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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. 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

  6. 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

  7. 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

  8. Matt Rogers | Department of Energy

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

    He earned an M.B.A. from Yale University's School of Management Matt is married to the Honorable Yvonne Gonzalez Rogers, who serves as a California Superior Court Judge on the ...

  9. 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...

  10. Roger Seitz Savannah River National Laboratory

    Office of Environmental Management (EM)

    Practical Considerations for Development and Selection of Scenarios Roger Seitz Savannah River ... Dust, Radon Drinking Water Fish Plant Foods Meat Milk Radioactively Contaminated ...

  11. 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...

  12. 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;...

  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 D. Kornberg Polymerase, DNA, RNA, and Transcription

    Office of Scientific and Technical Information (OSTI)

    Roger D. Kornberg Polymerase, DNA, RNA, and Transcription Resources with Additional Information Roger D. Kornberg Credit: Linda A. Cicero/ Stanford News Service Roger D. Kornberg was awarded the 2006 Nobel Prize in Chemistry "for his studies of the molecular basis of eukaryotic transcription". He determined 'how DNA's genetic blueprint is read and used to direct the process for protein manufacture. Kornberg carried out a significant part of the research leading to this prize at the

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

    Office of Legacy Management (LM)

    of Ohio Analytical Data Sheet 9908; August 2, 1956 MO.10-2 - MemorandumChecklist, Williams to File; Subject: Rogers Iron; June 1, 1990 MO.10-3 - DOE Memorandum; Williams to the...

  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. 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...

  19. 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

  20. ^ <\^ P. Franzmi, B. Leontic, D. Rahm and N. Saraios JS^'^'^'^^ Brookhaven National Laboratory, Upton, New York litHwIUl

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

    r . . - Submitted to Phys. Rev. Letters January 1965 B-40 (BC) , ^ i r A Search for Massive Particles Produced in Interactions at 30 BeV* BNL 8751 ( ^ ^ <\^ P. Franzmi, B. Leontic, D. Rahm and N. Saraios JS^'^'^'^^ Brookhaven National Laboratory, Upton, New York litHwIUl .<^W<,^' o<^V ^' Schwartz sSr . . , ,<= ^^ <^ Columbia University, New York, New York We report here the results of a search for moderately stable negatively charged particles in the mass region of 2.5 - 5.0

  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. 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.

  3. 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. Roberson recently announced the designation of Jeffrey M. Allison as Acting Manager for the Department of Energy (DOE) Savannah River Operations Office (SR). Mr. Allison is a career member of the Senior Executive Service with over 19 years of experience in engineering, safety, health, process development, and management

  4. 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, SC; February 22 -Today the Department of Energy (DOE) Savannah River Operations Office (SR) issued a Notice of Intent to prepare a Supplemental Environmental Impact Statement (SEIS) on the proposed replacement of the existing In-Tank Precipitation (ITP) process at the Savannah River Site (SRS). Replacement of the

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

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

    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...

  6. 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

  7. SR0014

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

    November 30, 2000 Media Contact: Jim Giusti (803) 725-2889 Draft EIS Issued On Future Closures Of SRS High-Level Waste Tanks Flag Ribbon Graphic AIKEN, 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 (EIS) on the proposed closing of additional high-level waste (HLW) tanks at the Savannah River Site (SRS). DOE-SR proposes to close the tank systems to protect human health and

  8. 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 Operations Office (SR) Acting Manager Jeffrey Allison will publicly release the recently published technical history of the Savannah River Site (SRS), SRS at Fifty. WHAT: Brief event involving local students and DOE-SR Acting Manager. WHEN: Wednesday, October 2, 2002, at 2:00 PM. WHERE: New Ellenton Middle School; SC Highway

  9. SR0706

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

    4, 2007 Media Contact: James Giusti (803) 952-7697 james-r.giusti@srs.gov DOE Honors Hepner as Federal Small Business Manger of the Year AIKEN, S.C., – David W. Hepner, Sr., Community Affairs/Small Business Program Manager for the U.S. Department of Energy (DOE) Savannah River Operations Office (SR) was recently honored as the Federal Small Business Manager of the Year for his dedication and high achievement to encourage small business participation in Fiscal Year 2006. Winners of DOE’s 2006

  10. 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

  11. 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

  12. 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

  13. 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 Energy's Savannah River Operations Office (SR) today issued its Accident Investigation Board's findings on the cause of plutonium intakes by seven Savannah River Site (SRS) employees in the FB-Line facility. On September 1, 1999, plutonium was released from a failed plutonium storage canister at the Site's FB-Line

  14. 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

  15. SR0013

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

    25, 2000 Media Contact: Rick Ford (803) 725-2889 Savannah River Operations Office Wins Best Practices Award Flag Ribbon Graphic The Department of Energy's Savannah River Operations Office (SR) has received the FY2000 "Human Resources/Equal Employment Opportunity Best Practices" Award from the Federal Personnel Management Institute (FPMI). The award is presented annually by FPMI to a single Federal organization that has "demonstrated outstanding innovation and creativity in

  16. 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 |

  17. 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

  18. 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 Energy (DOE) Savannah River Operations Office (SR) announces the availability of a Draft Supplemental Environmental Impact Statement (EIS) which evaluates alternatives for separating the high-activity and low-activity salt waste from the liquid high-level radioactive waste now stored in underground tanks at the Savannah

  19. 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 Department of Energy (DOE) Savannah River Operations Office (SR) announced in the Commerce Business Daily the availability of the Draft Request for Proposals (RFP) for the acquisition of services to design, construct, and commission a facility to process the salt fraction of high-level radioactive waste currently

  20. 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 AIKEN, SC; July 20 -Today the Department of Energy (DOE) Savannah River Operations Office (SR) announced the availability of the Savannah River Site Salt Processing Alternatives Final Supplemental Environmental Impact Statement (EIS). Based on DOE's evaluation of research results and comments received on the Draft

  1. SR0305

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

    2, 2003 Media Contact: Jim Giusti (803) 725-2889 DOE 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 host this month two public information workshops & seek public comments on the preservation of historical "Cold War" resources at SRS. As part of its compliance with the National Historic Preservation Act (NHPA) of 1966 (as amended), the Department will

  2. 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

  3. 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 performance award fee earned by Wackenhut Services, Incorporated, for the evaluation period January 25, 1999 through May 31, 1999. The letter announcing DOE’s award fee determination is available by calling (803) 725-2889 -DOE- SR-99-10 | Back |

  4. 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

  5. U.S. Department of Energy Contact: Roger Nelson U.S. DOE Carlsbad Field Office

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

    Contact: Roger Nelson U.S. DOE Carlsbad Field Office (575) 234-7213 www.wipp.energy.gov Carlsbad Field Office Waste Isolation Pilot Plant P.O. Box 2078 Carlsbad, New Mexico 88221 For Immediate Release WIPP Honored with Transportation Safety Award CARLSBAD, N.M., January 29, 2009 - The U.S. Department of Energy's (DOE) Waste Isolation Pilot Plant (WIPP) was honored by the United States Transportation Council (USTC) with an award for transportation safety. James Rispoli, former DOE Assistant

  6. 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.

  7. Paul V. Braun and John A. Rogers Materials Research Laboratory, University of Illinois at Urbana-Champaign

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

    V. Braun and John A. Rogers Materials Research Laboratory, University of Illinois at Urbana-Champaign Three-Dimensionally Architectured Optoelectronics Achievement: We have developed an approach for three- dimensional template-directed epitaxy of high- performance III-V semiconductor materials. We have demonstrated optoelectronic functionality by fabricating a 3D photonic crystal LED, the rst- ever electrically driven emission from a 3D photonic crystal device. We also demonstrate that the LED

  8. 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

  9. Delamere-JS

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

    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. ...

  10. 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

  11. 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

  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. 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

  14. SR-08-02.doc

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

    Media Contacts: For Immediate Release Embargoed until August 1, 2008 DOE: Julie Petersen, (803) 952-7697 julie.petersen@srs.gov SRNS: Will Callicott, (803) 952-9583 will.callicott@srs.gov DOE Authorizes New Contractor to Begin Management and Operations of the Savannah River Site Aiken, SC - Yesterday (July 31), the U.S. Department of Energy Savannah River Operations Office (DOE-SR) Manager, Jeffrey M. Allison, and the Savannah River Nuclear Solutions (SRNS) President and Chief Executive

  15. SR????

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

    28, 2006 Media Contact: James Giusti (803) 952-7697 Note To Editors and News Directors: Aiken, SC – On Thursday, November 30, U.S. Department of Energy Assistant Secretary for Environmental Management James Rispoli will speak at a ceremony marking the completion of T Area Closure at the Savannah River Site. T Area was the first operational area at SRS, starting up in 1952 and continuing to serve the site until 2002, when demolition began on its 28 facilities. Demolition was completed in 2004,

  16. SR????

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

    February 13, 2007 Media Contact: James Giusti (803) 952-7697 james-r.giusti@srs.gov DOE Seeks Public Input on Scope of Environmental Review for the Global Nuclear Energy Partnership Aiken, South Carolina – The U.S. Department of Energy’s Savannah River Operations Office today announced that the second public scoping meeting to begin the Programmatic Environmental Impact Statement (PEIS) for the President’s Global Nuclear Energy Partnership (GNEP) will be held on Thursday, February 15, 2007 at

  17. Rapid method to determine 89Sr/90Sr in large concrete samples

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

    Maxwell, Sherrod L.; Culligan, Brian; Hutchison, Jay B.; Utsey, Robin C.; Sudowe, Ralf; McAlister, Daniel R.

    2016-03-24

    A new rapid method has been developed that provides high quality low-level measurements of 89,90Sr in concrete samples with an MDA (Minimum Detectable Activity) of <1 mBq g-1. The new method is fast, meets new decommissioning regulatory limits and is robust even if refractory particles are present. The method utilizes a rapid fusion to ensure total dissolution of samples and rapid preconcentration and separation of 89,90Sr from 5-10 g concrete samples. When, the 89Sr/90Sr ratio is high, Sr can be isolated from up to 5g concrete samples, total 89/90Sr measured, and then 90Sr determined via 90Y separated after a periodmore » of ingrowth. Another approach allows the immediate determination of 90Sr in 10 g concrete aliquots without waiting for 90Y ingrowth, in instances where the shorter lived 89Sr is unlikely to be encountered.« less

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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...

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

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

    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

  4. 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

  5. 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

  6. 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

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

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

    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 Special Report: OAS-SR-04-01 Audit Report: OAS-SR-05-02 Special Report: OAS-SR-05-03

  8. .sup.82 Sr-.sup.82 Rb Radioisotope generator

    DOE Patents [OSTI]

    Grant, Patrick M.; Erdal, Bruce R.; O'Brien, Harold A.

    1976-01-01

    An improved .sup.82 Sr-.sup.82 Rb radioisotope generator system, based upon the complexing ion exchange resin Chelex-100, has been developed. Columns of this material can be easily and rapidly milked, and the Rb-Sr separation factor for a fresh generator was found to be > 10.sup.7. Approximately 80 percent of the .sup.82 Rb present was delivered in a 15-ml volume of aqueous 0.2 M NH.sub.4 Cl solution. After more than 6 liters of eluant had been put through the generator, the Rb-Sr separation factor was still observed to be > 10.sup.5, and no unusual strontium breakthrough behavior was seen in the system over nearly three .sup.82 Sr half lives.

  9. 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...

  10. 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....

  11. 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....

  12. 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...

  13. Brookhaven National Laboratory - Sr90 - Chemical Holes | Department of

    Office of Environmental Management (EM)

    Energy - Chemical Holes Brookhaven National Laboratory - Sr90 - Chemical Holes January 1, 2014 - 12:00pm Addthis US Department of Energy Groundwater Database Groundwater Master Report InstallationName, State: Brookhaven National Laboratory Responsible DOE Office: Office of Science Plume Name: Sr90 - Chemical Holes Remediation Contractor: Brookhaven Science Associates PBS Number: 30 Report Last Updated: 2014 Contaminants Halogenated VOCs/SVOCs Present?: No Fuel Present? No Metals Present? No

  14. Brookhaven National Laboratory - Sr90-Former HWMF | Department of Energy

    Office of Environmental Management (EM)

    -Former HWMF Brookhaven National Laboratory - Sr90-Former HWMF January 1, 2014 - 12:00pm Addthis US Department of Energy Groundwater Database Groundwater Master Report InstallationName, State: Brookhaven National Laboratory Responsible DOE Office: Office of Science Plume Name: Sr90-Former HWMF Remediation Contractor: Brookhaven Science Associates PBS Number: 30 Report Last Updated: 2014 Contaminants Halogenated VOCs/SVOCs Present?: No Fuel Present? No Metals Present? No Isotopes Present? Yes

  15. 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.

