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  1. GAVI and hepatitis B immunisation in India.

    PubMed

    Kolås, A

    2011-01-01

    In cooperation with Indian health authorities, the GAVI Alliance (GAVI) is introducing Hepatitis B (HepB) vaccination into the immunisation programmes of 11 'better-performing' Indian states. This article describes the concerns and interests of major stakeholders in the programme, including GAVI partners and the Indian government, and summarises Indian debates that have emerged in response to the project, especially on the issue of selective vs. universal immunisation. The article suggests that programme planning should be based on a good knowledge of disease prevalence and the relative importance of perinatal HepB transmission, which would require a comprehensive cross-country study of the epidemiology of HepB among different populations, the relative importance of different transmission routes and the degree of geographical variation in India. Based on this research, further studies could address the feasibility and cost-effectiveness of routine birth-dose administration and selective birth-dose immunisation of infants born to mothers who are chronic HepB virus carriers. The GAVI 'formula' could be strengthened by supporting the basic epidemiological research that is essential to effective programme planning in recipient countries, which are by definition among the world's poorest countries.

  2. Origins, design and implementation of the China GAVI project.

    PubMed

    Liang, Xiaofeng; Cui, Fuqiang; Hadler, Stephen; Wang, Xiaojun; Luo, Huiming; Chen, Yuansheng; Kane, Mark; Shapiro, Craig; Yang, Weizhong; Wang, Yu

    2013-12-27

    China received GAVI support for hepatitis B vaccination in 2001 because of high disease burden and strong government will to protect infants at risk. The China/GAVI project, implemented since 2002, was funded 50% by GAVI and 50% by the Government of China. The purpose of the project was to increase coverage of hepatitis B vaccine through a pro-poor approach targeting all counties of the 12 Western provinces and poverty counties of the 10 Central provinces, to accelerate integration of hepatitis B vaccine into routine immunization, and assure immunization injection safety. The mechanism of internal coordination among multiple government entities and international cooperation was established and comprehensive strategies were used to improve vaccine coverage and injection safety. After 8 years of implementation, 193,000 health care workers in 118,316 health care facilities participated in the project, mostly at the township hospitals level (55,051) and in community centres (104,547). Through the China GAVI project, the 85% HepB3 coverage goal was reached in 98% of GAVI China project counties, the 75% timely birth dose (TBD) coverage goal was reached in 80% of GAVI project counties, and AD syringes were introduced into 100% of GAVI-supported areas. Additionally, the GAVI project was instrumental in convincing the Chinese Government to sustainably introduce and fully fund HepB vaccine for all newborns in China. The impact of hepB vaccination on HBsAg prevalence was observed throughout China, as HBsAg prevalence (previously ~10%) is now less than 1% among children under 5 years of age.

  3. Financial challenges of immunization: a look at GAVI.

    PubMed Central

    Kaddar, Miloud; Lydon, Patrick; Levine, Ruth

    2004-01-01

    Securing reliable and adequate public funding for prevention services, even those that are considered highly cost effective, often presents a challenge. This has certainly been the case with childhood immunizations in developing countries. Although the traditional childhood vaccines cost relatively little, funding in poor countries is often at risk and subject to the political whims of donors and national governments. With the introduction of newer and more costly vaccines made possible under the Global Alliance for Vaccines and Immunization (GAVI), the future financial challenges have become even greater. Experience so far suggests that choosing to introduce new combination vaccines can significantly increase the costs of national immunization programmes. With this experience comes a growing concern about their affordability in the medium term and long term and a realization that, for many countries, shared financial responsibility between national governments and international donors may initially be required. This article focuses on how GAVI is addressing the challenge of sustaining adequate and reliable funding for immunizations in the poorest countries. PMID:15628208

  4. The GAVI Alliance and the ‘Gates approach’ to health system strengthening

    PubMed Central

    Storeng, Katerini T.

    2014-01-01

    Lauded for getting specific health issues onto national and international agendas and for their potential to improve value for money and outcomes, public-private global health initiatives (GHIs) have come to dominate global health governance. Yet, they have also been criticised for their negative impact on country health systems. In response, disease-specific GHIs have, somewhat paradoxically, appropriated the aim of health system strengthening (HSS). This article critically analyses this development through an ethnographic case study of the GAVI Alliance, which funds vaccines in poor countries. Despite GAVI's self-proclaimed ‘single-minded’ focus on vaccines, HSS support is fronted as a key principle of GAVI's mission. Yet, its meaning remains unclear and contested understandings of the health systems agenda abound, reflecting competing public health ideologies and professional pressures within the global health field. Contrary to broader conceptualisations of HSS that emphasise social and political dimensions, GAVI's HSS support has become emblematic of the so-called ‘Gates approach’ to global health, focused on targeted technical solutions with clear, measurable outcomes. In spite of adopting rhetoric supportive of ‘holistic’ health systems, GHIs like GAVI have come to capture the global debate about HSS in favour of their disease-specific approach and ethos. PMID:25156323

  5. Introducing new vaccines in the poorest countries: what did we learn from the GAVI experience with financial sustainability?

    PubMed

    Lydon, P; Levine, R; Makinen, M; Brenzel, L; Mitchell, V; Milstien, J B; Kamara, L; Landry, S

    2008-12-02

    This paper reviews the experience of the Global Alliance for Vaccines and Immunization (GAVI) in introducing hepatitis B and Haemophilus influenzae type b vaccines in the poorest countries, and explores how financing for immunization has changed since GAVI Fund resources were made available during its first wave of support between 2000 and 2006. The analysis of Financial Sustainability Plans in 50 countries allowed for some of the original funding assumptions of the GAVI approach to be tested against the realities in a wide set of countries, and to highlight implications for future immunization efforts. While the initial GAVI experience with financial sustainability has proved successful through the development of plans, and many countries have been able to both introduce new vaccines and mobilize additional financing for immunization, for future GAVI supported vaccine introduction, some country co-financing of these will be needed upfront for the approach to be more sustainable.

  6. GAVI and the Vaccine Fund--a boon for immunization in the developing world.

    PubMed

    Balaji, K A

    2004-01-01

    The Global Alliance for Vaccines and Immunization (GAVI) and The Vaccine Fund are two major global initiatives adopted with the objectives of improving access to immunization services particularly in the underdeveloped and developing countries and introduction of new but under-used vaccines in the developing countries in particular where these diseases are highly prevalent. GAVI is a collaborative mission that brings together governments in developing and industrialized countries, UNICEF, WHO, the World Bank, the Bill & Melinda Gates Foundation, vaccine manufacturers and all other stake holders to harness the strengths and experiences of multiple partners in immunization. The Vaccine Fund is a financing mechanism established to mobilize resources to serve the mission of GAVI. This article reviews the objectives, strategies, organization and the funding issues of this global initiative. In the Indian perspective, GAVI is presently playing a major role in introduction of Hepatitis-B vaccine for infants in India. The article outlined the pilot project currently being implemented by GoI and the future prospects of integrating Hepatitis-B vaccine and auto disable syringes into the routine immunization program as well as strengthening the routine immunization services when the government decides to expand the project.

  7. Overcoming challenges to sustainable immunization financing: early experiences from GAVI graduating countries.

    PubMed

    Saxenian, Helen; Hecht, Robert; Kaddar, Miloud; Schmitt, Sarah; Ryckman, Theresa; Cornejo, Santiago

    2015-03-01

    Over the 5-year period ending in 2018, 16 countries with a combined birth cohort of over 6 million infants requiring life-saving immunizations are scheduled to transition (graduate) from outside financial and technical support for a number of their essential vaccines. This support has been provided over the past decade by the GAVI Alliance. Will these 16 countries be able to continue to sustain these vaccination efforts? To address this issue, GAVI and its partners are supporting transition planning, entailing country assessments of readiness to graduate and intensive dialogue with national officials to ensure a smooth transition process. This approach was piloted in Bhutan, Republic of Congo, Georgia, Moldova and Mongolia in 2012. The pilot showed that graduating countries are highly heterogeneous in their capacity to assume responsibility for their immunization programmes. Although all possess certain strengths, each country displayed weaknesses in some of the following areas: budgeting for vaccine purchase, national procurement practices, performance of national regulatory agencies, and technical capacity for vaccine planning and advocacy. The 2012 pilot experience further demonstrated the value of transition planning processes and tools. As a result, GAVI has decided to continue with transition planning in 2013 and beyond. As the graduation process advances, GAVI and graduating countries should continue to contribute to global collective thinking about how developing countries can successfully end their dependence on donor aid and achieve self-sufficiency.

  8. Contribution of the GAVI Alliance to improving health and reducing poverty.

    PubMed

    Lob-Levyt, Julian

    2011-10-12

    The Global Alliance for Vaccines and Immunization (GAVI), now 10 years old, was established as a successful and innovative public-private partnership to deal with a fundamental inequity. The poorest children in the poorest parts of the world were being denied access to life-saving vaccines simply on the basis of cost. GAVI has been successful in mobilizing significant funding from donors and through innovative financing instruments, immunizing large numbers of children. GAVI has been less successful, at least in the time frames first envisaged, at quickly reducing the prices of new and under-used vaccines to levels affordable by the poorest countries. Vaccines remain some of the most cost effective of public health interventions. As GAVI seeks to introduce a new set of vaccines to tackle major killers such as pneumonia and diarrhoea, and emerging threats such as cervical cancer, it needs to raise significant additional funds. There is no single solution. Multiple and new instruments will be required to raise finance both globally and at the country level, and also to incentivize industry and others to provide vaccines at affordable prices to the poorest countries.

  9. Applying lessons learned from the USAID family planning graduation experience to the GAVI graduation process.

    PubMed

    Shen, Angela K; Farrell, Marguerite M; Vandenbroucke, Mary F; Fox, Elizabeth; Pablos-Mendez, Ariel

    2015-07-01

    As low income countries experience economic transition, characterized by rapid economic growth and increased government spending potential in health, they have increased fiscal space to support and sustain more of their own health programmes, decreasing need for donor development assistance. Phase out of external funds should be systematic and efforts towards this end should concentrate on government commitments towards country ownership and self-sustainability. The 2006 US Agency for International Development (USAID) family planning (FP) graduation strategy is one such example of a systematic phase-out approach. Triggers for graduation were based on pre-determined criteria and programme indicators. In 2011 the GAVI Alliance (formerly the Global Alliance for Vaccines and Immunizations) which primarily supports financing of new vaccines, established a graduation policy process. Countries whose gross national income per capita exceeds $1570 incrementally increase their co-financing of new vaccines over a 5-year period until they are no longer eligible to apply for new GAVI funding, although previously awarded support will continue. This article compares and contrasts the USAID and GAVI processes to apply lessons learned from the USAID FP graduation experience to the GAVI process. The findings of the review are 3-fold: (1) FP graduation plans served an important purpose by focusing on strategic needs across six graduation plan foci, facilitating graduation with pre-determined financial and technical benchmarks, (2) USAID sought to assure contraceptive security prior to graduation, phasing out of contraceptive donations first before phasing out from technical assistance in other programme areas and (3) USAID sought to sustain political support to assure financing of products and programmes continue after graduation. Improving sustainability more broadly beyond vaccine financing provides a more comprehensive approach to graduation. The USAID FP experience provides a

  10. Sustaining GAVI-supported vaccine introductions in resource-poor countries.

    PubMed

    Zuber, Patrick L F; El-Ziq, Ibrahim; Kaddar, Miloud; Ottosen, Ann E; Rosenbaum, Katinka; Shirey, Meredith; Kamara, Lidija; Duclos, Philippe

    2011-04-12

    Since 2000, GAVI provided essential support for an unprecedented increase in the use of hepatitis B (HepB) and Haemophilus influenzae (Hib) containing vaccines in resource poor countries. This increase was supported with significant funding from international donors, intended to be time-limited. To assess the sustainability of this important expansion of the global access to vaccines, we reviewed supply chains, financial resources for procurement and decision-making in countries that introduced hepatitis B or Hib vaccines with GAVI support. During the period studied, the types of vaccine products supplied fluctuated rapidly in relationship with the number of suppliers and availability of more combination products. The price of the cheaper vaccines decreased while that of pentavalent DTwP-HepB-Hib remained stable. In average, vaccine introduction was associated with an increase of national programs budget, with new vaccines representing more than half of that increase, while the part of GAVI contributions to the budget went from 25% to 46%. Less than 20% of the vaccine introductions were decided by a national advisory body. Strengthening supply chains, adjusting funding schemes and increasing national ownership will be key to the sustained use of hepatitis B and Hib vaccines and the eventual addition of other important vaccines where they are the most needed.

  11. The inception, achievements, and implications of the China GAVI Alliance Project on Hepatitis B Immunization.

    PubMed

    Kane, M A; Hadler, S C; Lee, L; Shapiro, C N; Cui, F; Wang, X; Kumar, R

    2013-12-27

    The China GAVI Hepatitis B Immunization Project was initiated in 2002 with the signing of a Memorandum of Understanding between GAVI and the Government of China. The Project was one of the three (China, India, and Indonesia) GAVI-initiated special projects done to support countries too large to receive full GAVI support for hepatitis B vaccine and safe injections. The Project in China was designed by the Chinese Government and partners to deliver free hepatitis B vaccine and safe injections to all newborns in the 12 Western Provinces and Poverty Counties in 10 Provinces of Central China (1301 Counties with approximately 5.6 million births per year), eliminating the gap in immunization coverage between wealthier and poorer regions of China. The project budget (USD 76 million) was equally shared by GAVI and the Chinese Government. Initially planned for 5 years, two no cost extensions extended the project to 2011. Although China produced hepatitis B vaccine, before the project the vaccine was sold to parents who were also charged a "user fee" for the syringe and vaccine administration. Basic Expanded Program on Immunization (EPI) vaccines such as BCG, DTP, Polio, and measles vaccines were provided free to parents, although they were charged a user fee. Vaccines were sold by China CDC Offices at provincial, prefecture, county level and township hospitals, and village doctors received a substantial portion of their income from the sale of hepatitis B and other vaccines. The result of charging for hepatitis B vaccine was that coverage was relatively high in Eastern and wealthier counties in Central China (~80-90%), but was much lower (~40%) in Western China and Poverty Counties where parents could not afford the vaccine. The Project was administered by the China MOH and China CDC EPI program, and two Project Co-managers, one from the Chinese Government and the other an international assignee, were chosen. The project had an oversight Operational Advisory Group composed

  12. GAViT: Genome Assembly Visualization Tool for Short Read Data

    SciTech Connect

    Syed, Aijazuddin; Shapiro, Harris; Tu, Hank; Pangilinan, Jasmyn; Trong, Stephan

    2008-03-14

    It is a challenging job for genome analysts to accurately debug, troubleshoot, and validate genome assembly results. Genome analysts rely on visualization tools to help validate and troubleshoot assembly results, including such problems as mis-assemblies, low-quality regions, and repeats. Short read data adds further complexity and makes it extremely challenging for the visualization tools to scale and to view all needed assembly information. As a result, there is a need for a visualization tool that can scale to display assembly data from the new sequencing technologies. We present Genome Assembly Visualization Tool (GAViT), a highly scalable and interactive assembly visualization tool developed at the DOE Joint Genome Institute (JGI).

  13. Country Ownership And Gavi Transition: Comprehensive Approaches To Supporting New Vaccine Introduction.

    PubMed

    Shen, Angela K; Weiss, Jonathan M; Andrus, Jon Kim; Pecenka, Clint; Atherly, Deborah; Taylor, Katherine; McQuestion, Michael

    2016-02-01

    Since the mid-2000s low- and lower-middle-income countries have been focusing on developing and using evidence for immunization policy making, with an increasing emphasis on cost-effectiveness analysis, program costing, and financial flows-particularly for the introduction of newer, more expensive vaccines. While this is critical to informing decisions, countries still need to increase national immunization investment and explore innovative approaches to augment financing of immunization programs. The need for increased financing is especially strong in countries transitioning from support by Gavi, the Vaccine Alliance. With increased fiscal space to finance health and immunization programs as a result of improved economic performance, low- and lower-middle-income countries can reach the health status enjoyed by wealthier nations within a generation. However, new strategies and approaches related to domestic resources for immunization programs are needed to achieve this goal. Governments will need to increase their investments and modify existing external immunization financing arrangements if country ownership of immunization programs and the full promise of new vaccines are to be realized.

  14. An analysis of GAVI, the Global Fund and World Bank support for human resources for health in developing countries.

    PubMed

    Vujicic, Marko; Weber, Stephanie E; Nikolic, Irina A; Atun, Rifat; Kumar, Ranjana

    2012-12-01

    Shortages, geographic imbalances and poor performance of health workers pose major challenges for improving health service delivery in developing countries. In response, multilateral agencies have increasingly recognized the need to invest in human resources for health (HRH) to assist countries in achieving their health system goals. In this paper we analyse the HRH-related activities of three agencies: the Global Alliance for Vaccines and Immunisation (GAVI); the Global Fund for Aids, Tuberculosis, and Malaria (the Global Fund); and the World Bank. First, we reviewed the type of HRH-related activities that are eligible for financing within each agency. Second, we reviewed the HRH-related activities that each agency is actually financing. Third, we reviewed the literature to understand the impact that GAVI, Global Fund and World Bank investments in HRH have had on the health workforce in developing countries. Our analysis found that by far the most common activity supported across all agencies is short-term, in-service training. There is relatively little investment in expanding pre-service training capacity, despite large health worker shortages in developing countries. We also found that the majority of GAVI and the Global Fund grants finance health worker remuneration, largely through supplemental allowances, with little information available on how payment rates are determined, how the potential negative consequences are mitigated, and how payments are to be sustained at the end of the grant period. Based on the analysis, we argue there is an opportunity for improved co-ordination between the three agencies at the country level in supporting HRH-related activities. Existing initiatives, such as the International Health Partnership and the Health Systems Funding Platform, could present viable and timely vehicles for the three agencies to implement this improved co-ordination.

