichiometry and an abrupt interface model. However, inclusion of intermixing in the compositional description of the interface results in successful prediction of the valence band offset and absence of band bending.

  15. Improvement in performance of electrically tunable devices based on nonlinear dielectric SrTiO{sub 3} using a homoepitaxial LaAlO{sub 3} interlayer

    SciTech Connect (OSTI)

    Jia, Q.X.; Findikoglu, A.T.; Reagor, D.; Lu, P.

    1998-08-01

    Improved structural and dielectric properties of nonlinear dielectric SrTiO{sub 3} thin films on LaAlO{sub 3} substrates were accomplished by incorporating a {ital homoepitaxial} LaAlO{sub 3} interlayer between the substrate and the dielectric film. Using this interlayer, the quality factor of SrTiO{sub 3} films with high-temperature superconducting YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} electrodes on LaAlO{sub 3} substrates was improved by more than 50{percent} at 4.2 GHz and 4 K. This improvement, combined with no change in nonlinearity, led to greater than a 50{percent} enhancement of the finesse factor (defined as the product of the quality factor and the fractional shift resonant frequency) for the coplanar waveguide microwave resonators. The reduced planar defect density in the SrTiO{sub 3} films was attributed to this improvement. {copyright} {ital 1998 American Institute of Physics.}

  16. Low-field magnetoresistance up to 400 K in double perovskite Sr{sub 2}FeMoO{sub 6} synthesized by a citrate route

    SciTech Connect (OSTI)

    Harnagea, L.; Jurca, B.; Berthet, P.

    2014-03-15

    A wet-chemistry technique, namely the citrate route, has been used to prepare high-quality polycrystalline samples of double perovskite Sr{sub 2}FeMoO{sub 6}. We report on the evolution of magnetic and magnetoresistive properties of the synthesized samples as a function of three parameters (i) the pH of the starting solution, (ii) the decomposition temperature of the citrate precursors and (iii) the sintering conditions. The low-field magnetoresistance (LFMR) value of our best samples is as high as 5% at room temperature for an applied magnetic field of 1 kOe. Additionally, the distinguishing feature of these samples is the persistence of LFMR, with a reasonably large value, up to 400 K which is a crucial parameter for any practical application. Our study indicates that the enhancement of LFMR observed is due to a good compromise between the grain size distribution and their magnetic polarization. -- Graphical abstract: The microstructure (left panel) and corresponding low-field magnetoresistance of one of the Sr{sub 2}FeMoO{sub 6} samples synthesized in the course of this work. Highlights: Samples of Sr{sub 2}FeMoO{sub 6} are prepared using a citrate route under varying conditions. Magnetoresistive properties are improved and optimized. Low-field magnetoresitence values as large as 5% at 300 K/1 kOe are reported. Persistence of low-field magnetoresistance up to 400 K.

  17. Structural features and enhanced high-temperature oxygen ion transport in SrFe{sub 1-x}Ta{sub x}O{sub 3-{delta}}

    SciTech Connect (OSTI)

    Markov, Alexey A.; Shalaeva, Elizaveta V.; Tyutyunnik, Alexander P.; Kuchin, Vasily V.; Patrakeev, Mikhail V.; Leonidov, Ilya A.; Kozhevnikov, Victor L.

    2013-01-15

    Structural features, oxygen non-stoichiometry and transport properties are studied in the oxide series SrFe{sub 1-x}Ta{sub x}O{sub 3-{delta}}, where x=0.2, 0.3 and 0.4. X-ray diffraction and electron microscopy data evidence formation of the inhomogeneous materials at x=0.3 and 0.4, which include phase constituents with a cubic perovskite and a double perovskite structure types. The composition, the amount and the typical grain size of the phase inhomogeneities are shown to depend both on doping and oxygen content. The increased oxygen-ion conductivity is observed in oxygen depleted materials, which is explained by the increase in the amount of cubic perovskite-like phase and development of interfacial pathways favorable for enhanced oxygen ion transport. - Graphical abstract: The structural studies, oxygen content and conductivity measurements suggest that oxygen depletion from the double perovskite phase constituent of SrFe{sub 1-x}Ta{sub x}O{sub 3-{delta}} for x>0.2 is accompanied by formation of pathways for fast ion transport. Black-Small-Square Highlights: Black-Right-Pointing-Pointer The double perovskite type regions are shown to exist in SrFe{sub 1-x}Ta{sub x}O{sub 3-{delta}}. Black-Right-Pointing-Pointer The oxygen depletion is accompanied with phase separation. Black-Right-Pointing-Pointer The phase separation favors formation of pathways for enhanced oxygen ion transport.

  18. Melt processing of the Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub y] superconductor in oxygen and argon atmospheres

    SciTech Connect (OSTI)

    Holesinger, T.G.; Miller, D.J. ); Chumbley, L.S. )

    1992-08-01

    Solidification and subsequent annealing of Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub y] (2212) in oxygen and argon atmospheres were investigated in order to identify alternative processing routes for controlling microstructures and superconducting properties. In addition to 2212, several other phases formed on cooling in O[sub 2] and did not disappear upon subsequent annealing. Crystallization in Ar resulted in a divorced eutetic structure of Bi[sub 2]Sr[sub 3-x]Ca[sub x]O[sub y] and Cu[sub 2]O/CuO. The superconductor was formed on subsequent anneals. Samples melted in Ar and then annealed generally possessed a more uniform microstructure compared with samples that were melted in oxygen and annealed. Compositional measurements of the 2212 phase suggest that CaO segregation in the melt may be minimized with an overall composition such as Bi[sub 2.15]Sr[sub 2]Ca[sub 0.85]Cu[sub 2]O[sub y].

  19. Melt processing of the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} superconductor in oxygen and argon atmospheres

    SciTech Connect (OSTI)

    Holesinger, T.G.; Miller, D.J.; Chumbley, L.S.

    1992-08-01

    Solidification and subsequent annealing of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (2212) in oxygen and argon atmospheres were investigated in order to identify alternative processing routes for controlling microstructures and superconducting properties. In addition to 2212, several other phases formed on cooling in O{sub 2} and did not disappear upon subsequent annealing. Crystallization in Ar resulted in a divorced eutetic structure of Bi{sub 2}Sr{sub 3-x}Ca{sub x}O{sub y} and Cu{sub 2}O/CuO. The superconductor was formed on subsequent anneals. Samples melted in Ar and then annealed generally possessed a more uniform microstructure compared with samples that were melted in oxygen and annealed. Compositional measurements of the 2212 phase suggest that CaO segregation in the melt may be minimized with an overall composition such as Bi{sub 2.15}Sr{sub 2}Ca{sub 0.85}Cu{sub 2}O{sub y}.

  20. Investigations of Ba{sub x}Sr{sub 1?x}TiO{sub 3} ceramics and powders prepared by direct current arc discharge technique

    SciTech Connect (OSTI)

    Li, Shuangbin; Wang, Xiaohan; Yao, Ying Jia, Yongzhong; Xie, Shaolei; Jing, Yan; Yuzyuk, Yu. I.

    2014-09-01

    Ba{sub x}Sr{sub 1?x}TiO{sub 3} ceramics with x ranging from 0 to 1 were prepared by direct current arc discharge technique and studied by means of x-ray diffraction (XRD) and Raman spectroscopy. The cubic-tetragonal ferroelectric phase transition in Ba{sub x}Sr{sub 1?x}TiO{sub 3} ceramics was found to occur at x???0.75. XRD investigation of as-grown BaTiO{sub 3} ceramics revealed co-existence of tetragonal and hexagonal modifications with a small amount of impurity phase BaTi{sub 4}O{sub 9}. No evidences of hexagonal phase were observed in Raman spectra of as-grown BaTiO{sub 3} ceramics, while Raman peaks related to hexagonal phase were clearly observed in the spectrum of fine-grain powders prepared from the same ceramics. A core-shell model for BaTiO{sub 3} ceramics prepared by direct current arc discharge technique is proposed. Absence of the hexagonal phase in any Ba{sub x}Sr{sub 1?x}TiO{sub 3} solid solution with x?

  1. Significant enhancement in thermoelectric properties of polycrystalline Pr-doped SrTiO{sub 3??} ceramics originating from nonuniform distribution of Pr dopants

    SciTech Connect (OSTI)

    Dehkordi, Arash Mehdizadeh; Bhattacharya, Sriparna; He, Jian; Alshareef, Husam N.; Tritt, Terry M.

    2014-05-12

    Recently, we have reported a significant enhancement (>70% at 500?C) in the thermoelectric power factor (PF) of bulk polycrystalline Pr-doped SrTiO{sub 3} ceramics employing a novel synthesis strategy which led to the highest ever reported values of PF among doped polycrystalline SrTiO{sub 3}. It was found that the formation of Pr-rich grain boundary regions gives rise to an enhancement in carrier mobility. In this Letter, we investigate the electronic and thermal transport in Sr{sub 1?x}Pr{sub x}TiO{sub 3} ceramics in order to determine the optimum doping concentration and to evaluate the overall thermoelectric performance. Simultaneous enhancement in the thermoelectric power factor and reduction in thermal conductivity in these samples resulted in more than 30% improvement in the dimensionless thermoelectric figure of merit (ZT) for the whole temperature range over all previously reported maximum values. Maximum ZT value of 0.35 was obtained at 500?C.

  2. Overcoming phase instability of RBaCo2O5+ (R = Y and Ho) by Sr substitution for application as cathodes in solid oxide fuel cells

    SciTech Connect (OSTI)

    Kim, Jung-Hyun; Young Nam, Kim; Bi, Zhonghe; Manthiram, Arumugam; Paranthaman, Mariappan Parans; Huq, Ashfia

    2013-01-01

    Phase instabilities of the RBaCo2O5+ (R = Y and Ho) layered-perovskites and their decompositions into RCoO3 and BaCoO3-z at 800 oC in air were investigated. This will restrict their high temperature applications such as cathodes in solid oxide fuel cell (SOFC). However, appropriate amount of Sr substitution ( 60 % for R = Y and 70 % for R = Ho) for Ba successfully stabilized the R(Ba1-xSrx)Co2O5+ phase at elevated temperatures. This can be explained by decreasing oxygen vacancies at R-O layer, decreasing R-O bonding length, and consequent improvement of structural integrity. In addition, the Sr substitution (x = 0.6 - 1.0) for Ba provided added benefit with respect to the chemical stability against Ce0.8Gd0.2O1.9 (GDC) electrolyte, which is a critical requirement for the cathodes in SOFC. Among the various compositions investigated, the Y(Ba0.3Sr0.7)Co2O5+ + GDC composite cathode delivered the optimum electrochemical performances with a stable phase demonstrating the potential as a cathode in SOFC.

  3. Effect of La{sup 3+} substitution with Gd{sup 3+} on the resistive switching properties of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films

    SciTech Connect (OSTI)

    Lee, Hong-Sub; Park, Chang-Sun; Park, Hyung-Ho

    2014-05-12

    This study demonstrated that the resistive switching voltage of perovskite manganite material could be controlled by A-site cation substitution in A MnO{sub 3} perovskite manganite structure. A partial substitution of La{sup 3+} in La{sub 0.7}Sr{sub 0.3}MnO{sub 3} with smaller cation Gd{sup 3+} induced A-site vacancy of the largest Sr{sup 2+} cation with surface segregation of SrO{sub y} due to ionic size mismatch, and the induced vacancies reduced migration energy barrier. The operating voltage decreased from 3.5?V to 2.5?V due to a favorable condition for electrochemical migration and redox of oxygen ions. Moreover, surface-segregated SrO{sub y} was enhanced with Gd-substitution and the SrO{sub y} reduced Schottky-like barrier height and resistive switching ratio from the potential drop and screening effect. The relationship between A-site vacancy generation resulting in surface segregation of SrO{sub y} and resistive switching behavior was also investigated by energy resolved x-ray photoelectron spectroscopy, O 1s near edge x-ray absorption spectroscopy, and current voltage measurement.

  4. Isothermal evaporation process simulation using the Pitzer model for the Quinary system LiCl–NaCl–KCl–SrCl2–H2O at 298.15 K

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

    Meng, Lingzong; Gruszkiewicz, Miroslaw S.; Deng, Tianlong; Guo, Yafei; Li, Dan

    2015-08-05

    In this study, the Pitzer thermodynamic model for solid-liquid equilibria in the quinary system LiCl–NaCl–KCl–SrCl2–H2O at 298.15 K was constructed by selecting the proper parameters for the subsystems in the literature. The solubility data of the systems NaCl–SrCl2–H2O, KCl–SrCl2–H2O, LiCl–SrCl2–H2O, and NaCl–KCl–SrCl2–H2O were used to evaluate the model. Good agreement between the experimental and calculated solubilities shows that the model is reliable. The Pitzer model for the quinary system at 298.15 K was then used to calculate the component solubilities and conduct computer simulation of isothermal evaporation of the mother liquor for the oilfield brine from Nanyishan district in themore » Qaidam Basin. The evaporation-crystallization path and sequence of salt precipitation, change in concentration and precipitation of lithium, sodium, potassium, and strontium, and water activities during the evaporation process were demonstrated. The salts precipitated from the brine in the order : KCl, NaCl, SrCl2∙6H2O, SrCl2∙2H2O, and LiCl∙H2O. The entire evaporation process may be divided into six stages. In each stage the variation trends for the relationships between ion concentrations or water activities and the evaporation ratio are different. This result of the simulation of brines can be used as a theoretical reference for comprehensive exploitation and utilization of this type of brine resources.« less

  5. Webpage Data 2014-05-06 1230-RogerNelsonVersion_rfk.xlsx

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

    GPS Location 01 3192014 Below MDC Below MDC GPS Location 02 3192014 Below MDC Below MDC GPS Location 03 3192014 Below MDC Below MDC GPS Location 04 3192014 Below MDC Below...

  6. Webpage Data 2014-05-06 1230-RogerNelsonVersion_rfk.xlsx

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    H-7 Pad (0-2 cm) 6132014 Below MDC Below MDC H-7 Pad (0-2 cm) (Duplicate) 6132014 Below MDC Below MDC GPS Location 01 (0-2 cm) 3192014 Below MDC Below MDC GPS Location 02...

  7. Webpage Data 2014-04-29 0900-RogerNelsonVersion.xlsx

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

    of radiation of about 620 millirem. A person receives about 10 millirems from a single chest x-ray procedure. For more comparisons, see the millirem comparisons poster. Dose...

  8. monolayers BUNKER,BRUCE C.; CARPICK,ROBERT W.; ASSINK,ROGER A...

    Office of Scientific and Technical Information (OSTI)

    P.; GULLEY,GERALD L. 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; SYNTHESIS; AQUEOUS SOLUTIONS; THIN FILMS; SILANES; HYDROLYSIS;...

  9. Webpage Data 2014-10-20 1430-RogerNelsonVersion.xlsx

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

    Biotic Rabbit/Sample of Opportunity 8/14/2014 Below MDC Below MDC Biotic Rabbit/Sample of Opportunity 7/29/2014 Below MDC Below MDC Biotic Deer/Sample of Opportunity 6/5/2014 Below MDC Below MDC Biotic Deer/Sample of Opportunity (Dup) 6/5/2014 Below MDC Below MDC Biotic Rabbit/Sample of Opportunity 5/15/2014 Below MDC Below MDC Biotic Quail/Location 2 3/25/2014 Below MDC Below MDC MDC = Minimum Detectable Concentration (An analytical laboratory limit below which any level present cannot be

  10. Meade, R. A. (Roger A.) 99 GENERAL AND MISCELLANEOUS//MATHEMATICS...

    Office of Scientific and Technical Information (OSTI)

    SCIENCE; FREEDOM OF INFORMATION ACT; HISTORICAL ASPECTS; LOS ALAMOS; RESEARCH PROGRAMS; WEAPONS; SECRECY PROTECTION The secrecy required by nuclear research during the Second...