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

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

    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...

  17. 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...

  18. 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.

  19. 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.

  20. Antonios Kelarakis > Sr. Researcher - University of Central Lancashire >

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

    Center Alumni > The Energy Materials Center at Cornell Antonios Kelarakis Sr. Researcher - University of Central Lancashire antonios.kelarakis@gmail.com Dr. Kelarakis worked with the Giannelis Group while at Cornell. He has since joined the University of Central Lancashire, where he is a Senior Researcher/Guild Research Fellow with School of Forensic and Investigative Sciences. Antonio's research interests include colloids, biomaterials, smart coatings and nanostructured materials for

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

    Energy Savers [EERE]

    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

  2. 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.

  3. THE FEDERAL ENERGY ADMINISTRATION By Roger Anders

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

    ... and Production Act, required the Federal Energy Administration to improve data collection by the creation of an assistant administrator for energy information and analysis. ...

  4. 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...

  5. Brookhaven National Laboratory - Sr-90 BGGR/WCF | Department of Energy

    Office of Environmental Management (EM)

    Sr-90 BGGR/WCF Brookhaven National Laboratory - Sr-90 BGGR/WCF January 1, 2014 - 12:00pm Addthis US Department of Energy Groundwater Database Groundwater Master Report InstallationName, State: Brookhaven National Laboratory Responsible DOE Office: Office of Science Plume Name: Sr-90 BGGR/WCF Remediation Contractor: Brookhaven Science Associate PBS Number: 30 Report Last Updated: 2014 Contaminants Halogenated VOCs/SVOCs Present?: No Fuel Present? No Metals Present? No Isotopes Present? Yes

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

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

    Energy 8 - In the Matter of Wayne C. Brunsilius, Sr. FIA-16-0018 - In the Matter of Wayne C. Brunsilius, Sr. 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 challenged OLM's search for responsive documents. When contacted by OHA, OLM stated that its subject matter expert searched the OLM Electronic Recordkeeping System (ERKS) for potentially responsive

  7. U. S. Department of Energy Savannah River Operations Office - DOE-SR News

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

    Release Archive Release Archive DOE-SR News Release Archive 2012 News Releases Savannah River Site Reaches Significant Milestone with Waste Tank Closure SR-2012-06 Adobe Acrobat PDF DOE to Extend Savannah River Nuclear Solutions Contract at Savannah River Site to September 2016 SR-2012-05 Adobe Acrobat PDF Savannah River Site Federal Employees Volunteer for United Way Campaign SR-2012-04 Adobe Acrobat PDF Installation of Six Large Process Tanks Mark Big Step in Construction of Critical Waste

  8. U. S. Department of Energy Savannah River Operations Office - DOE-SR News

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

    Releases Releases DOE-SR News Releases DOE Releases Draft Request for Proposal and Announces Pre-Solicitation Conference for Savannah River Site Liquid Waste Services SR-2016-03 Adobe Acrobat PDF SRS Breaks Ground for New Heating Plant at Biomass Cogeneration Facility SR-2015-04 Adobe Acrobat PDF Energy Department Adds Two Years to Liquid Waste Management Contract at Savannah River Site SR-2015-04 Adobe Acrobat PDF Partial Agreement Reached On Savannah River Site Tank Closure Milestone

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

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

    10-04 Special Inquiry: OAS-SR-10-04 September 22, 2010 Review of Allegations Regarding Hiring and Contracting in the Office of Energy Efficiency and Renewable Energy Not Available for Viewing More Documents & Publications Audit Special Inquiry: OAS-SR-10-04 Special Inquiry: OAS-SR-07-01 EERE Report, Special Inquiry: "Review of Allegations RegardingHiring and Contracting in the Office of Energy Efficiency andRenewable Energy" Report Number: OAS-SR- 10-04

  10. 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.

  11. Ferroelectric-like response from the surface of SrTiO₃ crystals at high temperatures

    SciTech Connect (OSTI)

    Jyotsna, Shubhra; Arora, Ashima; Sekhon, Jagmeet S.; Sheet, Goutam

    2014-09-14

    Since SrTiO₃ has a high dielectric constant, it is used as a substrate for a large number of complex physical systems for electrical characterization. Since SrTiO₃ crystals are known to be non-ferroelectric/non-piezoelectric at room temperature and above, SrTiO₃ has been believed to be a good choice as a substrate/base material for PFM (Piezoresponse Force Microscopy) on novel systems at room temperature. In this paper, from PFM-like measurement using an atomic force microscope on bare crystals of (110) SrTiO₃ we show that ferroelectric and piezoelectric-like response may originate from bare SrTiO₃ at remarkably high temperatures up to 420 K. Electrical domain writing and erasing are also possible using a scanning probe tip on the surface of SrTiO₃ crystals. This observation indicates that the role of the electrical response of SrTiO₃ needs to be revisited in the systems where signature of ferroelectricity/piezoelectricity has been previously observed with SrTiO₃ as a substrate/base material.

  12. 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}.

  13. 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.

  14. 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.

  15. News Media Contact: For Immediate Release Amy C. Scales, DOE-SR Wednesday, June 11, 2014

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

    Contact: For Immediate Release Amy C. Scales, DOE-SR Wednesday, June 11, 2014 (803) 952-7213 amy.caver@srs.gov U.S. Department of Energy Names New Deputy Manager AIKEN, S.C. (June 11, 2014) - The U.S. Department of Energy, Savannah River Operations Office (DOE-SR), announced today the selection of Mr. Terrel "Terry" J. Spears as the Deputy Manager of the Savannah River Site. "We are pleased to have Terry as our Deputy Manager," David Moody, DOE-SR Manager, said. "He has

  16. 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

  17. 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 ...

  18. Interrelation between Structure Magnetic Properties in La0.5Sr0...

    Office of Scientific and Technical Information (OSTI)

    Interrelation between Structure Magnetic Properties in La0.5Sr0.5CoO3 Citation Details In-Document Search Title: Interrelation between Structure Magnetic Properties in ...

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

    Office of Scientific and Technical Information (OSTI)

    in SrRuO3 by ionic gating Reversible control of charge transport and magnetic ... We report a reversible control of charge transport, metal-insulator crossover and ...

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

    Office of Scientific and Technical Information (OSTI)

    garnet primary pressure scale Citation Details In-Document Search Title: Revised calibration of the Sm:SrBsub 4Osub 7 pressure sensor using the Sm-doped yttrium-aluminum garnet ...

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

    Broader source: Energy.gov [DOE]

    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.

  2. 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 ...

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

    Office of Scientific and Technical Information (OSTI)

    under Nesup 2+ ion irradiation We systematically investigated the microstructural evolution of heteroepitaxial SrTiOsub 3 (STO) thin films grown on a single crystal LaAlOsub ...

  4. Special Report: OIG-SR-16-02 | Department of Energy

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

    Special Report: OIG-SR-16-02 Special Report: OIG-SR-16-02 April 26, 2016 The Department of Energy's Continued Support of the Texas Clean Energy Project Under the Clean Coal Power Initiative The Department of Energy's Clean Coal Power Initiative is a partnership with industry to demonstrate advanced coal-based technologies, with the goal of accelerating commercial deployment of promising technologies to ensure the nation has clean, reliable, and affordable electricity. In January 2010, the

  5. 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 The Advanced Fuel Cycle Initiative is developing advanced technologies to allow for the safe and economical disposal of waste from nuclear reactors. An important element of this initiative is the separation of key radionuclides . One of the systems being

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

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

    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

  7. 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

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

    Energy Savers [EERE]

    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

  9. Phase stability of the SrMnO[subscript 3] hexagonal perovskite system at

    Office of Scientific and Technical Information (OSTI)

    high pressure and temperature (Journal Article) | SciTech Connect stability of the SrMnO[subscript 3] hexagonal perovskite system at high pressure and temperature Citation Details In-Document Search Title: Phase stability of the SrMnO[subscript 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 [1] ; UC) [2] ; ESRF) [2] ; CNR-INFM) [2]

  10. 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,

  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. 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.

  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. 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

  16. 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.

  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. Electrolyte Gate-Controlled Kondo Effect in SrTiO3 (Journal Article) | DOE

    Office of Scientific and Technical Information (OSTI)

    PAGES Electrolyte Gate-Controlled Kondo Effect in SrTiO3 « Prev Next » Title: Electrolyte Gate-Controlled Kondo Effect in SrTiO3 Authors: Lee, Menyoung ; Williams, J. R. ; Zhang, Sipei ; Frisbie, C. Daniel ; Goldhaber-Gordon, D. Publication Date: 2011-12-12 OSTI Identifier: 1098385 Type: Publisher's Accepted Manuscript Journal Name: Physical Review Letters Additional Journal Information: Journal Volume: 107; Journal Issue: 25; Journal ID: ISSN 0031-9007 Publisher: American Physical Society

  19. 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

  20. SPECTROPOLARIMETRY OF THE TYPE Ia SN 2007sr TWO MONTHS AFTER MAXIMUM LIGHT

    SciTech Connect (OSTI)

    Zelaya, P.; Quinn, J. R.; Clocchiatti, A.; Baade, D.; Patat, F.; Hoeflich, P.; Maund, J.; Wang, L.; Wheeler, J. C.

    2013-02-01

    We present late-time spectropolarimetric observations of SN 2007sr, obtained with the Very Large Telescope at the ESO Paranal Observatory when the object was 63 days after maximum light. The late-time spectrum displays strong line polarization in the Ca II absorption features. SN 2007sr adds to the case of some normal Type Ia supernovae that show high line polarization or repolarization at late times, a fact that might be connected with the presence of high-velocity features at early times.

  1. Accessing a growth window for SrVO3 thin films (Journal Article) | SciTech

    Office of Scientific and Technical Information (OSTI)

    Connect Accessing a growth window for SrVO3 thin films Citation Details In-Document Search This content will become publicly available on October 6, 2016 Title: Accessing a growth window for SrVO3 thin films Authors: Brahlek, Matthew [1] ; Zhang, Lei [1] Search SciTech Connect for author "Zhang, Lei" Search SciTech Connect for ORCID "0000000215598469" Search orcid.org for ORCID "0000000215598469" ; Eaton, Craig [1] ; Zhang, Hai-Tian [1] Search SciTech Connect

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

    DOE Patents [OSTI]

    Dorris, Stephen E.; Poeppel, Roger B.; Prorok, Barton C.; Lanagan, Michael T.; Maroni, Victor A.

    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.

  3. 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.

  4. 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:

  5. Enhancing the Electron Mobility via Delta-Doping in SrTiO3

    SciTech Connect (OSTI)

    Kozuka, Y.

    2011-08-11

    We fabricated high-mobility {delta}-doped structures in SrTiO{sub 3} thin films in order to investigate the low temperature electronic transport properties of confined carriers in this system. An enhancement of the electron mobility above the bulk value was observed as the doped layer thickness decreased. High-field Hall measurements revealed that this mobility enhancement originates from higher-mobility electrons in the undoped clean regions, which have quantum-mechanically broadened from the doped layer. Because of the absence of apparent lattice misfit between the layers, this structure is highly suitable for investigating two-dimensional electron gases in SrTiO{sub 3}

  6. 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 × 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

  7. 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.

  8. 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

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

    DOE Patents [OSTI]

    Hinks, David G.; Capone, II, Donald W.

    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.

  11. 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

  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. 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.

  14. Jie Gao > Sr. Electrochemist - Spectrum Brands > Center Alumni > The Energy

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

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

  15. Carbon dioxide, hydrographic, and chemical data obtained during the R/Vs Roger Revelle and Thomas Thompson repeat hydrography cruises in the Pacific Ocean: CLIVAR CO2 sections P16S-2005 (9 January - 19 February, 2005) and P16N-2006 (13 February - 30 March, 2006)

    SciTech Connect (OSTI)

    Kozyr, Alex; Feely, R. A.; Sabine, C. L.; Millero, F. J.; Langdon, C.; Dickson, A. G.; Fine, R. A.; Bullister, J. L.; Hansell, D. A.; Carlson, C. A.; Sloyan, B. M.; McNichol, A. P.; Key, R. M.; Byrne, R. H.; Wanninkhof, R.