  15. Gates, GAVI, the glorious global funds and more: all you ever wanted to know.

    PubMed

    Nossal, Gustav J V

    2003-02-01

    Global immunization programmes have achieved some remarkable successes. In 1977, Frank Fenner's Commission declared smallpox to have been eradicated by an 11-year-long intensive campaign. The Expanded Programme on Immunization encompassed six important childhood vaccines and reached over three-quarters of the world's children. Polio eradication has gone remarkably well, with only 10 out of 200 countries reporting residual cases. But amidst all the good news, there is also bad news. Coverage is variable; infrastructure is crumbling; and newer vaccines are not being incorporated in many country programmes. The Bill and Melinda Gates Foundation has introduced a new dynamic here. From their initial gift of $100 million in December 1998, their commitment to date is US$1.5 billion - and rising. At the centre is a Global Children's Vaccine Fund which permitted the launch, in January 2000, of the Global Alliance for Vaccines and Immunization. This is targeted to the 74 poorest countries of the world and is designed to improve vaccination infrastructure, to purchase newer vaccines and to support research and development. Even before we know how successful this programme will be, it has had its imitators. The Global Fund to Fight AIDS, TB and Malaria borrowed many concepts from GAVI. The Global Alliance for Improved Nutrition announced in May 2002 does so as well, and is heavily supported by Gates. Highly effective parasite control programmes antedate all this but will be much strengthened. However, we still face a sizeable budgetary gap both for research and for bringing the best advances to all people who need them.

  16. Key outcomes and addressing remaining challenges--perspectives from a final evaluation of the China GAVI project.

    PubMed

    Yang, Weizhong; Liang, Xiaofeng; Cui, Fuqiang; Li, Li; Hadler, Stephen C; Hutin, Yvan J; Kane, Mark; Wang, Yu

    2013-12-27

    During the China GAVI project, implemented between 2002 and 2010, more than 25 million children received hepatitis B vaccine with the support of project, and the vaccine proved to be safe and effective. With careful consideration for project savings, China and GAVI continually adjusted the budget, additionally allowing the project to spend operational funds to support demonstration projects to improve timely birth dose (TBD), conduct training of EPI staff, and to monitor the project impact. Results from the final evaluation indicated the achievement of key outcomes. As a result of government co-investment, human resources at county level engaged in hepatitis B vaccination increased from 29 per county on average in 2002 to 66 in 2009. All project counties funded by the GAVI project use auto-disable syringes for hepatitis B vaccination and other vaccines. Surveyed hepatitis B vaccine coverage increased from 71% in 2002 to 93% in 2009 among infants. The HBsAg prevalence declined from 9.67% in 1992 to 0.96% in 2006 among children under 5 years of age. However, several important issues remain: (1) China still accounts for the largest annual number of perinatal HBV infections (estimated 84,121) in the WHO WPR region; (2) China still lacks a clear national policy for safe injection of vaccines; (3) vaccination of high risk adults and protection of health care workers are still not implemented; (4) hepatitis B surveillance needs to be refined to more accurately monitor acute hepatitis B; and (5) a program for treatment of persons with chronic HBV infection is needed. Recommendations for future hepatitis B control include: using the lessons learned from the China GAVI project for future introductions of new vaccines; addressing unmet needs with a second generation hepatitis B program to reach every infant, including screening mothers, and providing HBIG for infants born to HBsAg positive mothers; expanding vaccination to high risk adults; addressing remaining unsafe

  17. The Caraguataí syenitic suite, a ca. 2.7 Ga-old alkaline magmatism (petrology, geochemistry and U-Pb zircon ages). Southern Gavião block (São Francisco Craton), Brazil

    NASA Astrophysics Data System (ADS)

    Cruz, Simone Cerqueira Pereira; Peucat, Jean-Jacques; Teixeira, Leo; Carneiro, Maurício Antônio; Marques Martins, Adriano Alberto; Santana, Jocilene dos Santos; de Souza, Jailma Santos; Barbosa, Johildo Salomão Figueiredo; Leal, Ângela Beatriz Menezes; Dantas, Elton; Pimentel, Marcio

    2012-08-01

    The Gavião Block comprises amphibolite- and granulite-facies gneisses and migmatites of tonalitic, granodioritic and granitic compositions and supracrustal sequences including volcanosedimentary layers metamorphosed up to the amphibolite facies. In the region of Abaíra-Jussiape (BA), two main igneous suites, called Caraguataí and Jussiape, are exposed in the core of an anticline. The Caraguataí suite encompasses alkali-feldspar granites, syenites and quartz syenites that contain biotite, magnetite/hematite, apatite, titanite, hastingsite/pargasite and zircon as accessory minerals that were adjusted to the amphibolite facies. White mica and epidote minerals are related to retrograde greenschist facies. These rocks were deformed in dextral to reverse-dextral shear zones, giving origin to protomylonites and augen-mesomylonites to ultramylonites. The ultramylonites have a prominent banding parallel to the main foliation of the rocks. Lithogeochemical studies revealed subalkaline to alkaline, metaluminous to peraluminous, Fe-rich protolith for instead of to these rocks associated with A2-type magmatism and partial melting of igneous continental crust. In situ U-Pb zircon dating using the Laser Ablation ICPMS method was carried out for five samples of the Caraguataí alkaline suite. The ages obtained for an isotropic syenite (SCP 1470: 2680 ± 24 Ma), a foliated syenite (SCP 2035: 2703 ± 11 Ma), a syenitic augen gneiss (SCP 2017: 2706 ± 34 Ma) and two ultramylonitic syenitic banded gneisses (SCP 1446: 2711 ± 34 Ma and SCP 1809: 2698 ± 10 Ma) fall in the same range. The average of the 62 concordant analyses obtained from the five samples allows to determine a mean 207Pb/206Pb age of 2696 ± 5 Ma (±2σ) interpreted as that of the alkaline plutonism. The geochronologic data obtained up to now have not helped to constrain an age for the metamorphism that affected the study area. The A2 type of magmatism, instead of and the TDM model ages (ca. 3.2-3.8 Ga) and the

  18. Paleolithic hominin remains from Eshkaft-e Gavi (southern Zagros Mountains, Iran): description, affinities, and evidence for butchery.

    PubMed

    Scott, Jeremiah E; Marean, Curtis W

    2009-09-01

    Eshkaft-e Gavi is a cave located in the southern Zagros Mountains of Iran and is one of the few archaeological sites in the region to preserve both Middle Paleolithic and Upper Paleolithic occupations. Excavation of the site in the 1970s yielded an assemblage of lithic and faunal remains, including ten hominin specimens: a mandibular molar, four cranial fragments, a clavicular diaphysis, the proximal half of a metacarpal, a fragment of os coxa, the proximal diaphysis of a juvenile femur, and a patella. The bones derive from a minimum of four individuals, including two juveniles. Although many of these remains could be Epi-Paleolithic in age, one of the juvenile specimens-the mandibular molar-occurs at the base of the cave's Upper Paleolithic sequence. The remains are very fragmentary, but those that preserve diagnostic morphology indicate that they represent modern humans. The molar is taxonomically diagnostic, thus confirming the association of the Aurignacian-like Baradostian Industry with modern humans. Four of the specimens-a piece of frontal bone, the clavicle, the juvenile femur, and the patella-display clear evidence for intentional butchery in the form of stone-tool cutmarks. These cutmarked specimens, along with a fragment of parietal bone, are also burned. Although this evidence is consistent with cannibalism, the small sample makes it difficult to say whether or not the individuals represented by the hominin remains were butchered and cooked for consumption. Nevertheless, the cutmarked Eshkaft-e Gavi specimens add to a growing sample of hominin remains extending back into the Plio-Pleistocene that display evidence of intentional defleshing.

  19. Perceptions of the usefulness of external support to immunization coverage in Chad: an analysis of the GAVI-Alliance cash-based support

    PubMed Central

    Ferrinho, Paulo; Dramé, Mohammed; Tumusiime, Prosper

    2013-01-01

    Introduction Chad is one of the countries supported by the GAVI-Alliance that remains with unsatisfactory vaccination coverage. This paper tries to understand the main barriers to better coverage. Methods These barriers were categorised as up or downstream against the health system building blocks as proposed by WHO and compared with barriers and activities identified by the country in its health system's strengthening grant proposal as approved by the GAVI Alliance in 2007. Data were collected using a modified Delphi system and by analysis of grant and annual report documents. Results Most of the activities anticipated under the GAVI health system's strengthening proposal are activities targeting downstream barriers (the neglect of upstream issues is of major importance in a decentralised state like Chad) and aligned with, not complementary to, immunization services strengthening activities. Further, both set of cash grants are blind to important recommendations such as the need to address barriers at the level of leadership and governance and at the level of the financing system and also about initiatives to promote community demand of vaccination services. Conclusion In Chad slow vaccination progress is aggravated by several contextual barriers: the size of the country, the low population density, the nomadic nature of a significant part of its peoples, the recent civil war, associated with civil unrest and political instability and its geographical localization. In this situation it would be important to sustain downstream operations (the major focus of the ISS grant) while taking a long term view of the needs of the health system. The GAVI effectively supports downstream operations, but neglects the long term view. PMID:24106572

  20. The Siderian-Orosirian magmatism in the Gavião Paleoplate, Brazil: U-Pb geochronology, geochemistry and tectonic implications

    NASA Astrophysics Data System (ADS)

    Pereira Cruz, Simone Cerqueira; Figueiredo Barbosa, Johildo Salomão; Pinto, Marilda Santos; Peucat, Jean-Jacques; Paquette, Jean Louis; Santos de Souza, Jailma; de Souza Martins, Violeta; Júnior, Farid Chemale; Carneiro, Mauricio Antonio

    2016-08-01

    The southern portion of the Gavião Paleoplate is composed by Archean orthogneisses, Archean-Paleoproterozoic metavolcano-sedimentary rocks and Siderian-Rhyacian-Orosirian granitoids. Petrographic, geochemical, U-Pb (Laser Ablation, ICPMS) and Sm-Nd data are presented for five Paleoproterozoic granitoids that were recently mapped: Jussiape II, Lagoa das Almas, Humaitá, Belo Campo and Broco granitoids. These granitoids present U-Pb zircon (LA-ICPMS) ages of 2052 ± 43, 2114 ± 24, 2140 ± 9, 2049 ± 23 and 2038 ± 8 Ma, respectively. In addition to these granitoids, another twenty-five ones were identified and studied by several authors, resulting in a total of twenty-nine plutons. Despite the previous petrography, geochemistry and geochronology studies that have been performed, no model had been proposed to explain the tectonic setting of this extensive granitogenesis. Integration of the new data and the literature has been done and corresponds to the second part of the article. Based on U-Pb dating and geochemical data, Siderian-Rhyacian-Orosirian granitoids of the southern Gavião Paleoplate were classified into five groups, or five suites: 1 (2324 ± 6 to 2091 ± 6.6 Ma), 2a (2054 -6/+8 to 2041 ± 23 Ma), 2b (2066 ± 37 to 2019 ± 32 Ma), 2c (2058 ± 8 to 1852 ± 50 Ma) and 2d (2049 ± 12 to 1929 ± 16 Ma). The granitoids of Group 1 present heterogeneous deformation, while the granitoids of groups 2a to 2d are generally not deformed. Usually the rocks are potassic, but sodic granitic rocks can be found in samples of groups 1, 2c and 2d. Several chemical classification parameters are presented and discussed herein, but it is noteworthy that the granitoids of Group 1 are mainly classified as calcic to calc-alkalic, while the rocks of the second group are mostly classified as alkalic ones. In the remaining groups, the samples vary between calc-alkalic and alkali-calcic. The ɛNd values range between 4.0 and -15.4 and suggest an important and varied share of the

  1. 3.30 Ga high-silica intraplate volcanic-plutonic system of the Gavião Block, São Francisco Craton, Brazil: Evidence of an intracontinental rift following the creation of insulating continental crust

    NASA Astrophysics Data System (ADS)

    Zincone, Stefano A.; Oliveira, Elson P.; Laurent, Oscar; Zhang, Hong; Zhai, Mingguo

    2016-12-01

    High-silica rhyolites having U-Pb zircon ages of 3303 ± 11 Ma occur along the eastern border of the Gavião Block (Brazil) associated with the Contendas-Mirante and Mundo Novo supracrustal belts. Unlike many Archean greenstone sequences, they are not interlayered with mafic to intermediate units. Instead, they belong to an inter-related plutonic-volcanic system, together with granitic massifs having similar zircon crystallization ages of ca. 3293 ± 3 Ma and 3328 ± 3 Ma and plotting along the same geochemical trends as the rhyolites. The rhyolites show well-preserved primary volcanic features such as magma flow textures and euhedral phenocrysts. High emplacement temperatures are indicated by petrographic evidence (β-quartz phenocrysts), zircon saturation temperatures (915-820 °C) and geochemical data, especially high SiO2 (74-79 wt.%) together with elevated Fe2O3(T) ( 3 wt.%), MgO (0.5-1.5 wt.%) and low Al2O3 (< 11 wt.%). The rhyolites show homogeneous trace element ratios (La/YbN 4.8 ± 1.8; EuN/Eu* 0.55; Sr/Y 0.7) and negative ԐHf(3.3 Ga) from 0 to - 7, indicating derivation from a single crustal source for both occurrences. Specifically, the rhyolites would have derived from extraction and eruption of highly silicic residual liquid formed by crystallization of granitic magma in a relatively shallow (< 10 km) reservoir, now represented by the granite massifs. The granite magma was formed by melting or differentiation of material similar to the diorite gneiss that occurs regionally. The 3.30 Ga volcanic-plutonic systems formed after a period of crustal growth and stabilization of a thick continental lithosphere, represented by massive 3.40-3.33 Ga TTG and medium to high-K calk-alkaline magmatism in the Gavião Block. The 3.30 Ga-old rhyolites and granites would therefore have formed in an intracontinental tectonic setting after the formation and stabilization of new continental crust, and accordingly would represent the first stages of rifting and continental

  2. Who pays for cooperation in global health? A comparative analysis of WHO, the World Bank, the Global Fund to Fight HIV/AIDS, Tuberculosis and Malaria, and Gavi, the Vaccine Alliance.

    PubMed

    Clinton, Chelsea; Sridhar, Devi

    2017-01-27

    In this report we assess who pays for cooperation in global health through an analysis of the financial flows of WHO, the World Bank, the Global Fund to Fight HIV/AIDS, TB and Malaria, and Gavi, the Vaccine Alliance. The past few decades have seen the consolidation of influence in the disproportionate roles the USA, UK, and the Bill & Melinda Gates Foundation have had in financing three of these four institutions. Current financing flows in all four case study institutions allow donors to finance and deliver assistance in ways that they can more closely control and monitor at every stage. We highlight three major trends in global health governance more broadly that relate to this development: towards more discretionary funding and away from core or longer-term funding; towards defined multi-stakeholder governance and away from traditional government-centred representation and decision-making; and towards narrower mandates or problem-focused vertical initiatives and away from broader systemic goals.

  3. Coherent laser excitation of Ba-137 and Ba-138

    NASA Technical Reports Server (NTRS)

    Lam, Kai-Shue

    1992-01-01

    Computations are carried out for the 1S(6s2)-1P(6s,6p) coherent laser excitation of Ba-137 and Ba-138 in a magnetic field. Results are presented for both the steady-state and time-dependent excited-state populations of the Zeeman-split magnetic sublevels. The quantum-statistical Liouville-equation approach (for the reduced density matrix) is compared to the rate-equations approach. Significant differences are found between these, due to the interference between strongly overlapping lines (especially for Ba-137). The time-evolution profiles indicate that the Ba-137 transient time is much longer than that of Ba-138.

  4. Band-overlap metallization of BaS, BaSe and BaTe

    NASA Technical Reports Server (NTRS)

    Carlsson, A. E.; Wilkins, J. W.

    1983-01-01

    The insulator-metal transition volumes for BaS, BaSe, and BaTe are calculated for the first time, using the self-consistent augmented spherical wave technique. The metallized transition volumes are smaller than those corresponding to the NaCl yields CsCl structural transitions, but, 10 to 15% larger than those obtained by the Herzfeld dielectric theory. The calculated equilibrium energy gaps in the NaCl structure underestimate the measured ones by 50 to 60%.

  5. Event Structure and the "Ba" Construction.

    ERIC Educational Resources Information Center

    Rhys, Catrin Sian

    1996-01-01

    Much earlier controversy surrounding the Chinese "ba" construction stems from dissention over whether or not "ba" has any independent semantic content. "Ba" was assumed either to be a purely formal particle whose function was to assign case, or to have semantic content translating into thematic content. However, under the hypothesis that abstract…

  6. Y-Ba Superconducting Ceramics

    NASA Astrophysics Data System (ADS)

    Shunbao, Tian; Xiaofei, Li; Tinglian, Wen; Zuxiang, Lin; Shichun, Li; Huijun, Yu

    Polycrystalline Y-Ba-Cu-O superconducting materials have been studied. It was found that chemical composition and processing condition may play an important role in the final structure and superconducting properties. The density has been determined and compared with the calculated value according to the structure model reported by Bell Labs. The grain size and the morphology of the materials were observed by SEM.

  7. Thermoluminescence properties of nanophosphors BaSO₄:Dy and BaSO₄:Tb.

    PubMed

    Rezaee Ebrahim Saraee, Kadijeh; Aghay Kharieky, Amin

    2013-12-01

    Nanocrystalline BaSO4:Dy and BaSO4:Tb were prepared by the coprecipitation method. The materials were characterized with X-ray diffractometry, UV-visible spectroscopy, and scanning electron microscopy. The glow curves of the BaSO4:Dy and BaSO4:Tb nanophosphors feature main peaks at 505 K and 480 K, respectively. The responses to the (60)Co dose are linear in the range 0.1-1 kGy for BaSO4:Dy and in the range 0.1-7 kGy for BaSO4:Tb. The energy dependences of the responses were also studied.

  8. IBFM for Ba isotopes and chaoticity

    NASA Astrophysics Data System (ADS)

    Bucurescu, D.; Cáta-Danil, G.; Ivasçu, M.; Gizon, A.; Gizon, J.; Ur, C. A.