  11. A novel yellow-emitting SrAlSi{sub 4}N{sub 7}:Ce{sup 3+} phosphor for solid state lighting: Synthesis, electronic structure and photoluminescence properties

    SciTech Connect (OSTI)

    Ruan, Jian; Xie, Rong-Jun; Funahashi, Shiro; Tanaka, Yoshinori; Takeda, Takashi; Suehiro, Takayuki; Hirosaki, Naoto; Li, Yuan-Qiang

    2013-12-15

    Ce{sup 3+}-doped and Ce{sup 3+}/Li{sup +}-codoped SrAlSi{sub 4}N{sub 7} phosphors were synthesized by gas pressure sintering of powder mixtures of Sr{sub 3}N{sub 2}, AlN, ?-Si{sub 3}N{sub 4}, CeN and Li{sub 3}N. The phase purity, electronic crystal structure, photoluminescence properties of SrAlSi{sub 4}N{sub 7}:Ce{sup 3+}(Ce{sup 3+}/Li{sup +}) were investigated in this work. The band structure calculated by the DMol{sup 3} code shows that SrAlSi{sub 4}N{sub 7} has a direct band gap of 3.87 eV. The single crystal analysis of Ce{sup 3+}-doped SrAlSi{sub 4}N{sub 7} indicates a disordered Si/Al distribution and nitrogen vacnacy defects. SrAlSi{sub 4}N{sub 7} was identified as a major phase of the fired powders, and Sr{sub 5}Al{sub 5}Si{sub 21}N{sub 35}O{sub 2} and AlN as minor phases. Both Ce{sup 3+} and Ce{sup 3+}/Li{sup +} doped SrAlSi{sub 4}N{sub 7} phosphors can be efficiently excited by near-UV or blue light and show a broadband yellow emission peaking around 565 nm. A highest external quantum efficiency of 38.3% under the 450 nm excitation was observed for the Ce{sup 3+}/Li{sup +}-doped SrAlSi{sub 4}N{sub 7} (5 mol%). A white light LED lamp with color temperature of 6300 K and color rendering index of Ra=78 was achieved by combining Sr{sub 0.97}Al{sub 1.03}Si{sub 3.997}N/94/maccounttest14=t0005{sub 1}8193 {sub 7}:Ce{sup 3+}{sub 0.03} with a commercial blue InGaN chip. It indicates that SrAlSi{sub 4}N{sub 7}:Ce{sup 3+} is a promising yellow emitting down-conversion phosphor for white LEDs. - Graphical abstract: One-phosphor converted white light-emitting diode (LED) was fabricated by combining a blue LED chip and a yellow-emitting SrAlSi4N7:Ce{sup 3+} phosphor (see inset), which has the color rendering index of 78 and color temperature of 6300 K. - Highlights: We reported a new yellow nitride phosphor suitable for solid state lighting. We solved the crystal structure and evidenced a disordered Si/Al distribution. We fabricated a high color rendering white LEDs by using a single SrAlSi4N7:Ce.

  12. Instability, intermixing and electronic structure at the epitaxial LaAlO3/SrTiO3(001) heterojunction

    SciTech Connect (OSTI)

    Chambers, Scott A.; Engelhard, Mark H.; Shutthanandan, V.; Zhu, Zihua; Droubay, Timothy C.; Qiao, Liang; Sushko, P. V.; Feng, Tian; Lee, Hang Don; Gustafsson, Torgny; Garfunkel, Eric; Shah, A.B,; Zuo, J. M.; Ramasse, Q. M.

    2010-10-18

    The question of stability against diffusional mixing at the prototypical LaAlO3/SrTiO3(001) interface is explored using a multi-faceted experimental and theoretical approach. We combine analytical methods with a range of sensitivities to elemental concentrations and spatial separations to investigate interfaces grown using onaxis pulsed laser deposition. We also employ computational modeling based on the density function theory as well as classical force fields to explore the energetic stability of a wide variety of intermixed atomic configurations relative to the idealized, atomically abrupt model. Statistical analysis of the calculated energies for the various configurations is used to elucidate the relative thermodynamic stability of intermixed and abrupt configurations. We find that on both experimental and theoretical fronts, the tendency toward intermixing is very strong. We have also measured and calculated key electronic properties such as potential energy gradients and valence band discontinuity at the interface. We find no measurable electric field in either the LaAlO3 or SrTiO3, and that the valence band offset is near zero, partitioning the band discontinuity almost entirely to the conduction band edge. Significantly, we find it is not possible to account for these electronic properties theoretically without including extensive intermixing in our physical model of the interface. The atomic configurations which give the greatest electrostatic stability are those that eliminate the interface dipole by intermixing, calling into question the conventional explanation for conductivity at this interface electronic reconstruction. Rather, evidence is presented for La indiffusion and doping of the SrTiO3 below the interface as being the cause of the observed conductivity.

  13. Preferential Eu Site Occupation and Its Consequences in the Ternary Luminescent HalidesAB2I5:Eu2+(A=Li–Cs;B=Sr, Ba)

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

    Fang, C.  M.; Biswas, Koushik

    2015-07-22

    Several rare-earth-doped, heavy-metal halides have recently been identified as potential next-generation luminescent materials with high efficiency at low cost. AB2I5:Eu2+ (A=Li–Cs; B=Sr, Ba) is one such family of halides. Its members, such as CsBa2I5:Eu2+ and KSr2I5:Eu2+, are currently being investigated as high-performance scintillators with improved sensitivity, light yield, and energy resolution less than 3% at 662 keV. Within the AB2I5 family, our first-principles-based calculations reveal two remarkably different trends in Eu site occupation. The substitutional Eu ions occupy both eightfold-coordinated B1(VIII) and the sevenfold-coordinated B2(VII) sites in the Sr-containing compounds. However, in the Ba-containing crystals, Eu ions strongly prefer themore » B2(VII)sites. This random versus preferential distribution of Eu affects their electronic properties. The calculations also suggest that in the Ba-containing compounds one can expect the formation of Eu-rich domains. These results provide atomistic insight into recent experimental observations about the concentration and temperature effects in Eu-doped CsBa2I5. We discuss the implications of our results with respect to luminescent properties and applications. We also hypothesize Sr, Ba-mixed quaternary iodides ABaVIIISrVIII5:Eu as scintillators having enhanced homogeneity and electronic properties.« less

  14. Itinerant electrons, local moments, and magnetic correlations in the pnictide superconductors CeFeAsO₁₋xFxand Sr(Fe₁₋xCox)₂As₂

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

    Vilmercati, Paolo; Fedorov, Alexei; Bondino, Federica; Offi, Francesco; Panaccione, Giancarlo; Lacovig, Paolo; Simonelli, Laura; McGuire, Michael A.; Sefat, Athena S. M.; Mandrus, David; et al

    2012-06-15

    A direct and element-specific measurement of the local Fe spin moment has been provided by analyzing the Fe 3s core level photoemission spectra in the parent and optimally doped CeFeAsO₁₋xFx (x = 0, 0.11) and Sr(Fe₁₋xCox)2As2 (x = 0, 0.10) pnictides. The rapid time scales of the photoemission process allowed the detection of large local spin moments fluctuating on a 10⁻¹⁵ s time scale in the paramagnetic, antiferromagnetic, and superconducting phases, indicative of the occurrence of ubiquitous strong Hund's magnetic correlations. The magnitude of the spin moment is found to vary significantly among different families, 1.3μB in CeFeAsO and 2.1μBmore » in SrFe₂As₂. Surprisingly, the spin moment is found to decrease considerably in the optimally doped samples, 0.9μB in CeFeAsO₀.₈₉F₀.₁₁ and 1.3μB in Sr(Fe₀.₉Co₀.₁)₂As₂. The strong variation of the spin moment against doping and material type indicates that the spin moments and the motion of itinerant electrons are influenced reciprocally in a self-consistent fashion, reflecting the strong competition between the antiferromagnetic superexchange interaction among the spin moments and the kinetic energy gain of the itinerant electrons in the presence of a strong Hund's coupling. By describing the evolution of the magnetic correlations concomitant with the appearance of superconductivity, these results constitute a fundamental step toward attaining a correct description of the microscopic mechanisms shaping the electronic properties in the pnictides, including magnetism and high-temperature superconductivity.« less

  15. Distribution change of oxygen vacancies in layered perovskite type(Sr, La){sub n+1}Fe{sub n}O{sub 3n+1} (n=3)

    SciTech Connect (OSTI)

    Kagomiya, Isao Jimbo, Keigo; Kakimoto, Ken-ichi

    2013-11-15

    To elucidate characteristic oxygen vacancy formation in layered perovskite (Sr, La){sub n+1}Fe{sub n}O{sub 3n+1} with the perovskite layer number: n=3, oxygen vacancy content ? of the (Sr{sub 0.775}La{sub 0.225}){sub 4}Fe{sub 3}O{sub 10??} (SLF4310) was investigated using a titration technique and a thermogravimetric analysis. The equilibrium constant K for the reduction reaction: Oo{sup }+2Fe{sub Fe}{sup ?} (Fe{sup 4+})=1/2O{sub 2}+Vo{sup ??}+2Fe{sub Fe}{sup }(Fe{sup 3+}) was estimated using the vacancy content ?. The Arrhenius plot of the K reveals slope change at approximately 775 C. From the Rietveld analysis, the oxygen vacancies are the most remarkable at the O2 (O4) sites at lower (higher) temperatures than about 800 C, which temperature is approximately comparable with that of slope change in the K. These facts mean that distribution of vacancy sites in the SLF4310 changes at approximately 775 C, accompanying no structural phase transition. The vacancy distribution change affects to the ion conductivity of the SLF4310. - Graphical abstract: Crystal structure of (Sr{sub 0.775}La{sub 0.225}){sub 4}Fe{sub 3}O{sub 10??} (SLF4310) at 1000 C. Display Omitted - Highlights: Distribution change of oxygen vacancies is appeared at approximately 775 C. The distribution change with no structure phase transition is the first observation. The vacancy distribution change affects the ion conductivity of the SLF4310.

  16. Preferential Eu Site Occupation and Its Consequences in the Ternary Luminescent HalidesAB2I5:Eu2+(A=Li–Cs;B=Sr, Ba)

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

    Fang, C.  M.; Biswas, Koushik

    2015-07-22

    Several rare-earth-doped, heavy-metal halides have recently been identified as potential next-generation luminescent materials with high efficiency at low cost. AB2I5:Eu2+ (A=Li–Cs; B=Sr, Ba) is one such family of halides. Its members, such as CsBa2I5:Eu2+ and KSr2I5:Eu2+, are currently being investigated as high-performance scintillators with improved sensitivity, light yield, and energy resolution less than 3% at 662 keV. Within the AB2I5 family, our first-principles-based calculations reveal two remarkably different trends in Eu site occupation. The substitutional Eu ions occupy both eightfold-coordinated B1(VIII) and the sevenfold-coordinated B2(VII) sites in the Sr-containing compounds. However, in the Ba-containing crystals, Eu ions strongly prefer themore »B2(VII)sites. This random versus preferential distribution of Eu affects their electronic properties. The calculations also suggest that in the Ba-containing compounds one can expect the formation of Eu-rich domains. These results provide atomistic insight into recent experimental observations about the concentration and temperature effects in Eu-doped CsBa2I5. We discuss the implications of our results with respect to luminescent properties and applications. We also hypothesize Sr, Ba-mixed quaternary iodides ABaVIIISrVIII5:Eu as scintillators having enhanced homogeneity and electronic properties.« less

  17. SrAgZn and EuAgZn with KHg{sub 2}-type structureStructure, magnetic properties, and {sup 151}Eu Mssbauer spectroscopy

    SciTech Connect (OSTI)

    Gerke, Birgit; Rodewald, Ute Ch.; Niehaus, Oliver; Pttgen, Rainer

    2013-07-15

    Samples of SrAgZn and EuAgZn were synthesized by reaction of the elements in sealed tantalum crucibles. Both structures were refined on the basis of single crystal X-ray diffractometer data: KHg{sub 2}-type, Imma, a=476.7(1), b=780.9(2), c=810.1(2) pm, R{sub 1}/wR{sub 2}=0.0189/0.0119, 381 F values for SrAg{sub 1.12}Zn{sub 0.88} and a=474.43(9), b=760.8(2), c=799.0(2) pm, R{sub 1}/wR{sub 2}=0.0226/0.0483, 370 F values for EuAg{sub 1.17}Zn{sub 0.83} with 13 variables per refinement. Silver and zinc are randomly distributed on the Hg position and build up three-dimensional networks. EuAgZn shows ferromagnetic ordering at 29(1) K. In the temperature range from 75 to 300 K the sample shows CurieWeiss behaviour with ?{sub eff}=7.87(1) ?{sub B}/Eu atom and ?{sub P}=37.1(1) K, indicating divalent europium. {sup 151}Eu Mssbauer spectroscopic measurements confirmed the divalent state with an isomer shift of ?9.31 mm/s at 78 K. Temperature dependent {sup 151}Eu data show first magnetic hyperfine field splitting at 25 K and a saturated magnetization of 17 T at 5.2 K. The temperature dependence can be described by an S=7/2 Brillouin function. - Graphical abstract: The near neighbor coordination of the strontium and europium atoms in SrAg{sub 1.12}Zn{sub 0.88}, EuAg{sub 1.17}Zn{sub 0.83}, and EuAuZn. - Highlights: Synthesis of new intermetallic zinc compounds SrAgZn and EuAgZn. Ferromagnetic ordering of EuAgZn at 29 K. Magnetic hyperfine field splitting in the {sup 151}Eu Mssbauer spectrum.

  18. Fermi surface measurements in YBa sub 2 Cu sub 3 O sub 7-x and La sub 1. 874 Sr sub. 126 CuO sub 4

    SciTech Connect (OSTI)

    Howell, R.H.; Sterne, P.A.; Solal, F.; Fluss, M.J. ); Haghighi, H.; Kaiser, J.H.; Rayner, S.L.; West, R.N. ); Liu, J.Z; Shelton, R. ); Kojima, H. ); Kitazawa, K. )

    1991-06-25

    We report new, ultra high precision measurements of the electron-positron momentum spectra of YBa{sub 2}Cu{sub 3}O{sub 7-x} and La{sub 1.874}Sr{sub 126}CuO{sub 4}. The YBCO experiments were performed on twin free, single crystals and show discontinuities with the symmetry of the Fermi surface of the CuO chain bands. Conduction band and underlying features in LSCO share the same symmetry and can only be separated with the aid of LDA calculations. 5 refs., 3 figs.

  19. Magneto-transport in LaTi{sub 1?x}Mn{sub x}O{sub 3}/SrTiO{sub 3} oxide heterostructures

    SciTech Connect (OSTI)

    Kumar, Pramod Dogra, Anjana Budhani, R. C.

    2014-04-24

    We report the growth of ultrathin film of Mn doped LaTiO{sub 3} on TiO{sub 2} terminated SrTiO{sub 3} (001) substrate by pulsed laser deposition (PLD) and their electrical transport characteristics including magnetoresistance (MR). Though the replacement of Mn in LaTiO{sub 3} at the Ti site in dilute limit does not affect the metallic behaviour of films but variation in resistance is observed. Normalised resistance behaviour is explained on the basis of variation in charge carriers and increased interaction between Mn atoms in the system under investigation.

  20. Control of normal and abnormal bipolar resistive switching by interface junction on In/Nb:SrTiO{sub 3} interface

    SciTech Connect (OSTI)

    Sun, J.; Jia, C. H.; Li, G. Q.; Zhang, W. F.

    2012-09-24

    The resistive switching behaviors of indium (In)/Nb:SrTiO{sub 3} (NSTO) with different metal/semiconductor contacts are investigated. The In electrodes with the Schottky contacts are fabricated on NSTO surface using direct current reactive magnetron sputtering, and the fresh In is directly pressed to form the Ohmic contact. The device with one Schottky barrier displays a normal bipolar resistive switching (BRS) behavior, while the device with two Schottky barriers shows an abnormal BRS behavior. The results demonstrate that the injection and trapping or detrapping of carriers near the interface between the metal electrode and semiconductor are closely related to the resistive switching performance.

  1. Manipulation of subsurface carbon nanoparticles in Bi2Sr2CaCu2O8+? using a scanning tunneling microscope

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

    Stollenwerk, A. J.; Hurley, N.; Beck, B.; Spurgeon, K.; Kidd, T. E.; Gu, G.

    2015-03-19

    In this study, we present evidence that subsurface carbon nanoparticles in Bi?Sr?CaCu?O8+? can be manipulated with nanometer precision using a scanning tunneling microscope. High resolution images indicate that most of the carbon particles remain subsurface after transport observable as a local increase in height as the particle pushes up on the surface. Tunneling spectra in the vicinity of these protrusions exhibit semiconducting characteristics with a band gap of approximately 1.8 eV, indicating that the incorporation of carbon locally alters the electronic properties near the surface.

  2. Improvement of the physical properties of novel (1 ? y) Co{sub 0.8}Cu{sub 0.2}Fe{sub 2}O{sub 4} + (y) SrTiO{sub 3} nanocomposite

    SciTech Connect (OSTI)

    Ahmed, M.A.; Mansour, S.F.; Abdo, M.A.

    2013-05-15

    Graphical abstract: The ME coefficient as a function of magnetic field for the composites (1 ? y) Co{sub 0.8}Cu{sub 0.2}Fe{sub 2}O{sub 4} + (y) SrTiO{sub 3} (y = 40, 50, 60 and 80%). Highlights: ? T{sub C} and M{sub s} decrease with the increase of SrTiO{sub 3} concentration. ? The PE hysteresis loops were observed for all compositions. ? The maximum ME coefficient was observed for the composite with 60% SrTiO{sub 3}. - Abstract: Magnetoelectric (ME) nanocomposites (1 ? y) Co{sub 0.8}Cu{sub 0.2}Fe{sub 2}O{sub 4} + (y) SrTiO{sub 3} (y = 40, 50, 60, 80 and 100%) were prepared by standard ceramic method. Phase formation was checked using X-ray diffraction analysis. Both saturation magnetization (M{sub s}) and Curie temperature (T{sub C}) decrease with increasing SrTiO{sub 3} content. Temperature dependence of the dielectric constant reveals two maxima, one about 550 K corresponds to non-stoichiometry and lattice distortions while the second around 900 K corresponds to the Curie temperature (T{sub C}). The large value of ME output is due to the strain induced by lattice distortion in the ferrite phase by JahnTeller ions like Cu. Hence, JahnTeller effect in the ferrite leads to polarization in the piezoelectric phase.