    2009-05-01

    This report presents methods, and analytical and quality control procedures for salinity, oxygen, nutrients, total carbon dioxide (TCO2), total alkalinity (TALK), pH, discrete CO2 partial pressure (pCO2), dissolved organic carbon (DOC), chlorofluorocarbons (CFCs), radiocarbon, δ13C, and underway carbon measurements performed during the P16S-2005 (9 January - 19 February 2005) and P16N-2006 (13 February - 30 March, 2006) cruises in the Pacific Ocean. The research vessel (R/V) Roger Revelle departed Papeete, Tahiti, on January 9, 2005 for the Repeat Section P16S, nominally along 150°W, ending in Wellington, New Zealand, on February 19. During this cruise, samples were taken from 36 depths at 111 CTD stations between 16°S and 71°S. The Repeat Section P16N, nominally along 152°W, consisted of two legs. Leg 1 started on February 13, 2006 in Papeete, Tahiti, and finished on March 3, in Honolulu, Hawaii. The R/V Thomas G. Thompson departed Honolulu for Leg 2 on March 10, 2006 and arrived in Kodiak, Alaska, on March 30. During the P16N cruises, samples were taken from 34 or 36 depths at 84 stations between 17°S and 56.28°N. The research conducted on these cruises was part of a series of repeat hydrography sections jointly funded by the National Oceanic and Atmospheric Administration (NOAA) and the National Science Foundation (NSF) as part of the Climate Variability Program (CLIVAR)/CO2 Repeat Hydrography Program. The P16S and P16N data sets are available free of charge as a numeric data package (NDP) from the Carbon Dioxide Information Analysis Center (CDIAC). The NDP consists of the oceanographic data files and this printed documentation, which describes the procedures and methods used to obtain the data.

  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. 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

  18. 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.

  19. 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}

  20. Development of high through-put Sr isotope analysis for monitoring reservoir integrity for CO{sub 2} storage.

    SciTech Connect (OSTI)

    Wall, Andy; Jain, Jinesh; Stewart, Brian; Capo, Rosemary; Hakala, Alexandra J.; Hammack, Richard; Guthrie, George

    2012-01-01

    Recent innovations in multi-collector ICP-mass spectrometry (MC-ICP-MS) have allowed for rapid and precise measurements of isotope ratios in geological samples. Naturally occurring Sr isotopes has the potential for use in Monitoring, Verification, and Accounting (MVA) associated with geologic CO2 storage. Sr isotopes can be useful for: Sensitive tracking of brine migration; Determining seal rock leakage; Studying fluid/rock reactions. We have optimized separation chemistry procedures that will allow operators to prepare samples for Sr isotope analysis off site using rapid, low cost methods.

  1. Textured metastable VO{sub 2} (B) thin films on SrTiO{sub 3} substrates

    Office of Scientific and Technical Information (OSTI)

    with significantly enhanced conductivity (Journal Article) | SciTech Connect Textured metastable VO{sub 2} (B) thin films on SrTiO{sub 3} substrates with significantly enhanced conductivity Citation Details In-Document Search Title: Textured metastable VO{sub 2} (B) thin films on SrTiO{sub 3} substrates with significantly enhanced conductivity Textured metastable VO{sub 2} (B) thin films with a layered structure were grown on SrTiO{sub 3} (001) by pulsed laser deposition. The X-ray

  2. 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

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

    Office of Scientific and Technical Information (OSTI)

    multiferroic tunnel junctions (Journal Article) | DOE PAGES Octonary resistance states in La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 multiferroic tunnel junctions This content will become publicly available on October 6, 2016 « Prev Next » 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 multiferroic tunnel junction (MFTJ),

  4. 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.

  5. 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.

  6. 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.

  7. 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)].

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. Effect of {alpha} variation on the vibrational spectrum of Sr{sub 2}

    SciTech Connect (OSTI)

    Beloy, K.; Hauser, A. W.; Borschevsky, A.; Schwerdtfeger, P.; Flambaum, V. V.

    2011-12-15

    We consider the effect of {alpha} variation on the vibrational spectrum of Sr{sub 2} in the context of a planned experiment to test the stability of {mu}{identical_to}m{sub e}/m{sub p} using optically trapped Sr{sub 2} molecules [Zelevinsky et al., Phys. Rev. Lett. 100, 043201 (2008); Kotochigova et al., Phys. Rev. A 79, 012504 (2009)]. We find the prospective experiment to be 3 to 4 times less sensitive to fractional variation in {alpha} as it is to fractional variation in {mu}. Depending on the precision ultimately achieved by the experiment, this result may give justification for the neglect of {alpha} variation or, alternatively, may call for its explicit consideration in the interpretation of experimental results.

  14. 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.

  15. 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.

  16. 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.

  17. Role of the Interface on Radiation Damage in the SrTiO3/LaAlO3...

    Office of Scientific and Technical Information (OSTI)

    Role of the Interface on Radiation Damage in the SrTiO3LaAlO3 Heterostructure under Ne2+ ... Country of Publication: United States Language: English Word Cloud More Like This Full ...

  18. 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.

  19. Chemical isolation of .sup.82 Sr from proton-irradiated Mo targets

    DOE Patents [OSTI]

    Grant, Patrick M.; Kahn, Milton; O'Brien, Jr., Harold A.

    1976-01-01

    Spallation reactions are induced in Mo targets with 200-800 MeV protons to produce microcurie to millicurie amounts of a variety of radionuclides. A six-step radiochemical procedure, incorporating precipitation, solvent extractions, and ion exchange techniques, has been developed for the separation and purification of Sr radioactivities from other spallation products and the bulk target material. Radiostrontium can be quantitatively recovered in a sufficiently decontaminated state for use in biomedical generator development.

  20. 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

  1. 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 Research / Small Business Technology Transfer Funding Opportunities Nuclear Science Advisory Committee (NSAC) Community Resources Contact Information Nuclear Physics U.S. Department of

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Super-Stable, Highly Monodisperse Plasmonic Nanocrystals with 500 Gold Atoms: Au~500(SR)~120

    SciTech Connect (OSTI)

    Kumara, Chanaka; Zuo, Xiaobing; Ilavsky, Dr. Jan; Chapman, Karena; Cullen, David A; Dass, Amala

    2014-01-01

    Determining the composition of plasmonic nanoparticles is challenging due to a deficiency in tools capable of accurately evaluating the number of atoms. Mass spectrometry plays a significant role in determining nanoparticle composition at the atomic level. Significant progress has been made in understanding ultra-small gold nanoparticles, like Au25(SR)18 and Au38(SR)24, with a Au core diameter of 0.97 and 1.3 nm, respectively. However, progress in small plasmonic nanoparticles (2 - 5 nm) is currently challenging, due in part to limitations in synthesizing monodisperse nanoparticles. Here, we report a plasmonic nanocrystal that is highly monodisperse, with an unprecedented variation of less than 20 gold atoms. The composition of the super-stable plasmonic nanocrystals at 115 kDa was determined to contain Au500 10SR120 3. The Au~500 system, named Faraduarate-500, is the largest size to be characterized using high resolution ESI mass spectrometry. Atomic pair distribution function (PDF) data shows that the local atomic structure is consistent with a face-centered cubic (fcc) or Marks decahedral arrangement. High resolution scanning transmission electron microscopy images show that the diameter is 2.4 0.1 nm. The radius of gyration measured by small angle X-ray scattering (SAXS), is 1.05 0.05 nm, and the size and the shape of SAXS molecular envelope are in agreement with TEM and PDF measurements.

  7. 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.

  8. 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

  9. 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.

  10. 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

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

    SciTech Connect (OSTI)

    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 topotactic 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.

  12. 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.}

  13. 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.

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

    DOE Patents [OSTI]

    Marshall, Christopher D.; Payne, Stephen A.; Krupke, William F.

    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.

  15. 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.

  16. ABUNDANCES OF C, N, Sr, AND Ba ON THE RED GIANT BRANCH OF {omega} CENTAURI

    SciTech Connect (OSTI)

    Stanford, Laura M.; Da Costa, G. S.; Norris, John E. E-mail: gdc@mso.anu.edu.a

    2010-05-10

    Abundances relative to iron for carbon, nitrogen, strontium, and barium are presented for 33 stars on the red giant branch (RGB) of the globular cluster {omega} Centauri. They are based on intermediate-resolution spectroscopic data covering the blue spectral region analyzed using spectrum synthesis techniques. The data reveal the existence of a broad range in the abundances of these elements, and a comparison with similar data for main-sequence stars enables insight into the evolutionary history of the cluster. The majority of the RGB stars were found to be depleted in carbon, i.e., [C/Fe] < 0, while [N/Fe] for the same stars shows a range of {approx}1 dex, from [N/Fe] {approx} 0.7 to 1.7 dex. The strontium-to-iron abundance ratios varied from solar to mildly enhanced (0.0 {<=} [Sr/Fe] {<=} 0.8), with [Ba/Fe] generally equal to or greater than [Sr/Fe]. The carbon and nitrogen abundance ratios for the one known CH star in the sample, ROA 279, are [C/Fe] = 0.6 and [N/Fe] = 0.5 dex. Evidence for evolutionary mixing on the RGB is found from the fact that the relative carbon abundances on the main sequence are generally higher than those on the RGB. However, comparison of the RGB and main-sequence samples shows that the upper level of nitrogen enhancement is similar in both sets at [N/Fe] {approx} 2.0 dex. This is most likely the result of primordial rather than evolutionary mixing processes. One RGB star, ROA 276, was found to have Sr and Ba abundance ratios similar to the anomalous Sr-rich main-sequence star S2015448. High-resolution spectra of ROA 276 were obtained with the Magellan Telescope/MIKE spectrograph combination to confirm this result, revealing that ROA 276 is indeed an unusual star. For this star, calculations of the depletion effect, the potential change in surface abundance that results from the increased depth of the convective envelope as a star moves from the main sequence to the RGB, strongly suggest that the observed Sr enhancement in ROA 276 is of primordial origin, rather than originating from a surface accretion event.

  17. Microsoft PowerPoint - Session2_Rogers.pptx

    Gasoline and Diesel Fuel Update (EIA)

    Proved Reserves (Billion Cubic Feet) Michigan Shale Proved Reserves (Billion Cubic Feet) Decade Year-0 Year-1 Year-2 Year-3 Year-4 Year-5 Year-6 Year-7 Year-8 Year-9 2000's 3,281 2,894 2,499 2010's 2,306 1,947 1,345 1,418 1,432 - = No Data Reported; -- = Not Applicable; NA = Not Available; W = Withheld to avoid disclosure of individual company data. Release Date: 11/19/2015 Next Release Date: 12/31/2016 Referring Pages: Shale Natural Gas Proved Reserves as of Dec. 31 Michigan Shale Gas Proved

  18. 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...

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

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

    Pumpkin Power: Turning Food Waste into Energy Pumpkin Power: Turning Food Waste into Energy November 1, 2013 - 1:28pm Addthis Pumpkin Power: Turning Food Waste into Energy Matthew Loveless Matthew Loveless Data Integration Specialist, Office of Public Affairs What are the key facts? 1.4 billion pounds of pumpkins are produced in the U.S. each year, many of which end up in landfills or compost piles after Halloween. Oakland's EBMUD collects food waste and uses microbes to convert it into methane

  20. 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}.

  1. 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

  2. U. S. Department of Energy Savannah River Operations Office - DOE-SR News

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

    Releases Employee Headcount by County of Residence Per Quarter DOE-SR Headcount By County of Residence Per Quarter 1st Quarter FY 2016 Adobe Acrobat PDF 4th Quarter FY 2015 Adobe Acrobat PDF 3rd Quarter FY 2015 Adobe Acrobat PDF 2nd Quarter FY 2015 Adobe Acrobat PDF 1st Quarter FY 2015 Adobe Acrobat PDF 4th Quarter FY 2014 Adobe Acrobat PDF 3rd Quarter FY 2014 Adobe Acrobat PDF 2nd Quarter FY 2014 Adobe Acrobat PDF 1st Quarter FY 2014 Adobe Acrobat PDF 4th Quarter FY 2013 Adobe Acrobat PDF

  3. Rapid method to determine actinides and 89/90Sr in limestone and marble samples

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

    Maxwell, Sherrod L.; Culligan, Brian; Hutchison, Jay B.; Utsey, Robin C.; Sudowe, Ralf; McAlister, Daniel R.