    1992-06-01

    Fluctuation properties have been analysed for the energy levels predicted by IBFM calculations in the Ba isotopes121Ba to131Ba. The results indicate, in general, a situation which is close to the chaotic limit. For the lighter isotopes studied (121 and 123), a phase transition is obtained in the low-spin, positive parity states, from a situation close to regularity at low excitation energies, towards chaoticity at higher excitations.

  9. Ba2phenanthrene is the main component in the Ba-doped phenanthrene superconductor

    NASA Astrophysics Data System (ADS)

    Yan, Xun-Wang; Huang, Zhongbing; Lin, Hai-Qing

    2014-12-01

    We have systematically investigated the crystal structure of Ba-doped phenanthrene with various Ba doping levels by the first-principles calculations combined with the X-ray diffraction (XRD) spectra simulations. Although the experimental stoichiometry ratio of Ba atom and phenanthrene molecule is 1.5:1, the simulated XRD spectra, space group symmetry and optimized lattice parameters of Ba1.5phenanthrene are not consistent with the experimental ones, while the results for Ba2phenanthrene are in good agreement with the measurements. The strength difference of a few XRD peaks can be explained by the existence of pristine phenanthrene. Our findings suggest that instead of uniform Ba1.5phenanthrene, there coexist Ba2phenanthrene and undoped phenanthrene in the superconducting sample. The electronic calculations indicate that Ba2phenanthrene is a semiconductor with a small energy gap less than 0.05 eV.

  10. Ba{sub 2}phenanthrene is the main component in the Ba-doped phenanthrene superconductor

    SciTech Connect

    Yan, Xun-Wang; Huang, Zhongbing; Lin, Hai-Qing

    2014-12-14

    We have systematically investigated the crystal structure of Ba-doped phenanthrene with various Ba doping levels by the first-principles calculations combined with the X-ray diffraction (XRD) spectra simulations. Although the experimental stoichiometry ratio of Ba atom and phenanthrene molecule is 1.5:1, the simulated XRD spectra, space group symmetry and optimized lattice parameters of Ba{sub 1.5}phenanthrene are not consistent with the experimental ones, while the results for Ba{sub 2}phenanthrene are in good agreement with the measurements. The strength difference of a few XRD peaks can be explained by the existence of pristine phenanthrene. Our findings suggest that instead of uniform Ba{sub 1.5}phenanthrene, there coexist Ba{sub 2}phenanthrene and undoped phenanthrene in the superconducting sample. The electronic calculations indicate that Ba{sub 2}phenanthrene is a semiconductor with a small energy gap less than 0.05 eV.

  11. BaGe6 and BaGe(6-x): incommensurately ordered vacancies as electron traps.

    PubMed

    Akselrud, Lev; Wosylus, Aron; Castillo, Rodrigo; Aydemir, Umut; Prots, Yurii; Schnelle, Walter; Grin, Yuri; Schwarz, Ulrich

    2014-12-15

    We report the high-pressure high-temperature synthesis of the germanium-based framework compounds BaGe6 (P = 15 GPa, T = 1073 K) and BaGe(6-x) (P = 10 GPa, T = 1073 K) which are metastable at ambient conditions. In BaGe(6-x), partial fragmentation of the BaGe6 network involves incommensurate modulations of both atomic positions and site occupancy. Bonding analysis in direct space reveals that the defect formation in BaGe(6-x) is associated with the establishment of free electron pairs around the defects. In accordance with the electron precise composition of BaGe(6-x) for x = 0.5, physical measurements evidence semiconducting electron transport properties which are combined with low thermal conductivity.

  12. The BaBar electromagnetic calorimeter

    SciTech Connect

    Stahl, A.

    1997-07-01

    The progress on the design and construction of the BaBar electromagnetic calorimeter including its mechanical structure, the readout system, the mechanical and optical properties of the crystals, and the schedule for the final assembly and testing is summarized.

  13. Benzo[a]pyrene (BaP)

    Integrated Risk Information System (IRIS)

    Benzo [ a ] pyrene ( BaP ) ; CASRN 50 - 32 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarc

  14. Unitarity Triangles at BaBar

    SciTech Connect

    Martinez-Vidal, Fernando; /Valencia U., IFIC

    2011-11-23

    The BaBar experiment has used a variety of methods to determine the angles {alpha}, {beta}, and {gamma} of the Cabibbo-Kobayashi-Maskawa Unitarity Triangle, which give insight into the Standard Model description of CP violation in the quark sector of the electroweak interactions. Here we review the main experimental techniques and analyses, with emphasis in the most recent results.

  15. Magnetic comparison of BaCa and BaSr substituted hexaferrite powders

    NASA Astrophysics Data System (ADS)

    González-Angeles, A.; Lipka, J.; Grusková, A.; Sláma, J.; Jančárik, V.; Slugeň, V.

    2010-03-01

    Results on magnetic studies of Ba0.5Sr0.5Fe12-2x(ZnTi)xO19 and Ba0.75Ca0.25Fe12-2x(ZnTi)xO19, where x = 0.2 to 0.6, ferromagnetic powders prepared by mechanical alloying are discussed. The structural and magnetic properties of the resulting powders were analyzed by thermo-magnetic analysis, X-ray diffraction, scanning electron microscopy, Mössbauer spectroscopy and magnetic measurements. Curie temperature, Tc decreased dramatically (drop ~ 39%) for BaCa samples, whilst for BaSr samples remained almost without change (diminution ~ 2%) at x <= 0.2. SEM studies showed that all the particles present nearly hexagonal platelet shape.

  16. Electronic structure of Ca, Sr, and Ba under pressure.

    NASA Technical Reports Server (NTRS)

    Animalu, A. O. E.; Heine, V.; Vasvari, B.

    1967-01-01

    Electronic band structure calculations phase of Ca, Sr and Ba over wide range of atomic volumes under pressure electronic band structure calculations for fcc phase of Ca, Sr and Ba over wide range of atomic volumes under pressure electronic band structure calculations for fcc phase of Ca, Sr and Ba over wide range of atomic volumes under pressure

  17. Dynamics of photoexcited Ba+ cations in 4He nanodroplets

    NASA Astrophysics Data System (ADS)

    Leal, Antonio; Zhang, Xiaohang; Barranco, Manuel; Cargnoni, Fausto; Hernando, Alberto; Mateo, David; Mella, Massimo; Drabbels, Marcel; Pi, Martí

    2016-03-01

    We present a joint experimental and theoretical study on the desolvation of Ba+ cations in 4He nanodroplets excited via the 6p ← 6s transition. The experiments reveal an efficient desolvation process yielding mainly bare Ba+ cations and Ba+Hen exciplexes with n = 1 and 2. The speed distributions of the ions are well described by Maxwell-Boltzmann distributions with temperatures ranging from 60 to 178 K depending on the excitation frequency and Ba+ Hen exciplex size. These results have been analyzed by calculations based on a time-dependent density functional description for the helium droplet combined with classical dynamics for the Ba+. In agreement with experiment, the calculations reveal the dynamical formation of exciplexes following excitation of the Ba+ cation. In contrast to experimental observation, the calculations do not reveal desolvation of excited Ba+ cations or exciplexes, even when relaxation pathways to lower lying states are included.

  18. Crystal Structure and Thermodynamic Stability of Ba/Ti-Substituted Pollucites for Radioactive Cs/Ba Immobilization

    DOE PAGES

    Xu, Hongwu; Chavez, Manuel E.; Mitchell, Jeremy N.; ...

    2015-04-23

    An analogue of the mineral pollucite (CsAlSi2O6), CsTiSi2O6.5 has a potential host phase for radioactive Cs. However, as 137Cs and 135Cs transmute to 137Ba and 135Ba, respectively, through the beta decay, it is essential to study the structure and stability of this phase upon Cs → Ba substitution. In this work, two series of Ba/Ti-substituted samples, CsxBa(1-x)/2TiSi2O6.5 and CsxBa1-xTiSi2O7-0.5x, (x = 0.9 and 0.7), were synthesized by high-temperature crystallization from their respective precursors. Synchrotron X-ray diffraction and Rietveld analysis reveal that while CsxBa(1-x)/2TiSi2O6.5 samples are phase-pure, CsxBa1-xTiSi2O7-0.5x samples contain Cs3x/(2+x)Ba(1-x)/(2+x)TiSi2O6.5 pollucites (i.e., also two-Cs-to-one-Ba substitution) and a secondary phase, fresnoitemore » (Ba2TiSi2O8). Thus, the CsxBa1-xTiSi2O7-0.5x series is energetically less favorable than CsxBa(1-x)/2TiSi2O6.5. To study the stability systematics of CsxBa(1-x)/2TiSi2O6.5 pollucites, high-temperature calorimetric experiments were performed at 973 K with or without the lead borate solvent. Enthalpies of formation from the constituent oxides (and elements) have thus been derived. Our results show that with increasing Ba/(Cs + Ba) ratio, the thermodynamic stability of these phases decreases with respect to their component oxides. Hence, from the energetic viewpoint, continued Cs → Ba transmutation tends to destabilize the parent silicotitanate pollucite structure. However, the Ba-substituted pollucite co-forms with fresnoite (which incorporates the excess Ba), thereby providing viable ceramic waste forms for all the Ba decay products.« less

  19. Hadron Physics in BaBar

    SciTech Connect

    Lafferty, G.D.; /Manchester U.

    2005-08-29

    Some recent results in hadron physics from the BaBar experiment are discussed. In particular, the observation of two new charmed states, the D*{sub sJ}{sup +}(2317) and the D*{sub sJ}{sup +}(2457), is described, and results are presented on the first measurement of the rare decay mode of the B meson, B{sup 0} {pi}{sup 0}{pi}{sup 0}.

  20. Molecular evolution of the hypervariable region of the attachment glycoprotein gene in human respiratory syncytial virus subgroup B genotypes BA9 and BA10.

    PubMed

    Nagasawa, Koo; Hirano, Eiko; Kobayashi, Miho; Ryo, Akihide; Oishi, Kazunori; Obuchi, Masatsugu; Ishiwada, Naruhiko; Noda, Masahiro; Kuroda, Makoto; Shimojo, Naoki; Kimura, Hirokazu

    2015-12-01

    We studied the molecular evolution of the C-terminal 3rd hypervariable region in the attachment glycoprotein gene of human respiratory syncytial virus subgroup B (HRSV-B) genotypes BA9 and BA10. We performed time-scaled phylogenetic analyses using Bayesian Markov chain Monte Carlo methods. We also performed a genetic distance analysis (p-distance analysis), positive and negative selection analyses, and a Bayesian skyline plot (BSP) analysis. We found that genotype BA9 diverged from the common ancestor of genotypes BA7, BA8, and BA10, while genotype BA10 diverged from the ancestor of genotypes BA7 and BA8. Strains of both genotypes were distributed worldwide. BA9 and BA10 diverged between 1999 and 2001. Both BA9 and BA10 evolved rapidly (about 4.8×10(-3)substitutions/site/year) and formed three distinct lineages in a 10-year period. BA10 strains belonging to lineage 3 had large genetic distances (p-distance>0.07). Thus, it may be possible to classify these strains as a new genotype, BA11. No positive selection site was detected in either genotype. Phylodynamic analyses showed that the effective population size of BA10 decreased gradually since 2010 and BA9 slightly decreased since 2009. The results suggested that the recently prevalent HRSV-B genotypes BA9 and BA10 evolved uniquely, leading to epidemics of HRSV-B worldwide over a 15-year period.

  1. Topological phases in Ba-Borate glasses

    NASA Astrophysics Data System (ADS)

    Holbrook, Chad; Czaja, Andrew; Boolchand, Punit

    2015-03-01

    Twelve compositions in the (BaO)x(B2O3)100-x pseudo binary, in the 15% BaCO3, taking care to handle the materials in a dry ambient environment. Modulated- DSC and Raman scattering experiments were undertaken systematically as function of BaO content (x). Calorimetric measurements reveal Tg(x) to show a broad maximum and the non-reversing enthalpy to show a Gaussian-like reversibility window2, both centered near x = 28%. Raman scattering displays rich lineshapes with modes similar to those observed in Na-Borates2. Modes near 808 cm-1, 770 cm-1, 740 cm-1 and 705 cm-1 are observed, and identified with breathing modes of pure and mixed rings from characteristic structural groupings2. These preliminary results suggest that glasses at x <24% are in the stressed-rigid phase, in the 24% 30% in the flexible phase. Supported by NSF Grant DMR 08-53957.

  2. New Spectroscopy at BaBar

    SciTech Connect

    Mazzoni, M.A.; /INFN, Rome

    2007-04-18

    The Babar experiment at the SLAC B factory has accumulated a high luminosity that offers the possibility of systematic studies of quarkonium spectroscopy and of investigating rare new phenomena. Recent results in this field are presented. In recent times spectroscopy has become exciting again, after the discovery of new states that are not easily explained by conventional models. States such as the X(3872) and the Y(4260) could be new excited charmonium states, but require precise measurements for positive identification. The BaBar experiment [1] is installed at the asymmetric storage ring PEP-II. 90% of the data accumulated by BaBar are taken at the Y(4S) (10.58 GeV) and 10% just below (10.54 GeV). The BaBar detector includes a 5-layer, double-sided silicon vertex tracker and a 40-layer drift chamber in a 1.5 T solenoidal magnetic field, which detect charged particles and measures their momenta and ionization energy losses. Photons, electrons, and neutral hadrons are detected with a CsI(Tl)-crystal electromagnetic calorimeter. An internally reflecting ring-imaging Cherenkov is also used for particle id. Penetrating muon and neutral hadrons are identified by an array of resistive-plate chambers embedded in the steel of the flux return. The detector allows good track and vertex resolution, good particle id and good photon detection so it is especially suited for spectroscopy studies.

  3. Atomic absorption background of Ba in EXAFS analysis of BaFe(12)O(19) nanoparticles.

    PubMed

    Padeznik Gomilšek, Jana; Kodre, Alojz; Arčon, Iztok; de Panfilis, Simone; Makovec, Darko

    2011-07-01

    The approximate barium X-ray atomic absorption in the energy region of L-edges is reconstructed from the absorption spectrum of an aqueous solution of BaCl(2). The result is corroborated by comparison with pure atomic absorption spectra of neighbour elements Xe and Cs. The application of the atomic absorption signal as a proper EXAFS background is demonstrated and discussed in the analysis of Ba hexaferrite nanoparticles with a very weak structural signal. The essential gain is found in the decrease of uncertainty intervals of structural parameters and their correlations. A simple analytical model of the absorption background for the practical EXAFS analysis is demonstrated.

  4. Structure refinement and dielectric relaxation of M-type Ba, Sr, Ba-Sr, and Ba-Pb hexaferrites

    NASA Astrophysics Data System (ADS)

    Ashima; Sanghi, Sujata; Agarwal, Ashish; Reetu; Ahlawat, Neetu; Monica

    2012-07-01

    M-type hexaferrites with compositions BaFe12O19 (BFO), SrFe12O19 (SFO), Ba0.5Sr0.5Fe12O19 (BSFO), and Ba0.5Pb0.5Fe12O19 (BPFO) were synthesized by commercial solid state reaction method. The Rietveld refinement of x-ray powder diffraction revealed a single hexagonal phase with space group P63/mmc for BFO, SFO, and BSFO samples, whereas BPFO sample contains hematite (α-Fe2O3) phase with space group R3c along with the M-type main phase. All the samples show dispersion in dielectric constant (ɛ') and dielectric loss (tan δ) values with frequency. The values of ɛ' and tan δ increase with increase in temperature due to increase in the number of charge carriers and their mobilities, which are thermally activated. The reciprocal temperature dependence of conductivity (σac) and the most probable relaxation time (τM″) satisfies the Arrhenius relation. A perfect overlapping of the normalized plots of modulus isotherms on a single "super curve" for all the studied temperatures reveals a temperature independence of dynamic processes involved in conduction and for relaxation. Further, the complex plots of M* (M″ vs M') indicate that dc conductivity dominates in the region below the M″max point. Above M″max, the variations follow Jonscher power law (σ = Aωs) implying that ac conductivity is dominating in this region. Among the prepared samples, SFO hexaferrite has lowest values of σac, ɛ', and tan δ making it suitable for use in microwave devices.

  5. Structure refinement and dielectric relaxation of M-type Ba, Sr, Ba-Sr, and Ba-Pb hexaferrites

    SciTech Connect

    Ashima; Sanghi, Sujata; Agarwal, Ashish; Reetu; Ahlawat, Neetu; Monica

    2012-07-01

    M-type hexaferrites with compositions BaFe{sub 12}O{sub 19} (BFO), SrFe{sub 12}O{sub 19} (SFO), Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19} (BSFO), and Ba{sub 0.5}Pb{sub 0.5}Fe{sub 12}O{sub 19} (BPFO) were synthesized by commercial solid state reaction method. The Rietveld refinement of x-ray powder diffraction revealed a single hexagonal phase with space group P6{sub 3}/mmc for BFO, SFO, and BSFO samples, whereas BPFO sample contains hematite ({alpha}-Fe{sub 2}O{sub 3}) phase with space group R3c along with the M-type main phase. All the samples show dispersion in dielectric constant ({epsilon} Prime ) and dielectric loss (tan {delta}) values with frequency. The values of {epsilon} Prime and tan {delta} increase with increase in temperature due to increase in the number of charge carriers and their mobilities, which are thermally activated. The reciprocal temperature dependence of conductivity ({sigma}{sub ac}) and the most probable relaxation time ({tau}{sub M Double-Prime }) satisfies the Arrhenius relation. A perfect overlapping of the normalized plots of modulus isotherms on a single 'super curve' for all the studied temperatures reveals a temperature independence of dynamic processes involved in conduction and for relaxation. Further, the complex plots of M{sup *} (M Double-Prime vs M Prime ) indicate that dc conductivity dominates in the region below the M Double-Prime {sub max} point. Above M Double-Prime {sub max}, the variations follow Jonscher power law ({sigma} = A{omega}{sup s}) implying that ac conductivity is dominating in this region. Among the prepared samples, SFO hexaferrite has lowest values of {sigma}{sub ac}, {epsilon} Prime , and tan {delta} making it suitable for use in microwave devices.