  3. Method of forming a dielectric thin film having low loss composition of Ba.sub.x Sr.sub.y Ca.sub.1-x-y TiO.sub.3 : Ba.sub.0.12-0.25 Sr.sub.0.35-0.47 Ca.sub.0.32-0.53 TiO.sub.3

    DOE Patents [OSTI]

    Xiang, Xiao-Dong (Alameda, CA); Chang, Hauyee (Berkeley, CA); Takeuchi, Ichiro (Albany, CA)

    2000-01-01

    A dielectric thin-film material for microwave applications, including use as a capacitor, the thin-film comprising a composition of barium strontium calcium and titanium of perovskite type (Ba.sub.x Sr.sub.y Ca.sub.1-x-y)TiO.sub.3. Also provided is a method for making a dielectric thin film of that formula over a wide compositional range through a single deposition process.

  4. sr0923.docx

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

    Peters of Peters Machine and Welding in Beech Island, S.C. They had to borrow money to stay afloat, and were hoping that someone or some company would need their particular...

  5. SR-06-04

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

    Giusti (803) 952-7697 Media Advisory: Historic Preservation Signing Ceremony Flag Ribbon Art Note To News Directors & Editors On July 8, 2004, at 3:30 p.m., the Savannah River...

  6. SR0920.docx

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

    to solve complex problems it is a win-win for industry and the environment," said Casey Knapp, project manager for new technology. Often, traditional remediation systems that...

  7. sr0801.doc

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

    Office, P.O. Box A, Aiken, S.C. 29802 NEWS MEDIA CONTACTS: For Immediate Release June 19, 2008 Julie Petersen (803) 952-7690 julie.petersen@srs.gov Jim Giusti (803) 952-7684 james-r.giusti@srs.gov DOE Marks Key Cleanup and Closure Milestones at its Savannah River Site AIKEN, S.C. - U.S. Department of Energy (DOE) Assistant Secretary for Environmental Management (EM) James A. Rispoli today marked the start of normal operations of interim salt waste processing facilities - the Actinide Removal

  8. sr0934.doc

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

    and about 25 people during permanent operations," said Secretary Chu in addressing an audience of over 150 stakeholders and employees during the groundbreaking ceremony at SRS....

  9. SR0914.docx

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

    Savannah River Nuclear Solutions, LLC, (SRNS) the operating contractor for SRS, is in the process of hiring over 2,000 new employees to accelerate site cleanup activities under the...

  10. SR0929.docx

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

    legacy oil, which was generated as early as 1985, includes 70 55-gallon carbon-steel drums welded shut which contain plastic bottles and large kegs of oil. So far, 43 of the 70...

  11. SR0915.docx

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

    owned and operated by Energy Solutions. Over the next 14 months, approximately 14,800 drums of DUO will be shipped out of South Carolina for final disposal using 52 DOE-owned...

  12. sr0907.docx

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

    of TRU waste to WIPP on May 8, 2001. SRS has safely shipped more than 28,200 55-gallon drums of TRU waste for disposal at the WIPP geologic repository since that time. "This is a...

  13. sr0933.docx

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

    of contaminated lead to an off-site processing facility in Oak Ridge, Tenn. for recycling. Savannah River Nuclear Solutions, the management and operating contractor, and...

  14. sr0932.docx

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

    Recovery Act money started to be awarded, the site needed more trailers," said Richard Moore, the company's commercial sales manager. That's when Fogle jumped on the opportunity....

  15. SR0908.docx

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

    Paivi Nettamo, SRNS, (803) 952-6938 paivi.nettamo@srs.gov North Augusta Man Starts Work at SRS Thanks to the Recovery Act AIKEN, S.C., June 9, 2009 - During these...

  16. SR-01-04

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

    April 29, 2004 Media Contact: Bill Taylor (803) 952-7697 SRS to Host "Carolina Challenge" Security Police Competition Flag Ribbon Art Aiken, SC -- The U.S. Department of Energy...

  17. SR-03-04

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

    3, 2004 Media Contact: Bill Taylor (803) 952-7697 Wackenhut Services Inc. -- SRS Award Fee Determination Flag Ribbon Art NOTE TO EDITORS AND NEWS DIRECTORS: The Department of...

  18. sr0905.doc

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

    julie.petersen@srs.gov DOE Sets Energy Savings Contract in Motion for New Renewable Energy Fueled Plant at SRS New Steam Production Biomass Plant and Boilers to Yield Public...

  19. sr0924.docx

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

    waste left the Site on September 10. PUREX solvent, which stands for Plutonium Uranium Extraction solvent, was used to separate uranium and plutonium from fission products...

  20. SR201003.docx

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

    SRS Tank 5 Moves to Closure Aiken, SC -- American Recovery and Reinvestment Act funding is helping accelerate tank closures at the Department of Energy's (DOE) Savannah River...

  1. SR-04-04

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

    5, 2004 Media Contact: Jim Giusti (803) 952-7697 Media Advisory: Tritium Celebration Flag Ribbon Art Note to News Directors and Editors: AIKEN, S.C. (June 25, 2004)-The National Nuclear Security Administration (NNSA) Savannah River Site Office and Westinghouse Savannah River Company will host a recognition ceremony at 11:30 on Thursday, July 1, for approximately 700 craft and other personnel working on the site's two large Defense Programs project: the Tritium Extraction Facility (TEF) and the

  2. SR201002.docx

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

    Recovery Act Funding Accelerates Tank Closure at the Savannah River Site Aiken, SC (Dec. 9) - "Innovate and accelerate safely" describes the upgrade work underway at H Area Waste Tank 13, an American Recovery and Reinvestment Act project being performed by Savannah River Remediation LLC ( SRR). Placed in service in 1956, Tank 13 is an underground waste storage tank with a capacity of over a million gallons. It has been out of active service for more than twenty-five (25) years and

  3. SR0921.docx

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

    responsible for the management and operations of SRS for the DOE. De'Lisa Bratcher, Environmental Justice Program Manager for DOE-Savannah River, said she was touched, time after...

  4. SR0909.docx

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

    paivi.nettamo@srs.gov SAVANNAH RIVER SITE SET DATES FOR RECOVERY ACT PROJECT TOWN HALL MEETINGS AND JOB FAIRS Barnwell, S.C., June 17, 2009 * Allendale, S.C., June 24, 2009...

  5. SR0913.docx

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

    paivi.nettamo@srs.gov SAVANNAH RIVER SITE SET DATES FOR RECOVERY ACT PROJECT TOWN HALL MEETINGS AND JOB FAIRS Aiken, S.C., July 7, 2009 * Augusta, G.A., July 20, 2009 Aiken,...

  6. SR0911.docx

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    will be customized by the customer. This test consists of a review of history, blood work, an electrocardiogram (EKG) and pulmonary function, and audio testing. Some...

  7. 2010SR01.docx

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

    Paivi Nettamo, SRNS, (803) 952-6938 paivi.nettamo@srs.gov 100 th Recovery Act TRU Shipment Leaves SRS for Permanent Disposition Recovery Act Accelerates TRU Shipment as Part of Site Clean-Up Plan Aiken, S.C. - Transuranic (TRU) waste leaving the Department of Energy's (DOE) Savannah River Site (SRS) by truck in November for the Waste Isolation Pilot Plant (WIPP), near Carlsbad, N.M., marked the 100 th shipment for the Recovery Act Project and the 128 th shipment for the 2009 calendar year. The

  8. 2010SR04.docx

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

    Savannah River Nuclear Solutions Schedules Series for Small Businesses Interested in Recovery Act Contracts (Aiken, S.C.) - A series of luncheons for small businesses interested in securing contracts related to the American Recovery and Reinvestment Act (ARRA) at the Department of Energy's (DOE) Savannah River Site (SRS) has been scheduled. The series is organized by the management and operations contractor at the Site, Savannah River Nuclear Solutions LLC (SRNS). "We want to assure that

  9. 2010SR05.doc

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

    Big Top Tent Keeps TRU Waste Trucks, Tanks Dry before Inspection and Shipping Big Top Aids Solid Waste Management in Shipping Protocol Aiken, S.C. - Important projects for the Recovery Act - and not a circus act - are being performed under the Big Top at Solid Waste Management facility at the Department of Energy's (DOE) Savannah River Site (SRS). The jumbo-size vinyl tent with a metal frame measuring 160 feet long, 24 feet wide, and 20 feet high is used in the Site's E Area to shelter trucks

  10. 2010sr07.doc

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

    February 23, 2010 james-r.giusti@srs.gov Kyle Bryant, EPA-4, (404) 562-9073 bryant.kyle@epa.gov Paivi Nettamo, SRNS, (803) 952-6938 paivi.nettamo@srs.gov SRS Moves Forward With Final Closure of Cold War Reactors AIKEN, S.C. - With the beginning of a new decade, the U.S. Department of Energy's (DOE) Savannah River Site (SRS) is moving forward with its decommissioning activities for the SRS Cold War Production Reactors. The Department approved the construction start of the in-situ decommissioning

  11. 2010sr13.doc

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

    April 13, 2010 james-r.giusti@srs.gov DOE Announces Intention to Offer State of Georgia Additional Enviromental Monitoring Funds AIKEN, SC - The Department of Energy (DOE) today announced its intention to fund additional independent environmental monitoring of the Savannah River Site (SRS) by the State of Georgia. Through its grant program, DOE's Savannah River Operations Office will provide the Georgia Department of Natural Resources financial assistance to conduct independent environmental

  12. 2010sr14.doc

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

    John Lindsay, SRR, (803) 208-6253 john02lindsay@srs.gov Regional Businesses Benefit as Recovery Act Funding Flows into the Economy at SRS More than $11 million in local and small business contracts awarded Aiken, SC -- Local and small businesses in the Central Savannah River Area (CSRA) have benefited from more than $11 million worth of new business since last October, as part of the Department of Energy's (DOE) American Recovery and Reinvestment Act projects at the Savannah River Site (SRS).

  13. 2010sr15.doc

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

    With ARRA Funds, P-Reactor Disassembly Basin Project Moves One Step Closer to Final Decommissioning Aiken, S.C. - Funding through the American Recovery and Reinvestment Act has moved the Department of Energy one step closer to closing the book on the Cold War-era P- Reactor facility at the Savannah River Site (SRS). With the installation, testing and startup of six evaporator units, SRS can begin removing about 4.6 million gallons of water from the 105-P Reactor Disassembly Basin - a phase of in

  14. 2010sr16.doc

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

    Recovery Act Funds Put Aiken Technical College Rad Con Graduates to Work Early Aiken, S.C. - Using $200,000 in American Recovery and Reinvestment Act funds from the U.S. Department of Energy's Savannah River Site (SRS), the Aiken Technical College's (ATC) Radiation Protection Technology Program will be able to catapult 16 graduates into the local work force nearly six months ahead of schedule. "The program's first graduates are a success story that has come to life in a short period of

  15. 2010sr17.doc

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

    Thursday, May 13, 2010 james-r.giusti@srs.gov DOE to Host Public Education Forum on Use of Performance Assessments Aiken, SC -- The U.S. Department of Energy (DOE) will host a public education forum on the development and use of Performance Assessments (PAs) for making waste management decisions at DOE sites across the complex. The educational forum, planned in coordination with the Savannah River Site (SRS) Citizen's Advisory Board Waste Management Committee, will facilitate public involvement

  16. 2010sr18.doc

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

    Tuesday, May 25, 2010 james-r.giusti@srs.gov Paivi Nettamo, SRNS, (803) 292-2484 paivi.nettamo@srs.gov SRS Demolishes Massive Cooling Tower, Continues Progress on Environmental Footprint Reduction (Aiken, S.C.) - The Savannah River Site's (SRS) massive K Cooling Tower was safely demolished today as part of the Site-wide Footprint Reduction Initiative funded by the American Recovery and Reinvestment Act (ARRA). As the second-largest cooling tower to be demolished worldwide, the 450 foot-tall and

  17. 2010sr19.doc

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

    Wednesday, June 2, 2010 james-r.giusti@srs.gov John Lindsay, SRR, (803) 208-6253 john02lindsay@srs.gov Blowing Bubbles Using Recovery Act Funds, SRS Looks to Apply Novel Solutions to Unique Challenges Aiken, SC - Blowing bubbles is not usually associated with processing liquid radioactive waste. Nevertheless, new bubbler technology and other enhancements are soon expected to double the amount of radioactive waste processed annually at the Department of Energy's (DOE) Savannah River Site (SRS).

  18. 2010sr20.doc

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

    Monday, June 21, 2009 james-r.giusti@srs.gov John Lindsay, SRR, (803) 208-6253 john02lindsay@srs.gov New Robot Supports SRS Waste Tank Closures Aiken, SC (June 21) - Movie-goers may have Iron Man 2, but thanks to the American Recovery and Reinvestment Act, the Department of Energy's (DOE) Savannah River Site (SRS) has its own super hero - "Tizzy," a tank-cleaning robot. Tizzy will remove high- level solid radioactive material from the floor of SRS waste tanks and transfer the material

  19. 2010sr21.doc

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

    Wednesday July 7, 2010 james-r.giusti@srs.gov DOE and NRC to Hold Public Meeting on SRS F Tank Farm Waste Determination Draft Basis Document Aiken, SC - The U.S. Department of Energy (DOE) will hold a public meeting with the Nuclear Regulatory Commission (NRC) on the development of the Section 3116 Draft Basis Document for F Tank Farm at the Savannah River Site on July 13 and 14, 2010. The meeting is to help DOE in the identification of issues with the reasonability of the approach to

  20. 2010sr24.doc

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

    25, 2010 james-r.giusti@srs.gov DOE Presents "Star of Excellence" Award to Savannah River Site Contractor AIKEN, S.C. - U.S. Department of Energy (DOE) recently awarded its Voluntary Protection Program "Star of Excellence" to Savannah River Nuclear Solutions for 2010. "Time and again Savannah River Nuclear Solutions has proven how highly they value employee safety," said Inés Triay, Ph.D., DOE Assistant Secretary for Environmental Management. "We recognize

  1. 2010sr25.doc

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

    Tuesday, August 31, 2010 james-r.giusti@srs.gov John Lindsay, SRR, (803) 208-6253 john02lindsay@srs.gov Tank 37 Salt Removal Marks Second Liquid Waste Project Completed Recovery Act Project at SRS Aiken, SC -- Moving radioactive salt safely, closing liquid waste tanks and saving money are the drivers behind the successful completion of another American Recovery and Reinvestment Act project at the Department of Energy's Savannah River Site (SRS). Acknowledging the Tank 37 achievement, Terrel

  2. 2011_sr_03.doc

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

    Wednesday, February 23, 2011 james-r.giusti@srs.gov Paivi Nettamo, SRNS, (803) 646-6075 paivi.nettamo@srs.gov Recovery Act's HWCTR Project Empty of Equipment, Ready for Grouting AIKEN, S.C. - Thanks to investments from the American Recovery and Reinvestment Act, the next phase has begun on decommissioning the Heavy Water Components Test Reactor (HWCTR) at the Savannah River Site (SRS). With the reactor building now empty of its two steam generators and the reactor vessel, work can start on

  3. 2011sr01.doc

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

    Tuesday, February 1, 2011 james-r.giusti@srs.gov Paivi Nettamo, SRNS, (803) 646-6075 paivi.nettamo@srs.gov Recovery Act Funds Test Reactor Dome Removal in Historic D&D Project AIKEN, S.C. - The landscape of the Savannah River Site (SRS) is a little flatter and a little less colorful with the removal today of the 75-foot-tall rusty-orange dome from the Cold War-era test reactor. This $25-million reactor decommissioning and deactivation project is funded By the American Recovery and

  4. 2011sr02.docx

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

    Thursday, February 10, 2011 james-r.giusti@srs.gov Paivi Nettamo, SRNS, (803) 952-6938 paivi.nettamo@srs.gov Savannah River Site Makes Progress on Recovery Act-funded Cleanup AIKEN, S.C. - The Savannah River Site's (SRS) American Reinvestment and Recovery Act program recently disposition of more than 1,000 cubic meters of legacy transuranic waste (TRU). This represents 20 percent of the 5,000 cubic meter inventory of TRU waste that will be disposed as part of the site's Recovery Act program and

  5. SR-02-02

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

    of Energy accident investigation. The injured worker has been released from the hospital and is in rehabilitation at a Georgia facility The direct cause of the fall was the...

  6. sr0906.docx

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

    May 27, 2009 james-r.giusti@srs.gov Fran Poda, SRNS, (803) 952-8671 fran.poda@srs.gov DOE's H-Canyon Finishes Processing Old Reactor Components From Nevada Test Site AIKEN, S.C.,...

  7. sr0928.docx

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

    15, 2009 james-r.giusti@srs.gov Paivi Nettamo, SRNS, (803) 952-6938 paivi.nettamo@srs.gov Savannah River Site to Bring More Local Small Businesses Opportunities Through a Recovery...

  8. SR0918.docx

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

    August 21, 2009 james-r.giusti@srs.gov Paivi Nettamo, SRNS, (803) 952-6938 paivi.nettamo@srs.gov 1000 th Employee Hired under the Recovery Act to Accelerate Cleanup at Savannah...

  9. SR0925.docx

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

    Friday, October 2, 2009 james-r.giusti@srs.gov Dean Campbell, SRR, (803)208-8270 dean.campbell@srs.gov Savannah River Remediation Starts 200 Million in Liquid Waste Work Under the...