    2016-04-12

    A new method for the determination of actinides and radiostrontium in limestone and marble samples has been developed that utilizes a rapid sodium hydroxide fusion to digest the sample. Following rapid pre-concentration steps to remove sample matrix interferences, the actinides and 89/90Sr are separated using extraction chromatographic resins and measured radiometrically. The advantages of sodium hydroxide fusion versus other fusion techniques will be discussed. This approach has a sample preparation time for limestone and marble samples of <4 hours.

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

    DOE Patents [OSTI]

    Shi, Donglu

    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.

  5. 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)

  6. 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.

  7. 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 the information that all Federal Agencies are required to make available to the public. The Act, as it is applicable to the Department of Energy (Department), is presented in 10 CFR 1004. According to the Department's most recent Annual FOIA Report, in Fiscal Year (FY) 2009, 1,809 FOIA requests were received. Of these,

  8. 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

  9. 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.

  10. 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.

  11. 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.}

  12. 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 +}.

  13. SR0006

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

    technology are on display at the Department of Energy Environmental Management Science Program (EMSP) National Workshop in Atlanta, GA on April 25-27 at the Westin Peachtree Plaza. ...

  14. SR0005

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

    will be on display at the Department of Energy Environmental Management Science Program (EMSP) National Workshop in Atlanta, GA on April 24-27 at the Westin Peachtree Plaza. ...

  15. SR0208

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

    U.S. Government Bookstore, First Union Plaza, 999 Peachtree Street NE, Suite 120, Atlanta, GA 30309-3964, (404) 347-1900. A CD-Rom version is also available by contacting the ...

  16. SR0001

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

    For Immediate Release January 12, 2000 Media Contact: Bill Taylor (803) 725-2889 Nuclear Security Oversight Panel Visits SRS As Part Of NSSA Tour Flag Ribbon Art Representatives from the Special Oversight Panel on Department of Energy Reorganization will be visiting the Savannah River Site (SRS) on Thursday, January 13, 2000. The Panel is touring Department of Energy facilities that will become part of the National Nuclear Security Administration (NNSA). Members of the Panel will provide

  17. SR0002

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

    , 2000 Media Contact: Bill Taylor (803) 725-2889 General Eugene Habiger, DOE Security Czar To Visit SRS Flag Ribbon Art General Eugene Habiger (USAF Retired), the Department of Energy's Security Czar and Director of Security and Emergency Response, will visit the Savannah River Site (SRS) on Wednesday, February 2, 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

  18. 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 the Department of Energy's (DOE) Fiscal Year 2001 budget presentation that will be provided via satellite downlink starting at 1:30 p.m., Monday, February 7, 2000, at Aiken Technical College's Learning Resource Center amphitheater. The annual DOE budget roll out will feature an introduction by Secretary of Energy Bill

  19. SR0007

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

    Environmental Cleanup Technology Conference To Be Held Flag Ribbon Art The Savannah River Operations Office of the Department of Energy is hosting the Environmental 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 successes and innovations from the two co-sponsoring federal agencies-the Department of Defense and the Environmental Protection Agency-and DOE sites; promote the

  20. SR0010

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

    1, 2000 Media Contact: Jim Giusti (803) 725-2889 DOE Hosts Radioactive Materials Transportation Workshop Flag Ribbon Art Note To Editors And News Directors: Aiken, SC - The Department of Energy will host an informational transportation workshop tomorrow and Friday (June 22-23) in Augusta, GA. The workshop is part of an ongoing series to involve state and local officials, and is designed to help share information about DOE transportation of radioactive materials. The theme of this particular

  1. SR0011

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

    26, 2000 Media Contact: Rick Ford (803) 725-2889 Energy Secretary Bill Richardson to Visit Savannah River Site Groundbreaking for Tritium Facility, 50th Anniversary on Agenda Flag Ribbon Art Media Advisory Secretary of Energy Bill Richardson will be at the Savannah River Site and Fort Discovery on Thursday, July 27, to break ground for the new $400 million Tritium Extraction Facility and celebrate the 50th Anniversary of the Savannah River Site. Secretary Richardson will be joined by Gen. John

  2. 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

  3. 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 - The Department of Energy's (DOE) Assistant Secretary for Environment, Safety and Health, Dr. David Michaels, will hold a public meeting to discuss the new Federal compensation program for DOE contract employees such as Savannah River Site workers who have work related illnesses. The meeting will be held Thursday,

  4. 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 MEDIA AVAILABILITY 6:15 p.m. Thursday, December 7 Aiken Technical College's Continuing Education Confernce Center, Room 733 PRIOR TO: DOE Meeting to Focus on New Compensation Program for Work-Related Illness Effecting SRS Employees The Department of Energy's (DOE) Assistant Secretary for Environment, Safety and Health,

  5. 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 the Savannah River Site's observation of Martin Luther King Jr. Day on Wednesday, January 10, 2001. The observance will be held in the Main Administration Area's cafeteria, starting at 2 p.m. The site-wide observance will feature Mr. Marshall Smith of Orangeburg, S.C., noted for his renditions of Dr. King's speeches.

  6. 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

  7. SR0104

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

    8, 2001 Media Contact: James Giusti (803) 725-2889 Savannah River Site Sends First Shipment of Transuranic Waste to WIPP Flag Ribbon Art AIKEN, S.C., May 8 – The first shipment of transuranic, or TRU, waste from the Savannah River Site (SRS) to the Waste Isolation Pilot Plant (WIPP), located in Carlsbad, 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 fiscal year

  8. 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 14, 2001) - The U.S. Departments of Labor and Energy will hold two public meetings at 1 p.m. and 7 p.m., Tuesday, June 19 at the North Augusta Community Center, North Augusta, SC, for employees and families who may be eligible for compensation under the Energy Employees Occupational Illness Compensation Program Act.

  9. 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

  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 nuclear weapons workers can go for help to file claims for compensation under the Energy Employees Occupational Illness Compensation Program Act will begin operations with an opening ceremony at 11 a.m., Friday, July 27. The Energy Employees Compensation Center at 1708 Bunting Drive, North Augusta, SC, is sponsored

  11. 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 Flag Ribbon Art AIKEN, SC -- The U.S. Department of Energy (DOE) announced that it has selected Caustic Side Solvent Extraction as the Savannah River Site (SRS) Salt Processing preferred alternative for treating salt-bearing high-level radioactive waste. The Department's decision is outlined in a Record of Decision (ROD)

  12. SR0113?

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

    December 5, 2001 Media Contact: Bill Taylor (803) 725-2889 DOE Announces Availability Of Final RFP For SRS Salt Processing Facility Flag Ribbon Art Aiken, SC -- Today the Department of Energy (DOE) made available the Final Request for Proposals (RFP) for the acquisition of services to design, construct, and commission a facility to process the salt portion of high-level radioactive waste currently stored in underground tanks at the Savannah River Site (SRS). The Salt Waste Processing Facility

  13. 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 public is invited to a presentation and discussion of the Department of Energy's recent Top-To-Bottom Review of the Environmental Management (EM) program and the Savannah River Site Fiscal Year (FY) 2003 EM budget request. WHO: Senior Savannah River Site Officials WHEN: Friday, February 8, 2002 2 - 3 p.m. WHERE: Aiken

  14. 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 Department of Energy (DOE) Savannah River Site (SRS) announced today the availability of the Final Environmental Impact Statement (EIS) on the proposed closing of additional high-level waste (HLW) tanks at SRS. The EIS evaluated three alternatives regarding closure of the HLW tanks: (1) Stabilize Tanks; (2) Clean and Remove

  15. 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 Energy (DOE) announced that it has selected the Stabilize Tanks and Fill with Grout preferred alternative for additional closures of high-level waste tanks at the Savannah River Site (SRS). The Department's decision is outlined in a Record of Decision (ROD) published in today's Federal Register. An Environmental Impact

  16. 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 Department of Energy (DOE) took the first step in commissioning a Salt Waste Processing Facility (SWPF) at the Savannah River Site (SRS) by awarding two contracts for the facility's conceptual design. The SWPF is intended to process the high-level radioactive waste salt solutions currently stored in underground tanks at SRS.

  17. SR0209

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

    4, 2002 Media Contact: Bill Taylor (803) 725-2889 DOE/NNSA to Host Modern Pit Facility Media Availability Flag Ribbon Art U. S. Department of Energy National Nuclear Security Administration (NNSA) representatives will host a media availability at 4 p.m. on Monday, October 28, 2002, to discuss the upcoming public scoping meeting for the development of a Modern Pit Facility. The media availability session will be held at 4 p.m. in the North Augusta Community Center, 101 Brookside Drive, North

  18. 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 helicopters will be visible over the Savannah River Site February 3 - 14. The helicopters, UH-60 "Blackhawks," will be testing radiological monitoring equipment for use by various federal agencies. The tests will be conducted by placing radiological source materials in selected area throughout the Department of

  19. SR0303

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

    2, 2003 Media Contact: Julie Petersen (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 and Canada will meet in Columbia, South Carolina, June 3-5 to share information on innovative and cost-effective environmental cleanup techniques. The conference-the Environmental Restoration Technology End Users Conference will be at the Sheraton Columbia Convention Center. It is

  20. SR0304

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

    12, 2003 Media Contact: Jim Giusti (803) 725-2889 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, of the National Nuclear Security Administration congratulated more than 200 craftsmen and other personnel who fabricated and installed the internals of the first two "gloveboxes" of the Site's new Tritium Extraction Facility, or TEF. This important work was

  1. 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)

  2. SR0503

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

    14, 2005 Media Contact: James Giusti (803) 952-7697 NNSA Breaks Ground On MOX Facility Site Preparation Begins at Savannah River Site Flag Ribbon Art Aiken, S.C. - The National Nuclear Security Administration's (NNSA) plutonium disposition program today moved another step forward with the start of site preparation for its Mixed Oxide (MOX) Fuel Fabrication Facility at the Savannah River Site. NNSA Administrator Linton F. Brooks and U.S. Senator Lindsey Graham led a group of U.S. and Russian

  3. SR0505

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

    1, 2005 Media Contact: James Giusti (803) 952-7697 Subcontract Awarded for MOX Facility Site Preparation Work Flag Ribbon Art Aiken, S.C. - The National Nuclear Security Administration's (NNSA) plutonium disposition program has moved another step forward with the start of site preparation for its Mixed Oxide (MOX) Fuel Fabrication Facility at the Savannah River Site. NNSA announced today that the first subcontract for this work has been awarded to MDM Services Corporation, a small business

  4. SR0601

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

    May 4, 2006 Media Contact: James Giusti (803) 952-7697 SRS Makes 200th Shipment of Low Enriched Uranium AIKEN, S.C. -- A joint National Nuclear Security Administration and Office of Environmental Management nonproliferation program at the Savannah River Site (SRS) completed its 200th shipment of low enriched uranium (LEU) to Erwin, TN, earlier today. This is the final step at SRS in the process of turning weapons-grade uranium into electricity. Under SRS' Highly Enriched Uranium (HEU) Blend Down

  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 Completed Ahead of Schedule and Under Budget Aiken , S.C. – The U.S. Department of Energy (DOE) today started radioactive operations of its Glass Waste Storage Building #2 (GWSB#2) at the Savannah River Site (SRS). This facility will safely store waste once processed into a glassified form in the Defense Waste

  6. 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 materials stabilization recently when the Savannah River Site stabilized the last of the materials identified under Defense Nuclear Facilities Safety Board (DNFSB) recommendations. “This accomplishment fulfills DNFSB’s 94-1 and 2000-1 recommendations and is indicative of the Department's commitment to safe facility

  7. SR0605

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

    DOE’s SRS Disposes of its 20,000th Drum of TRU Waste AIKEN, S.C., (October 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 shipment to the Waste Isolation Pilot Plant (WIPP), in New Mexico. Until recently, these drums were covered with mounds of earth at SRS’s central waste management facility. The drums were generated during decades of nuclear operations at SRS.