  6. Growth and Characterization of Sputtered BSTO/BaM Multilayers

    SciTech Connect

    Srinath, S.; Frey, N. A.; Heindl, R.; Srikanth, H.; Coffey, K. R.; Dudney, Nancy J

    2005-01-01

    Multilayers of Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BSTO) and BaFe{sub 12}O{sub 19} (BaM), with tunable permeability and permittivity are attractive systems for radio frequency and microwave applications. We have grown multilayers of BSTO and BaM using magnetron sputtering on Al{sub 2}O{sub 3} substrates. Film growth conditions such as sputtering parameters were optimized to obtain high quality multilayers. X-ray diffraction established that both BSTO and BaM were formed and cross-sectional SEM studies showed sharp interfaces between BSTO and BaM layers. Magnetization showed a large coercivity ( {approx}2000 Oe) consistent with the hexaferrite component. The hysteresis loops also revealed the distinct influence of magnetocrystalline and shape anisotropies at different temperatures.

  7. Growth and characterization of sputtered BSTO/BaM multilayers

    NASA Astrophysics Data System (ADS)

    Srinath, S.; Frey, N. A.; Heindl, R.; Srikanth, H.; Coffey, K. R.; Dudney, N. J.

    2005-05-01

    Multilayers of Ba0.5Sr0.5TiO3 (BSTO) and BaFe12O19 (BaM), with tunable permeability and permittivity are attractive systems for radio frequency and microwave applications. We have grown multilayers of BSTO and BaM using magnetron sputtering on Al2O3 substrates. Film growth conditions such as sputtering parameters were optimized to obtain high quality multilayers. X-ray diffraction established that both BSTO and BaM were formed and cross-sectional SEM studies showed sharp interfaces between BSTO and BaM layers. Magnetization showed a large coercivity (˜2000Oe ) consistent with the hexaferrite component. The hysteresis loops also revealed the distinct influence of magnetocrystalline and shape anisotropies at different temperatures.

  8. Preparation of directionally solidified BaTi2O5-Ba6Ti17O40 eutectic by the floating zone method

    NASA Astrophysics Data System (ADS)

    Shiga, K.; Katsui, H.; Goto, T.

    2017-02-01

    The BaTi2O5-Ba6Ti17O40 eutectic (BaO-68.7 mol% TiO2) was directionally solidified by the floating zone (FZ) method and crystalline phases, microstructures and orientation were investigated. Ba6Ti17O40 with faceted rod-like shape was dispersed in the BaTi2O5 matrix. The growth directions of BaTi2O5 and Ba6Ti17O40 were parallel to the b and a axis, respectively, and the orientation relations were BaTi2O5 (010)//Ba6Ti17O40(60 2 ̅) and BaTi2O5 (001)//Ba6Ti17O40 (001).

  9. Geoenvironmental weathering/deterioration of landfilled MSWI-BA glass.

    PubMed

    Wei, Yunmei; Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki; Zhao, Chun; Peng, Xuya; Gao, Junmin

    2014-08-15

    Municipal solid waste incineration bottom ash (MSWI-BA) glass serves as a matrix of assorted bottom ash (BA) compounds. Deterioration of the BA glass phases is quite important as they regulate the distribution of a series of toxic elements. This paper studied landfilled MSWI-BA samples from the mineralogical and geochemical viewpoint to understand the deterioration behavior of the BA glass phases as well as mechanisms involved. Bulk analysis by PXRD as well as micro-scale analysis by optical microscopy and SEM/EDX was conducted for such purposes. The results revealed that dissolution of the BA glass phases has resulted in a deterioration layer of 10(0)-10(2)μm thickness after years of disposal. This rapid weathering process is highly relevant to the specific glass characteristics and solution pH. The BA glass phases with more embedded compounds and cracks/fissures tend to be more vulnerable. Moreover, the generally alkaline pH in ash deposit favors a rapid disruption of the glass phase. The weathering products are mainly gel phases (including Al-Si gel, Ca-Al-Si gel, Fe-Al-Si gel etc.) with iron oxide/hydroxide as accessory products. Breakdown of the BA glass phases triggers chemical evolution of the embedded compounds. Based on all the findings above, a model is proposed to illustrate a general evolution trend for the landfilled MSWI-BA glass phases.

  10. Polarizabilities of Ba and Ba{sub 2}: Comparison of molecular beam experiments with relativistic quantum chemistry

    SciTech Connect

    Schaefer, Sascha; Mehring, Max; Schaefer, Rolf; Schwerdtfeger, Peter

    2007-11-15

    The dielectric response to an inhomogeneous electric field has been investigated for Ba and Ba{sub 2} within a molecular beam experiment. The ratio of the polarizabilities per atom of Ba{sub 2} and Ba is determined to be 1.30{+-}0.13. The experimental result is compared to a high level ab initio quantum chemical coupled cluster calculation with an energy-consistent scalar relativistic small-core pseudopotential for Ba. For the barium atom a polarizability of 40.82 A{sup 3} is obtained and the isotropic value of the polarizability calculated for Ba{sub 2} is 97.88 A{sup 3}, which is in good agreement with the experimental results, demonstrating that a quantitative understanding of the interaction between two closed-shell heavy element metal atoms has been achieved.

  11. Revisiting the BaO2/BaO redox cycle for solar thermochemical energy storage.

    PubMed

    Carrillo, A J; Sastre, D; Serrano, D P; Pizarro, P; Coronado, J M

    2016-03-21

    The barium peroxide-based redox cycle was proposed in the late 1970s as a thermochemical energy storage system. Since then, very little attention has been paid to such redox couples. In this paper, we have revisited the use of reduction-oxidation reactions of the BaO2/BaO system for thermochemical heat storage at high temperatures. Using thermogravimetric analysis, reduction and oxidation reactions were studied in order to find the main limitations associated with each process. Furthermore, the system was evaluated through several charge-discharge stages in order to analyse its possible degradation after repeated cycling. Through differential scanning calorimetry the heat stored and released were also determined. Oxidation reaction, which was found to be slower than reduction, was studied in more detail using isothermal tests. It was observed that the rate-controlling step of BaO oxidation follows zero-order kinetics, although at high temperatures a deviation from Arrhenius behaviour was observed probably due to hindrances to anionic oxygen diffusion caused by the formation of an external layer of BaO2. This redox couple was able to withstand several redox cycles without deactivation, showing reaction conversions close to 100% provided that impurities are previously eliminated through thermal pre-treatment, demonstrating the feasibility of this system for solar thermochemical heat storage.

  12. Ba(OH)2 Equilibria in the System Ba-O-H-F, With Application to the Formation of Ba2YCu3O6.5 + x From BaF2-Precursors

    PubMed Central

    Cook, L. P.; Wong-Ng, W.; Feenstra, R.

    2005-01-01

    The ex situ process for fabricating Ba2YCu3O6.5 + x superconducting tapes from BaF2- based precursors involves a hydration/oxidation reaction at ≈730 °C to 750 °C generally written as: (2BaF2+Y+3Cu)(amorphous)+(2H2O+2.25O2)(g)→Ba2YCu3O6.5+x(s)+4HF(g). However, microscopic observations of partially processed films suggest the presence of a transient liquid phase during conversion. Alternatively, the conversion reaction can be rewritten as the sum of several intermediate steps, including the formation of a barium hydroxide liquid: (BaF2)(amorphous)+2H2O(g)→Ba(OH)2(liq)+2HF(g). To evaluate the possibility of a hydroxide liquid conversion step, thermodynamic calculations on the stability of Ba(OH)2(liq) have been completed from 500 °C to 900 °C at 0.1 MPa ptotal. Based on currently available data, the calculated phase diagrams suggest that a viable hydroxide reaction path exists in the higher part of this temperature range. The calculations indicate that Ba(OH)2(liq) may be stable at log pH2O (Pa) values from ≈4 to 5, provided log pHF (Pa) values can be maintained below 0 to −1. Limited experimental confirmation is provided by results of an experiment on BaF2(s) at 815 °C, 0.1 MPa pH2O, in which essentially all F at the surface was replaced by O. It is therefore possible that processing routes exist for producing Ba2YCu3O6.5 + x based on the presence of a Ba(OH)2 liquid, which might have an effect on conversion rates and texturing in the superconducting film. PMID:27308108

  13. A Dubious Distinction? The BA versus the BS in Psychology

    ERIC Educational Resources Information Center

    Pfund, Rory A.; Norcross, John C.; Hailstorks, Robin; Aiken, Leona S.; Stamm, Karen E.; Christidis, Peggy

    2016-01-01

    Previous studies have documented small differences between the bachelor of arts (BA) and the bachelor of science (BS) psychology degrees in their general education core requirements, particularly mathematics and science courses. But are there differences between the BA and BS degrees within the psychology curriculum? Using data from the…

  14. Thermodynamics and existing phase of Ba-phenanthrene

    NASA Astrophysics Data System (ADS)

    Heguri, Satoshi; Thi Nhu Phan, Quynh; Tanabe, Yoichi; Tanigaki, Katsumi

    2014-10-01

    The thermodynaqmics for intercalation of phenanthrene (PHN) with Ba, for which superconductivity has been reported, is studied in comparison with its isomer of a linear aromatic hydrocarbon of anthracene (AN). Contrary to previous reports by other authors, the important observation that Ba is intercalated into neither PHN nor AN without affecting their molecular structures is unambiguously made by differential scanning calorimetry measurements and annealing time dependences observed by powder x-ray diffraction (XRD) measurements. The reactions of Ba and PHN at elevated temperatures lead this system to molecular decomposition instead of intercalation, resulting in the Ba C2 carbide or amorphous carbon formation, which is clearly supported by XRD and Raman spectroscopy. The phenomena of metallicity and superconductivity in PHN intercalated with alkaline-earth metals (Ba or Sr) should be reconsidered.

  15. Vibrational properties of the gallium monohydrides SrGaGeH, BaGaSiH, BaGaGeH, and BaGaSnH

    SciTech Connect

    Evans, Michael J.; Lee, Myeong H.; Holland, Gregory P.; Daemen, Luke L.; Sankey, Otto F.; Haeussermann, Ulrich

    2009-08-15

    Vibrational properties of the gallium monohydrides SrGaGeH, BaGaSiH, BaGaGeH, and BaGaSnH (AeGaTtH) have been investigated by means of inelastic neutron scattering (INS) and first principles calculations. The compounds contain separated Ga-H units being part of a two dimensional polyanionic layer, [TtGaH]{sup 2-} (Tt=Si, Ge, Sn). The INS spectra show internal Ga-H bending and stretching modes at frequencies around 900 and 1200 cm{sup -1}, respectively. While the stretching mode is virtually invariant with respect to the variable chemical environment of the Ga-H unit, the bending mode frequency varies and is highest for BaGaSiH and lowest for BaGaSnH. The stretching mode is a direct measure of the Ga-H bond strength, whereas the bending mode reflects indirectly the strength of alkaline earth metal-hydrogen interaction. Accordingly, the terminal Ga-H bond in solid state AeGaTtH is distinct, but-compared to molecular gallium hydrides-very weak. - Graphical abstract: Vibrational properties of the gallium monohydrides SrGaGeH, BaGaSiH, BaGaGeH, and BaGaSnH have been investigated and revealed Ga-H stretching mode frequencies around 1200 cm{sup -1}. This implies that the terminal Ga-H bond in solid state polyanionic gallium hydrides is very weak compared to molecular gallium hydride species.

  16. Innovative methodology for the synthesis of Ba-M hexaferrite BaFe{sub 12}O{sub 19} nanoparticles

    SciTech Connect

    Ahmed, M.A.; Helmy, N.; El-Dek, S.I.

    2013-09-01

    Graphical abstract: Transmission electron microscope images for the BaFe12O19. - Highlights: • BaFe{sub 12}O{sub 19}nanoparticles were prepared in single-phase from organometallic precursors. • BaFe{sub 12}O{sub 19} possesses small size 65 nm, H{sub C} = 3695 Oe and M{sub s} = 58 emu/g. • This method of preparation could be extended in the synthesis of other metal oxide nanoparticles. - Abstract: In this piece of work, high quality and homogeneity, barium hexaferrite (BaM) BaFe{sub 12}O{sub 19} nanoparticles were prepared from organometallic precursors for the 1st time. This method is based on the formation of supramolecular crystal structure of Ba[Fe(H{sub 3}NCH{sub 2}CH{sub 2}NH{sub 3})]Cl{sub 7}·8H{sub 2}O. The crystal structure, morphology and magnetic properties of BaFe{sub 12}O{sub 19} at two different annealing temperatures namely 1000 °C and 1200 °C were investigated using X-ray diffraction, transmission electron microscope TEM and vibrating sample magnetometry (VSM). The results show that monophasic nanoparticles of hexaferrites were obtained. Nanoparticles of crystallite size 40–50 nm distinguished by narrow distribution and excellent homogeneity were obtained with superior magnetic properties which suggested single-domain particles of Ba-M hexaferrite.

  17. G factor of the 2/sub 1//sup +/ state in /sup 140/Ba and /sup 142/Ba

    SciTech Connect

    Pauling, L.

    1987-06-01

    A simple calculation on the basis of the revolving cluster model leads to the value 0.495 for the g factor of /sub //sub <1/ /sub 56//sup 42/Ba/sub 86/, in agreement with the experimental value 0.48 +- 0.14. The same value is predicted for /sup 140/Ba.

  18. Crystal Structure and Thermodynamic Stability of Ba/Ti-Substituted Pollucites for Radioactive Cs/Ba Immobilization

    SciTech Connect

    Xu, Hongwu; Chavez, Manuel E.; Mitchell, Jeremy N.; Garino, Terry J.; Schwarz, Haiqing L.; Rodriguez, Mark A.; Rademacher, David X.; Nenoff, Tina Maria

    2015-04-23

    An analogue of the mineral pollucite (CsAlSi2O6), CsTiSi2O6.5 has a potential host phase for radioactive Cs. However, as 137Cs and 135Cs transmute to 137Ba and 135Ba, respectively, through the beta decay, it is essential to study the structure and stability of this phase upon Cs → Ba substitution. In this work, two series of Ba/Ti-substituted samples, CsxBa(1-x)/2TiSi2O6.5 and CsxBa1-xTiSi2O7-0.5x, (x = 0.9 and 0.7), were synthesized by high-temperature crystallization from their respective precursors. Synchrotron X-ray diffraction and Rietveld analysis reveal that while CsxBa(1-x)/2TiSi2O6.5 samples are phase-pure, CsxBa1-xTiSi2O7-0.5x samples contain Cs3x/(2+x)Ba(1-x)/(2+x)TiSi2O6.5 pollucites (i.e., also two-Cs-to-one-Ba substitution) and a secondary phase, fresnoite (Ba2TiSi2O8). Thus, the CsxBa1-xTiSi2O7-0.5x series is energetically less favorable than CsxBa(1-x)/2TiSi2O6.5. To study the stability systematics of CsxBa(1-x)/2TiSi2O6.5 pollucites, high-temperature calorimetric experiments were performed at 973 K with or without the lead borate solvent. Enthalpies of formation from the constituent oxides (and elements) have thus been derived. Our results show that with increasing Ba/(Cs + Ba) ratio, the thermodynamic stability of these phases decreases with respect to their component oxides. Hence, from the energetic viewpoint, continued Cs → Ba transmutation tends to destabilize the parent silicotitanate pollucite structure. However, the Ba-substituted pollucite co-forms with fresnoite (which incorporates the excess Ba

  19. Structural Transformation of Hexagonal (0001)BaTiO3 Ceramics to Tetragonal (111)BaTiO3 Ceramics

    NASA Astrophysics Data System (ADS)

    Watanabe, Takayuki; Shimada, Mikio; Aiba, Toshiaki; Yabuta, Hisato; Miura, Kaoru; Oka, Kengo; Azuma, Masaki; Wada, Satoshi; Kumada, Nobuhiro

    2011-09-01

    A ceramic slurry that contains a 6H-type Ba(Ti0.95Mn0.05)O3 powder was casted into a plaster mold under 10 T magnetic field to form a green compact of (0001)-oriented Ba(Ti0.95Mn0.05)O3. After sintering the green compact at 1300 °C in air, it was confirmed that the (0001)-oriented 6H-type perovskite structure transformed to a (111)-oriented 3C-type perovskite structure. The structural transformation was again examined using hexagonal BaTiO3 prepared by reducing pseudo-cubic BaTiO3 powder in H2 atmosphere. In this case, the preferred (0001) orientation was not confirmed for the green compacts. After sintering the green compacts at 1300 °C in air, mixed crystal orientations of (100)/(001) and (111) were observed for the resultant tetragonal BaTiO3 ceramics. This (100)/(001) orientation was suppressed by annealing the hexagonal BaTiO3 powder at 1000 °C before slip-casting, leading to highly (111)-oriented ceramics. It was found that the green compacts of (0001)-oriented hexagonal BaTiO3 can transform into (111)-oriented tetragonal BaTiO3 ceramics, maintaining the macroscopic crystal orientations due to a similar atomic stacking along [0001] of 6H-type BaTiO3 and [111] of 3C-type BaTiO3.

  20. Electronic structure of BaO/W cathode surfaces

    NASA Technical Reports Server (NTRS)

    Muller, Wolfgang

    1989-01-01

    The local electronic structure of the emissive layer of barium dispenser thermionic cathodes is investigated theoretically using the relativistic scattered-wave approach. The interaction of Ba and O with W, Os, and W-Os alloy surfaces is studied with atomic clusters modeling different absorption environments representative of B- and M-type cathodes. Ba is found to be strongly oxidized, while O and the metal substrate are in a reduced chemical state. The presence of O enhances the surface dipole and Ba binding energy relative to Ba on W. Model results for W-Os alloy substrates show only relatively small changes in Ba and O for identical geometries, but very large charge redistributions inside the substrate, which are attributed to the electronegativity difference between Os and W. If Os is present in the surface layer, the charge transfer from Ba to the substrate and the Ba binding energy increase relative to W. Explanations are offered for the improved electron emission from alloy surfaces and the different emission enhancement for different alloy substrates.