  10. sr0927.docx

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

    8, 2009 james-r.giusti@srs.gov Paivi Nettamo, SRNS, (803) 952-6938 paivi.nettamo@srs.gov Job Information And Other Training Opportunities Available Through Road To Recovery Tour...

  11. sr0931.docx

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

    Thursday, October 28, 2009 james-r.giusti@srs.gov Paivi.Nettamo, SRNS, (803) 292-2484 paivi.nettamo@srs.gov Road To Recovery Tour Helps Local Yarn Plant Workers Start Job Search...

  12. SR0919.docx

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

    Tuesday, September 1, 2009 james-r.giusti@srs.gov Paivi Nettamo, SRNS, (803) 952-6938 paivi.nettamo@srs.gov Dean Campbell, SRR, (803) 208-8270 dean.campbell@srs.gov Small Business...

  13. sr0930.doc

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

    CONTACTS FOR IMMEDIATE RELEASE Julie Petersen, (803) 952-7690 Monday, October 26, 2009 julie.petersen@srs.gov Kelly Ling, (803) 952-9172 kelly.ling@srs.gov DOE to Honor Nuclear...

  14. 2010sr32.doc

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

    and twenty cubic yards of the cement slurry, the approximate volume of large at-home swimming pool, was poured into the reactor vessel over two days. The next step in the reactor...

  15. sr0926.docx

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

    over five billion gallons of groundwater - enough to fill 7,575 Olympic sized swimming pools - has been successfully extracted and remediated from Savannah River Site's...

  16. SR-02-04

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

    200 security police officers, representing the DOE sites, U.S. military, local police forces and a team from the United Kingdom. WSI-SRS team members include Security Police...

  17. SR Fill History

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

    systems recovered with troubleshooting 2 1008 08:33 To 1008 17:02 8.49   S26 Cab.3 Gespac PS 1.27 Investigation, standarize, refilled 3 1008 18:18 To 1013 08:00...

  18. 2010sr23.doc

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

    Drainage at the Largest Closed Seepage Basins on SRS Aiken, S.C. - Preventing the migration of contamination from rainwater runoff at a closed seepage basin at the Department...

  19. 2010SR06.docx

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

    additional facilities that are scheduled for D&D. Rapid prototyping automates the translation of CAD drawings into three-dimensional models. Bobbitt describes the equipment used...

  20. SR-05-04

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

    (TCON) are major endeavors designed to equip the NNSA to meet the nation's need for tritium, a radioactive form of hydrogen gas that is a vital component of nuclear weapons. ...

  1. SR0910.docx

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

    then remove it and transport it to a special maintenance cell, where personnel wearing air-supplied protective plastic suits to prevent personal contamination would manually...

  2. SR0916.docx

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

    birth of commercial nuclear power. "This is an exhilarating time at SRS," says Diana Hannah, project manager for the DOE. "The Recovery Act has brought new life to this project...

  3. 2010sr22.doc

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

    from transportation and disposal of contaminated soils and concrete," said Diana Hannah, SRS D-Area Federal Project Director. Pilot testing of the process to remove tritium...

  4. Atomic and electronic structures of SrTiO3/GaAs heterointerfaces: An 80-kV atomic-resolution electron energy-loss spectroscopy study

    SciTech Connect (OSTI)

    Qiao, Q.; Klie, Robert F; Ogut, Serdar; Idrobo Tapia, Juan C

    2012-01-01

    We have examined the atomic and electronic structures of epitaxially grown, ultrathin SrTiO{sub 3} (100) films on GaAs (001) using 80-kV aberration-corrected atomic-resolution Z-contrast imaging and electron energy-loss spectroscopy (EELS) to develop a fundamental understanding of the interfacial structure-property relationships. We find that the interface is atomically abrupt and no surface reconstruction of the GaAs (001) surface is observed. Using atomic-column resolved EELS, we examine the oxygen vacancy and Ti concentrations in the SrTiO{sub 3} film and across the heterointerface. We show that Ti diffuses into the first few monolayers of GaAs. Using a combination of EELS and first-principles calculations, we present evidence for the formation of As oxides at the interface depending on the thin-film growth conditions. These findings are used to explain the differences in the transport behavior of the films.

  5. A striking effect of ionic-liquid anions in the extraction of Sr2+ and Cs+ by dicyclohexano-18-crown-6

    SciTech Connect (OSTI)

    Luo, Huimin; Dai, Sheng; Bonnesen, Peter V; Haverlock, Tamara; Moyer, Bruce A; Buchanan III, A C

    2006-01-01

    The nature of the ionic-liquid (IL) anion has been found to have a remarkable effect on the solvent extraction of Sr2+ and Cs+ by dicyclohexano-18-crown-6 dissolved in ionic liquids. In particular, the extraction efficiency increases with the hydrophobicity of the IL anion as reflected by the solubility in water of ILs having a common cation. Since a cation-exchange mechanism is operating in these systems, the influence of the IL anion is in large part attributable to an expected Le Chatelier effect in which a greater aqueous concentration of IL cation, obtained when using an IL anion of lower hydrophobicity, opposes cation exchange. This dependence is opposite to that found for IL cations, indicating a significant advantage of using ILs with hydrophobic anions for cation extraction. Furthermore, the extraction selectivity for Sr2+ over Na+, K+, and Cs+ can be significantly improved through the use of hydrophobic anions for the ILs containing 1-ethyl-3-methylimidazolium or 1-butyl-3-methylimidazolium cations.

  6. Structural phase transition and magnetism in hexagonal SrMnO{sub 3} by magnetization measurements and by electron, x-ray, and neutron diffraction studies

    SciTech Connect (OSTI)

    Daoud-Aladine, A.; Chapon, L. C.; Knight, K. S.; Martin, C.; Hervieu, M.; Brunelli, M.; Radaelli, P. G.

    2007-03-01

    The structural and magnetic properties of the hexagonal four-layer form of SrMnO{sub 3} have been investigated by combining magnetization measurements, electron diffraction, and high-resolution synchrotron x-ray and neutron powder diffraction. Below 350 K, there is subtle structural phase transition from hexagonal symmetry (space group P6{sub 3}/mmc) to orthorhombic symmetry (space group C222{sub 1}) where the hexagonal metric is preserved. The second-order phase transition involves a slight tilting of the corner-sharing Mn{sub 2}O{sub 9} units composed of two face-sharing MnO{sub 6} octahedra and the associated displacement of Sr{sup 2+} cations. The phase transition is described in terms of symmetry-adapted displacement modes of the high symmetry phase. Upon further cooling, long range magnetic order with propagation vector k=(0,0,0) sets in below 300 K. The antiferromagnetic structure, analyzed using representation theory, shows a considerably reduced magnetic moment indicating the crucial role played by direct exchange between Mn centers of the Mn{sub 2}O{sub 9} units.

  7. Structural distortions in the spin-gap regime of the quantum antiferromagnet SrCu{sub 2}(BO{sub 3}){sub 2}

    SciTech Connect (OSTI)

    Vecchini, C.; Adamopoulos, O.; Chapon, L.C.; Lappas, A.; Kageyama, H.; Ueda, Y.; Zorko, A.

    2009-12-15

    We report the first crystallographic study within the low-temperature (<40 K) spin-gap region of the two-dimensional frustrated antiferromagnet SrCu{sub 2}(BO{sub 3}){sub 2}. The crystal system does not deviate from the tetragonal I-42m space group symmetry. However, our high-resolution neutron powder diffraction measurements uncover subtle structural modifications below 34 K, concomitant to the formation of the dimer singlet ground state. Intimate spin-lattice coupling leads to negative thermal expansion of the tetragonal structure, which reflects into particular local lattice adjustments. The extracted structural parameters suggest the reduction of the buckling found in the copper-borate planes and the strengthening of the leading, in-plane intra-dimer superexchange interaction. The observed contraction along the c-axis, associated with the inter-dimer exchange in adjacent layers, indicates the involvement of weaker three-dimensional interactions in the magnetic properties. The rules posed by the crystal symmetry do not preclude Dzyaloshinsky-Moriya interactions, which therefore remain as an important source of spin anisotropy necessary to rationalise the ground state behaviour. - Abstract: We report the first crystallographic study within the low-temperature spin-gap region of the two-dimensional frustrated antiferromagnet SrCu{sub 2}(BO{sub 3}){sub 2}. Subtle spin-lattice coupling was unveiled in the low-temperature region. Display Omitted

  8. Atomic and electronic structures of single-layer FeSe on SrTiO3(001): The role of oxygen deficiency

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

    Bang, Junhyeok; Li, Zhi; Sun, Y. Y.; Samanta, Amit; Zhang, Y. Y.; Zhang, Wenhao; Wang, Lili; Chen, X.; Ma, Xucun; Xue, Q.-K.; et al

    2013-06-06

    Using first-principles calculation, we propose an interface structure for single triple-layer FeSe on the SrTiO3(001) surface, a high-Tc superconductor found recently. The key component of this structure is the oxygen deficiency on the top layer of the SrTiO3 substrate, as a result of Se etching used in preparing the high-Tc samples. The O vacancies strongly bind the FeSe triple layer to the substrate giving rise to a (2×1) reconstruction, as observed by scanning tunneling microscopy. The enhanced binding correlates to the significant increase of Tc observed in experiment. The O vacancies also serve as the source of electron doping, whichmore » modifies the Fermi surface of the first FeSe layer by filling the hole pocket near the center of the surface Brillouin zone, as suggested from angle-resolved photoemission spectroscopy measurement.« less

  9. Band-Gap Reduction and Dopant Interaction in Epitaxial La,Cr Co-doped SrTiO3 Thin Films

    SciTech Connect (OSTI)

    Comes, Ryan B.; Sushko, Petr; Heald, Steve M.; Colby, Robert J.; Bowden, Mark E.; Chambers, Scott A.

    2014-12-03

    We show that by co-doping SrTiO3 (STO) epitaxial thin films with equal amounts of La and Cr it is possible to produce films with an optical band gap ~0.9 eV lower than that of undoped STO. Sr1-xLaxTi1-xCrxO3 thin films were deposited by molecular beam epitaxy and characterized using x-ray photoelectron spectroscopy and x-ray absorption near-edge spectroscopy to show that the Cr dopants are almost exclusively in the Cr3+ oxidation state. Extended x-ray absorption fine structure measurements and theoretical modeling suggest that it is thermodynamically preferred for La and Cr dopants to occupy nearest neighbor A- and B-sites in the lattice. Transport measurements show that the material exhibits variable-range hopping conductivity with high resistivity. These results create new opportunities for the use of doped STO films in photovoltaic and photocatalytic applications.

  10. Investigation of LaxSr1-xCoyM1-yO3-d (M = Mn Fe) perovskite materials as thermochemical energy storage media.

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

    Babiniec, Sean Michael; Ambrosini, Andrea; Coker, Eric Nicholas; Miller, James E.

    2015-06-23

    Materials in the LaxSr1–xCoyMn1–yO3–δ (LSCM) and LaxSr1–xCoyFe1–yO3–δ (LSCF) families are candidates for high-temperature thermochemical energy storage due to their facility for cyclic endothermic reduction and exothermic oxidation. A set of 16 LSCM and 21 LSCF compositions were synthesized by a modified Pechini method and characterized by powder X-ray diffraction and thermogravimetric analysis. All materials were found to be various symmetries of the perovskite phase. LSCM was indexed as tetragonal, cubic, rhombohedral, or orthorhombic as a function of increased lanthanum content. For LSCF, compositions containing low lanthanum content were indexed as cubic while materials with high lanthanum content were indexed asmore » rhombohedral. An initial screening of redox activity was completed by thermogravimetric analysis for each composition. The top three compositions with the greatest recoverable redox capacity for each family were further characterized in equilibrium thermogravimetric experiments over a range of temperatures and oxygen partial pressures. As a result, these equilibrium experiments allowed the extraction of thermodynamic parameters for LSCM and LSCF compositions operated in thermochemical energy storage conditions.« less

  11. Phase transition in the Ruddlesden-Popper layered perovskite Li{sub 2}SrTa{sub 2}O{sub 7}

    SciTech Connect (OSTI)

    Pagnier, T.; Rosman, N.; Galven, C.; Suard, E.; Fourquet, J.L.; Le Berre, F.; Crosnier-Lopez, M.P.

    2009-02-15

    The crystal structure of the Ruddlesden-Popper layered perovskite Li{sub 2}SrTa{sub 2}O{sub 7} has been characterized at various temperatures between -185 and 300 deg. C by several techniques: X-ray and neutron powder diffraction, single crystal diffraction, transmission electron microscopy and Raman spectroscopy. The low temperature structure has been confirmed to be orthorhombic Cmcm with a small octahedra antiphase tilting ({phi}{phi}0) ({phi}{phi}0) inside the perovskite blocks. With temperature, the tilting progressively vanishes leading around 230 deg. C to a tetragonal symmetry (S.G. I4/mmm). This reversible phase transition, followed by X-ray and neutron thermodiffraction and thermal Raman measurements, is considered as of second order. An attribution of the Raman bands based on normal mode analysis is proposed. - Graphical abstract: Thermal evolution of Li{sub 2}SrTa{sub 2}O{sub 7} X-ray powder diffraction patterns showing the structural transformation from orthorhombic to tetragonal cell.

  12. Human dose assessment for the radionuclides {sup 90}Sr and {sup 90}Y at TA-35 SWMU 35-003 (r) and Ten Site Canyon

    SciTech Connect (OSTI)

    Jarmer, D.; Lyman, J.

    1997-07-01

    This report gives an estimate of the radiological dose to an individual living on or working at a site contaminated with strontium-90 ({sup 90}Sr) and yttrium-90 ({sup 90}Y). The site consists of a small receiving canyon that drains into Ten-Site Canyon at the eastern end of Los Alamos National Laboratory`s technical area 35 (TA-35). Between 1951 and 1963 a wastewater treatment facility located at TA-35 discharged water containing {sup 90}Sr and {sup 90}Y to this receiving canyon. The authors used the RESRAD computer code to calculate the dose to an on-site individual, based on two exposure scenarios: (1) a person working at the site for eight hours a day, five days a week, for twenty-five years and (2) a farmer living at the site twenty four hours a day, seven days a week, for thirty years. The exposure pathways considered were direct exposure to external radiation; inhalation of contaminated dusts; and ingestion of plants, water, and soil. The authors found that the maximum estimated dose rates were 1 and 21 mrem y{sup {minus}1} for the worker and farmer scenarios respectively. The authors have concluded that the value for the worker scenario is well below the DOE dose limit of 100 mrem y{sup {minus}1} but the farmer is overexposed.

  13. Quantifying stoichiometry-induced variations in structure and energy of a SrTiO3 symmetric ?13 {510}/<100?>?grain boundary

    SciTech Connect (OSTI)

    Yang, Hao; Lee, H. S.; Sarahan, M. C.; Sato, Yoichi; Chi, Miaofang; Moeck, Peter; Ikuhara, Yuichi; Browning, Nigel D.

    2013-04-01

    shown to readily accommodate nonstoichiometry changing the electrostatic potential at the boundary plane and effectively controlling material properties such as capacitance, magnetoresistance and superconductivity. Understanding and quantifying exactly how variations in atomic scale nonstoichiometry at the boundary plane extend to the practical mesoscale operating length of the system is therefore critical for improving the overall properties. Bicrystals of SrTiO3 were fabricated to provide the model GB model structures that are analysed in this paper. We show that statistical analysis of aberration-corrected scanning transmission electron microscope images acquired from a large area of GB is an effective routine to understanding the variation in boundary structure that occurs to accommodate nonstoichiometry. In the case of the SrTiO3 22.6 ?13 (510)/[100] GB analysed here, the symmetric atomic structures observed from a micron-long GB can be categorized as two different competing structural arrangements, with and without a rigid-body translation along the boundary plane. How this quantified experimental approach can provide direct insights into the GB energetics is further confirmed from the first principles density functional theory, and the effect of nonstoichiometry in determining the GB energies is quantified.

  14. Anisotropic-strain-relaxation-induced crosshatch morphology in epitaxial SrTiO{sub 3}/NdGaO{sub 3} thin films

    SciTech Connect (OSTI)

    Tan, X. L.; Chen, F.; Chen, P. F.; Xu, H. R.; Chen, B. B.; Jin, F.; Gao, G. Y.; Wu, W. B.

    2014-10-15

    We investigate the strain relaxation and surface morphology of epitaxial SrTiO{sub 3} (STO) films grown on (001){sub O} and (110){sub O} planes of orthorhombic NdGaO{sub 3} (NGO), and (001) plane of cubic (LaAlO{sub 3}){sub 0.3}(Sr{sub 2}AlTaO{sub 6}){sub 0.7} (LSAT) substrates. Although the average lattice mismatches are similar, strikingly regular crosshatched surface patterns can be found on STO/NGO(001){sub O}[(110){sub O}] films, contrary to the uniform surface of STO/LSAT(001). Based on the orientation and thickness dependent patterns and high-resolution x-ray diffractions, we ascribe the crosshatch morphology to the anisotropic strain relaxation with possibly the 60 misfit dislocation formation and lateral surface step flow in STO/NGO films, while an isotropic strain relaxation in STO/LSAT. Further, we show that the crosshatched STO/NGO(110){sub O} surface could be utilized as a template to modify the magnetotransport properties of epitaxial La{sub 0.6}Ca{sub 0.4}MnO{sub 3} films. This study highlights the crucial role of symmetry mismatch in determining the surface morphology of the perovskite oxide films, in addition to their epitaxial strain states, and offers a different route for designing and fabricating functional perovskite-oxide devices.