  8. SR0606

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

    31, 2006 Media Contact: James Giusti (803) 952-7697 DOE Issues Draft Request for Proposals for Savannah River Site Contractor WASHINGTON , DC -- The Department of Energy (DOE) today announced solicitation of comments on a draft Request for Proposals (RFP) for the competitive selection of a management and operating (M&O) contractor for the Savannah River Site (SRS). DOE is issuing the draft RFP in order to facilitate competition by providing potential offerors with the maximum opportunity to

  9. 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

  10. SR0701?

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

    8, 2007 Media Contact: James Giusti (803) 952-7697 james-r.giusti@srs.gov DOE Issues Draft Request for Proposals for SRS Liquid Waste Contract WASHINGTON , DC -- The U.S. Department of Energy (DOE) today announced the release of a draft Request for Proposals (RFP) for the competitive selection of a Liquid Waste (LW) contractor for the Savannah River Site (SRS). The primary facilities related to this procurement include liquid radioactive waste tank farms, the Defense Waste Processing Facility,

  11. SR0703

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

    March 23, 2007 Media Contact: James Giusti (803) 952-7697 james-r.giusti@srs.gov DOE Requests Proposals for Management and Operating Contractor at Savannah River Site WASHINGTON , DC -- The U.S. Department of Energy (DOE) today issued its Request for Proposals (RFP) for the competitive selection of a management and operating (M&O) contractor for the Savannah River Site (SRS). The total value of the five-year contract is $4 billion. All proposals are due to the Department no later than May

  12. 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, 2004)-Congressman J. Gresham Barrett will join senior officials of the U.S. Department of Energy-Headquarters (DOE-HQ) at the Savannah River Site (SRS) on Monday, July 19, 2004, to discuss the Site's accelerated cleanup activities. DOE-HQ officials include: Lee Otis, DOE General Counsel; Jill Sigal, DOE Principal

  13. SR0704

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

    April 13, 2007 Media Contact: Julie Petersen (803) 952-7697 julie.petersen@srs.gov Savannah River Site Employees Honored with President’s Volunteer Service Award AIKEN, S.C., – The U.S. Department of Energy (DOE) has honored several Savannah River Site (SRS) employees with the President’s Volunteer Service Award (PVSA) for their notable volunteerism and civic participation. “It is an honor to be part of a work family whose members give so selflessly to help make a positive difference in

  14. 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 AIKEN, S.C., – As part of a collaborative process between the Department of Energy (DOE), the Washington Savannah River Company (WSRC), and Honeywell Building Solutions, the Savannah River Site (SRS) broke ground on a new clean energy efficient steam plant today, the first of two energy infrastructure upgrade projects..

  15. 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. Department of Energy (DOE) authorized the construction of the Salt Waste Processing Facility (SWPF) at the Savannah River Site (SRS) following independent validation of the DOE’s cost and schedule estimate. The new facility will treat highly radioactive salt solutions currently stored in underground tanks at SRS and

  16. 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) Savannah River Site (SRS) has finished a complete inventory of classified removable electronic media (CREM) as part of a DOE-wide stand-down that was ordered by the Secretary of Energy, Spencer Abraham. DOE has permitted SRS to end the stand-down and continue normal operations that involve these classified materials,

  17. 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 Richardson will visit the Savannah River Site (SRS) Thursday, June 24, 1999 to make an announcement concerning the future of 10,000 acres at the site. WHAT: 8:30 am Photo opportunity only with Secretary Richardson and elected officials. 9:00 am Dedication ceremony with Secretary Richardson and South Carolina Department

  18. 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 Ribbon Art Aiken, S.C. (June 24) -- Secretary of Energy Bill Richardson today designated 10,000 acres of the Savannah River Site (SRS) as a biological and wildlife refuge creating the Crackerneck Wildlife Management Area and Ecological Reserve. The agreement, co-signed by South Carolina Department of Natural Resources

  19. 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 renewed the Savannah River Site (SRS) security contract with Wackenhut Services Inc., a five-year contract valued at $300 million. Wackenhut Services Inc. (WSI) has provided security and protective services at SRS, a 310-square mile DOE facility, since 1983. Security services for SRS include: An armed paramilitary

  20. SR9902

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

    8, 1999 Media Contact: Rick Ford (803) 725-2889 DOE To Present Savannah River Site's Upcoming Fiscal Year 2000 Budget Flag Ribbon Art Aiken, SC - (Jan. 28, 1999) The public is invited to view the Department of Energy's (DOE) Fiscal Year 2000 budget presentation that will be provided via satellite downlink starting at 1:00 p.m., Monday, February 1, 1999, at Aiken Technical College's Learning Resource Center amphitheater. The annual DOE budget roll out will feature an introduction by Secretary of

  1. SR9904

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

    March 26, 1999 Media Contact: Bill Taylor (803) 725-2889 World's First Underground Waste Repository Begins Operations First Shipment of Transuranic Radioactive Waste Arrives at WIPP Flag Ribbon Art CARLSBAD, N.M. (March 26,1999) -- Energy Secretary Bill Richardson today announced that the first shipment of defense-generated transuranic radioactive waste arrived safely at the U.S. Department of Energy's (DOE) Waste Isolation Pilot Plant (WIPP). Hundreds of people were on hand to watch this

  2. 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

  3. SR9909

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

    13, 1999 Media Contact: Julie Petersen (803) 725-2889 DOE Awards SRS Contractors For Outstanding Safety & Health Programs Flag Ribbon Art Aiken, S.C. - In separate ceremonies at the Savannah River Site (SRS) today, U.S. Department of Energy (DOE) Deputy Assistant Secretary for Worker Health and Safety, Joe Fitzgerald, presented awards to SRS contractors, Wackenhut Services, Inc. (WSI) and Westinghouse Savannah River Company (WSRC), for significant achievements in DOE's Voluntary Protection

  4. 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

  5. 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 Director of Security and Emergency Response will be at the Savannah River Site on Wednesday, August 18, 1999. Gen. Habiger, the former Commander-In-Chief, U.S. Strategic Command, has recently been named by the Secretary of Energy as the DOE's Security Czar. While at the Savannah River Site, he will visit first-hand

  6. SR9913

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

    10, 1999 Media 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 Office has initiated action to establish a Type-B Investigation Board as a result of a preliminary dose estimate for the one of the seven SRS workers contaminated in routine operations in FB Line on September 1, 1999. The preliminary dose estimate exceed established federal exposure limits and exceeds

  7. 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

  8. SR9916

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

    5, 1999 Media Contact: 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 released for public comment the draft Savannah River Site (SRS) 2000 Strategic Plan. The draft SRS Strategic Plan 2000 has been developed with input from the Site's workforce and management team. The plan will be used to guide the missions and work performed in the Site's stewardship of the Nation's

  9. 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...

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Doping SrTiO3 supported FeSe by excess atoms and oxygen vacancies

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

    Shanavas, Kavungal Veedu; Singh, David J.

    2015-07-24

    Photoemission studies of FeSe monolayer films on SrTiO3 substrate have shown electronic structures that deviate from pristine FeSe, consistent with heavy electron doping. With the help of first-principles calculations we studied the effect of excess Fe and Se atoms on the monolayer and oxygen vacancies in the substrate in order to understand the reported Fermi surface in this system. We find that both excess Fe and Se atoms prefer the same adsorption site above the bottom Se atoms on the monolayer. The adsorbed Fe is strongly magnetic and contributes electrons to the monolayer, while excess Se hybridizes with the monolayermore » Fe-d states and partially opens a gap just above the Fermi energy. We also find that the two-dimensional electron gas generated by the oxygen vacancies is partly transferred to the monolayer and can potentially suppress the hole pockets around the Γ point. Furthermore, both O vacancies in the SrTiO3 substrate and excess Fe over the monolayer can provide high levels of electron doping.« less

  16. 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.

  17. 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

  18. 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 Ti–t2g states, even though structural relaxations diminish the effect in dxy bands. A tight-binding model, explicitly including Ti–d and O–p states as well as next-nearest-neighbor interactions, is derived to understand the first-principles results. Effective Rashbamore » Hamiltonians 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

  19. 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:

  20. Oxygen-vacancy-induced polar behavior in (LaFeO3)2/(SrFeO3) superlattices

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Oxygen-vacancy-induced polar behavior in (LaFeO3)2/(SrFeO3) superlattices Citation Details In-Document Search Title: Oxygen-vacancy-induced polar behavior in (LaFeO3)2/(SrFeO3) superlattices Authors: Mishra, Rohan [1] ; Kim, Young-Min [1] ; Salafranca Laforga, Juan I [1] ; Kim, Seong Keun [2] ; Chang, Seohyoung [2] ; Bhattacharya, Anand [2] ; Fong, Dillon [2] ; Pennycook, Stephen J [1] ; Pantelides, Sokrates T [1] ; Borisevich, Albina Y [1] + Show Author

  1. 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

  2. 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.

  3. Role of double Ti O 2 layers at the interface of FeSe/ SrTi O 3

    Office of Scientific and Technical Information (OSTI)

    superconductors (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Role of double Ti O 2 layers at the interface of FeSe/ SrTi O 3 superconductors Citation Details In-Document Search This content will become publicly available on May 16, 2017 Title: Role of double Ti O 2 layers at the interface of FeSe/ SrTi O 3 superconductors Authors: Zou, Ke ; Mandal, Subhasish ; Albright, Stephen D. ; Peng, Rui ; Pu, Yujia ; Kumah, Divine ; Lau, Claudia ; Simon, Georg H.

  4. 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.

  5. Role of double Ti O 2 layers at the interface of FeSe/ SrTi O 3

    Office of Scientific and Technical Information (OSTI)

    superconductors (Journal Article) | DOE PAGES Publisher's Accepted Manuscript: Role of double Ti O 2 layers at the interface of FeSe/ SrTi O 3 superconductors This content will become publicly available on May 16, 2017 « Prev Next » Title: Role of double Ti O 2 layers at the interface of FeSe/ SrTi O 3 superconductors Authors: Zou, Ke ; Mandal, Subhasish ; Albright, Stephen D. ; Peng, Rui ; Pu, Yujia ; Kumah, Divine ; Lau, Claudia ; Simon, Georg H. ; Dagdeviren, Omur E. ; He, Xi ;

  6. Role of the Interface on Radiation Damage in the SrTiO3/LaAlO3

    Office of Scientific and Technical Information (OSTI)

    Heterostructure under Ne2+ Ion Irradiation (Journal Article) | SciTech Connect Role of the Interface on Radiation Damage in the SrTiO3/LaAlO3 Heterostructure under Ne2+ Ion Irradiation Citation Details In-Document Search Title: Role of the Interface on Radiation Damage in the SrTiO3/LaAlO3 Heterostructure under Ne2+ Ion Irradiation Authors: Bi, Zhenxing [1] ; Uberuaga, Blas [1] ; Vernon, Lj [1] ; Aguiar, Jeffery [1] ; Fu, Engang [1] ; Zheng, Shijan [1] ; Zhang, Shixiong [1] ; Wang, Yongqiang

  7. Electric Field Penetration in Au/Nb:SrTiO3 Schottky Junctions Probed by Bias-Dependent Internal Photoemission

    SciTech Connect (OSTI)

    Hikita, Y.

    2011-08-15

    Electric field penetration into the metallic side of a Schottky junction is in principle a universal phenomenon, the magnitude of which increases with the semiconductor permittivity. Here, we quantitatively probe this effect using bias-dependent internal photoemission spectroscopy at the Schottky junction between a large dielectric permittivity semiconductor SrTiO{sub 3} and gold. A clear linear reduction of the barrier height with increasing interface electric field was observed, highlighting the importance of field penetration into the gold. The interfacial permittivity of SrTiO{sub 3} at the interface is reduced from the bulk value, reflecting intrinsic suppression at the interface.

  8. X-ray absorption near-edge spectra of overdoped La 2 - x Sr x CuO 4 high-

    Office of Scientific and Technical Information (OSTI)

    T c superconductors (Journal Article) | SciTech Connect 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 overdoped La 2 - x Sr x CuO 4 high- T c superconductors Authors: Ahmed, Towfiq ; Das, Tanmoy ; Kas, J. J. ; Lin, Hsin ; Barbiellini, B. ; Vila, Fernando D. ; Markiewicz, R. S. ; Bansil, A. ; Rehr, J. J. Publication Date: 2011-03-11 OSTI Identifier: 1100031 Type:

  9. 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.