  1. Stellar neutron capture cross sections of the Ba isotopes

    NASA Astrophysics Data System (ADS)

    Voss, F.; Wisshak, K.; Guber, K.; Käppeler, F.; Reffo, G.

    1994-11-01

    The neutron capture cross sections of 134Ba, 135Ba, 136Ba, and 137Ba were measured in the energy range from 5 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li (p,n)7 Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4π barium fluoride detector. The cross section ratios were determined with an overall uncertainty of ~3%, an improvement by factors of 5 to 8 compared to existing data. Severe discrepancies were found with respect to previous results. As a new possibility in time of flight experiments, isomeric cross section ratios could be determined for 135Ba, 136Ba, and 137Ba. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=10 keV and 100 keV. These stellar cross sections were used in an s-process analysis. For the s-only isotopes 134Ba and 136Ba the Ns<σ> ratio was determined to 0.875+/-0.025. Hence, a significant branching of the s-process path at 134Cs can be claimed for the first time, in contrast to predictions from the classical approach. This branching yields information on the s-process temperature, indicating values around T8=2. The new cross sections are also important for the interpretation of barium isotopic anomalies, which were recently discovered in SiC grains of carbonaceous chondrite meteorites. Together with the results from previous experiments on tellurium and samarium, a general improvement of the Ns<σ> systematics in the mass range A=120-150 is achieved. This yields a more reliable separation of s- and r-process contributions for comparison with stellar observations, but reveals a 20% discrepancy with respect to the solar barium abundance.

  2. Ba-hexaferrite Films for Next Generation Microwave Devices (invited)

    SciTech Connect

    Harris,V.; Chen, Z.; Chen, Y.; Yoon, S.; Sakai, T.; Geiler, A.; Yang, A.; He, Y.; Ziemer, K.; et al.

    2006-01-01

    Next generation magnetic microwave devices require ferrite films to be thick (>300 {mu}m), self-biased (high remanent magnetization), and low loss in the microwave and millimeter wave bands. Here we examine recent advances in the processing of thick Ba-hexaferrite (M-type) films using pulsed laser deposition (PLD), liquid-phase epitaxy, and screen printing. These techniques are compared and contrasted as to their suitability for microwave materials processing and industrial production. Recent advances include the PLD growth of BaM on wide-band-gap semiconductor substrates and the development of thick, self-biased, low-loss BaM films by screen printing.

  3. Ba2TeO: A new layered oxytelluride

    DOE PAGES

    Besara, T.; Ramirez, D.; Sun, J.; ...

    2015-02-01

    For single crystals of the new semiconducting oxytelluride phase, Ba2TeO, we synthesized from barium oxide powder and elemental tellurium in a molten barium metal flux. Ba2TeO crystallizes in tetragonal symmetry with space group P4/nmm (#129), a=5.0337(1) Å, c=9.9437(4) Å, Z=2. The crystals were characterized by single crystal x-ray diffraction, heat capacity and optical measurements. Moreover, the optical measurements along with electronic band structure calculations indicate semiconductor behavior with a band gap of 2.93 eV. Resistivity measurements show that Ba2TeO is highly insulating.

  4. Operability test report for 211BA flow proportional sampler

    SciTech Connect

    Weissenfels, R.D.

    1995-01-01

    This operability report will verify that the 211-BA flow proportional sampler functions as intended by design. The sampler was installed by Project W-007H and is part of BAT/AKART for the BCE liquid effluent stream.

  5. Double Resonance Spectroscopy of BaF Autoionizing Rydberg States

    NASA Astrophysics Data System (ADS)

    Barnum, Timothy J.; Grimes, David; Zhou, Yan; Field, Robert W.

    2015-06-01

    We have studied the ν=1 Rydberg states of BaF in the energy region E=38800-39100 wn (n*=15-25) via optical-optical double resonance spectroscopy. Rydberg states excited above the first ionization potential spontaneously autoionize and 138Ba19F+ ions are detected by TOF-MS. In addition, BaF possesses a particularly low ionization potential, which allows for the study of autoionization dynamics in the absence of predissociative decay. This work extends the assignments of core-penetrating Rydberg states of BaF (Jakubek and Field, 2000) for applications to state-selective ion production schemes. Polarization and Stark spectroscopy techniques will be discussed in the context of accurate and efficient assignment of spectra.

  6. Leptonic B Decays at BaBar

    SciTech Connect

    Baracchini, Elisabetta; /Rome U. /INFN, Rome

    2011-11-10

    We will present the most recent results on leptonic B decays B{sup {+-}(0)} {yields} K*{sup {+-}(0)}{nu}{bar {nu}} and B{sup {+-}} {yields} {mu}{sup {+-}}{nu}, based on the data collected by the BaBar detector at PEP-II, an asymmetric e{sup +}e{sup -} collider at the center of mass energy of the {Upsilon}(4S) resonance. Rare B decays have always been a standard probe for New Physics (NP) searches. The very low Standard Model (SM) rate of these decays often make them unaccessible with the present experimental datasets, unless NP effects enhance the rate up to the current experimental sensitivity. Moreover, as NP effects can modify the decay kinematic, particular attention must be paid in order to perform a model independent analysis. A B-Factory provides an unique environment to investigate these processes. The high number of B{bar B} pairs produced by a B-Factory often allows to approach the needed experimental sensitivity. Moreover, the clean environment and the closed kinematic of the initial state enable to obtaining a very pure sample where to look for these decays.

  7. Effect of local environment on crossluminescence kinetics in SrF2:Ba and CaF2:Ba solid solutions

    NASA Astrophysics Data System (ADS)

    Terekhin, M. A.; Makhov, V. N.; Lebedev, A. I.; Sluchinskaya, I. A.

    2015-10-01

    Spectral and kinetic properties of extrinsic crossluminescence (CL) in SrF2:Ba(1%) and CaF2:Ba(1%) are compared with those of intrinsic CL in BaF2 and are analyzed taking into account EXAFS data obtained at the Ba LIII edge and results of first-principles calculations. The CL decay time was revealed to be longer in SrF2:Ba and CaF2:Ba compared to BaF2. This fact contradicts the expected acceleration of luminescence decay which could result from an increased overlap of wave functions in solid solutions due to shortening of the Ba-F distance obtained in both EXAFS measurements and first-principles calculations. This discrepancy is explained by the effect of migration and subsequent non-radiative decay of the Ba(5p) core holes in BaF2 and by decreasing of the probability of optical transitions between Ba(5p) states and the valence band in SrF2:Ba and CaF2:Ba predicted by first-principles calculations.

  8. Ba termination of Ge(001) studied with STM.

    PubMed

    Koczorowski, W; Grzela, T; Radny, M W; Schofield, S R; Capellini, G; Czajka, R; Schroeder, T; Curson, N J

    2015-04-17

    We use controlled annealing to tune the interfacial properties of a sub-monolayer and monolayer coverages of Ba atoms deposited on Ge(001), enabling the generation of either of two fundamentally distinct interfacial phases, as revealed by scanning tunneling microscopy. Firstly we identify the two key structural phases associated with this adsorption system, namely on-top adsorption and surface alloy formation, by performing a deposition and annealing experiment at a coverage low enough (∼0.15 ML) that isolated Ba-related features can be individually resolved. Subsequently we investigate the monolayer coverage case, of interest for passivation schemes of future Ge based devices, for which we find that the thermal evaporation of Ba onto a Ge(001) surface at room temperature results in on-top adsorption. This separation (lack of intermixing) between Ba and Ge layers is retained through successive annealing steps to temperatures of 470, 570, 670 and 770 K although a gradual ordering of the Ba layer is observed at 570 K and above, accompanied by a decrease in Ba layer density. Annealing above 770 K produces the 2D surface alloy phase accompanied by strain relief through monolayer height trench formation. An annealing temperature of 1070 K sees a further change in surface morphology but retention of the 2D surface alloy characteristic. These results are discussed in view of their possible implications for future semiconductor integrated circuit technology.

  9. CONSTRAINING INTRACLUSTER GAS MODELS WITH AMiBA13

    SciTech Connect

    Molnar, Sandor M.; Umetsu, Keiichi; Ho, Paul T. P.; Koch, Patrick M.; Victor Liao, Yu-Wei; Lin, Kai-Yang; Liu, Guo-Chin; Nishioka, Hiroaki; Birkinshaw, Mark; Bryan, Greg; Haiman, Zoltan; Shang, Cien; Hearn, Nathan

    2010-11-10

    Clusters of galaxies have been extensively used to determine cosmological parameters. A major difficulty in making the best use of Sunyaev-Zel'dovich (SZ) and X-ray observations of clusters for cosmology is that using X-ray observations it is difficult to measure the temperature distribution and therefore determine the density distribution in individual clusters of galaxies out to the virial radius. Observations with the new generation of SZ instruments are a promising alternative approach. We use clusters of galaxies drawn from high-resolution adaptive mesh refinement cosmological simulations to study how well we should be able to constrain the large-scale distribution of the intracluster gas (ICG) in individual massive relaxed clusters using AMiBA in its configuration with 13 1.2 m diameter dishes (AMiBA13) along with X-ray observations. We show that non-isothermal {beta} models provide a good description of the ICG in our simulated relaxed clusters. We use simulated X-ray observations to estimate the quality of constraints on the distribution of gas density, and simulated SZ visibilities (AMiBA13 observations) for constraints on the large-scale temperature distribution of the ICG. We find that AMiBA13 visibilities should constrain the scale radius of the temperature distribution to about 50% accuracy. We conclude that the upgraded AMiBA, AMiBA13, should be a powerful instrument to constrain the large-scale distribution of the ICG.

  10. Ba termination of Ge(001) studied with STM

    NASA Astrophysics Data System (ADS)

    Curson, Neil; Koczorowski, Wojciech; Grzela, Tomasz; Radny, Marian; Schofield, Steven; Capellini, Giovanni; Czajka, Ryszard; Schroeder, Thomas

    2015-03-01

    We use controlled annealing to tune the interfacial properties of a sub-monolayer and monolayer coverages of Ba atoms deposited on Ge(001), enabling the generation of either of two fundamentally distinct interfacial phases, as revealed by scanning tunneling microscopy (STM). Firstly we identify the two key structural phases associated with this adsorption system, namely on-top adsorption and surface alloy formation, by performing a deposition and annealing experiment at a coverage low enough (0.15 ML) such that isolated Ba-related features can be individually resolved. Subsequently we investigate the monolayer coverage case, of interest for passivation schemes of future Ge based devices, for which we find that thermal evaporation of Ba onto a Ge(001) surface at room temperature results in on-top adsorption. This separation (lack of intermixing) between Ba and Ge layers is retained through successive annealing steps up to 770 K with a gradual ordering of the Ba layer at 570 K and above and a decrease in Ba layer density. Annealing above 770 K produces the 2-D surface alloy phase accompanied by strain relief through monolayer height trench formation. At 1070 K the surface morphology changes again but remains a 2-D surface alloy. WK and NJC acknowledge EPSRC grant EP/I02865X/1. WK, MWR and R.C. acknowledge the Polish Ministry of Science and Higher Education for support (Project No. N-N202-195840).

  11. Electronic structure, optical properties and bonding in alkaline earth halo-fluoride scintillators: BaClF, BaBrF and BaIF

    SciTech Connect

    Yedukondalu, N.; Babu, K. Ramesh; Bheemalingam, Ch.; Singh, David J; Vaitheeswaran, G.; Kanchana, V.

    2011-01-01

    We report first-principles studies of the structural, electronic, and optical properties of the alkaline-earth halofluorides, BaXF (X = Cl, Br, and I), including pressure dependence of structural properties. The band structures show clear separation of the halogen p derived valence bands into higher binding energy F and lower binding energy X derived manifolds reflecting the very high electronegativity of F relative to the other halogens. Implications of this for bonding and other properties are discussed. We find an anisotropic behavior of the structural parameters especially of BaIF under pressure. The optical properties on the other hand are almost isotropic, in spite of the anisotropic crystal structures.

  12. Structural properties of ultrafine Ba-hexaferrite nanoparticles

    SciTech Connect

    Makovec, Darko; Primc, Darinka; Sturm, Saso; Kodre, Alojz; Hanzel, Darko; Drofenik, Miha

    2012-12-15

    Crystal structure of ultrafine Ba-hexaferrite (BaFe{sub 12}O{sub 19}) nanoparticles was studied using X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDXS), X-ray absorption fine structure (XAFS), and Moessbauer spectroscopy (MS), to be compared to the structure of larger nanoparticles and the bulk. The nanoparticles were synthesized with hydrothermal treatment of an appropriate suspension of Ba and Fe hydroxides in the presence of a large excess of OH{sup -}. The ultrafine nanoparticles were formed in a discoid shape, {approx}10 nm wide and only {approx}3 nm thick, comparable to the size of the hexagonal unit cell in the c-direction. The HRTEM image analysis confirmed the hexaferrite structure, whereas EDXS showed the composition matching the BaFe{sub 12}O{sub 19} formula. XAFS and MS analyses showed considerable disorder of the structure, most probably responsible for the low magnetization. - Graphical abstract: Left: HREM image of an ultrafine Ba-hexaferrite nanoparticle (inset: TEM image of the nanoparticles); Right: the experimental HRTEM image is compared with calculated image and corresponding atomic model. Highlights: Black-Right-Pointing-Pointer Crystal structure of ultrafine Ba-hexaferrite (BaFe{sub 12}O{sub 19}) nanoparticles was compared to the structure of the bulk. Black-Right-Pointing-Pointer Thickness the discoid nanoparticles was comparable to the size of the hexagonal unit cell in the c-direction. Black-Right-Pointing-Pointer Considerable disorder of the nanoparticles' structure is most probably responsible for their low magnetization.

  13. BaTiO3-Based Non-Reducible Low-Loss Dielectric Ceramics

    NASA Astrophysics Data System (ADS)

    Nakamura, Tomoyuki; Sano, Harunobu; Konoike, Takehiro; Tomono, Kunisaburo

    1999-09-01

    Dielectrics composed of BaTiO3-rare earth oxide-MgO havebeenstudied to design a non-reducible low-loss dielectricmaterial. Curie temperatures of dielectrics composed ofBaTiO3 Gd2O3 MgO were lowered by Gd2O3, which provided thedielectrics with low power loss. It was found that the addition ofBaZrO3 to BaTiO3 Gd2O3 MgO decreased the capacitance change withtemperature. Gd2O3 diffused easily into BaTiO3, but, it could noteasily diffuse into BaTiO3 to which BaZrO3 had been added. It wasconsidered that BaZrO3 prevented the Gd2O3 diffusion into BaTiO3,resulting the remains of ferroelectricity and reduced capacitancechange. Thus non-reducible and low power loss X7R dielectricceramics were developed.

  14. Prediction of a stable half-metal ferromagnetic BaCl solid

    NASA Astrophysics Data System (ADS)

    Greschner, Michael J.; Klug, Dennis D.; Yao, Yansun

    2016-03-01

    The modification of Ba in BaCl compounds from alkaline-metal to transition- and half-metal behavior is explored. High-pressure structural changes in BaCl are predicted using an ab initio structure search method. Dynamically stable bcc and R -3 m forms of BaCl are predicted at 15 and 10 GPa, respectively. The BaCl forms are more stable than elemental Ba plus BaC l2 above ˜10 GPa. Ba in stable BaCl adopts transition-metal properties via an s -d transition. At ambient pressure the fcc structure is ferromagnetic, and the bcc structure is half metallic and ferromagnetic. The transition-metal electronic structure found is sufficient to support superconductivity, with Tc as high as 3.4 K near ambient pressure.

  15. Influence of excess Ba concentration on the dielectric nonlinearity in Mn and V-doped BaTiO3 multi layer ceramic capacitors

    NASA Astrophysics Data System (ADS)

    Yoon, Seok-Hyun; Kim, Sun-Jung; Kim, Sang-Hyuk; Kim, Doo-Young

    2013-12-01

    The effect of excess Ba concentration on the dielectric nonlinearity was investigated in Mn and V-doped BaTiO3 multi layer ceramic capacitors (MLCC) under the same grain size condition, which was described by the Preisach model utilizing the first order reversal curve (FORC) distribution. The high-field dielectric constant and its ac field dependence dramatically changed increasing to a maximum and then decreasing with the increase of Ba concentration. The saturation polarization which scales to the magnitude of spontaneous polarization also showed similar behavior. These results indicate that the dependence of the dielectric constant on the Ba concentration is associated with the variation of both domain wall contribution and the magnitude of the spontaneous polarization, which could be correlated with the same dependence on the Ba concentration of the reversible FORC distribution at zero bias and the irreversible FORC distribution near origin. In the corresponding bulk specimens of the dielectrics of MLCC, almost the same amount of the Ba2TiSi2O8 second phases were detected irrespective of Ba concentration, which shows that the excess Ba incorporate into BaTiO3. Thus, low and high Ba concentration corresponds to Ba-deficient and Ba-rich or Ti-deficient BaTiO3, respectively, which results in a small spontaneous polarization and low domain wall density. The intermediate Ba concentration for the maximum dielectric constant is supposed to be near stoichiometric condition in the ABO3 structure corresponding to large spontaneous polarization and high domain wall density. The excess Ba concentration and its resultant A/B stoichiometry is a crucial factor controlling dielectric properties.