  15. Atomic and electronic structures of single-layer FeSe on SrTiO3(001): The role of oxygen deficiency

    SciTech Connect (OSTI)

    Bang, Junhyeok; Li, Zhi; Sun, Y. Y.; Samanta, Amit; Zhang, Y. Y.; Zhang, Wenhao; Wang, Lili; Chen, X.; Ma, Xucun; Xue, Q.-K.; Zhang, S. B.

    2013-06-06

    Using first-principles calculation, we propose an interface structure for single triple-layer FeSe on the SrTiO3(001) surface, a high-Tc superconductor found recently. The key component of this structure is the oxygen deficiency on the top layer of the SrTiO3 substrate, as a result of Se etching used in preparing the high-Tc samples. The O vacancies strongly bind the FeSe triple layer to the substrate giving rise to a (21) reconstruction, as observed by scanning tunneling microscopy. The enhanced binding correlates to the significant increase of Tc observed in experiment. The O vacancies also serve as the source of electron doping, which modifies the Fermi surface of the first FeSe layer by filling the hole pocket near the center of the surface Brillouin zone, as suggested from angle-resolved photoemission spectroscopy measurement.

  16. Structural characterisation of BaTiO{sub 3} thin films deposited on SrRuO{sub 3}/YSZ buffered silicon substrates and silicon microcantilevers

    SciTech Connect (OSTI)

    Colder, H.; Jorel, C. Mchin, L.; Domengs, B.; Marie, P.; Boisserie, M.; Guillon, S.; Nicu, L.; Galdi, A.

    2014-02-07

    We report on the progress towards an all epitaxial oxide layer technology on silicon substrates for epitaxial piezoelectric microelectromechanical systems. (101)-oriented epitaxial tetragonal BaTiO{sub 3} (BTO) thin films were deposited at two different oxygen pressures, 5.10{sup ?2} mbar and 5.10{sup ?3} mbar, on SrRuO{sub 3}/Yttria-stabilized zirconia (YSZ) buffered silicon substrates by pulsed laser deposition. The YSZ layer full (001) orientation allowed the further growth of a fully (110)-oriented conductive SrRuO{sub 3} electrode as shown by X-ray diffraction. The tetragonal structure of the BTO films, which is a prerequisite for the piezoelectric effect, was identified by Raman spectroscopy. In the BTO film deposited at 5.10{sup ?2} mbar strain was mostly localized inside the BTO grains whereas at 5.10{sup ?3} mbar, it was localized at the grain boundaries. The BTO/SRO/YSZ layers were finally deposited on Si microcantilevers at an O{sub 2} pressure of 5.10{sup ?3} mbar. The strain level was low enough to evaluate the BTO Young modulus. Transmission electron microscopy (TEM) was used to investigate the epitaxial quality of the layers and their epitaxial relationship on plain silicon wafers as well as on released microcantilevers, thanks to Focused-Ion-Beam TEM lamella preparation.

  17. Evolution of competing magnetic order in the Jeff=1/2 insulating state of Sr2Ir1-xRuxO4

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

    Calder, Stuart A.; Kim, Jong-Woo; Cao, Guixin; Cantoni, Claudia; May, Andrew F; Cao, Huibo B.; Aczel, Adam A.; Matsuda, Masaaki; Choi, Yongseong; Haskel, Daniel; et al

    2015-10-27

    We investigate the magnetic properties of the series Sr2Ir1-xRuxO4 with neutron, resonant x-ray and magnetization measurements. The results indicate an evolution and coexistence of magnetic structures via a spin flop transition from ab-plane to c-axis collinear order as the 5d Ir4+ ions are replaced with an increasing concentration of 4d Ru4+ ions. The magnetic structures within the ordered regime of the phase diagram (x<0.3) are reported. Despite the changes in magnetic structure no alteration of the Jeff=1/2 ground state is observed. This behavior of Sr2Ir1-xRuxO4 is consistent with electronic phase separation and diverges from a standard scenario of hole doping.more » The role of lattice alterations with doping on the magnetic and insulating behavior is considered. Our results presented here provide insight into the magnetic insulating states in strong spin-orbit coupled materials and the role perturbations play in altering the behavior.« less

  18. Nanocrystalline Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3??} synthesized using a chelating route for use in IT-SOFC cathodes: Microstructure, surface chemistry and electrical conductivity

    SciTech Connect (OSTI)

    Scurtu, Rares; Somacescu, Simona; Calderon-Moreno, Jose Maria; Culita, Daniela; Bulimestru, Ion; Popa, Nelea; Gulea, Aurelian; Osiceanu, Petre

    2014-02-15

    Nanocrystalline Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3??} powders were synthesized by a chelating route using different polyfunctional H{sub x}APC acids (APC=aminopolycarboxylate; x=3, 4, 5). Different homologous aminopolycarboxylic acids, namely nitrilotriacetic (H{sub 3}nta), ethylenediaminetetraacetic (H{sub 4}edta), 1,2-cyclohexanediaminetetracetic (H{sub 4}cdta) and diethylenetriaminepentaacetic (H{sub 5}dtpa) acid, were used as chelating agents to combine Sm, Sr, Co elements into a perovskite structure. The effects of the chelating agents on the crystalline structure, porosity, surface chemistry and electrical properties were investigated. The electrical properties of the perovskite-type materials emphasized that their conductivities in the temperature range of interest (600800 C) depend on the nature of the precursors as well as on the presence of a residual Co oxide phase as shown by XRD and XPS analysis. The surface chemistry and the surface stoichiometries were determined by XPS revealing a complex chemical behavior of Sr that exhibits a peculiar surface phase and bulk phase chemistry within the detected volume (<10 nm). - Graphical abstract: Synthesis of nanocrystalline Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3??} powders by a chelating route and the investigation of the microstructure, surface chemistry and electrical properties. Display Omitted - Highlights: Nanocrystalline Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3??} obtained by a chelating synthesis route. Cubic perovskite structures with crystallite sizes ?232 nm. The porous nature revealed by N{sub 2} adsorption/desorption (BET). The surface chemistry and the surface stoichiometries highlighted by XPS. A complex chemical behavior of Sr exhibits a peculiar surface phase and bulk phase chemistry.

  19. A combined Sm-Nd, Rb-Sr, and U-Pb isotopic study of Mg-suite norite 78238: Further evidence for early differentiation of the Moon

    SciTech Connect (OSTI)

    Edmunson, J; E.Borg, L; Nyquist, L E; Asmerom, Y

    2008-11-17

    Lunar Mg-suite norite 78238 was dated using the Sm-Nd, Rb-Sr, and U-Pb isotopic systems in order to constrain the age of lunar magma ocean solidification and the beginning of Mg-suite magmatism, as well as to provide a direct comparison between the three isotopic systems. The Sm-Nd isotopic system yields a crystallization age for 78238 of 4334 {+-} 37 Ma and an initial {var_epsilon}{sub Nd}{sup 143} value of -0.27 {+-} 0.74. The age-initial {var_epsilon}{sub Nd}{sup 143} (T-I) systematics of a variety of KREEP-rich samples, including 78238 and other Mg-suite rocks, KREEP basalts, and olivine cumulate NWA 773, suggest that lunar differentiation was completed by 4492 {+-} 61 Ma assuming a Chondritic Uniform Reservoir bulk composition for the Moon. The Rb-Sr isotopic systematics of 78238 were disturbed by post-crystallization processes. Nevertheless, selected data points yield two Rb-Sr isochrons. One is concordant with the Sm-Nd crystallization age, 4366 {+-} 53 Ma. The other is 4003 {+-} 95 Ma and is concordant with an Ar-Ar age for 78236. The {sup 207}Pb-{sup 206}Pb age of 4333 {+-} 59 Ma is concordant with the Sm-Nd age. The U-Pb isotopic systematics of 78238 yield linear arrays equivalent to younger ages than the Pb-Pb system, and may reflect fractionation of U and Pb during sample handling. Despite the disturbed nature of the U-Pb systems, a time-averaged {mu} ({sup 238}U/{sup 204}Pb) value of the source can be estimated at 27 {+-} 30 from the Pb-Pb isotopic systematics. Because KREEP-rich samples are likely to be derived from source regions with the highest U/Pb ratios, the relatively low {mu} value calculated for the 78238 source suggests the bulk Moon does not have an exceedingly high {mu} value.

  20. Computational insights on crystal structures of the oxygen-evolving complex of photosystem II with either Ca²⁺ or Ca²⁺ substituted by Sr²⁺

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

    Vogt, Leslie; Ertem, Mehmed Z.; Pal, Rhitankar; Brudvig, Gary W.; Batista, Victor S.

    2015-01-15

    The oxygen-evolving complex of photosystem II can function with either Ca²⁺ or Sr²⁺ as the heterocation, but the reason for differing turnover rates remains unresolved despite reported X-ray crystal structures for both forms. Using quantum mechanics/molecular mechanics (QM/MM) calculations, we optimize structures with each cation in both the resting state (S₁) and in a series of reduced states (S₀, S₋₁, and S-₂). Through comparison with experimental data, we determine that X-ray crystal structures with either Ca²⁺ or Sr²⁺ are most consistent with the S-₂ state, Mn₄[III,III,III,II] with O4 and O5 protonated. As expected, the QM/MM models show that Ca²⁺/Sr²⁺ substitutionmore » results in elongation of the heterocation bonds and displaces terminal waters W3 and W4. The optimized structures also show that hydrogen-bonded W5 is displaced in all S states with Sr²⁺ as the heterocation, suggesting that this water may play a critical role during water oxidation.« less

  1. The Impacts of Cation Stoichiometry and Substrate Surface Quality on Nucleation, Structure, Defect Formation, and Intermixing in Complex Oxide HeteroepitaxyLaCrO3 on SrTiO3(001)

    SciTech Connect (OSTI)

    Qiao, Liang; Zhang, Hongliang; Bowden, Mark E.; Varga, Tamas; Shutthanandan, V.; Colby, Robert J.; Du, Yingge; Kabius, Bernd C.; Sushko, P. V.; Biegalski, Michael D.; Chambers, Scott A.

    2013-06-20

    Our ability to design and fabricate electronic devices with reproducible properties using complex oxides is critically dependent on our ability to controllably synthesize these materials in thin-film form. Structure-property relationships are intimately tied to film and interface composition. Here we report on the effects of cation stoichiometry in LaCrO3 heteroepitaxial films prepared using molecular beam epitaxy. We show that LaCrO3 films grow pseudomorphically on SrTiO3(001) over an wide range of La-to-Cr atom ratios. However, the growth mode and structural quality are sensitive to the La-to-Cr ratio, with La-rich films being of considerably lower structural quality than Cr-rich films. Cation mixing occurs at the interface for all La-to-Cr ratios investigated, and is not quenched by deposition at ambient temperature. Indiffused La atoms occupy Sr sites in the substrate. The presence of defects in the SrTiO3 substrate is implicated in promoting La indiffusion by comparing the properties of LaCrO3/SrTiO3 with those of LaCrO3/Si, both prepared at ambient temperature. Additionally, pulsed laser deposition is shown to result in more extensive interfacial mixing than molecular beam epitaxy for deposition at ambient temperature on Si.

  2. Strain Accommodation By Facile WO6 Octahedral Distortion and Tilting During WO3 Heteroepitaxy on SrTiO3(001)

    SciTech Connect (OSTI)

    Du, Yingge; Gu, Meng; Varga, Tamas; Wang, Chong M.; Bowden, Mark E.; Chambers, Scott A.

    2014-08-27

    In this paper, we show that compared to other BO6 octahedra in ABO3 structured perovskite oxides, the WO6 octahedra in tungsten trioxide (WO3) can withstand a much larger degree of distortion and tilting to accommodate interfacial strain, which in turn strongly impact the nucleation, structure, and defect formation during the epitaxial growth of WO3 on SrTiO3(001). A meta-stable tetragonal phase can be stabilized by epitaxy and a thickness dependent phase transition (tetragonal to monoclinic) is observed. In contrast to misfit dislocations to accommodate the interfacial stain, the facial WO6 octahedral distortion and tilting give rise to three types of planar defects that affect more than 15 monolayers from the interface. These atomically resolved, unusual interfacial defects may significantly alter the electronic, electrochromic, and mechanical properties of the epitaxial films.

  3. Enhancing mid-infrared spectral response at the LaAlO{sub 3}/SrTiO{sub 3} interface by magnetic field

    SciTech Connect (OSTI)

    Feng, Xin; Zhao, Kun Xi, Jian-Feng; Xiang, Wen-Feng; Lu, Zhi-Qing; Sun, Qi; Wu, Shi-Xiang; Ni, Hao

    2014-12-15

    Many unexpected properties have been found in the LaAlO{sub 3}/SrTiO{sub 3} heterostructure, but the interaction of the many ground states at its interface remains unclear. Here, we demonstrate an optical property of this n-type heterostructure where the mid-infrared spectral responsivity at the interface is enhanced by an external magnetic field. The field intensity ranged from 0.8 to 6 kOe at a low temperature (19?K) as measured with our spectral response measurement system. Two spectral peaks related to the spin-orbit coupling effect were also observed at wavelengths 2400?nm and 3700?nm. The intriguing phenomena relate to changes in the crystallographic structure and subband structure at the interface.

  4. Structural and dielectric properties of Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} thin films grown by PLD

    SciTech Connect (OSTI)

    James, K. K.; Satish, B.; Jayaraj, M. K.

    2014-01-28

    Ferroelectric thin films of Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} (BST) were deposited on Si/SiO{sub 2}/TiO{sub 2}/Pt (PtSi) substrate by pulsed laser deposition (PLD). Crystalline films with perovskite structure were obtained without post-deposition annealing. Phase purity of the deposited films was confirmed by x-ray diffraction. The lowest value of FWHM obtained for the film deposited at oxygen pressure 5.410{sup ?4} mbar and substrate temperature 600C, indicates the high crystallinity of the film. The room temperature dielectric constant at 100 kHz was 85. Butterfly loop, which is the characteristic of ferroelectric materials, was obtained in the regime of ?4 to +4V. The leakage current density was nearly 910{sup ?13} Acm{sup ?2}.

  5. Phase transitions in heated Sr{sub 2}MgTeO{sub 6} double perovskite oxide probed by X-ray diffraction and Raman spectroscopy

    SciTech Connect (OSTI)

    Manoun, Bouchaib Tamraoui, Y.; Lazor, P.; Yang, Wenge

    2013-12-23

    Double-perovskite oxide Sr{sub 2}MgTeO{sub 6} has been synthetized, and its crystal structure was probed by the technique of X-ray diffraction at room temperature. The structure is monoclinic, space group I2/m. Temperature-induced phase transitions in this compound were investigated by Raman spectroscopy up to 550?C. Two low-wavenumber modes corresponding to external lattice vibrations merge at temperature of around 100?C, indicating a phase transition from the monoclinic (I2/m) to the tetragonal (I4/m) structure. At 300?C, changes in the slopes of temperature dependencies of external and OTeO bending modes are detected and interpreted as a second phase transition from the tetragonal (I4/m) to the cubic (Fm-3m) structure.

  6. Structure and magnetic properties of three-dimensional (La,Sr)MnO{sub 3} nanofilms on ZnO nanorod arrays

    SciTech Connect (OSTI)

    Gao Haiyong; Gao Puxian; Shimpi, Paresh; Guo Yanbing; Cai Wenjie; Lin Huijan; Staruch, M.; Jain, Menka

    2011-03-21

    Three-dimensional (3D) cubic perovskite (La,Sr)MnO{sub 3} (LSMO) nanofilms have been deposited on ZnO nanorod arrays with controlled dimensionality and crystallinity by radio frequency (rf) magnetron sputtering and post thermal annealing. Compared to the two-dimensional (2D) LSMO nanofilm on flat Si, the structure and magnetic properties of 3D LSMO nanofilms on ZnO nanorod arrays have a strong anisotropic morphology and thickness dependence. Ferromagnetic property has been observed in both 2D and 3D LSMO nanofilms while a ferromagnetic-superparamagnetic transition was revaled in 3D LSMO nanofilms on ZnO nanorod array with decreasing nanofilm thickness, due to a large surface dispersion effect. The LSMO/ZnO nanofilm/nanorod structures could open up new avenues for intriguing magnetic properties studies and applications of nanoscale perovskites.

  7. Energy-dependent crossover from anisotropic to isotropic magnetic dispersion in lightly-doped La1.96Sr0.04CuO4

    SciTech Connect (OSTI)

    Matsuda, Masaaki; Granroth, Garrett E; Fujita, M.; Yamada, K.; Tranquada, John M.

    2013-01-01

    Inelastic neutron scattering experiments have been performed on lightly-doped La$_{1.96}$Sr$_{0.04}$CuO$_{4}$, which shows diagonal incommensurate spin correlations at low temperatures. We previously reported that this crystal, with a single orthorhombic domain, exhibits the ``hourglass" dispersion at low energies [Phys. Rev. Lett. 101, 197001 (2008)]. In this paper, we investigate in detail the energy evolution of the magnetic excitations up to 65 meV. It is found that the anisotropic excitations at low energies, dispersing only along the spin modulation direction, crossover to an isotropic, conical dispersion that resembles spin waves in the parent compound La$_2$CuO$_{4}$. The change from two-fold to full symmetry on crossing the waist of the hourglass reproduces behavior first identified in studies of underdoped YBa$_2$Cu$_3$O$_{6+x}$. We discuss the significance of these results.