  10. 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)

  11. 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.

  12. Native SrTiO3 (001) surface layer from resonant Ti L2,3 reflectance spectroscopy

    SciTech Connect (OSTI)

    Valvidares, Manuel; Huijben, Mark; Yu, Pu; Ramesh, Ramamoorthy; Kortright, Jeffrey

    2010-11-03

    We quantitatively model resonant Ti L2,3 reflectivity Rs,p(q, hn) from several SrTiO3 (001) single crystals having different initial surface preparations and stored in ambient conditions before and between measurements. All samples exhibit unexpected 300 K Rs(hn) - Rp(hn) anisotropy corresponding to weak linear dichroism and tetragonal distortion of the TiO6 octahedra indicating a surface layer with properties different from cubic SrTiO3. Oscillations in Rs(q) confirm a ubiquitous surface layer 2-3 nm thick that evolves over a range of time scales. Resonant optical constant spectra derived from Rs,p(hn) assuming a uniform sample are refined using a single surface layer to fit measured Rs(q). Differences in surface layer and bulk optical properties indicate that the surface is significantly depleted in Sr and enriched in Ti and O. While consistent with the tendency of SrTiO3 surfaces toward non-stoichiometry, this layer does not conform simply to existing models for the near surface region and apparently forms via room temperature surface reactions with the ambient. This new quantitative spectral modeling approach is generally applicable and has potential to study near-surface properties of a variety of systems with unique chemical and electronic sensitivities.

  13. 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.

  14. Oxygen octahedral distortions in LaMO3/SrTiO3 superlattices

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

    Sanchez-Santolino, Gabriel; Cabero, Mariona; Varela, Maria; Garcia-Barriocanal, Javier; Leon, Carlos; Pennycook, Stephen J.; Santamaria, Jacobo

    2014-04-24

    Here we study the interfaces between the Mott insulator LaMnO3 (LMO) and the band insulator SrTiO3 (STO) in epitaxially grown superlattices with different thickness ratios and different transport and magnetic behaviors. Using atomic resolution electron energy-loss spectrum imaging, we analyze simultaneously the structural and chemical properties of these interfaces. We find changes in the oxygen octahedral tilts within the LaMnO3 layers when the thickness ratio between the manganite and the titanate layers is varied. Superlattices with thick LMO and ultrathin STO layers present unexpected octahedral tilts in the STO, along with a small amount of oxygen vacancies. On the othermore » hand, thick STO layers exhibit undistorted octahedra while the LMO layers present reduced O octahedral distortions near the interfaces. In conclusion, these findings will be discussed in view of the transport and magnetic differences found in previous studies.« less

  15. 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.

  16. 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.

  17. 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.

  18. Role of the interface on radiation damage in the SrTiO{sub 3}/LaAlO{sub 3}

    Office of Scientific and Technical Information (OSTI)

    heterostructure under Ne{sup 2+} ion irradiation (Journal Article) | SciTech Connect Role of the interface on radiation damage in the SrTiO{sub 3}/LaAlO{sub 3} heterostructure under Ne{sup 2+} ion irradiation Citation Details In-Document Search Title: Role of the interface on radiation damage in the SrTiO{sub 3}/LaAlO{sub 3} heterostructure under Ne{sup 2+} ion irradiation We systematically investigated the microstructural evolution of heteroepitaxial SrTiO{sub 3} (STO) thin films grown on a

  19. 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}.

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

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

    4301601.1 1 EIA 2014 Energy Conference July 14, 2014 Crude Exports Session Jake Dweck Presentation (20 minutes, about 2,500-3,000 words) OPENING SLIDE Thanks, Lynn, and thanks to Adam Sieminski and the rest of the good folks at EIA for extending me the invitation to present today. Lynn and John did an excellent job describing economic data and projections, and Jason ably discussed policy realities and options. Any solution to our crude export paradigm, however, must be implemented through laws

  1. (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...

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

    SciTech Connect (OSTI)

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

    2015-10-08

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

  3. 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

  4. A complete strain temperature phase diagram for BiFeO3 films on SrTiO3 and

    Office of Scientific and Technical Information (OSTI)

    LaAlO3 (0 0 1) (Journal Article) | SciTech Connect A complete strain temperature phase diagram for BiFeO3 films on SrTiO3 and LaAlO3 (0 0 1) Citation Details In-Document Search Title: A complete strain temperature phase diagram for BiFeO3 films on SrTiO3 and LaAlO3 (0 0 1) Authors: Siemons, Wolter [1] ; Beekman, Christianne [1] ; MacDougall, Gregory J [1] ; Zarestky, Jerel L [1] ; Nagler, Stephen E [1] ; Christen, Hans M [1] + Show Author Affiliations ORNL [ORNL Publication Date: 2014-01-01

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  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. Erbium and nitrogen co-doped SrTiO{sub 3} with highly visible light photocatalytic activity and stability by solvothermal synthesis

    SciTech Connect (OSTI)

    Xu, Jing; Wei, Yuelin; Huang, Yunfang; Wang, Jing; Zheng, Xuanqing; Sun, Zhixian; Wu, Ying; Tao, Xinling; Fan, Leqing; Wu, Jihuai

    2015-10-15

    Highlights: • Er/N co-doped SrTiO{sub 3} was prepared by a solvothermal process at low temperature. • The co-doping induces the band gap narrowing and prominent absorbance in visible light region. • The samples show excellent catalytic activity and stability under visible light irradiation. - Abstract: Erbium–nitrogen co-doped SrTiO{sub 3} photocatalysts have been synthesized by a facile solvothermal method. The resulting samples were analyzed by FE-SEM, XRD, BET-surface area and UV–vis. The UV–vis absorption spectra of these powders indicated that erbium–nitrogen co-doped SrTiO{sub 3} possessed stronger absorption bands in the visible light region in comparison with that of pure SrTiO{sub 3}. The occurrence of the erbium–nitrogen co-doped cubic SrTiO{sub 3} induced the higher photocatalytic activities for the degradation of methyl orange (MO) under irradiation by ultraviolet light and visible light, respectively, being superior to that of pure SrTiO{sub 3} and commercial TiO{sub 2} (P-25) powders. In addition, the Er–N co-doped SrTiO{sub 3} (initial molar ratios of Sr/Er/N = 1:0.015:0.1, designated as S5) sample showed the best photocatalytic activity with the degradation rate as high as 98% after 30 min under the visible light irradiation. After five cycles, the photocatalytic activity of the S5 catalyst showed no significant decrease, which indicated that the photocatalysts were stable under visible light irradiation.

  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. 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.

  15. 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

  16. 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

  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. 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)

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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}.

  9. 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}.

  10. 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.

  11. 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.

  12. 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.

  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. (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.

  15. Decoupling of the antiferromagnetic and insulating states in Tb-doped Sr2IrO4

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

    Wang, J. C.; Aswartham, S.; Ye, Feng; Terzic, J.; Zheng, H.; Haskel, Daniel; Chikara, Shalinee; Choi, Yong; Schlottmann, P.; Custelcean, Radu; et al

    2015-12-08

    Sr2IrO4 is a spin-orbit coupled insulator with an antiferromagnetic (AFM) transition at TN = 240 K. We report results of a comprehensive study of single-crystal Sr2Ir1-xTbxO4 (0≤x≤0.03). This study found that mere 3% (x=0.03) tetravalent Tb4+(4f7) substituting for Ir4+ (rather than Sr2+) completely suppresses the long-range collinear AFM transition but retains the insulating state, leading to a phase diagram featuring a decoupling of magnetic interactions and charge gap. The insulating state at x = 0.03 is characterized by an unusually large specific heat at low temperatures and an incommensurate magnetic state having magnetic peaks at (0.95, 0, 0) and (0,more » 0.95, 0) in the neutron diffraction, suggesting a spiral or spin density wave order. It is apparent that Tb doping effectively changes the relative strength of the SOI and the tetragonal CEF and enhances the Hund’s rule coupling that competes with the SOI, and destabilizes the AFM state. However, the disappearance of the AFM accompanies no metallic state chiefly because an energy level mismatch for the Ir and Tb sites weakens charge carrier hopping and renders a persistent insulating state. Furthermore, this work highlights an unconventional correlation between the AFM and insulating states in which the magnetic transition plays no critical role in the formation of the charge gap in the iridate.« less

  16. Electronic structure, transport, and phonons of SrAgChF (Ch = S,Se,Te): Bulk superlattice thermoelectrics

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

    Gudelli, Vijay Kumar; Kanchana, V.; Vaitheeswaran, G.; Singh, David J.; Svane, Axel; Christensen, Niels Egede; Mahanti, Subhendra D.

    2015-07-15

    Here, we report calculations of the electronic structure, vibrational properties, and transport for the p-type semiconductors, SrAgChF (Ch = S, Se, and Te). We find soft phonons with low frequency optical branches intersecting the acoustic modes below 50 cm–1, indicative of a material with low thermal conductivity. The bands at and near the valence-band maxima are highly two-dimensional, which leads to high thermopowers even at high carrier concentrations, which is a combination that suggests good thermoelectric performance. These materials may be regarded as bulk realizations of superlattice thermoelectrics.

  17. LaL2SrL8Mn207BelowTc : Exchange StricthR ECEI VED

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

    088-00-105 58916-00-105 9714E3 co C--q 03/64 - 1 Sign Reversal of the MN-0 bond Compressibility r in LaL2SrL8Mn207BelowTc : Exchange StricthR ECEI VED in the Ferromagnetic State JUL Q 7 1997 O S T I D. N. Argyriout§ J. F. Mitchell, J. B. Goodenough * , 0. Chmaissemt S. Short, and J. D. Jorgensen t Science and Technology Center for Superconductivity and Materials Science Division Argonne National Laboratory Argonne, IL 60439 * Center for Materials Science and Engineering, ECT 9.102 University of

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Critical thickness and strain relaxation in molecular beam epitaxy-grown SrTiO{sub 3} films

    SciTech Connect (OSTI)

    Wang, Tianqi; Ganguly, Koustav; Marshall, Patrick; Xu, Peng; Jalan, Bharat

    2013-11-18

    We report on the study of the critical thickness and the strain relaxation in epitaxial SrTiO{sub 3} film grown on (La{sub 0.3}Sr{sub 0.7})(Al{sub 0.65}Ta{sub 0.35})O{sub 3} (001) (LSAT) substrate using the hybrid molecular beam epitaxy approach. No change in the film's lattice parameter (both the in-plane and the out-of-plane) was observed up to a film thickness of 180 nm, which is in sharp contrast to the theoretical critical thickness of ∼12 nm calculated using the equilibrium theory of strain relaxation. For film thicknesses greater than 180 nm, the out-of-plane lattice parameter was found to decrease hyperbolically in an excellent agreement with the relaxation via forming misfit dislocations. Possible mechanisms are discussed by which the elastic strain energy can be accommodated prior to forming misfit dislocations leading to such anomalously large critical thickness.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Unconventional Electronic Reconstruction in Undoped (Ba,Sr)Fe2As2 Across the Spin Density Wave Transition

    SciTech Connect (OSTI)

    Yi, M.

    2010-06-02

    Through a systematic high-resolution angle-resolved photoemission study of the iron pnictide compounds (Ba,Sr)Fe{sub 2}As{sub 2}, we show that the electronic structures of these compounds are significantly reconstructed across the spin density wave transition, which cannot be described by a simple folding scenario of conventional density wave ordering. Moreover, we find that LDA calculations with an incorporated suppressed magnetic moment of 0.5{mu}{sub B} can match well the details in the reconstructed electronic structure, suggesting that the nature of magnetism in the pnictides is more itinerant than local, while the origin of suppressed magnetic moment remains an important issue for future investigations.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Experimental determination of the radial dose function of {sup 90}Sr/{sup 90}Y IVBT sources

    SciTech Connect (OSTI)

    Holmes, Shannon M.; DeWerd, Larry A.; Micka, John A.