  16. How Extended Is Wernicke's Area? Meta-Analytic Connectivity Study of BA20 and Integrative Proposal

    PubMed Central

    Bernal, Byron

    2016-01-01

    Understanding the functions of different brain areas has represented a major endeavor of contemporary neurosciences. The purpose of this paper was to pinpoint the connectivity of Brodmann area 20 (BA20) (inferior temporal gyrus, fusiform gyrus) in language tasks. A meta-analysis was conducted to assess the language network in which BA20 is involved. The DataBase of Brainmap was used; 11 papers corresponding to 12 experimental conditions with a total of 207 subjects were included in this analysis. Our results demonstrated seven clusters of activation including other temporal lobe areas (BA3, BA21), the insula, and the prefrontal cortex; minor clusters in the cingulate gyrus and the occipital lobe were observed; however, the volumes of all the activation clusters were small. Our results suggest that regardless of BA20 having certain participation in language processes it cannot be considered as a core language processing area (Wernicke's area); nonetheless, it could be regarded as kind of language processing marginal area, participating in “extended Wernicke's area” or simply “Wernicke's system.” It is suggested that “core Wernicke's area” roughly corresponds to BA21, BA22, BA41, and BA42, while a “language associations area” roughly corresponds to BA20, BA37, BA38, BA39, and BA40 (“extended Wernicke's area” or “Wernicke's system”). PMID:27006905

  17. Bismuthates: BaBiO3 and related superconducting phases

    NASA Astrophysics Data System (ADS)

    Sleight, Arthur W.

    2015-07-01

    BaBiO3 has the perovskite structure, but tilting of the BiO6 octahedra destroy the ideal cubic symmetry except at temperatures above 820 K. BaBiO3 is a diamagnetic semiconductor due to a charge density wave (CDW), which is equivalent to a Ba2Bi3+Bi5+O6 representation. Recent calculations and experimental results confirm that there is no significant deviation from the oxidation states of 3+ and 5+. Superconductivity with a Tc as high as 13 K occurs for BaPb1-xBixO3 phases where the 6s band is about 25% filled, and superconductivity with a Tc as high as 34 K occurs for Ba1-xKxBiO3 phases where the 6s band is about 35% filled. Structures in these two solid solutions can have cubic, tetragonal, orthorhombic, or monoclinic symmetry. However, superconductivity has only been observed when the symmetry is tetragonal.

  18. Thermodynamics and existing phase of Ba-phenanthrene

    NASA Astrophysics Data System (ADS)

    Heguri, Satoshi; Thi Nhu Phan, Quynh; Tanabe, Yoichi; Tanigaki, Katsumi

    2015-03-01

    The recent discovery of superconductivity in potassium doped picene suggested the possibility of a new class of superconductors. The problem is that no satisfactory guide to improve the superconducting shielding fraction had been provided until recently. However, a high superconducting shielding fraction of 65 % was reported for Ba1.5(phenanthrene). Considering this situation, phenanthrene (PHN) appears to be a key material for confirming the existence of metallicity and superconductivity in the aromatic hydrocarbon (AHC) family, and also for clarifying the physical properties and superconducting mechanism of AHC superconductors. In the present work, the thermodynamics for intercalation of PHN with Ba is studied in comparison with its isomer of anthracene (AN). Contrarily to previous reports by other authors, the important observation that Ba is intercalated into neither PHN nor AN without affecting their molecular structures is unambiguously made by differential scanning calorimetry measurements and annealing time dependences observed by powder x-ray diffraction measurements. The reactions of Ba and PHN at elevated temperatures lead this system to molecular decomposition instead of intercalation. The phenomena of metallicity and superconductivity in PHN intercalated with alkaline earth metals (Ba or Sr) should be reconsidered.

  19. Observation of the Nuclear Magnetic Octupole Moment of 137Ba+

    NASA Astrophysics Data System (ADS)

    Hoffman, Matthew

    Single trapped ions are ideal systems in which to test atomic physics at high precision, which can in turn be used for searches for violations of fundamental symmetries and physics beyond the standard model, in addition to quantum computation and a number of other applications. The ion is confined in ultra-high vacuum, is laser cooled to mK temperatures, and kept well isolated from the environment which allows these experimental efforts. In this thesis, a few diagnostic techniques will be discussed, covering a method to measure the linewidth of a narrowband laser in the presence of magnetic field noise, as well as a procedure to measure the ion's temperature using such a narrowband laser. This work has led to two precision experiments to measure atomic structure in 138Ba+, and 137Ba+ discussed here. First, employing laser and radio frequency spectroscopy techniques in 138Ba+, we measured the Lande- gJ factor of the 5D5/2 level at the part-per-million level, the highest precision to date. Later, the development of apparatus to efficiently trap and laser cool 137Ba+ has enabled a measurement of the hyperfine splittings of the 5D3/2 manifold, culminating in the observation of the nuclear magnetic octupole moment of 137Ba+.

  20. Flux Pinning of Y-Ba-Cu-O Films Doped With BaZrO3 Nanoparticles by Multilayer and Single Target Methods (Postprint)

    DTIC Science & Technology

    2007-06-01

    AFRL-RZ-WP-TP-2012-0130 FLUX PINNING OF Y-Ba-Cu-O FILMS DOPED WITH BaZrO3 NANOPARTICLES BY MULTILAYER AND SINGLE TARGET METHODS (POSTPRINT...To) February 2012 Journal Article Postprint 04 April 2005 – 04 April 2007 4. TITLE AND SUBTITLE FLUX PINNING OF Y-Ba-Cu-O FILMS DOPED WITH BaZrO3...effort was completed in 2007. 14. ABSTRACT The superconducting properties of YBa2Cu3O7-x (YBCO or 123) thin films doped with BaZrO3 (BZO

  1. Study of F- Production in BaBar RPCs

    SciTech Connect

    Band, H.R.; Bellini, F.; Covarelli, R.; Di Marco, E.; D'Orazio, A.; Ferroni, F.; Li Gioi, L.; Lopez, L.; Polci, F.; /Rome U. /INFN, Rome

    2008-02-22

    The BaBar detector has operated over 200 2nd generation Resistive Plate Chambers (RPCs) in the forward endcap since 2002. Many chambers have increased noise rates and high voltage currents. These aging symptoms are correlated with the integrated RPC current as expected, but also depend on the rate and direction of the gas flow, indicating that pollutants produced in the gas can accelerate aging of downstream RPC surfaces. HF produced by decomposition of the Freon 134a component of the BaBar RPC gas in electric discharges has been proposed as the main pollutant. This paper presents measurements of HF production and absorption rates in BaBar RPCs. Since many of the highest rate chambers in the forward endcap were converted to avalanche mode operation, a comparison of HF production in streamer and avalanche mode RPCs is made. Correlations between the HF production rate and other chamber operating conditions were also explored.

  2. Reflectors for canning a BaF 2 crystal

    NASA Astrophysics Data System (ADS)

    Sinha, B. K.; Bhattacharya, R.

    1989-03-01

    The performance of BaF 2 crystals with various reflectors like teflon tape, ZrO 2, Al 2O 3 and CaF 2 powders is tested by measuring the energy and time resolution at different energies. It is shown that CaF 2 powder is a somewhat better reflector than the Al 2O 3 powder so far used by different workers. It is also seen that the reflectivity of CaF 2 powder for the BaF 2 emission spectrum is not much inferior to that of teflon tape which is, however, the best reported so far. Based on these observations a method of canning a BaF 2 crystal is proposed.

  3. Physical properties of single crystalline BaSn{sub 5}

    SciTech Connect

    Lin, Xiao; Budko, Sergey; Canfield, Paul

    2012-01-30

    We present a comprehensive study of the binary intermetallic superconductor, BaSn{sub 5}. High-quality single crystalline BaSn{sub 5} was grown out of a Sn flux. Detailed thermodynamic and transport measurements were performed to study BaSn{sub 5}'s normal and superconducting state properties. This material appears to be a strongly coupled, multiband superconductor. H{sub c2}(T) is almost isotropic. De Haas–van Alphen oscillations were observed and two effective masses were estimated from the FFT spectra. Hydrostatic pressure causes a decrease in the superconducting transition temperature at the rate of ≈−0.053 ± 0.001 K/kbar.

  4. Processing of R-Ba-Cu-O superconductors

    SciTech Connect

    Wu, H.

    1998-02-23

    Precipitation processes were developed to introduce second phases as flux pinning centers in Gd-Ba-Cu-O and Nd-Ba-Cu-O superconductors. In Gd-Ba-Cu-O, precipitation is caused by the decrease of the upper solubility limit of Gd{sub 1+x}Ba{sub 2{minus}x}Cu{sub 3}O{sub 7} solid solution (Gd123ss) in low oxygen partial pressure. Processing of supersaturated Gd{sub 1.2}Ba{sub 1.8}Cu{sub 3}O{sub 7} in low oxygen partial pressure can produce dispersed second phases. Gd211 is formed as a separate phase while extensive Gd124 type stacking fault is formed instead of a separate CuO phase. As a result of the precipitation reaction, the transition temperature and critical current density are increased. In Nd-Ba-Cu-O, precipitation is caused by the decrease of the lower solubility limit of Nd{sub 1+x}Ba{sub 2{minus}x}Cu{sub 3}O{sub 7} solid solution (Nd123ss) in oxygen. DTA results reveal the relative stability of Nd123ss in different oxygen partial pressures. In 1 bar oxygen partial pressure, Nd123ss with x = 0.1 is the most stable phase. In lower oxygen partial pressures, the most stable composition shifts towards the stoichiometric composition. The relative stability changes faster with decreasing oxygen partial pressure. Therefore, processing in oxygen and air tends to produce broad superconducting transitions but sharp transitions can be achieved in 0.01 bar and 0.001 bar oxygen partial pressures. While the lower solubility limits in 0.01 bar and 0.001 bar oxygen partial pressures remain at x = 0.00, the solubility limits in oxygen and air show a narrowing with decreasing temperature. Because of the narrowing of the solubility range in oxygen, oxygen annealing of Nd123 initially processed in low oxygen partial pressures will result in precipitation of second phases. The equilibrium second phase is BaCuO{sub 2} for temperature above 608 C, and at lower temperatures the equilibrium second phases are Ba{sub 2}CuO{sub 3.3} and Ba{sub 2}Cu{sub 3}O{sub 5+y}. However, annealing at

  5. Antiferromagnetic Critical Fluctuations in BaFe$_2$As$_2$

    SciTech Connect

    Wilson, Stephen D; Yamani, Z.; Rotundu, C. R.; Freelon, B.; Valdivia, P. N.; Bourret-Courchesne, E. D.; Lynn, J W; Chi, Songxue; Hong, Tao; Birgeneau, R. J.

    2010-01-01

    Magnetic correlations near the magnetostructural phase transition in the bilayer iron-pnictide parent compound, BaFe{sub 2}As{sub 2}, are measured. In close proximity to the antiferromagnetic phase transition in BaFe{sub 2}As{sub 2}, a crossover to three-dimensional critical behavior is anticipated and has been preliminarily observed. Here we report complementary measurements of two-dimensional magnetic fluctuations over a broad temperature range about T{sub N}. The potential role of two-dimensional critical fluctuations in the magnetic phase behavior of BaFe{sub 2}As{sub 2} and their evolution near the anticipated crossover to three-dimensional critical behavior and long-range order are discussed.

  6. BaH molecular spectroscopy with relevance to laser cooling

    NASA Astrophysics Data System (ADS)

    Tarallo, M. G.; Iwata, G. Z.; Zelevinsky, T.

    2016-03-01

    We describe a simple experimental apparatus for laser ablation of barium monohydride (BaH) molecules and the study of their rovibrational spectra relevant to direct laser cooling. BaH is a promising candidate for laser cooling and ultracold fragmentation, both of which are precursors to novel experiments in many-body physics and precision measurement. We present a detailed analysis of the properties of ablation plumes that can improve the understanding of surface ablation and deposition technologies. A range of absorption spectroscopy and collisional thermalization regimes has been studied. We directly measured the Franck-Condon factor of the B 2Σ+(v'=0 ) ←X 2Σ+(v''=1 ) cycling transition. Prospects for production of a high luminosity cryogenic BaH beam are outlined.

  7. Bi3+ Luminescence in ABiO2Cl (A = Sr, Ba) and BaBiO2Br

    SciTech Connect

    Porter-Chapman, Yetta D.; Bourret-Courchesne, Edith E.; Derenzo,Stephen E.

    2007-01-18

    Trivalent bismuth luminescence is reported in three Sillenbismuth oxyhalide phases, SrBiO2Cl, BaBiO2Cl, and BaBiO2Br. Thesecompounds exhibit Bi 6s6->6 s2 emission under UV and X-ray radiation.At room temperature, BaBiO2Cl shows the most intense light emission, withspectral and decay properties similar to those found in Bi4Ge3O12 (BGO).At low temperatures, each phase show an increase in the photoluminescenceintensities and a narrowing of the emission peaks. In contrast to thetemperature dependence of BGO, X-ray excited luminescence intensities ofall three phases remain relatively constant throughout the temperaturerange 10 - 295 K. This result indicates that the Sillen phases undergoless thermal quenching than BGO. The low temperature and room temperatureradio-luminescence decay times were determined from pulsed x-raymeasurements. At room temperature, SrBiO2Cl exhibits faster decays thanBGO, while, BaBiO2Cl and BaBiO2Br have decay times similar toBGO.

  8. The interaction of NO2 with BaO: from cooperative adsorption to Ba(NO3)2 formation

    SciTech Connect

    Yi, Cheol-Woo W.; Kwak, Ja Hun; Szanyi, Janos

    2007-10-25

    The effect of water on the morphology of BaO/Al2O3-based NOx storage materials was investigated using Fourier transform infrared spectroscopy, temperature programmed desorption, and time-resolved synchrotron X-ray diffraction techniques. The results of this multi-spectroscopy study reveal that, in the presence of water, surface Ba-nitrates convert to bulk nitrates, and water facilitates the formation of large Ba(NO3)2 particles. The conversion of surface to bulk Ba-nitrates is completely reversible, i.e. after the removal of water from the storage material a significant fraction of the bulk nitrates re-convert to surface nitrates. NO2 exposure of a H2O-containing (wet) BaO/Al2O3 sample results in the formation of nitrites and bulk nitrates exclusively, i.e. no surface nitrates form. After further exposure to NO2, the nitrites completely convert to bulk nitrates. The amount of NOx taken up by the storage material is, however, essentially unaffected by the presence of water, regardless of whether the water was dosed prior to or after NO2 exposure. Based on the results of this study we are now able to explain most of the observations reported in the literature on the effect of water on NOx uptake on similar storage materials.

  9. Experimental determination of the partition coefficient for Ba in Neogloboquadrina dutertrei suggests calcification occurs in a Ba-enriched microenvironment

    NASA Astrophysics Data System (ADS)

    Fehrenbacher, J. S.; Russell, A. D.; Davis, C. V.; Spero, H. J.; Chu, E.

    2015-12-01

    The Ba/Ca ratio in several spinose planktic foraminifer species varies as a function of the Ba/Ca concentration of seawater and is not affected by other parameters such as the seawater salinity, temperature and pH (Honisch et al., 2011). Since seawater Ba concentration is linearly related to Ba in nearshore environments, Ba/Ca ratios in spinose species shows promise as an indicator of past changes in monsoon strength and river runoff (e. g. Weldeab et al. 2007). In contrast, the non-spinose foraminifers often have intrashell variability in Ba/Ca, with Ba/Ca ratios much higher than expected for the range of Ba concentrations observed in the ocean. Furthermore, the Ba/Ca ratio can vary by over a factor of 10 within a single specimen. This suggests either 1) the partition coefficient for Ba in non-spinose species differs from that determined for spinose species, or 2) non-spinose species calcify in a micro-environment that is enriched in Ba. We conducted experiments on live specimens to determine the partition coefficient for Ba in the non-spinose foraminifer N. dutertrei. Specimens were collected via plankton net from the Southern California Bight and cultured at the Wrigley Marine Science Center, Santa Catalina Island during the summer of 2013-2015. We use isotopically labeled seawater (87Sr) to identify discrete portions of calcite that grew in culture. We use laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for trace element analyses and to identify ocean grown vs. culture grown calcite. We show that the partition coefficient is similar to the spinose species: N. dutertrei incorporates Ba as a function of seawater chemistry. We conclude from these observations that N. dutertrei forms its calcite from fluids enriched in Ba, and hypothesize that this process occurs via attachment to organic-rich particles such as marine snow.

  10. Phase relationships in the BaO-Ga2O3-Ta2O5 system and the structure of Ba6Ga21TaO40.

    PubMed

    Cao, Jiang; Yu, Xiaodi; Kuang, Xiaojun; Su, Qiang

    2012-07-16

    Phase relationships in the BaO-Ga(2)O(3)-Ta(2)O(5) ternary system at 1200 °C were determined. The A(6)B(10)O(30) tetragonal tungsten bronze (TTB) related solution in the BaO-Ta(2)O(5) subsystem dissolved up to ~11 mol % Ga(2)O(3), forming a ternary trapezoid-shaped TTB-related solid solution region defined by the BaTa(2)O(6), Ba(1.1)Ta(5)O(13.6), Ba(1.58)Ga(0.92)Ta(4.08)O(13.16), and Ba(6)GaTa(9)O(30) compositions in the BaO-Ga(2)O(3)-Ta(2)O(5) system. Two ternary phases Ba(6)Ga(21)TaO(40) and eight-layer twinned hexagonal perovskite solid solution Ba(8)Ga(4-x)Ta(4+0.6x)O(24) were confirmed in the BaO-Ga(2)O(3)-Ta(2)O(5) system. Ba(6)Ga(21)TaO(40) crystallized in a monoclinic cell of a = 15.9130(2) Å, b = 11.7309(1) Å, c = 5.13593(6) Å, β = 107.7893(9)°, and Z = 1 in space group C2/m. The structure of Ba(6)Ga(21)TaO(40) was solved by the charge flipping method, and it represents a three-dimensional (3D) mixed GaO(4) tetrahedral and GaO(6)/TaO(6) octahedral framework, forming mixed 1D 5/6-fold tunnels that accommodate the Ba cations along the c axis. The electrical property of Ba(6)Ga(21)TaO(40) was characterized by using ac impedance spectroscopy.