  8. Dopant-Induced Nanoscale Electronic Inhomogeneities in Ca2-xSrxRuO4

    SciTech Connect (OSTI)

    Zhang, Jiandi; Ismail, #; Moore, R. G.; Wang, S. -C.; Ding, H.; Jin, Rongying; Mandrus, David; Plummer, E Ward

    2006-01-01

    Ca{sub 2-x}Sr{sub x}RuO{sub 4} single crystals with 0.1 {le} x {le} 2.0 have been studied systematically using scanning tunneling microscopy (STM) and spectroscopy, low-energy electron diffraction, and angle resolved photoelectron spectroscopy (ARPES). In contrast with the well-ordered lattice structure, the local density of states at the surface clearly shows a strong doping dependent nanoscale electronic inhomogeneity, regardless of the fact of isovalent substitution. Remarkably, the surface electronic roughness measured by STM and the inverse spectral weight of quasiparticle states determined by ARPES are found to vary with x in the same manner as the bulk in-plane residual resistivity, following the Nordheim rule. For the first time, the surface measurements - especially those with STM - are shown to be in good agreement with the bulk transport results, all clearly indicating a doping-induced electronic disorder in the system.

  9. Investigation into the effect of Si doping on the cell symmetry and performance of Sr{sub 1−y}Ca{sub y}FeO{sub 3−δ} SOFC cathode materials

    SciTech Connect (OSTI)

    Porras-Vazquez, Jose M.; Smith, R.I.; Slater, Peter R.

    2014-05-01

    In this paper we report the successful incorporation of silicon into Sr{sub 1−y}Ca{sub y}FeO{sub 3−δ} perovskite materials for potential applications as electrode materials for Solid Oxide Fuel Cells. It is observed that Si doping leads to a change from a tetragonal or orthorhombic structure (with partial ordering of oxygen vacancies) to a cubic one (with the oxygen vacancies disordered). The structures of the phases, SrFe{sub 0.85}Si{sub 0.15}O{sub 3−δ}, Sr{sub 0.75}Ca{sub 0.25}Fe{sub 0.85}Si{sub 0.15}O{sub 3−δ} and Sr{sub 0.5}Ca{sub 0.5}Fe{sub 0.85}Si{sub 0.15}O{sub 3−δ}, were analysed using neutron powder diffraction. The data confirmed the cubic unit cell, with no long range oxygen vacancy ordering. Conductivity measurements showed an improvement in the conductivity on Si doping, especially for samples with high Ca content. Composite electrodes comprising 50% Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} and 50% Sr{sub 1−y}Ca{sub y}(Fe/Si)O{sub 3−δ} on dense Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} pellets were therefore examined in air. An improvement in the area specific resistances (ASR) values is observed for the Si-doped samples with respect to the undoped samples. Thus the results show that silicon can be incorporated into Sr{sub 1−y}Ca{sub y}FeO{sub 3−δ}-based materials and can have a beneficial effect on the performance, making them potentially suitable for use as cathode material in Solid Oxide Fuel Cells (SOFC). - Graphical abstract: X-ray diffraction patterns for: (left) Sr{sub 0.75}Ca{sub 0.25}Fe{sub 1−x}Si{sub x}O{sub 3−δ} (x=0, 0.05, 0.10 and 0.15) and (right) Sr{sub 0.25}Ca{sub 0.75}Fe{sub 1−x}Si{sub x}O{sub 3−δ} (x=0, 0.05, 0.10 and 0.15), showing the stabilization of the cubic form of these series through silicon doping. For the latter Sr{sub 0.25}Ca{sub 0.75}Fe{sub 1−x}Si{sub x}O{sub 3−δ} phase, the stabilisation is not quite complete at 15% Si doping. - Highlights: • In Sr{sub 1−y}Ca{sub y}Fe{sub 1−x}Si{sub x}O{sub 3−δ} materials Si doping results in a change from tetragonal or orthorhombic symmetry. • An improvement in the conductivity is observed on Si doping. • An improvement in the area specific resistances (ASR) values is observed on Si doping. • Silicon can have a beneficial effect on the performance in perovskite materials.

  10. The site occupation and valence of Mn ions in the crystal lattice of Sr{sub 4}Al{sub 14}O{sub 25} and its deep red emission for high color-rendering white light-emitting diodes

    SciTech Connect (OSTI)

    Chen, Lei; Xue, Shaochan; Chen, Xiuling; Bahader, Ali; Deng, Xiaorong; Zhao, Erlong; Jiang, Yang; Chen, Shifu; Chan, Ting-Shan; Zhao, Zhi; Zhang, Wenhua

    2014-12-15

    Highlights: Different valences of Mn ions in Sr{sub 4}Al{sub 14}O{sub 25} were identified using XANES and EPR. Red luminescence was attributed to Mn{sup 4+} occupying the center of AlO{sub 6} octahedron. The Mn{sup 3+} incorporated in the center of AlO{sub 4} tetrahedron was non-luminescent. The bond-valence theory was used to analyze the effective valences of cations. A white LED device with CRI up to Ra 93.23 was packaged by using the red phosphor. - Abstract: The synthesis and component of red phosphor, Sr{sub 4}Al{sub 14}O{sub 25}: Mn, were optimized for application in white light-emitting diodes. The microstructure and morphology were investigated by the X-ray diffraction and scanning electron microscopy. Different valences of Mn ions in Sr{sub 4}Al{sub 14}O{sub 25} were discriminated using the electron paramagnetic resonance and X-ray absorption near-edge structure spectroscopy techniques. The bond-valence theory was used to analyze the effective valences of Sr{sup 2+} and Al{sup 3+} in Sr{sub 4}Al{sub 14}O{sub 25}. As a result, the strong covalence of Al{sup 3+} in the AlO{sub 4} tetrahedron other than in the AlO{sub 6} octahedron is disclosed. The deep red emission is attributed to Mn{sup 4+} occupying the center of AlO{sub 6} octahedron. The mechanism of energy transfer is mainly through dipoledipole interaction, revealed by the analyses of critical distance and concentration quench. A high color rendering white LED prototype with color-rendering index up to Ra 93.23 packaged by using the red phosphor demonstrates its applicability.

  11. Interfacial charge-mediated non-volatile magnetoelectric coupling in Co0.3Fe0.7/Ba0.6Sr0.4TiO3/Nb:SrTiO3 multiferroic heterostructures

    SciTech Connect (OSTI)

    Zhou, Ziyao; Howe, Brandon M.; Liu, Ming; Nan, Tianxiang; Chen, Xing; Mahalingam, Krishnamurthy; Sun, Nian X.; Brown, Gail J.

    2015-01-13

    The central challenge in realizing non-volatile, E-field manipulation of magnetism lies in finding an energy efficient means to switch between the distinct magnetic states in a stable and reversible manner. In this work, we demonstrate using electrical polarization-induced charge screening to change the ground state of magnetic ordering in order to non-volatilely tune magnetic properties in ultra-thin Co0.3Fe0.7/Ba0.6Sr0.4TiO3/Nb:SrTiO3 (001) multiferroic heterostructures. A robust, voltage-induced, non-volatile manipulation of out-of-plane magnetic anisotropy up to 40 Oe is demonstrated and confirmed by ferromagnetic resonance measurements. This discovery provides a framework for realizing charge-sensitive order parameter tuning in ultra-thin multiferroic heterostructures, demonstrating great potential for delivering compact, lightweight, reconfigurable, and energy-efficient electronic devices.

  12. Octonary resistance states in La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 multiferroic tunnel junctions

    SciTech Connect (OSTI)

    Yue -Wei Yin; Tao, Jing; Huang, Wei -Chuan; Liu, Yu -Kuai; Yang, Sheng -Wei; Dong, Si -Ning; Zhu, Yi -Mei; Li, Qi; Li, Xiao -Guang

    2015-10-06

    General drawbacks of current electronic/spintronic devices are high power consumption and low density storage. A multiferroic tunnel junction (MFTJ), employing a ferroelectric barrier layer sandwiched between two ferromagnetic layers, presents four resistance states in a single device and therefore provides an alternative way to achieve high density memories. Here, an MFTJ device with eight nonvolatile resistance states by further integrating the design of noncollinear magnetization alignments between the ferromagnetic layers is demonstrated. Through the angle-resolved tunneling magnetoresistance investigations on La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 junctions, it is found that, besides collinear parallel/antiparallel magnetic configurations, the MFTJ shows at least two other stable noncollinear (45° and 90°) magnetic configurations. As a result, combining the tunneling electroresistance effect caused by the ferroelectricity reversal of the BaTiO3 barrier, an octonary memory device is obtained, representing potential applications in high density nonvolatile storage in the future.

  13. Synthesis, crystal structure and photoluminescence of a new Eu-doped Sr containing sialon (Sr{sub 0.94}Eu{sub 0.06})(Al{sub 0.3}Si{sub 0.7}){sub 4}(N{sub 0.8}O{sub 0.2}){sub 6}

    SciTech Connect (OSTI)

    Yamane, Hisanori; Shimooka, Satoshi; Uheda, Kyota

    2012-06-15

    Colorless transparent platelet single crystals of a novel Eu{sup 2+}-doped strontium silicon aluminum oxynitride, (Sr{sub 0.94}Eu{sub 0.06})(Al{sub 0.3}Si{sub 0.7}){sub 4}(N{sub 0.8}O{sub 0.2}){sub 6}, were prepared at 1800 Degree-Sign C and 0.92 MPa of N{sub 2}. Fundamental reflections of electron and X-ray diffraction of the crystals were indexed with a face-centered orthorhombic unit cell (a=5.8061(5) A, b=37.762(3) A, c=9.5936(9) A). Diffuse streaks elongated in the b-axis direction were observed around the fundamental reflections hkl with h=2n+1 of the electron and X-ray diffraction, indicating stacking faults of (0 1 0)[1 0 0]/2. A crystal structure model without the stacking faults was obtained using the X-ray diffraction data of the fundamental reflections with the space group Fdd2. A SiN{sub 4}-tetrahedron double layer of [SiN{sub 2}]{sub 2} and a Sr/Eu double layer of [(Sr{sub 0.94}Eu{sub 0.06})Al{sub 1.2}Si{sub 0.8}N{sub 0.8} O{sub 1.2}]{sub 2} are stacked alternately along the b-axis direction. The title compound showed an emission with a peak wavelength of 490 nm under 334 nm excitation at room temperature. - Graphical abstract: Single crystals of a novel Eu{sup 2+}-doped strontium silicon aluminum oxynitride, (Sr{sub 0.94}Eu{sub 0.06})(Al{sub 0.3}Si{sub 0.7}){sub 4}(N{sub 0.8}O{sub 0.2}){sub 6}, having stacking faults on the (0 1 0) plane of an orthorhombic cell, were prepared at 1800 Degree-Sign C and 0.92 MPa of N{sub 2}. The compound showed emission with a peak wavelength of 490 nm under 334 nm excitation at room temperature. Highlights: Black-Right-Pointing-Pointer A new compound Eu{sup 2+}-doped (Sr{sub 0.94}Eu{sub 0.06})(Al{sub 0.3}Si{sub 0.7}){sub 4}(N{sub 0.8}O{sub 0.2}){sub 6} was prepared. Black-Right-Pointing-Pointer Stacking faults in the compound were clarified by electron and X-ray diffraction. Black-Right-Pointing-Pointer A basic crystal structure model was obtained based on the X-ray diffraction data. Black-Right-Pointing-Pointer An emission of 490 nm under 334 nm excitation at room temperature was observed.

  14. Luminescence properties of a blue-emitting phosphor: (Sr{sub 1?x}Eu{sub x})Si{sub 9}Al{sub 19}ON{sub 31} (0

    SciTech Connect (OSTI)

    Liu, Lihong; Xie, Rong-Jun; Hirosaki, Naoto; Dierre, Benjamin; Sekiguchi, Takashi

    2013-11-15

    Blue-emitting Sr{sub 1?x}Eu{sub x}Si{sub 9}Al{sub 19}ON{sub 31} phosphors were synthesized at 1800 C for 2 h under 1 MPa N{sub 2} by using the gas-pressure sintering method (GPS). The microstructure, photoluminescence (PL) properties of the prepared phosphors were investigated. Under the 290 nm excitation, broad PL emission bands with peak positions at 448490 nm were detected. The concentration quenching was not observed owing to the large distance betweenEu{sup 2+} ions that made the nonradiative energy transfer between neighboring Eu{sup 2+} ions difficult. The blue phosphor generally showed a small thermal quenching at low Eu{sup 2+} concentrations. The absorption and external quantum efficiency of the synthesized Sr{sub 0.5}Eu{sub 0.5}Si{sub 9}Al{sub 19}ON{sub 31} were 85% and 62% upon the 365 nm excitation, respectively. The interesting PL results indicate that Sr{sub 1?x}Eu{sub x}Si{sub 9}Al{sub 19}ON{sub 31} has great potentials as a blue phosphor for white LEDs applications. - Graphical abstract: Sr{sub 0.7}Eu{sub 0.3}Si{sub 9}Al{sub 19}ON{sub 31} gives blue-emitting at 471 nm. Excitation spectrum is composed of five bands in the range of 250450 nm, which are matching well with emission wavelength of UV LEDs. Display Omitted - Highlights: Blue-emitting Sr{sub 1?x}Eu{sub x}Si{sub 9}Al{sub 19}ON{sub 31} phosphors were synthesized by gas-pressure sintering method. The concentration quenching was not observed in this phosphor. This blue phosphor generally showed a small thermal quenching at low Eu{sup 2+} concentrations. The absorption and external quantum efficiency of the synthesized Sr{sub 0.5}Eu{sub 0.5}Si{sub 9}Al{sub 19}ON{sub 31} were 85% and 62% upon the 365 nm excitation.

  15. Investigation of the phase equilibria and phase transformations associated with the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} superconductor

    SciTech Connect (OSTI)

    Holesinger, T.

    1993-12-09

    The solid solution region and reaction kinetics of the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (2212) superconductor were examined as a function of temperature and oxygen partial pressure. Crystallization studies from the glassy and molten states were undertaken to determine the phase transformation and kinetics associated with the formation of 2212 and other competing phases. Crystallization of nominal 2212 glasses was found to proceed in two steps with the formation of Bi{sub 2}Sr{sub 2{minus}x}Ca{sub x}CuO{sub y} (2201) and Cu{sub 2}O followed by Bi{sub 2}Sr{sub 3{minus}x}Ca{sub x}O{sub y}, CaO, and SrO. The 2212 phase converts from the 2201 phase with increasing temperatures. However, its formation below 800 C was kinetically limited. At 800 C and above, a nearly full conversion to the 2212 phase was achieved after only one minute although considerably longer anneal times were necessary for the system to reach equilibrium. In low oxygen partial pressures, the solidus is reduced to approximately 750 C. Solidification studies revealed an eutectic structure separating the incongruently melting 2212/2201 phases at high oxygen partial pressures from the congruently melting Bi{sub 2}Sr{sub 3{minus}x}Ca{sub x}O{sub y} (23x) and Bi{sub 2}Sr{sub 2{minus}x}Ca{sub x}O{sub y} (22x) phases present at low oxygen partial pressures. During solidification in various oxygen partial pressures, the separation of CaO in the melt and the initial crystallization of alkaline-earth cuprates leaves behind a Bi-rich liquid from which it is impossible to form single-phase 2212. Hence, significant amounts of 2201 were also present in these samples. These problems could be reduced by melt processing in inert atmospheres. Bulk 2212 material produced in this manner was found to possess high transition temperatures, high intergranular critical current densities below 20K, and modest critical current densities at 77K.

  16. In situ characterization of strontium surface segregation in epitaxial La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films as a function of oxygen partial pressure

    SciTech Connect (OSTI)

    Fister, Tim T.; Fong, Dillon D.; Eastman, Jeffrey A.; Baldo, Peter M.; Highland, Matthew J.; Fuoss, Paul H.; Balasubramaniam, Kavaipatti R.; Meador, Joanna C.; Salvador, Paul A.

    2008-10-13

    Using in situ synchrotron measurements of total reflection x-ray fluorescence, we find evidence of strontium surface segregation in (001)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films over a wide range of temperatures (25-900 deg. C) and oxygen partial pressures (pO{sub 2}=0.15-150 Torr). The strontium surface concentration is observed to increase with decreasing pO{sub 2}, suggesting that the surface oxygen vacancy concentration plays a significant role in controlling the degree of segregation. Interestingly, the enthalpy of segregation becomes less exothermic with increasing pO{sub 2}, varying from -9.5 to -2.0 kJ/mol. In contrast, the La{sub 0.7}Sr{sub 0.3}MnO{sub 3} film thickness and epitaxial strain state have little impact on segregation behavior.

  17. Total reflection inelastic x-ray scattering from a 10 nm thick La{sub 0.6}Sr{sub 0.2}CoO{sub 3} thin film.

    SciTech Connect (OSTI)

    Fister, T. T.; Fong, D. D.; Eastman, J. A.; Iddir, H.; Zapol, P.; Fuoss, P. H.; Balasubramanian, M.; Gordon, R. A.; Balasubramaniam, K. R.; Salvador, P. A.; Simon Fraser Univ.; Carnegie Mellon Univ.