    2006-09-15

    A series of measurements were undertaken using both high sensitivity radiochromic film and new lithium fluoride thermoluminescent dosimeters in a liquid water medium to define the radial dose function of {sup 90}Sr/{sup 90}Y beta emitting intravascular brachytherapy sources more accurately. These measurements of a single 5 French source pellet served to verify current Monte Carlo transport models and extrapolation chamber measurements of the radial dose function, thus providing the recommended independent published measurements for g(r) of these sources. A slight deviation in the published radial dose function at depth leads the authors to recommend that treatment planning be performed using updated g(r) values from current Monte Carlo transport models verified by measurements such as those shown in this investigation.

  11. 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.

  12. 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)

  13. 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.}

  14. Structure symmetry determination and magnetic evolution in Sr2Ir1–xRhxO4

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

    Ye, Feng; Wang, Xiaoping; Hoffmann, Christina; Wang, Jinchen; Chi, Songxue; Matsuda, Masaaki; Chakoumakos, Bryan C.; Fernandez-Baca, Jaime A.; Cao, Gang

    2015-11-23

    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 structure retains a tetragonal symmetry (space group I41/a) with two distinct magnetic Ir sites in the unit cell forming staggered IrO6 rotation. Upon Rh doping, the magnetic order is suppressed and the magnetic moment of Ir4+ is reduced from 0.21 μB/Ir for x = 0 to 0.18 μB/Ir for x = 0.12. As a result, the magnetic structure at x = 0.12 is different from thatmore » of the parent compound while the moments remain in the basal plane.« less

  15. 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.

  16. The effect of strontium non-stoichiometry on the physical properties of double perovskite Sr{sub 2}FeMoO{sub 6}

    SciTech Connect (OSTI)

    Harnagea, L. Berthet, P.

    2015-02-15

    We present a detailed study on the effect of strontium non-stoichiometry on the properties of double perovskite Sr{sub 2}FeMoO{sub 6} (SFMO). A citrate route has been used to prepare high quality polycrystalline samples with (2−x)Sr:Fe:Mo (x=0, 0.02, 0.04) and (2+x)Sr:Fe:Mo (x=0.02, 0.04, 0.10) cationic ratios. The strontium deficient samples exhibit a significant decrease in their values of saturation magnetization (Ms), Curie temperature (Tc) and magnetoresistance (MR) compared to the stoichiometric SFMO. On the other hand, the samples prepared with an excess of strontium, respectively those with x=0.02 and 0.04, show remarkably superior magneto–transport characteristics, despite of their increased level of Fe/Mo disorder and somewhat diminished magnetic properties compared to the stoichiometric SFMO. We also show that these samples exhibit superior MR values under low magnetic field and persisting up to temperatures as high as 400 K. - Graphical abstract: Evolution of the magnetization versus temperature under an applied magnetic field of 1000 Oe (left panel) and magnetoresistance versus applied magnetic field at 300 K (right panel) for strontium off-stoichiometric Sr{sub 2}FeMoO{sub 6} samples. - Highlights: • Strontium nonstoichiometric samples of Sr{sub 2}FeMoO{sub 6} are prepared by a citrate route. • The nonstoichiometric samples exhibit an increased Fe/Mo disorder in the structure. • We observed important changes in their magnetic and magnetoresistive properties. • Improved magnetoresistive properties for samples prepared with strontium excess.

  17. 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.

  18. Breakdown by magnetic field in a La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/MgO/Fe spin valve

    SciTech Connect (OSTI)

    Wu Xiaojie; Meng Jian; Zhang Zhenzhong

    2012-03-19

    A La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/MgO/Fe spin valve with inverse tunneling magnetoresistance (TMR) was fabricated on a (100) SrTiO{sub 3} substrate by radio frequency magnetron sputtering. Giant TMR ratios up to 540% were obtained. The breakdown of the spin valve was observed at high magnetic field, which was attributed to the joint action of the invalidation of MgO barrier and the shift of Fermi energy in La{sub 0.7}Sr{sub 0.3}MnO{sub 3} at high magnetic field.

  19. 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+}'.

  20. 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.

  1. 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}.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Oxygen surface exchange kinetics and stability of (La,Sr)2 CoO4±δ/La 1-xSrxMO3-δ (M = Co and Fe) hetero-interfaces at intermediate temperatures

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

    Lee, Dongkyu; Lee, Yueh-Lin; Hong, Wesley T.; Biegalski, Michael D.; Morgan, Dane; Shao-Horn, Yang

    2015-01-01

    Heterostructured oxide interfaces created by decorating Ruddlesden-Popper phases (A2BO4) or perovskites on perovskites have shown not only pronounced cation segregation at the interface and in the A2BO4 structure but also much enhanced kinetics for oxygen electrocatalysis at elevated temperatures. In this study, we report and compare the time-dependent surface exchange kinetics and stability of (La0.5Sr0.5)2CoO4 -decorated (LSC214) La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF113) and La0.8Sr0.2CoO3-δ (LSC113) thin films. While LSC214 decoration on LSC113 greatly reduced the degradation in the surface exchange kinetics as a function of time relative to LSC113, LSCF113 with LSC214 coverage showed comparable surface exchange kinetics and stability to LSCF113. Thismore » difference can be explained by greater surface stability of LSCF113 than LSC113 under testing conditions, and that LSC214 decoration on LSC113 reduced the decomposition of LSC113 to form secondary phases that impedes oxygen exchange kinetics, and thus resulted in enhanced stability. This hypothesis is supported by the observations that annealing at 550 °C led to the formation of Sr-rich secondary particles on LSC113 while no such particles were observed on LSCF113. Density functional theory (DFT) computation provides further support, which revealed greater capacity of surface Sr segregation for LSCF113 having SrO termination than LSC113 having (La0.25Sr0.75)O termination for the experimental conditions, and lower energy gain to move Sr from LSCF113 into LSC214 relative to the LSC214-LSC113 system.« less

  14. 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.

  15. 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.

  16. 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

  17. Growth control of oxygen stoichiometry in homoepitaxial SrTiO3 films by pulsed laser epitaxy in high vacuum

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

    Lee, Ho Nyung; Ambrose Seo, Sung S.; Choi, Woo Seok; Rouleau, Christopher M.

    2016-01-29

    In many transition metal oxides, oxygen stoichiometry is one of the most critical parameters that plays a key role in determining the structural, physical, optical, and electrochemical properties of the material. However, controlling the growth to obtain high quality single crystal films having the right oxygen stoichiometry, especially in a high vacuum environment, has been viewed as a challenge. In this work, we show that, through proper control of the plume kinetic energy, stoichiometric crystalline films can be synthesized without generating oxygen defects even in high vacuum. We use a model homoepitaxial system of SrTiO3 (STO) thin films on singlemore » crystal STO substrates. Physical property measurements indicate that oxygen vacancy generation in high vacuum is strongly influenced by the energetics of the laser plume, and it can be controlled by proper laser beam delivery. Thus, our finding not only provides essential insight into oxygen stoichiometry control in high vacuum for understanding the fundamental properties of STO-based thin films and heterostructures, but it expands the utility of pulsed laser epitaxy of other materials as well.₃« less

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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].

  7. 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}.

  8. 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.

  9. 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.

  10. 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?

  11. 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.}

  12. 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.

  13. Magnetic behavior of the Bi{sub 2−y}Sr{sub y}Ir{sub 2}O{sub 7} pyrochlore solid solution

    SciTech Connect (OSTI)

    Cosio-Castaneda, C.; Mora, P. de la; Morales, F.; Escudero, R.; Tavizon, G.

    2013-04-15

    The temperature dependence of magnetic susceptibility of the Bi{sub 2−y}Sr{sub y}Ir{sub 2}O{sub 7} system was studied from 2 to 300 K. According to these measurements, the solid solution (0≤y≤0.9) does not show any magnetic transition; however, a noticeable deviation from the Curie–Weiss law occurs and the magnetic behavior of this system can be ascribed to short-range magnetic order that is also present in several geometrically frustrated systems. The Pauli magnetic susceptibility decreases as the Sr content increases, this can be associated with a shift towards Ir{sup 5+} in samples; also the Ir effective magnetic moment decreases. The estimated Wilson-ratio indicates the presence of strong electron–electron correlations. - Graphical abstract: Temperature dependence of the magnetic susceptibility of Bi{sub 2−y}Sr{sub y}Ir{sub 2}O{sub 7}. The samples of this system showed no magnetic transition down to 2 K. Analyzing magnetic data (symbols for experimental data, continuous line for the Curie–Weiss (CW) equation and black dots for a modified CW equation), it is found that this system departures from a CW-like equation and the magnetic parameters C and θ notably deviate from the expected values for Ir. Better fittings with a modified CW equation are shown in the A and B insets. Highlights: ► The magnetic susceptibility of the Bi{sub 2−x}Sr{sub x}Ir{sub 2}O{sub 7} system is discussed. ► No magnetic transition is observed. ► Magnetic measurements on the Bi{sub 2−y}Sr{sub y}Ir{sub 2}O{sub 7} indicate the existence of Ir{sup 5+}. ► The magnetic susceptibility does not follow a Curie–Weiss law. ► A modified Curie–Weiss equation describes correctly the magnetic susceptibility.

  14. 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

  15. monolayers BUNKER,BRUCE C.; CARPICK,ROBERT W.; ASSINK,ROGER A...

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    P.; GULLEY,GERALD L. 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; SYNTHESIS; AQUEOUS SOLUTIONS; THIN FILMS; SILANES; HYDROLYSIS;...

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    Office of Legacy Management (LM)

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    Office of Environmental Management (EM)

    Asset Utilization Index (AUI) Guidance Asset Utilization Index (AUI) Guidance PDF icon AUI Guidance_090227.pdf More Documents & Publications Three Year Rolling Timeline The Department&#8217;s real property assets are vital to the accomplishment of its mission Three-year Rolling Timeline

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  3. 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.

  4. Decoupling of the antiferromagnetic and insulating states in Tb-doped Sr2IrO4

    SciTech Connect (OSTI)

    Wang, J. C.; Aswartham, S.; Ye, Feng; Terzic, J.; Zheng, H.; Haskel, Daniel; Chikara, Shalinee; Choi, Yong; Schlottmann, P.; Custelcean, Radu; Yuan, S. J.; Cao, G.

    2015-12-08

    Sr2IrO4 is a spin-orbit coupled insulator with an antiferromagnetic (AFM) transition at TN = 240 K. We report results of a comprehensive study of single-crystal Sr2Ir1-xTbxO4 (0≤x≤0.03). This study found that mere 3% (x=0.03) tetravalent Tb4+(4f7) substituting for Ir4+ (rather than Sr2+) completely suppresses the long-range collinear AFM transition but retains the insulating state, leading to a phase diagram featuring a decoupling of magnetic interactions and charge gap. The insulating state at x = 0.03 is characterized by an unusually large specific heat at low temperatures and an incommensurate magnetic state having magnetic peaks at (0.95, 0, 0) and (0, 0.95, 0) in the neutron diffraction, suggesting a spiral or spin density wave order. It is apparent that Tb doping effectively changes the relative strength of the SOI and the tetragonal CEF and enhances the Hund’s rule coupling that competes with the SOI, and destabilizes the AFM state. However, the disappearance of the AFM accompanies no metallic state chiefly because an energy level mismatch for the Ir and Tb sites weakens charge carrier hopping and renders a persistent insulating state. Furthermore, this work highlights an unconventional correlation between the AFM and insulating states in which the magnetic transition plays no critical role in the formation of the charge gap in the iridate.

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. SrAgZn and EuAgZn with KHg{sub 2}-type structure—Structure, magnetic properties, and {sup 151}Eu Mössbauer spectroscopy

    SciTech Connect (OSTI)

    Gerke, Birgit; Rodewald, Ute Ch.; Niehaus, Oliver; Pöttgen, 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 F² 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 F² 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 Curie–Weiss behaviour with μ{sub eff}=7.87(1) μ{sub B}/Eu atom and θ{sub P}=37.1(1) K, indicating divalent europium. {sup 151}Eu Mössbauer 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 Mössbauer spectrum.

  13. 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.

  14. 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.