  11. The Danish Microbiology Database (MiBa) 2010 to 2013.

    PubMed

    Voldstedlund, M; Haarh, M; Mølbak, K

    2014-01-09

    The Danish Microbiology Database (MiBa) is a national database that receives copies of reports from all Danish departments of clinical microbiology. The database was launched in order to provide healthcare personnel with nationwide access to microbiology reports and to enable real-time surveillance of communicable diseases and microorganisms. The establishment and management of MiBa has been a collaborative process among stakeholders, and the present paper summarises lessons learned from this nationwide endeavour which may be relevant to similar projects in the rapidly changing landscape of health informatics.

  12. Electron microscopy of a Gd-Ba-Cu-O superconductor

    NASA Technical Reports Server (NTRS)

    Ramesh, R.; Thomas, G.; Meng, R. L.; Hor, P. H.; Chu, C. W.

    1989-01-01

    An electron microscopy study has been carried out to characterize the microstructure of a sintered Gd-Ba-Cu-O superconductor alloy. The GdBa2Cu3O(7-x) phase in the oxygen annealed sample is orthorhombic, while in the vacuum annealed sample it is tetragonal. It is shown that the details of the fine structure in the 001-line zone axis convergent beam patterns can be used to distinguish between the orthorhombic form and the tetragonal form. In addition to this matrix phase, an amorphous phase is frequently observed at the triple grain junctions. Gd-rich inclusions have been observed inside the matrix phase.

  13. Reaction kinetics and magnetic properties of Ba and Sr ferrites

    NASA Astrophysics Data System (ADS)

    Melzer, K.; Martin, A.; Klink, T.; Wartewig, P.

    1992-04-01

    This Mössbauer study is concerned with the formation mechanism of hexaferrites (n=6) and of monoferrites (n=1) in the systems (1) BaCO3+nFe2O3, (2) SrCO3+nFe2O3 and (3) 0.5BaCO3+0.5SrCO3+nFe2O3. With a molar ratio of 1∶1 for the starting materials one gets final reaction products with different crystalline structures. The experimental results indicate that the thermodynamical final state of the hexaferrite formation is reached on different routes. Various reaction models are discussed.

  14. New insights into the application of the valence rules in Zintl phases-Crystal and electronic structures of Ba7Ga4P9, Ba7Ga4As9, Ba7Al4Sb9, Ba6CaAl4Sb9, and Ba6CaGa4Sb9

    NASA Astrophysics Data System (ADS)

    He, Hua; Stoyko, Stanislav; Bobev, Svilen

    2016-04-01

    Crystals of three new ternary pnictides-Ba7Al4Sb9, Ba7Ga4P9, and Ba7Ga4As9 have been prepared by reactions of the respective elements in molten Al or Pb fluxes. Single-crystal X-ray diffraction studies reveal that the three phases are isotypic, crystallizing in the orthorhombic Ba7Ga4Sb9-type structure (space group Pmmn, Pearson symbol oP40, Z=2), for which only the prototype is known. The structure is based on TrPn4 tetrahedra (Tr=Al, Ga; Pn=P, As, Sb), connected in an intricate scheme into 1D-ribbons. Long interchain Pn-Pn bonds (dP-P>3.0 Å; dAs-As>3.1 Å; dSb-Sb>3.3 Å) account for the realization of 2D-layers, separated by Ba2+ cations. Applying the classic valance rules to rationalize the bonding apparently fails, and Ba7Ga4Sb9 has long been known as a metallic Zintl phase. Earlier theoretical calculations, both empirical and ab-initio, suggest that the possible metallic properties originate from filled anti-bonding Pn-Pn states, and the special roles of the "cations" in this crystal structure. To experimentally probe this hypothesis, we sought to synthesize the ordered quaternary phases Ba6CaTr4Sb9 (Tr=Al, Ga). Single-crystal X-ray diffraction work confirms Ba6.145(3)Ca0.855Al4Sb9 and Ba6.235(3)Ca0.765Ga4Sb9, with Ca atoms preferably substituting Ba on one of the three available sites. The nuances of the five crystal structures are discussed, and the chemical bonding in Ba7Ga4As9 is interrogated by tight-binding linear muffin-tin orbital calculations.

  15. Synthesis, structural characterization and optical properties of new compounds: Centrosymmetric Ba2GaMQ5 (M=Sb,Bi; Q=Se,Te), Ba2InSbTe5 and noncentrosymmetric Ba2InSbSe5

    NASA Astrophysics Data System (ADS)

    Hao, Wenyu; Mei, Dajiang; Yin, Wenlong; Feng, Kai; Yao, Jiyong; Wu, Yicheng

    2013-02-01

    The six compounds Ba2GaMQ5 (M=Sb,Bi; Q=Se,Te) and Ba2InSbQ5 (Q=Se,Te) have been synthesized for the first time. Ba2GaMQ5 (M=Sb,Bi; Q=Se,Te) and Ba2InSbTe5 crystallize in the centrosymmetric space group Pnma, while Ba2InSbSe5 belongs to the noncentrosymmetric polar space group Cmc21. The structures of the six new compounds contain infinite [MM]4-∞1 anionic chains built by MQ4 (M'=Ga,In) tetrahedra and heavily distorted M'Q6 (M'=Sb,Bi) octahedra. Ba2InSbSe5 possesses a band gap of 1.92(5) eV and exhibits a weak powder second harmonic generation signal using the 2090 nm laser as fundamental wavelength.

  16. Growth and characterization of acentric BaHf(BO{sub 3}){sub 2} and BaZr(BO{sub 3}){sub 2}

    SciTech Connect

    Mączka, Mirosław; Szymborska-Małek, Katarzyna; Gągor, Anna; Majchrowski, Andrzej

    2015-05-15

    Growth, single crystal X-ray diffraction, polarized Raman and infrared (IR) studies of BaHf(BO{sub 3}){sub 2} are presented. Raman and IR spectra of polycrystalline BaZr(BO{sub 3}){sub 2} are also reported to facilitate assignment of modes. BaHf(BO{sub 3}){sub 2} borate crystallizes in trigonal system, space group R3c, with lattice parameters: a=5.1540(4) Å, c=33.901(3) Å. It accommodates dolomite-like structure doubled in the c direction, which is built of alternating layers of HfO{sub 6} octahedra and BaO{sub 6} distorted trigonal prisms that are connected through borate groups. The obtained structural as well as spectroscopic data show that BaHf(BO{sub 3}){sub 2} is isostructural with BaZr(BO{sub 3}){sub 2} and the deviations from centrosymmetry is small. - Graphical abstract: Arrangement of BO{sub 3} groups in BaHf(BO{sub 3}){sub 2} along the c direction in one unit cell. Dark and light blue denote different borate groups. - Highlights: • BaHf(BO{sub 3}){sub 2} single crystals were grown. • X-ray diffraction showed that this borate crystallizes in the acentric R3c structure. • Raman and IR spectra were measured for BaHf(BO{sub 3}){sub 2} and BaZr(BO{sub 3}){sub 2}, respectively. • Assignment of modes is proposed.

  17. Phase Transitions in Quasi-one-dimensional Selenide BaNbSe 3and Superconductivity in BaNb 2Se 5

    NASA Astrophysics Data System (ADS)

    Ohtani, T.; Honji, S.; Takano, M.

    1997-08-01

    Samples with various compositions around BaNbSe3were prepared. X-ray analysis revealed that the compound is stable at the composition of BaNb0.80Se3, which formally requires Nb5+ions (d0). The single-phase region extends to the composition BaNb0.95Se3. A semiconductor-to-metal transition was observed at ∼140 K in BaNb0.95Se3. Seebeck measurements showed that the dominant carriers were electrons, which are considered to originate from Nb4+ions (d1) coexisting with Nb5+ions. On the basis of detailed phase study, the transition was revealed to be intrinsic to BaNb0.95Se3with a very slight Ba deficiency. BaNb0.95Se3with a slight Ba excess shows a semiconductor-to-semiconductor transition at 200-300 K. Seebeck measurements showed that the dominant carriers are electrons above the transition and are holes below the transition. A new compound, BaNb2Se5with a BaTa2S5-type structure, was found to show superconductivity at 2.5 K.

  18. Nonlinearity parameter B/A of biological tissue ultrasound imaging in echo mode

    SciTech Connect

    Toulemonde, M. Varray, F.; Bernard, A.; Basset, O.; Cachard, C.

    2015-10-28

    The nonlinearity B/A parameter influences the distortion of ultrasound waves during their propagation in tissue. Normal and pathological media have different B/A values and this parameter may be used to characterize them. In this paper the multitaper coherent plane wave compounding (MCPWC) is combined with the extended comparative method (ECM) to estimate the B/A parameter in simulation and acquisition. Using plane wave transmission and orthogonal apodization during beam forming improves the B/A estimation and delineation.

  19. PEM Fuel Cell System Replacement for BA-559O Battery

    DTIC Science & Technology

    2007-11-02

    H Power Corp. developed a fuel cell system to demonstrate that fuel cells can be effectively designed for missions requiring a high degree of...equivalent in size to that of a BA-5590 battery. The system comprised an air-cooled fuel cell stack, a metal-hydride-based fuel storage section, and a