    2011-01-18

    To study equilibrium changes in composition, valence, and electronic structure near the surface and into the bulk, we demonstrate the use of a new approach, total-reflection inelastic x-ray scattering, as a sub-keV spectroscopy capable of depth profiling chemical changes in thin films with nanometer resolution. By comparing data acquired under total x-ray reflection and penetrating conditions, we are able to separate the O K-edge spectra from a 10 nm La{sub 0.6}Sr{sub 0.4}CoO{sub 3} thin film from that of the underlying SrTiO{sub 3} substrate. With a smaller wavelength probe than comparable soft x-ray absorption measurements, we also describe the ability to easily access dipole-forbidden final states, using the dramatic evolution of the La N{sub 4,5} edge with momentum transfer as an example.

  18. The effect of oxygen vacancies on the electronic phase transition in La{sub 1/3}Sr{sub 2/3}FeO{sub 3} films

    SciTech Connect (OSTI)

    Sichel-Tissot, Rebecca J.; Devlin, Robert C.; May, Steven J.; Ryan, Philip J.; Kim, Jong-Woo

    2013-11-18

    Synchrotron x-ray diffraction and electrical resistivity were used to probe the electronic phase transition in two strained La{sub 1/3}Sr{sub 2/3}FeO{sub 3} films on (001) SrTiO{sub 3} substrates, one nominally stoichiometric and one with a higher concentration of oxygen vacancies. We present evidence that oxygen vacancies inhibit the size of charge ordered domains and reduce the abruptness of the phase transition. Additionally, the correlation lengths measured from (4/3 4/3 4/3) peaks, arising from charge disproportionation, increase rapidly across the transition, suggesting that the resistivity increase at the transition temperature is caused by the nucleation and growth of charge ordered domains.

  19. Continuously-tuned tunneling behaviors of ferroelectric tunnel junctions based on BaTiO{sub 3}/La{sub 0.67}Sr{sub 0.33}MnO{sub 3} heterostructure

    SciTech Connect (OSTI)

    Ou, Xin; Xu, Bo Yin, Qiaonan; Xia, Yidong; Yin, Jiang; Liu, Zhiguo; Gong, Changjie; Lan, Xuexin

    2014-05-15

    In this work, we fabricate BaTiO{sub 3}/La{sub 0.67}Sr{sub 0.33}MnO{sub 3} (BTO/LSMO) ferroelectric tunnel junction on (001) SrTiO{sub 3} substrate by pulsed laser deposition method. Combining piezoresponse force and conductive-tip atomic force microscopy, we demonstrate robust and reproducible polarization-controlled tunneling behaviors with the resulting tunneling electroresistance value reaching about 10{sup 2} in ultrathin BTO films (?1.2 nm) at room temperature. Moreover, local poling areas with different conductivity are finally achieved by controlling the relative proportion of upward and downward domains, and different poling areas exhibit stable transport properties.

  20. The impacts of cation stoichiometry and substrate surface quality on nucleation, structure, defect formation, and intermixing in complex oxide heteroepitaxy LaCrO3 on SrTiO3(001)

    SciTech Connect (OSTI)

    Qiao, Liang; Zhang, K. H. L; Bowden, Mark E; Varga, Tamas; Shutthanandan, Vaithiyalingam; Colby, Robert; Du, Yingge; Kabius, Bernd; Sushko, Peter V; Biegalski, Michael D; Chambers, S. A.

    2013-01-01

    Our ability to design and fabricate electronic devices with reproducible properties using complex oxides is critically dependent on our ability to controllably synthesize these materials in thin-film form. Structure-property relationships are intimately tied to film and interface composition Here we report on the effect of cation stoichiometry on structural quality and defect formation in LaCrO3 heteroepitaxial films prepared using molecular beam epitaxy. We calculate from first principles the regions of stability of various candidate defects as a function of Cr and O chemical potential, along with the predicted effects of these defects on structural parameters. We show that epitaxial LaCrO3 films readily nucleate and remain coherently strained on SrTiO3(001) over a wide range of La-to-Cr atom ratios, but that La-rich films are of considerably lower structural quality than stoichiometric and Cr-rich films. Cation imbalances are accompanied by anti-site defect formation, as deduced by comparing experimental trends in the c lattice parameter with those from first-principles calculations. Cation mixing occurs at the interface for all La-to-Cr ratios investigated, and is not quenched by deposition on SrTiO3(001) at ambient temperature. Indiffused La atoms occupy Sr sites, most likely facilitated by Sr vacancy formation in STO resulting from high-temperature oxygen annealing required to prepare the substrate. Intermixing is effectively quenched by using molecular beam epitaxy to deposit LaCrO3 at ambient temperature on defect free Si(001). However, analogous pulsed laser deposition on Si is accompanied by cation mixing.

  1. Low loss composition of BaxSryCa1-x-yTiO3: Ba0.12-0.25Sr0.35-0.47Ca0.32-0.53TiO3

    DOE Patents [OSTI]

    Xiang, Xiao-Dong (Alameda, CA); Chang, Hauyee (Berkeley, CA); Takeuchi, Ichiro (Albany, CA)

    2001-01-01

    A dielectric thin-film material for microwave applications, including use as a capacitor, the thin-film comprising a composition of barium strontium calcium and titanium of perovskite type (Ba.sub.x Sr.sub.y Ca.sub.1-x-y)TiO.sub.3. Also provided is a method for making a dielectric thin film of that formula over a wide compositional range through a single deposition process.

  2. Controlling superconductivity in La2-xSrxCuO4+? by ozone and vacuum annealing

    SciTech Connect (OSTI)

    Leng, Xiang; Bozovic, Ivan

    2014-11-21

    In this study we performed a series of ozone and vacuum annealing experiments on epitaxial La2-xSrxCuO4+? thin films. The transition temperature after each annealing step has been measured by the mutual inductance technique. The relationship between the effective doping and the vacuum annealing time has been studied. Short-time ozone annealing at 470 C oxidizes an underdoped film all the way to the overdoped regime. The subsequent vacuum annealing at 350 C to 380 C slowly brings the sample across the optimal doping point back to the undoped, non-superconducting state. Several ozone and vacuum annealing cycles have been done on the same sample and the effects were found to be repeatable and reversible Vacuum annealing of ozone-loaded LSCO films is a very controllable process, allowing one to tune the doping level of LSCO in small steps across the superconducting dome, which can be used for fundamental physics studies.

  3. Microstructural effects on the oxygen exchange kinetics of La{<_0.7}Sr{<_0.3}MnO{<_3} thin films.

    SciTech Connect (OSTI)

    Yan, L.; Kavaipatti, B.; Chang, K-C.; You, H.; Salvador, P.

    2011-01-01

    We investigated the relative contribution of the native surface and of the grain boundaries intersecting the surface to the chemical surface exchange of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSM) thin films. The chemical surface exchange coefficients, k{sub chem}, were determined using electrical conductivity relaxation (ECR). Two k{sub chem} values were obtained, indicating two surface exchange processes occurred in parallel. These two k{sub chem} values had different activation energies (Ea), which were interpreted as belonging to (1) the native surface response of individual grains/variants and (2) the variant/grain boundaries of the textured films. The first process has an activation energy of E{sub a,1} {approx} 1.57 eV, while E{sub a,2} {approx} 0.87 eV. The k{sub chem,2} values are almost 3 orders of magnitude higher than the k{sub chem,1} values at low temperatures. At higher temperatures, the data can be fit with one k{sub chem} that has an intermediate value of Ea, indicative of a transition region.

  4. Ferroelectric nanoscale domains and the 905 K phase transition in SrSnO{sub 3}: A neutron total-scattering study

    SciTech Connect (OSTI)

    Goodwin, Andrew L.; Redfern, Simon A. T.; Dove, Martin T.; Keen, David A.; Tucker, Matthew G.

    2007-11-01

    The 905 K Pnma-Imma phase transition in SrSnO{sub 3} is studied here using a combination of variable-temperature neutron total scattering together with the reverse Monte Carlo (RMC) refinement method. The real-space RMC configurations obtained are analyzed in terms of bond distance and bond-angle distributions, and a geometric algebra approach is used to quantify the associated octahedral-tilting distributions. What emerges from this analysis is that the transition is displacive in nature, in contrast to the results of a recent average-structure investigation in which an order-disorder model was proposed [E. H. Mountstevens et al., Phys. Rev. B 71, 220102(R) (2005)]. Three-dimensional diffuse scattering patterns calculated from the same RMC configurations reveal the existence of an additional disorder mechanism which persists across the Pnma-Imma transition. The ''reflection conditions'' of this diffuse scattering, together with displacement correlation calculations, point to the existence of ferroelectric nanoscale domains within the configurations, which are found to extend across planar regions of approximately 10-15 A ring in diameter.

  5. Neutron scattering study of spin ordering and stripe pinning in superconducting La1.93Sr0.07CuO4

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

    Jacobsen, H.; Zaliznyak, I. A.; Savici, A. T.; Winn, B. L.; Chang, S.; Hücker, M.; Gu, G. D.; Tranquada, J. M.

    2015-11-20

    Tmore » he relationships among charge order, spin fluctuations, and superconductivity in underdoped cuprates remain controversial. We use neutron scattering techniques to study these phenomena in La1.93Sr0.07CuO4 a superconductor with a transition temperature of c = 20 K. At << c, we find incommensurate spin fluctuations with a quasielastic energy spectrum and no sign of a gap within the energy range from 0.2 to 15 meV. A weak elastic magnetic component grows below ~ 10 K, consistent with results from local probes. Regarding the atomic lattice, we have discovered unexpectedly strong fluctuations of the CuO6 octahedra about Cu-O bonds, which are associated with inequivalent O sites within the CuO2 planes. Moreover, we observed a weak elastic (3 ⁻30) superlattice peak that implies a reduced lattice symmetry. he presence of inequivalent O sites rationalizes various pieces of evidence for charge stripe order in underdoped La2-xSrxCuO4. he coexistence of superconductivity with quasi-static spin-stripe order suggests the presence of intertwined orders; however, the rotation of the stripe orientation away from the Cu-O bonds might be connected with evidence for a finite gap at the nodal points of the superconducting gap function.« less

  6. Direct observation of oxygen-vacancy-enhanced polarization in a SrTiO3-buffered ferroelectric BaTiO3 film on GaAs

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

    Qiao, Q.; Zhang, Y.; Contreras-Guerrero, Rocio; Droopad, Ravi; Pantelides, S. T.; Pennycook, Stephen J.; Ogut, Serdar; Klie, Robert F.

    2015-11-16

    The integration of functional oxide thin-films on compound semiconductors can lead to a class of reconfigurable spin-based optoelectronic devices if defect-free, fully reversible active layers are stabilized. However, previous first-principles calculations predicted that SrTiO3 thin filmsgrown on Si exhibit pinned ferroelectric behavior that is not switchable, due to the presence of interfacial vacancies. Meanwhile, piezoresponse force microscopy measurements have demonstrated ferroelectricity in BaTiO3 grown on semiconductor substrates. The presence of interfacial oxygen vacancies in such complex-oxide/semiconductor systems remains unexplored, and their effect on ferroelectricity is controversial. We also use a combination of aberration-corrected scanning transmission electron microscopy and first-principles densitymore » functional theory modeling to examine the role of interfacial oxygen vacancies on the ferroelectricpolarization of a BaTiO3 thin filmgrown on GaAs. Moreover, we demonstrate that interfacial oxygen vacancies enhance the polar discontinuity (and thus the single domain, out-of-plane polarization pinning in BaTiO3), and propose that the presence of surface charge screening allows the formation of switchable domains.« less

  7. Cation Intermixing And Electronic Deviations At The Insulating LaCrO3/SrTiO3(001) Interface

    SciTech Connect (OSTI)

    Colby, Robert J.; Qiao, Liang; Zhang, Hongliang; Shutthanandan, V.; Ciston, Jim; Kabius, Bernd C.; Chambers, Scott A.

    2013-10-29

    The interface between polar perovskite LaCrO3 (LCO) and non-polar SrTiO3(001) (STO), grown by molecular beam epitaxy, is examined using a combination of electron microscopy, spectroscopy, and Rutherford backscattering spectrometry. The LCO/STO(001) interface is insulating, a potential counter example for the claim that polar/nonpolar perovskite interfaces should be conductive by virtue of an electronic reconstruction to alleviate the polar discontinuity. The A-site cations of these ABO3 perovskites are found to diffuse across the interface to a greater extent than the B-site cations, based on high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), energy dispersive x-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). The B-site cation valences are shown to be partially reduced near the interface by analysis of EELS near-edge structures. The location and direction of these electronic modifications do not intuitively compensate the charge imbalance imposed by uneven cation inter-diffusion, and yet both the film and interface are insulating. These results highlight the importance of both the physical and electronic structure of such complex interfaces in determining their characteristics. Furthermore, the extent of inter-diffusion is shown to increase with increasing LCO film thickness, suggesting a potential mechanism behind the critical thickness for interfacial conductivity in other polar/non-polar oxide systems, and a fundamental limitation on the formation of abrupt interfaces in LCO/STO(001).

  8. In-situ imaging of the nucleation and growth of epitaxial anatase TiO2(001) films on SrTiO3(001)

    SciTech Connect (OSTI)

    Du, Yingge; Kim, Dong Jun; Kaspar, Tiffany C.; Chamberlin, Sara E.; Lyubinetsky, Igor; Chambers, Scott A.

    2012-09-30

    The growth of TiO2 anatase films on Nb doped SrTiO3(001) by oxygen-assisted molecular beam epitaxy has been studied in-situ by scanning tunneling microscopy. We show that the initial growth follows the Stranski-Krastanov mode, where islands form on top of a wetting layer consisting of two monolayers (ML) of TiO2. The epitaxial islands subsequently nucleate and coalescence into large commonly-oriented crystallites. The (4x4) reconstruction observed by reflection high-energy electron diffraction (RHEED) is shown to result from the coexistence of individual (4x1) and (1x4) reconstructions present on different crystallite surfaces. The anatase grows in units of bilayers, resulting in a step height of 2 ML (~0.5 nm). This result explains the fact that the measured period of the RHEED specular-beam intensity oscillations corresponds to the time required for deposition of 2 ML. Ar ion sputtering and UHV annealing results in a transformation to coexisting (4x1) and (1x4) reconstructed terraces on individual crystallites, as commonly observed by ex-situ STM studies.

  9. Topological crystalline insulator Pb{sub x}Sn{sub 1-x}Te thin films on SrTiO{sub 3} (001) with tunable Fermi levels

    SciTech Connect (OSTI)

    Guo, Hua; Liu, Jun-Wei; Wang, Zhen-Yu; Wu, Rui; Ji, Shuai-Hua; Duan, Wen-Hui; Chen, Xi Xue, Qi-Kun; Yan, Chen-Hui; Zhang, Zhi-Dong; Wang, Li-Li; He, Ke; Ma, Xu-Cun

    2014-05-01

    In this letter, we report a systematic study of topological crystalline insulator Pb{sub x}Sn{sub 1-x}Te (0 < x < 1) thin films grown by molecular beam epitaxy on SrTiO{sub 3}(001). Two domains of Pb{sub x}Sn{sub 1-x}Te thin films with intersecting angle of ? ? 45 were confirmed by reflection high energy diffraction, scanning tunneling microscopy, and angle-resolved photoemission spectroscopy (ARPES). ARPES study of Pb{sub x}Sn{sub 1-x}Te thin films demonstrated that the Fermi level of PbTe could be tuned by altering the temperature of substrate whereas SnTe cannot. An M-shaped valance band structure was observed only in SnTe but PbTe is in a topological trivial state with a large gap. In addition, co-evaporation of SnTe and PbTe results in an equivalent variation of Pb concentration as well as the Fermi level of Pb{sub x}Sn{sub 1-x}Te thin films.

  10. Tunability of conduction at the LaAlO{sub 3}/SrTiO{sub 3} heterointerface: Thickness and compositional studies

    SciTech Connect (OSTI)

    Breckenfeld, E.; Bronn, N.; Mason, N.; Martin, L. W.

    2014-09-22

    The role of chemistry, film thickness, and oxygen pressure in influencing the electrical and thermal transport properties of LaAlO{sub 3}/SrTiO{sub 3} heterointerfaces is explored. Unit-cell precise growth was accomplished for films between 3 and 160 unit cells thick using reflection high-energy electron diffraction-assisted pulsed-laser deposition. Subsequent temperature-dependent studies of electrical resistivity reveal three important observations: (1) by tuning the laser fluence, we can systematically tune the interfacial conductance in a step-wise manner in this system, (2) all films exhibit a critical thickness of 34 unit cells for the onset of conduction, and (3) the nature of the conductance is highly influenced by the stoichiometry of the LaAlO{sub 3} film with La-deficient samples showing dramatic changes with thickness, while stoichiometric and La-excess films show little dependence. Time-domain thermoreflectance studies show a diminished interfacial thermal conductance for the La-deficient films when compared to La-excess and stoichiometric films, suggesting that the interfacial conductance is more influenced by extrinsic factors such as oxygen deficiency.