  15. Enhanced electrical and magnetic properties in La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films deposited on CaTiO{sub 3}-buffered silicon substrates

    SciTech Connect (OSTI)

    Adamo, C.; Méchin, L.; Guillet, B.; Wu, S.; Routoure, J.-M.; Heeg, T.; Katz, M.; Pan, X. Q.; Mercone, S.; Schubert, J.; Zander, W.; Misra, R.; Schiffer, P.; and others

    2015-06-01

    We investigate the suitability of an epitaxial CaTiO{sub 3} buffer layer deposited onto (100) Si by reactive molecular-beam epitaxy (MBE) for the epitaxial integration of the colossal magnetoresistive material La{sub 0.7}Sr{sub 0.3}MnO{sub 3} with silicon. The magnetic and electrical properties of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films deposited by MBE on CaTiO{sub 3}-buffered silicon (CaTiO{sub 3}/Si) are compared with those deposited on SrTiO{sub 3}-buffered silicon (SrTiO{sub 3}/Si). In addition to possessing a higher Curie temperature and a higher metal-to-insulator transition temperature, the electrical resistivity and 1/f noise level at 300 K are reduced by a factor of two in the heterostructure with the CaTiO{sub 3} buffer layer. These results are relevant to device applications of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films on silicon substrates.

  16. 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.

  17. 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; Chang, Hauyee; Takeuchi, Ichiro

    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.

  18. 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...

  19. SR0917.docx

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

    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...

  20. 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...

  1. 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...

  2. 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 (DOE) and Wackenhut Services Incorporated (WSI) will host the 32nd Annual Security Police Officer Training Competition (SPOTC) "Carolina Challenge," May 2 - 6, at the Savannah River Site (SRS) Advanced Tactical Training Academy (ATTA). SPOTC is a tactically oriented security firearms competition

  3. SR-02-02

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

    3, 2002 Media Contact: Jim Giusti (803) 725-2889 NNSA Release Accident Investigation Report On TEF Construction Worker Accident Flag Ribbon Art Aiken, SC - The National Nuclear Security Administration's (NNSA) Savannah River Site Office (SRSO) today issued its Accident Investigation Board's findings on the cause of an accident at the Tritium Extraction Facility (TEF) construction site in which one worker was injured. On April 2, 2002, at the Savannah River Site, a carpenter helping to erect

  4. SR-03-04

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    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 Energy's Savannah River Operations Office Manager has determined the award fee amount of the Savannah River Site security contractor, Wackenhut Services Inc.-Savannah River Site. The Award Fee Determination letter that covers the period of October 1, 2003 through March 31, 2004 can be obtained by calling (803) 952-7697.

  5. 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

  6. SR-05-04

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

    4 Media Contact: Jim Giusti (803) 952-7697 NNSA And WSRC Reconition Of Progress In Key Tritium Facilities Flag Ribbon Art (Aiken, SC) -- Personnel from the National Nuclear Security Administration (NNSA) Savannah River Site Office (SRSO) joined with the Westinghouse Savannah River Company team on Thursday, July 1, to recognize the hundreds of craft personnel and other employees who have contributed to the exceptional progress on two key tritium projects. The Tritium Extraction Facility (TEF) and

  7. SR-06-04

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

    6, 2004 Media Contact: Jim 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 Operations Office will host a ceremonial signing of a programmatic agreement between the U. S. Department of Energy (DOE), National Nuclear Security Administration, the South Carolina State Historic Preservation Office, and the Advisory Council on Historic Preservation (ACHP) for the

  8. SR0908.docx

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

    Tuesday, June 9, 2009 james-r.giusti@srs.gov 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 tough economic times, earning a paycheck has become increasingly challenging for many South Carolinians. For one North Augusta sheet-metal worker, a job and a return to economic stability is one result of the Department of Energy's Recovery Act funding at the Savannah River Site (SRS). James

  9. SR0909.docx

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

    AIKEN, SC 29802 NEWS MEDIA CONTACT: FOR IMMEDIATE RELEASE Jim Giusti, (803) 952-7697 Thursday, June 11, 2009 james-r.giusti@srs.gov Paivi Nettamo, SRNS, (803) 952-6938 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 Aiken, SC - The Department of Energy announced today that DOE's Savannah River Operations Office and Savannah River Nuclear Solutions, LLC, (SRNS) will host

  10. SR0910.docx

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

    Monday, June 22, 2009 james-r.giusti@srs.gov Angeline French, (SRNL), (803) 725-2854 angeline.french@srnl.doe.gov Dean Campbell, WSRC, (803) 208-8270 dean.campbell@srs.gov DOE'S SRNL AND DWPF HONORED BY WHITE HOUSE FOR ENVIRONMENTAL ACHIEVEMENT AIKEN, S.C. (June 17, 2009) - The U.S. Department of Energy's Savannah River National Laboratory (SRNL) and its Defense Waste Processing Facility (DWPF) at the Savannah River Site were honored by the White House for an innovative environmental initiative

  11. SR0913.docx

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

    NEWS MEDIA CONTACT: FOR IMMEDIATE RELEASE Jim Giusti, DOE, (803) 952-7697 Wednesday, July 1, 2009 james-r.giusti@srs.gov Paivi Nettamo, SRNS, (803) 952-6938 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, SC - The Department of Energy announced today that DOE's Savannah River Operations Office and Savannah River Nuclear Solutions, LLC, (SRNS) will host two town hall

  12. SR0914.docx

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    AIKEN, SC 29802 NEWS MEDIA CONTACT: FOR IMMEDIATE RELEASE Jim Giusti, DOE, (803) 952-7697 Thursday, July 16, 2009 james-r.giusti@srs.gov Paivi Nettamo, SRNS, (803) 952-6938 paivi.nettamo@srs.gov Road Construction Contract Awarded to Local Company for Improved Access to SRS Aiken, SC (July 16) -- Savannah River Nuclear Solutions officials recently awarded a contract worth nearly $300,000 to a local road construction company to improve traffic flow through the two primary security check points,

  13. SR0915.docx

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

    (803) 952-7697 Friday, July 17, 2009 james-r.giusti@srs.gov DOE Awards $3.4 million Contract To Ship Depleted Uranium Oxide Out of South Carolina Recovery Act in Action Aiken, SC (July 17) -- The Department of Energy's Savannah River Operations Office announced today the award of $3.4 million contract to Cavanagh Service Group for shipping services of depleted uranium oxide (DUO) under the American Reinvestment and Recovery Act project at the Savannah River Site. Cavanagh Services Group, Inc.,

  14. SR0921.docx

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

    Leads DOE Complex in EPA's Superfund Job Training Initiative Superfund Trainees Defy Circumstances To Gain Recovery Act Jobs AIKEN, S.C. (Sept. 2) - A U.S. Environmental Protection Agency (EPA) program is being implemented for the first time in the U.S. Department of Energy Complex at the Savannah River Site (SRS). The program builds a foundation for hope and a brighter future for the program's men and women who will begin their careers as Recovery Act workers. The Superfund Job Training

  15. 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 Recovery Act at the Savannah River Site Aiken, SC (Sept. 25) - The U.S. Department of Energy (DOE) today announced the start of $200 million in projects to accelerate Liquid Waste remediation work at the Savannah River Site (SRS) by replacing aging and unreliable infrastructure while preparing for future waste

  16. SR0929.docx

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

    Monday, October 26, 2009 james-r.giusti@srs.gov Paivi Nettamo, SRNS, (803) 952-6938 paivi.nettamo@srs.gov Mixed Waste Shipment Enables Consolidation of N-Area Storage Facilities Recovery Act Accelerates Clean-up Project Slated for 2053 AIKEN, S.C. (Oct. 26) - Earlier this month, a shipment offsite of seven barrels of tritium- and mercury-contaminated oil put the Savannah River Site (SRS) on a fast track to remove legacy mixed waste originally scheduled for disposition in 2053. "Not only is

  17. 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

  18. 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 Site's F Tank Farm. The project is receiving $1.4 million in Recovery Act funding, which will allow for important steps that are necessary to moving the tank to closure. Ron Boisvert, Savannah River Remediation LLC's project manager for the Tank 5 and 6 closure projects, said, "The Recovery Act funding we have received

  19. 2010SR05.doc

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

    remarked Reinhard Friske, the TRU waste shipping manager. "Inspections are performed inside the tent. Before, we were all out in the elements." The Big Top, which was...

  20. sr0801.doc

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

    ... Other facts: * No safety issues, radiological issues or recordable injuries during building, testing or operating. * Regulator comments quoted in Weapons Complex Monitor: "The ...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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 ... American Recovery and Reinvestment Act (ARRA) at the Department of Energy's (DOE) Savannah ...

  7. 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...

  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. 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...

  10. 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...

  11. 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

  12. 2010SR06.docx

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

    james-r.giusti@srs.gov Angeline French, SRNL, (803) 725-2854 angeline.french@srnl.doe.gov SRNL Precision Models Aid Recovery Act Cleanup at SRS AIKEN, S.C. - In a project that's part engineering, part history detective, and part high- tech craft project, the U.S. Department of Energy's (DOE) Savannah River National Laboratory (SRNL) is creating computer-produced scale replicas of the Savannah River Site's reactor buildings to support the American Recovery and Reinvestment Act project here. Use

  13. 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).

  14. 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

  15. 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

  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. 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

  18. 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

  19. 2010sr23.doc

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

    11, 2010 james-r.giusti@srs.gov Paivi Nettamo, SRNS, (803) 952-6938 paivi.nettamo@srs.gov Recovery Act Funding Improves Stormwater 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 of Energy's (DOE) Savannah River Site (SRS) can be as simple as a new concrete ditch and as complicated as making sure the runoff flows correctly. The American Recovery and Reinvestment Act is

  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. 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

  2. 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

  3. 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

  4. sr0907.docx

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

    (803) 952-6938 paivi.nettamo@srs.gov Savannah River Site Makes Its 1,000 th Transuranic ... is made to the Waste Isolation Pilot Plant (WIPP) located near Carlsbad, New Mexico. ...

  5. sr0931.docx

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

    The initiative by the Savannah River Site to offer assistance to those seeking work was especially important in an area where a local yarn plant is now faced with closure. "I got a ...

  6. sr0932.docx

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

    ... Farms provides landscaping and erosion control to the Mixed Oxide Fuel (MOX) Fabrication Project Facility, Advanced Technical Training Area (ATTA), and T Area. Carolina Fresh Farms ...

  7. 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.,...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  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...

  16. 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...

  17. 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...

  18. 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...

  19. Field-dependent magnetization of BiFeO3 in ultrathin La0.7Sr0.3MnO3/BiFeO3

    Office of Scientific and Technical Information (OSTI)

    superlattice (Journal Article) | SciTech Connect Journal Article: Field-dependent magnetization of BiFeO3 in ultrathin La0.7Sr0.3MnO3/BiFeO3 superlattice Citation Details In-Document Search This content will become publicly available on December 2, 2016 Title: Field-dependent magnetization of BiFeO3 in ultrathin La0.7Sr0.3MnO3/BiFeO3 superlattice We report the observation of field-induced magnetization of BiFeO3 (BFO) in an ultrathin La0.7Sr0.3MnO3 (LSMO)/BFO superlattice using polarized

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Structural instability of the CoO4 tetrahedral chain in SrCoO3-δ 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-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 tetrahedral chain structure, which constitutes a key ingredient to understand the electronic and structural properties of the brownmillerite SrCoO2.5.

  6. Average and local structure of the Pb-free ferroelectric perovskites (Sr,Sn)TiO3 and (Ba,Ca,Sn)TiO3

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

    Laurita, Geneva; Page, Katharine; Suzuki, Shoichiro; Seshadri, Ram

    2015-12-16

    The characteristic structural off -centering of Pb2+ in oxides, associated with its 6s2 lone pair, allows it to play a dominant role in polar materials, and makes it a somewhat ubiquitous component of ferroelectrics. In this work, we examine the compounds Sr0.9Sn0.1TiO3 and Ba0.79Ca0.16Sn0.05TiO3 using neutron total scattering techniques with data acquired at di erent temperatures. In these compounds, previously reported as ferroelectrics, Sn2+ appears to display some of the characteristics of Pb2+. We compare the local and long-range structures of the Sn2+-substituted compositions to the unsubstituted parent compounds SrTiO3 and BaTiO3. Lastly, we find that even at these smallmore » substitution levels, the Sn2+ lone pairs drive the local ordering behavior, with the local structure of both compounds more similar to the structure of PbTiO3 rather than the parent compounds.« less

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. Nanocrystalline Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3−δ} 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−δ} 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 (600–800 °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−δ} 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−δ} obtained by a chelating synthesis route. • Cubic perovskite structures with crystallite sizes ∼23±2 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.