  11. Modelling of the Arc-Jet Plasma Flow in the SR5 Nozzle Using a Thermochemical Nonequilibrium and a State-to-State Approach

    SciTech Connect (OSTI)

    Lino da Silva, M.; Passarinho, F.; Alexandrova, T.; Dudeck, M.

    2005-05-16

    A numerical code has been set-up for estimating the relative importance of the different nonequilibrium physical-chemical processes in the SR5 facility arc-jet plasma generator. The code assumes a quasi-1D description of the flow in the plasma generator convergent-divergent nozzle, allowing the modelling of a large array of processes at low computational cost. The center streamline of the flow is simulated in the nozzle throat where arc energy input is treated as a constant energy input. This center streamline is not assumed to be affected by nozzle walls cooling in the diverging section. Chemical, V-T, V-V, V-D and R-T processes are taken into account for CO2-N2 and N2-O2 flows. The results for a CO2-N2 flow show that rotational equilibrium and near vibrational equilibrium are reached in the nozzle throat, and that the sudden expansion in the diverging section leads to a freezing of chemical compositions and vibrational temperatures, and also rotational nonequilibrium. Only chemical processes are found to affect sensibly the flow macroscopic parameters. Finally a comparison with a state-to-state model for an N2-O2 flow in the diverging section proved that some differences between the vibrational temperatures could be expected due to non-Boltzmann vibrational levels distributions. This is particularly true for the O2 first vibrational temperature.

  12. Epitaxial c-axis oriented BaTiO{sub 3} thin films on SrTiO{sub 3}-buffered Si(001) by atomic layer deposition

    SciTech Connect (OSTI)

    Ngo, Thong Q.; McDaniel, Martin D.; Ekerdt, John G., E-mail: ekerdt@che.utexas.edu [Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Posadas, Agham B.; Demkov, Alexander A. [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States); Hu, Chengqing; Yu, Edward T. [Department of Electrical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Bruley, John [IBM Research Division, Yorktown Heights, New York 10593 (United States)

    2014-02-24

    Atomic layer deposition (ALD) of epitaxial c-axis oriented BaTiO{sub 3} (BTO) on Si(001) using a thin (1.6?nm) buffer layer of SrTiO{sub 3} (STO) grown by molecular beam epitaxy is reported. The ALD growth of crystalline BTO films at 225??C used barium bis(triisopropylcyclopentadienyl), titanium tetraisopropoxide, and water as co-reactants. X-ray diffraction (XRD) reveals a high degree of crystallinity and c-axis orientation of as-deposited BTO films. Crystallinity is improved after vacuum annealing at 600??C. Two-dimensional XRD confirms the tetragonal structure and orientation of 720-nm thick films. The effect of the annealing process on the BTO structure is discussed. A clean STO/Si interface is found using in-situ X-ray photoelectron spectroscopy and confirmed by cross-sectional scanning transmission electron microscopy. The capacitance-voltage characteristics of 720?nm-thick BTO films are examined and show an effective dielectric constant of ?660 for the heterostructure.

  13. Relaxor nature in lead-free Sr{sub 5}LaTi{sub 3}Nb{sub 7}O{sub 30} tetragonal tungsten bronze ceramics

    SciTech Connect (OSTI)

    Li Zhu, Xiao; Department of Materials and Ceramic Engineering, Centre for Research in Ceramics and Composite Materials, CICECO, University of Aveiro, 3810-193 Aveiro ; Li, Kun; Qiang Liu, Xiao; Ming Chen, Xiang; Asif Rafiq, Muhammad

    2013-09-28

    Lead-free tetragonal tungsten bronze Sr{sub 5}LaTi{sub 3}Nb{sub 7}O{sub 30} ceramics were prepared and the correlation of the relaxor nature and crystal structure was studied using dielectric spectroscopy and powder X-ray diffraction. Three dielectric relaxations were observed below the deviation temperature T{sub D}? 330 K. Relaxation I and II followed the Vogel-Fulcher law with the freezing temperatures of 189 K and ?90 K. Low temperature relaxation III, which was first observed in filled tungsten bronze, followed well the Arrhenius law. Dielectric response becomes static below 50 K. Polarization-field (P-E) hysteresis loops were evaluated from 183 K to 298 K. P{sub r} value of 0.41?C/cm{sup 2} was observed at 183 K. Deviation of lattice parameter c from the linear contraction and increasing of tetragonality (c/a ratio) were observed below T{sub D}, reflecting the structure change during the formation of polar nanoregions and the following freezing process. Opposite tendency was observed below 100 K for all the lattice parameters, corresponding to relaxation III. Generally, the main dielectric relaxation I and II were attributed to flipping and breathing of polar nanoregions along c axis, while the concerted rotations of the oxygen octahedra in the ab plane were suggested as the origin of relaxation III.

  14. Electric-field-induced strain effects on the magnetization of a Pr0.67Sr0.33MnO3 film

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

    Zhang, B.; Sun, C. -J.; Lu, W.; Venkatesan, T.; Han, M. -G.; Zhu, Y.; Chen, J.; Chow, G. M.

    2015-05-26

    The electric-field control of magnetic properties of Pr0.67Sr0.33MnO3 (PSMO) film on piezoelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMNT) substrate was investigated. The piezoelectric response of the PMNT substrate to the electric field produced strain that was coupled to the PSMO film. The in-plane compressive (tensile) strain increased (decreased) the magnetization. The change of magnetic moment was associated with the Mn ions. First principle simulations showed that the strain-induced electronic redistribution of the two eg orbitals (3dz2 and 3dx2-y2) of Mn ions was responsible for the change of magnetic moment. This work demonstrates that the magnetoelectric effect in manganite/piezoelectric hetero-structures originates from the change inmore » eg orbital occupancy of Mn ions induced by strain rather than the interfacial effect.« less

  15. Direct correlation and strong reduction of native point defects and microwave dielectric loss in air-annealed (Ba,Sr)TiO{sub 3}

    SciTech Connect (OSTI)

    Zeng, Z. Q.; Podpirka, A.; Kirchoefer, S. W.; Asel, T. J.; Brillson, L. J.

    2015-05-04

    We report on the native defect and microwave properties of 1 ?m thick Ba{sub 0.50}Sr{sub 0.50}TiO{sub 3} (BST) films grown on MgO (100) substrates by molecular beam epitaxy (MBE). Depth-resolved cathodoluminescence spectroscopy (DRCLS) showed high densities of native point defects in as-deposited BST films, causing strong subgap emission between 2.0?eV and 3.0?eV due to mixed cation V{sub C} and oxygen Vo vacancies. Post growth air anneals reduce these defects with 2.2, 2.65, and 3.0?eV V{sub O} and 2.4?eV V{sub C} intensities decreasing with increasing anneal temperature and by nearly two orders of magnitude after 950?C annealing. These low-defect annealed BST films exhibited high quality microwave properties, including room temperature interdigitated capacitor tunability of 13% under an electric bias of 40?V and tan?? of 0.002 at 10?GHz and 40?V bias. The results provide a feasible route to grow high quality BST films by MBE through post-air annealing guided by DRCLS.

  16. Metalsemiconductor transition in atomically thin Bi{sub 2}Sr{sub 2}Co{sub 2}O{sub 8} nanosheets

    SciTech Connect (OSTI)

    Wang, Yang; Cheng, Rui; Dong, Jianjin; Liu, Yuan; Zhou, Hailong; Yu, Woo Jong; Terasaki, Ichiro; Huang, Yu; Duan, Xiangfeng

    2014-09-01

    Two-dimensional layered materials have attracted considerable attention since the discovery of graphene. Here we demonstrate that the layered Bi{sub 2}Sr{sub 2}Co{sub 2}O{sub 8} (BSCO) can be mechanically exfoliated into single- or few-layer nanosheets. The BSCO nanosheets with four or more layers display bulk metallic characteristics, while the nanosheets with three or fewer layers have a layer-number-dependent semiconducting characteristics. Charge transport in bilayer or trilayer BSCO nanosheets exhibits Mott 2D variable-range-hopping (VRH) conduction throughout 2 K300 K, while the charge transport in monolayers follows the Mott-VRH law above a crossover temperature of 75 K, and is governed by Efros and Shklovskii-VRH laws below 75 K. Disorder potentials and Coulomb charging both contribute to the transport gap of these nanodevices. Our study reveals a distinct layer number-dependent metal-to-semiconductor transition in a new class of 2D materials, and is of great significance for both fundamental investigations and practical devices.

  17. Sr{sub 4}Ru{sub 6}ClO{sub 18}, a new Ru{sup 4+/5+} oxy-chloride, solved by precession electron diffraction: Electric and magnetic behavior

    SciTech Connect (OSTI)

    Roussel, Pascal; Palatinus, Lukas; Belva, Frdric; Daviero-Minaud, Sylvie; Mentre, Olivier; Huve, Marielle

    2014-04-01

    The crystal structure of Sr{sub 4}Ru{sub 6}ClO{sub 18}, a new Ru{sup 4+/5+} oxo-chloride, has been determined from Precession Electron Diffraction (PED) data acquired on a nanocrystal in a transmission electron microscope using the technique of electron diffraction tomography. This approach is described in details following a pedagogic route and a systematic comparison is made of this rather new method with other experimental methods of electron diffraction, and with the standard single crystal X-ray diffraction technique. Both transport and magnetic measurements, showed a transition at low temperature that may be correlated to Ru{sup 4+}/Ru{sup 5+} charge ordering. - Graphical abstract: Structure of Sr{sub 4}Ru{sub 6}ClO{sub 18}, determined using Precession Electron Diffraction data. - Highlights: Structure of Sr{sub 4}Ru{sub 6}ClO{sub 18} was solved ab initio using precession electron diffraction. This was done both on a nanometric sample and on a micrometric one. Different type of experimental methods of electron diffraction are compared. Single crystal X-ray diffraction was used to confirm the results. Transport properties were characterized and show exotic behavior.

  18. Growth of large-domain YBa{sub 2}Cu{sub 3}O{sub x} with new seeding crystals of CaNdAlO{sub 4} and SrLaGaO{sub 4}.

    SciTech Connect (OSTI)

    Shi, D.; Hull, J. R.; LeBlanc, D.; LeBlanc, M. A. R.; Dabkowski, A.; Chang, Y.; Jiang, Y.; Zhang, Z.; Fan, H.; Energy Technology; Univ. of Cincinnati; Univ. of Ottawa; McMaster Univ.; Chinese Academy of Sciences

    1995-05-10

    Single crystals of CaNdAlO{sub 4} and SrLaGaO{sub 4} were used as seeds to grow large domains of YBa{sub 2}Cu{sub 3}O{sub x} for levitation applications. These crystals have high melting temperatures (> 1500 C) and similar lattice structures to that of YBa{sub 2}Cu{sub 3}O{sub x}. In a seeded melt-texturing method developed previously, the single crystals of CaNdAlO{sub 4}, SrLaGaO{sub 4}, and NdBa{sub 2}Cu{sub 3}O{sub x} were used as seeds for comparison. After melt processing, scanning electron microscopy analysis did not reveal any major differences in all these seeded melt-textured samples. However, the levitation forces in the samples seeded with single crystals of CaNdAlO{sub 4} and SrLaGaO{sub 4} increased considerably compared to that of the sample seeded with NdBa{sub 2}Cu{sub 3}O{sub x}. A model is proposed to describe the domain growth mechanism during seeded melt processing.

  19. Synthesis and characterization of perovskite-type Sr{sub x}Y{sub 1−x}FeO{sub 3−δ} (0.63≤x<1.0) and Sr{sub 0.75}Y{sub 0.25}Fe{sub 1−y}M{sub y}O{sub 3−δ} (M=Cr, Mn, Ni), (y=0.2, 0.33, 0.5)

    SciTech Connect (OSTI)

    Biendicho, J.J.; Shafeie, S.; Frenck, L.; Gavrilova, D.; Böhme, S.; Bettanini, A.M.; Svedlindh, P.; Hull, S.; Zhao, Z.; Istomin, S.Ya.; Grins, J.; Svensson, G.

    2013-04-15

    Oxygen-deficient ferrates with the cubic perovskite structure Sr{sub x}Y{sub 1−x}FeO{sub 3−δ} were prepared in air (0.71≤x≤0.91) as well as in N{sub 2} (x=0.75 and 0.79) at 1573 K. The oxygen content of the compounds prepared in air increases with increasing strontium content from 3−δ=2.79(2) for x=0.75 to 3−δ=2.83(2) for x=0.91. Refinement of the crystal structure of Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79} using TOF neutron powder diffraction (NPD) data shows high anisotropic atomic displacement parameter (ADP) for the oxygen atom resulting from a substantial cation and anion disorder. Electron diffraction (ED) and high-resolution electron microscopy (HREM) studies of Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79} reveal a modulation along 〈1 0 0〉{sub p} with G± ∼0.4〈1 0 0〉{sub p} indicating a local ordering of oxygen vacancies. Magnetic susceptibility measurements at 5–390 K show spin-glass behaviour with dominating antiferromagnetic coupling between the magnetic moments of Fe cations. Among the studied compositions, Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79} shows the lowest thermal expansion coefficient (TEC) of 10.5 ppm/K in air at 298–673 K. At 773–1173 K TEC increases up to 17.2 ppm/K due to substantial reduction of oxygen content. The latter also results in a dramatic decrease of the electrical conductivity in air above 673 K. Partial substitution of Fe by Cr, Mn and Ni according to the formula Sr{sub 0.75}Y{sub 0.25}Fe{sub 1−y}M{sub y}O{sub 3−δ} (y=0.2, 0.33, 0.5) leads to cubic perovskites for all substituents with y=0.2. Their TECs are higher in comparison with un-doped Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79}. Only M=Ni has increased electrical conductivity compared to un-doped Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79}. - Graphical abstract: Oxygen-deficient ferrates with the cubic perovskite structure Sr{sub x}Y{sub 1−x}FeO{sub 3−δ} were prepared both in air (0.71≤x≤0.91) and N{sub 2} (x=0.75 and 0.79) at 1573 K. Refinement of the crystal structure of Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79} using TOF neutron powder diffraction (NPD) data (S.G. Pm-3m, a=3.86455(3) Å; χ{sup 2}=6.71, R{sub p}=0.03; R{sub wp}=0.04) confirmed the cubic perovskite structure. The observed high anisotropic atomic displacement parameter for the oxygen atom indicates a substantial anion sublattice disorder. Electron diffraction (ED) and high-resolution electron microscopy (HREM) studies of Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79} show compositional modulation along 〈1 0 0〉{sub p} with G± ∼0.4〈1 0 0〉{sub p} indicating ordering of oxygen vacancies at the local scale. Highlights: ► Cubic perovskites Sr{sub x}Y{sub 1−x}FeO{sub 3−δ} (0.71≤x<0.91) were synthesized. ► Sr{sub 0.75}Y{sub 0.25}Fe{sub 1−y}M{sub y}O{sub 3−δ}, M=Cr, Mn, Ni were prepared. ► High-temperature conductivity properties and crystal structure were studied. ► High-temperature thermal expansion behavior was investigated.

  20. Crystal structure, characterization and thermoelectric properties of the type-I clathrate Ba{sub 8-y}Sr{sub y}Al{sub 14}Si{sub 32} (0.6{<=}y{<=}1.3) prepared by aluminum flux

    SciTech Connect (OSTI)

    Roudebush, John H.; Toberer, Eric S.; Hope, Hakon; Jeffrey Snyder, G.; Kauzlarich, Susan M.

    2011-05-15

    The title compound was prepared as single crystals using an aluminum flux technique. Single crystal and powder X-ray diffraction indicate that this composition crystallizes in the clathrate type-I structure, space group Pm3-bar n. Electron microprobe characterization indicates the composition to be Ba{sub 8-y}Sr{sub y}Al{sub 14.2(2)}Si{sub 31.8(2)} (0.77Sr atom preferentially occupies the 2a position; mixed Al/Si occupancy was found on all framework sites. These refinements are consistent with a fully occupied framework and nearly fully occupied cation guest sites as found by microprobe analysis. Temperature dependent electrical resistivity and thermal conductivity have been measured from room temperature to 1200 K on a hot-pressed pellet. Electrical resistivity reveals metallic behavior. The negative Seebeck coefficient indicates transport processes dominated by electrons as carriers. Thermal conductivity is between 22 and 25 mW/cm K. The sample shows n-type conductivity with a maximum figure of merit, zT of 0.3 at 1200 K. A single parabolic band model predicts a five-fold increase in zT at 800 K if carrier concentration is lowered. -- Graphical abstract: The inorganic type-I clathrate phase with nominal composition Ba{sub 7}Sr{sub 1}Al{sub 14}Si{sub 32} has been prepared by Al flux. Single crystal diffraction at 90 and 12 K reveal that the framework is fully occupied with the cation sites nearly fully occupied. The lattice thermal conductivity is low thereby suggesting further optimization of the carrier concentration will lead to a high zT. Display Omitted Highlights: {yields} Ba{sub 7}Sr{sub 1}Al{sub 14}Si{sub 32} is a light element phase ideal for thermoelectric power generation. {yields} Ba{sub 7}Sr{sub 1}Al{sub 14}Si{sub 32} is a high melting point cubic structure ideal for efficient power generation. {yields} The framework is fully occupied with the cation sites nearly fully occupied. {yields} Further optimization of the carrier concentration is expected to lead to a high zT.