  20. The BaBar detector: Upgrades, operation and performance

    SciTech Connect

    Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; del Amo Sanchez, P.; Gaillard, J. -M.; Hicheur, A.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prudent, X.; Robbe, P.; Tisserand, V.; Zghiche, A.; Grauges, E.; Garra Tico, J.; Lopez, L.; Martinelli, M.; Palano, A.; Pappagallo, M.; Pompili, A.; Chen, G. P.; Chen, J. C.; Qi, N. D.; Rong, G.; Wang, P.; Zhu, Y. S.; Eigen, G.; Stugu, B.; Sun, L.; Abrams, G. S.; Battaglia, M.; Borgland, A. W.; Breon, A. B.; Brown, D. N.; Button-Shafer, J.; Cahn, R. N.; Charles, E.; Clark, A. R.; Day, C. T.; Furman, M.; Gill, M. S.; Groysman, Y.; Jacobsen, R. G.; Kadel, R. W.; Kadyk, J. A.; Kerth, L. T.; Kolomensky, Yu. G.; Kral, J. F.; Kukartsev, G.; LeClerc, C.; Levi, M. E.; Lynch, G.; Merchant, A. M.; Mir, L. M.; Oddone, P. J.; Orimoto, T. J.; Osipenkov, I. L.; Pripstein, M.; Roe, N. A.; Romosan, A.; Ronan, M. T.; Shelkov, V. G.; Suzuki, A.; Tackmann, K.; Tanabe, T.; Wenzel, W. A.; Zisman, M.; Barrett, M.; Bright-Thomas, P. G.; Ford, K. E.; Harrison, T. J.; Hart, A. J.; Hawkes, C. M.; Knowles, D. J.; Morgan, S. E.; O'Neale, S. W.; Penny, R. C.; Smith, D.; Soni, N.; Watson, A. T.; Watson, N. K.; Goetzen, K.; Held, T.; Koch, H.; Kunze, M.; Lewandowski, B.; Pelizaeus, M.; Peters, K.; Schmuecker, H.; Schroeder, T.; Steinke, M.; Fella, A.; Antonioli, E.; Boyd, J. T.; Chevalier, N.; Cottingham, W. N.; Foster, B.; Mackay, C.; Walker, D.; Abe, K.; Asgeirsson, D. J.; Cuhadar-Donszelmann, T.; Fulsom, B. G.; Hearty, C.; Knecht, N. S.; Mattison, T. S.; McKenna, J. A.; Thiessen, D.; Khan, A.; Kyberd, P.; McKemey, A. K.; Randle-Conde, A.; Saleem, M.; Sherwood, D. J.; Teodorescu, L.; Blinov, V. E.; Bukin, A. D.; Buzykaev, A. R.; Druzhinin, V. P.; Golubev, V. B.; Korol, A. A.; Kravchenko, E. A.; Onuchin, A. P.; Serednyakov, S. I.; Skovpen, Yu. I.; Solodov, E. P.; Telnov, V. I.; Todyshev, K. Yu.; Yushkov, A. N.; Best, D. S.; Bondioli, M.; Bruinsma, M.; Chao, M.; Curry, S.; Eschrich, I.; Kirkby, D.; Lankford, A. J.; Mandelkern, M.; Martin, E. C.; McMahon, S.; Mommsen, R. K.; Stoker, D. P.; Abachi, S.; Buchanan, C.; Hartfiel, B. L.; Weinstein, A. J. R.; Atmacan, H.; Foulkes, S. D.; Gary, J. W.; Layter, J.; Liu, F.; Long, O.; Shen, B. C.; Vitug, G. M.; Wang, K.; Yasin, Z.; Zhang, L.; Hadavand, H. K.; Hill, E. J.; Paar, H. P.; Rahatlou, S.; Schwanke, U.; Sharma, V.; Berryhill, J. W.; Campagnari, C.; Cunha, A.; Dahmes, B.; Hong, T. M.; Kovalskyi, D.; Kuznetsova, N.; Levy, S. L.; Lu, A.; Mazur, M. A.; Richman, J. D.; Verkerke, W.; Beck, T. W.; Beringer, J.; Eisner, A. M.; Flacco, C. J.; Grillo, A. A.; Grothe, M.; Heusch, C. A.; Kroseberg, J.; Lockman, W. S.; Martinez, A. J.; Nesom, G.; Schalk, T.; Schmitz, R. E.; Schumm, B. A.; Seiden, A.; Spencer, E.; Spradlin, P.; Turri, M.; Walkowiak, W.; Wang, L.; Wilder, M.; Williams, D. C.; Wilson, M. G.; Winstrom, L. O.; Chen, E.; Cheng, C. H.; Doll, D. A.; Dorsten, M. P.; Dvoretskii, A.; Echenard, B.; Erwin, R. J.; Fang, F.; Flood, K.; Hitlin, D. G.; Metzler, S.; Narsky, I.; Oyang, J.; Piatenko, T.; Porter, F. C.; Ryd, A.; Samuel, A.; Yang, S.; Zhu, R. Y.; Andreassen, R.; Devmal, S.; Geld, T. L.; Jayatilleke, S.; Mancinelli, G.; Meadows, B. T.; Mishra, K.; Sokoloff, M. D.; Abe, T.; Antillon, E. A.; Barillari, T.; Becker, J.; Blanc, F.; Bloom, P. C.; Chen, S.; Clifton, Z. C.; Derrington, I. M.; Destree, J.; Dima, M. O.; Ford, W. T.; Gaz, A.; Gilman, J. D.; Hachtel, J.; Hirschauer, J. F.; Johnson, D. R.; Kreisel, A.; Nagel, M.; Nauenberg, U.; Olivas, A.; Rankin, P.; Roy, J.; Ruddick, W. O.; Smith, J. G.; Ulmer, K. A.; van Hoek, W. C.; Wagner, S. R.; West, C. G.; Zhang, J.; Ayad, R.; Blouw, J.; Chen, A.; Eckhart, E. A.; Harton, J. L.; Hu, T.; Toki, W. H.; Wilson, R. J.; Winklmeier, F.; Zeng, Q. L.; Altenburg, D.; Feltresi, E.; Hauke, A.; Jasper, H.; Karbach, M.; Merkel, J.; Petzold, A.; Spaan, B.; Wacker, K.; Brandt, T.; Brose, J.; Colberg, T.; Dahlinger, G.; Dickopp, M.; Eckstein, P.; Futterschneider, H.; Kaiser, S.; Kobel, M. J.; Krause, R.; Müller-Pfefferkorn, R.; Mader, W. F.; Maly, E.; Nogowski, R.; Otto, S.; Schubert, J.; Schubert, K. R.; Schwierz, R.; Sundermann, J. E.; Volk, A.; Wilden, L.; Bernard, D.; Brochard, F.; Cohen-Tanugi, J.; Dohou, F.; Ferrag, S.; Latour, E.; Mathieu, A.; Renard, C.; Schrenk, S.; T'Jampens, S.; Thiebaux, Ch.; Vasileiadis, G.; Verderi, M.; Anjomshoaa, A.; Bernet, R.; Clark, P. J.; Lavin, D. R.; Muheim, F.; Playfer, S.; Robertson, A. I.; Swain, J. E.; Watson, J. E.; Xie, Y.; Andreotti, D.; Andreotti, M.; Bettoni, D.; Bozzi, C.; Calabrese, R.; Carassiti, V.; Cecchi, A.; Cibinetto, G.; Cotta Ramusino, A.; Evangelisti, F.; Fioravanti, E.; Franchini, P.; Garzia, I.; Landi, L.; Luppi, E.; Malaguti, R.; Negrini, M.; Padoan, C.; Petrella, A.; Piemontese, L.; Santoro, V.; Sarti, A.; Anulli, F.; Baldini-Ferroli, R.; Calcaterra, A.; Finocchiaro, G.; Pacetti, S.; Patteri, P.; Peruzzi, I. M.; Piccolo, M.; Rama, M.; de Sangro, R.; Santoni, M.; Zallo, A.; Bagnasco, S.; Buzzo, A.; Capra, R.; Contri, R.; Crosetti, G.; Lo Vetere, M.; Macri, M. M.; Minutoli, S.; Monge, M. R.; Musico, P.; Passaggio, S.; Pastore, F. C.; Patrignani, C.; Pia, M. G.; Robutti, E.; Santroni, A.; Tosi, S.; Bhuyan, B.; Prasad, V.; Bailey, S.; Brandenburg, G.; Chaisanguanthum, K. S.; Lee, C. L.; Morii, M.; Won, E.; Wu, J.; Adametz, A.; Dubitzky, R. S.; Marks, J.; Schenk, S.; Uwer, U.; Klose, V.; Lacker, H. M.; Aspinwall, M. L.; Bhimji, W.; Bowerman, D. A.; Dauncey, P. D.; Egede, U.; Flack, R. L.; Gaillard, J. R.; Gunawardane, N. J. W.; Morton, G. W.; Nash, J. A.; Nikolich, M. B.; Panduro Vazquez, W.; Sanders, P.; Smith, D.; Taylor, G. P.; Tibbetts, M.; Behera, P. K.; Chai, X.; Charles, M. J.; Grenier, G. J.; Hamilton, R.; Lee, S. -J.; Mallik, U.; Meyer, N. T.; Chen, C.; Cochran, J.; Crawley, H. B.; Dong, L.; Eyges, V.; Fischer, P. -A.; Lamsa, J.; Meyer, W. T.; Prell, S.; Rosenberg, E. I.; Rubin, A. E.; Gao, Y. Y.; Gritsan, A. V.; Guo, Z. J.; Lae, C. K.; Schott, G.; Albert, J. N.; Arnaud, N.; Beigbeder, C.; Breton, D.; Davier, M.; Derkach, D.; Dû, S.; Firmino da Costa, J.; Grosdidier, G.; Höcker, A.; Laplace, S.; Le Diberder, F.; Lepeltier, V.; Lutz, A. M.; Malaescu, B.; Nief, J. Y.; Petersen, T. C.; Plaszczynski, S.; Pruvot, S.; Roudeau, P.; Schune, M. H.; Serrano, J.; Sordini, V.; Stocchi, A.; Tocut, V.; Trincaz-Duvoid, S.; Wang, L. L.; Wormser, G.; Bionta, R. M.; Brigljević, V.; Lange, D. J.; Simani, M. C.; Wright, D. M.; Bingham, I.; Burke, J. P.; Chavez, C. A.; Coleman, J. P.; Forster, I. J.; Fry, J. R.; Gabathuler, E.; Gamet, R.; George, M.; Hutchcroft, D. E.; Kay, M.; Parry, R. J.; Payne, D. J.; Schofield, K. C.; Sloane, R. J.; Touramanis, C.; Azzopardi, D. E.; Bellodi, G.; Bevan, A. J.; Clarke, C. K.; Cormack, C. M.; Di Lodovico, F.; Dixon, P.; George, K. A.; Menges, W.; Potter, R. J. L.; Sacco, R.; Shorthouse, H. W.; Sigamani, M.; Strother, P.; Vidal, P. B.; Brown, C. L.; Cowan, G.; Flaecher, H. U.; George, S.; Green, M. G.; Hopkins, D. A.; Jackson, P. S.; Kurup, A.; Marker, C. E.; McGrath, P.; McMahon, T. R.; Paramesvaran, S.; Salvatore, F.; Vaitsas, G.; Winter, M. A.; Wren, A. C.; Brown, D. N.; Davis, C. L.; Denig, A. G.; Fritsch, M.; Gradl, W.; Griessinger, K.; Hafner, A.; Prencipe, E.; Allison, J.; Alwyn, K. E.; Bailey, D. S.; Barlow, N. R.; Barlow, R. J.; Chia, Y. M.; Edgar, C. L.; Forti, A. C.; Fullwood, J.; Hart, P. A.; Hodgkinson, M. C.; Jackson, F.; Jackson, G.; Kelly, M. P.; Kolya, S. D.; Lafferty, G. D.; Lyon, A. J.; Naisbit, M. T.; Savvas, N.; Weatherall, J. H.; West, T. J.; Williams, J. C.; Yi, J. I.; Anderson, J.; Farbin, A.; Hulsbergen, W. D.; Jawahery, A.; Lillard, V.; Roberts, D. A.; Schieck, J. R.; Simi, G.; Tuggle, J. M.; Blaylock, G.; Dallapiccola, C.; Hertzbach, S. S.; Kofler, R.; Koptchev, V. B.; Li, X.; Moore, T. B.; Salvati, E.; Saremi, S.; Staengle, H.; Willocq, S. Y.; Cowan, R.; Dujmic, D.; Fisher, P. H.; Henderson, S. W.; Koeneke, K.; Lang, M. I.; Sciolla, G.; Spitznagel, M.; Taylor, F.; Yamamoto, R. K.; Yi, M.; Zhao, M.; Zheng, Y.; Klemetti, M.; Lindemann, D.; Mangeol, D. J. J.; Mclachlin, S. E.; Milek, M.; Patel, P. M.; Robertson, S. H.; Biassoni, P.; Cerizza, G.; Lazzaro, A.; Lombardo, V.; Neri, N.; Palombo, F.; Pellegrini, R.; Stracka, S.; Bauer, J. M.; Cremaldi, L.; Eschenburg, V.; Kroeger, R.; Reidy, J.; Sanders, D. A.; Summers, D. J.; Zhao, H. W.; Godang, R.; Brunet, S.; Cote, D.; Nguyen, X.; Simard, M.; Taras, P.; Viaud, B.; Nicholson, H.; Cavallo, N.; De Nardo, G.; Fabozzi, F.; Gatto, C.; Lista, L.; Monorchio, D.; Onorato, G.; Paolucci, P.; Piccolo, D.; Sciacca, C.; Baak, M. A.; Raven, G.; Snoek, H. L.; Jessop, C. P.; Knoepfel, K. J.; LoSecco, J. M.; Wang, W. F.; Allmendinger, T.; Benelli, G.; Brau, B.; Corwin, L. A.; Gan, K. K.; Honscheid, K.; Hufnagel, D.; Kagan, H.; Kass, R.; Morris, J. P.; Rahimi, A. M.; Regensburger, J. J.; Smith, D. S.; Ter-Antonyan, R.; Wong, Q. K.; Blount, N. L.; Brau, J.; Frey, R.; Igonkina, O.; Iwasaki, M.; Kolb, J. A.; Lu, M.; Potter, C. T.; Rahmat, R.; Sinev, N. B.; Strom, D.; Strube, J.; Torrence, E.; Borsato, E.; Castelli, G.; Colecchia, F.; Crescente, A.; Dal Corso, F.; Dorigo, A.; Fanin, C.; Furano, F.; Gagliardi, N.; Galeazzi, F.; Margoni, M.; Marzolla, M.; Michelon, G.; Morandin, M.; Posocco, M.; Rotondo, M.; Simonetto, F.; Solagna, P.; Stevanato, E.; Stroili, R.; Tiozzo, G.; Voci, C.; Akar, S.; Bailly, P.; Ben-Haim, E.; Bonneaud, G.; Briand, H.; Chauveau, J.; Hamon, O.; John, M. J. J.; Lebbolo, H.; Leruste, Ph.; Malclès, J.; Marchiori, G.; Martin, L.; Ocariz, J.; Perez, A.; Pivk, M.; Prendki, J.; Roos, L.; Sitt, S.; Stark, J.; Thérin, G.; Vallereau, A.; Biasini, M.; Covarelli, R.; Manoni, E.; Pennazzi, S.; Pioppi, M.; Angelini, C.; Batignani, G.; Bettarini, S.; Bosi, F.; Bucci, F.; Calderini, G.; Carpinelli, M.; Cenci, R.; Cervelli, A.; Forti, F.; Giorgi, M. A.; Lusiani, A.; Marchiori, G.; Morganti, M.; Morsani, F.; Paoloni, E.; Raffaelli, F.; Rizzo, G.; Sandrelli, F.; Triggiani, G.; Walsh, J. J.; Haire, M.; Judd, D.; Biesiada, J.; Danielson, N.; Elmer, P.; Fernholz, R. E.; Lau, Y. P.; Lu, C.; Miftakov, V.; Olsen, J.; Lopes Pegna, D.; Sands, W. R.; Smith, A. J. S.; Telnov, A. V.; Tumanov, A.; Varnes, E. W.; Baracchini, E.; Bellini, F.; Bulfon, C.; Buccheri, E.; Cavoto, G.; D'Orazio, A.; Di Marco, E.; Faccini, R.; Ferrarotto, F.; Ferroni, F.; Gaspero, M.; Jackson, P. D.; Lamanna, E.; Leonardi, E.; Li Gioi, L.; Lunadei, R.; Mazzoni, M. A.; Morganti, S.; Piredda, G.; Polci, F.; del Re, D.; Renga, F.; Safai Tehrani, F.; Serra, M.; Voena, C.; Bünger, C.; Christ, S.; Hartmann, T.; Leddig, T.; Schröder, H.; Wagner, G.; Waldi, R.; Adye, T.; Bly, M.; Brew, C.; Condurache, C.; De Groot, N.; Franek, B.; Geddes, N. I.; Gopal, G. P.; Olaiya, E. O.; Ricciardi, S.; Roethel, W.; Wilson, F. F.; Xella, S. M.; Aleksan, R.; Bourgeois, P.; Emery, S.; Escalier, M.; Esteve, L.; Gaidot, A.; Ganzhur, S. F.; Giraud, P. -F.; Georgette, Z.; Graziani, G.; Hamel de Monchenault, G.; Kozanecki, W.; Langer, M.; Legendre, M.; London, G. W.; Mayer, B.; Micout, P.; Serfass, B.; Vasseur, G.; Yèche, Ch.; Zito, M.; Allen, M. T.; Akre, R.; Aston, D.; Azemoon, T.; Bard, D. J.; Bartelt, J.; Bartoldus, R.; Bechtle, P.; Becla, J.; Benitez, J. F.; Berger, N.; Bertsche, K.; Boeheim, C. T.; Bouldin, K.; Boyarski, A. M.; Boyce, R. F.; Browne, M.; Buchmueller, O. L.; Burgess, W.; Cai, Y.; Cartaro, C.; Ceseracciu, A.; Claus, R.; Convery, M. R.; Coupal, D. P.; Craddock, W. W.; Crane, G.; Cristinziani, M.; DeBarger, S.; Decker, F. J.; Dingfelder, J. C.; Donald, M.; Dorfan, J.; Dubois-Felsmann, G. P.; Dunwoodie, W.; Ebert, M.; Ecklund, S.; Erickson, R.; Fan, S.; Field, R. C.; Fisher, A.; Fox, J.; Franco Sevilla, M.; Fulsom, B. G.; Gabareen, A. M.; Gaponenko, I.; Glanzman, T.; Gowdy, S. J.; Graham, M. T.; Grenier, P.; Hadig, T.; Halyo, V.; Haller, G.; Hamilton, J.; Hanushevsky, A.; Hasan, A.; Hast, C.; Hee, C.; Himel, T.; Hryn'ova, T.; Huffer, M. E.; Hung, T.; Innes, W. R.; Iverson, R.; Kaminski, J.; Kelsey, M. H.; Kim, H.; Kim, P.; Kharakh, D.; Kocian, M. L.; Krasnykh, A.; Krebs, J.; Kroeger, W.; Kulikov, A.; Kurita, N.; Langenegger, U.; Leith, D. W. G. S.; Lewis, P.; Li, S.; Libby, J.; Lindquist, B.; Luitz, S.; Lüth, V.; Lynch, H. L.; MacFarlane, D. B.; Marsiske, H.; McCulloch, M.; McDonald, J.; Melen, R.; Menke, S.; Metcalfe, S.; Messner, R.; Moss, L. J.; Mount, R.; Muller, D. R.; Neal, H.; Nelson, D.; Nelson, S.; Nordby, M.; Nosochkov, Y.; Novokhatski, A.; O'Grady, C. P.; O'Neill, F. G.; Ofte, I.; Ozcan, V. E.; Perazzo, A.; Perl, M.; Petrak, S.; Piemontese, M.; Pierson, S.; Pulliam, T.; Ratcliff, B. N.; Ratkovsky, S.; Reif, R.; Rivetta, C.; Rodriguez, R.; Roodman, A.; Salnikov, A. A.; Schietinger, T.; Schindler, R. H.; Schwarz, H.; Schwiening, J.; Seeman, J.; Smith, D.; Snyder, A.; Soha, A.; Stanek, M.; Stelzer, J.; Su, D.; Sullivan, M. K.; Suzuki, K.; Swain, S. K.; Tanaka, H. A.; Teytelman, D.; Thompson, J. M.; Tinslay, J. S.; Trunov, A.; Turner, J.; van Bakel, N.; van Winkle, D.; Va'vra, J.; Wagner, A. P.; Weaver, M.; Weinstein, A. J. R.; Weber, T.; West, C. A.; Wienands, U.; Wisniewski, W. J.; Wittgen, M.; Wittmer, W.; Wright, D. H.; Wulsin, H. W.; Yan, Y.; Yarritu, A. K.; Yi, K.; Yocky, G.; Young, C. C.; Ziegler, V.; Chen, X. R.; Liu, H.; Park, W.; Purohit, M. V.; Singh, H.; Weidemann, A. W.; White, R. M.; Wilson, J. R.; Yumiceva, F. X.; Sekula, S. J.; Bellis, M.; Burchat, P. R.; Edwards, A. J.; Majewski, S. A.; Meyer, T. I.; Miyashita, T. S.; Petersen, B. A.; Roat, C.; Ahmed, M.; Ahmed, S.; Alam, M. S.; Bula, R.; Ernst, J. A.; Jain, V.; Liu, J.; Pan, B.; Saeed, M. A.; Wappler, F. R.; Zain, S. B.; Gorodeisky, R.; Guttman, N.; Peimer, D.; Soffer, A.; De Silva, A.; Lund, P.; Krishnamurthy, M.; Ragghianti, G.; Spanier, S. M.; Wogsland, B. J.; Eckmann, R.; Ritchie, J. L.; Ruland, A. M.; Satpathy, A.; Schilling, C. J.; Schwitters, R. F.; Wray, B. C.; Drummond, B. W.; Izen, J. M.; Kitayama, I.; Lou, X. C.; Ye, S.; Bianchi, F.; Bona, M.; Gallo, F.; Gamba, D.; Pelliccioni, M.; Bomben, M.; Borean, C.; Bosisio, L.; Cossutti, F.; Della Ricca, G.; Dittongo, S.; Grancagnolo, S.; Lanceri, L.; Poropat, P.; Rashevskaya, I.; Vitale, L.; Vuagnin, G.; Manfredi, P. F.; Re, V.; Speziali, V.; Frank, E. D.; Gladney, L.; Guo, Q. H.; Panetta, J.; Azzolini, V.; Lopez-March, N.; Martinez-Vidal, F.; Milanes, D. A.; Oyanguren, A.; Agarwal, A.; Albert, J.; Banerjee, Sw.; Bernlochner, F. U.; Brown, C. M.; Choi, H. H. F.; Fortin, D.; Fransham, K. B.; Hamano, K.; Kowalewski, R.; Lewczuk, M. J.; Nugent, I. M.; Roney, J. M.; Sobie, R. J.; Back, J. J.; Gershon, T. J.; Harrison, P. F.; Ilic, J.; Latham, T. E.; Mohanty, G. B.; Puccio, E.; Band, H. R.; Chen, X.; Cheng, B.; Dasu, S.; Datta, M.; Eichenbaum, A. M.; Hollar, J. J.; Hu, H.; Johnson, J. R.; Kutter, P. E.; Li, H.; Liu, R.; Mellado, B.; Mihalyi, A.; Mohapatra, A. K.; Pan, Y.; Pierini, M.; Prepost, R.; Scott, I. J.; Tan, P.; Vuosalo, C. O.; von Wimmersperg-Toeller, J. H.; Wu, S. L.; Yu, Z.; Greene, M. G.; Kordich, T. M. B.

    2013-11-01

    The BaBar detector operated successfully at the PEP-II asymmetric e+e- collider at the SLAC National Accelerator Laboratory from 1999 to 2008. This report covers upgrades, operation, and performance of the collider and the detector systems, as well as the trigger, online and offline computing, and aspects of event reconstruction since the beginning of data taking.

  1. Thin film processing of photorefractive BaTiO3

    NASA Technical Reports Server (NTRS)

    Schuster, Paul R.; Potember, Richard S.

    1991-01-01

    The principle objectives of this ongoing research involve the preparation and characterization of polycrystalline single-domain thin films of BaTiO3 for photorefractive applications. These films must be continuous, free of cracks, and of high optical quality. The two methods proposed are sputtering and sol-gel related processing.

  2. Recent Results From BaBar in Tau Physics

    SciTech Connect

    Lewczuk, Mateusz; /Victoria U.

    2009-06-25

    The BaBar collaboration has accumulated over 400 million {tau}-pairs which can be used to study charged leptonic and hadronic weak currents to unprecedented precision. This note presents results on lepton universality, measurements of |V{sub us}|, and searches for {tau} decays which violate lepton flavour conservation, or {tau} decays that proceed through a suppressed second class current.

  3. Generator Coordinate Method Analysis of Xe and Ba Isotopes

    NASA Astrophysics Data System (ADS)

    Higashiyama, Koji; Yoshinaga, Naotaka; Teruya, Eri

    Nuclear structure of Xe and Ba isotopes is studied in terms of the quantum-number projected generator coordinate method (GCM). The GCM reproduces well the energy levels of high-spin states as well as low-lying states. The structure of the low-lying states is analyzed through the GCM wave functions.

  4. Recent Measurements of sin2beta at BaBar

    SciTech Connect

    Sciolla, Gabriella; /MIT

    2005-12-14

    The angle {beta} is the most accurately measured quantity that determines the Unitarity Triangle. In this article I review the various measurements of this angle performed by the BaBar Collaboration, and discuss their implications in the search for new physics.

  5. Backscatter Mossbauer Spectrometer (BaMS) for extraterrestrial applications

    NASA Astrophysics Data System (ADS)

    Agresti, D. G.; Shelfer, T. D.; Pimperl, M. M.; Wills, E. L.; Shen, M. H.; Morris, R. V.

    1993-06-01

    Mossbauer spectroscopy is a nuclear gamma resonance technique particularly well suited to the study of materials that contain iron (Fe-57). It can provide information on the oxidation state of iron as well as the type and proportion of iron-containing mineral species in a sample of interest. Iron Mossbauer spectroscopy (FeMS) has been applied to samples believed to have come from Mars (SNC meteorites) and has been helpful in refining the choice among putative Martian surface materials by suggesting a likely nanophase component of the Martian regolity. FeMS spectrum of a Martial analogue material (Hawaiian palagonite) is shown; it is dominated by ferric-bearing phases and shows evidence of a nanophase component. FeMS has also been applied to lunar materials. It can be used to measure the maturity of lunar surface material and has been proposed as a prospector for lunar ilmenite, an oxygen resource mineral. Several years ago we suggested a backscatter Mossbauer spectrometer (BaMS) for a Mars rover mission. Backscatter design was selected as most appropriate for in-situ application because no sample preparation is required. Since that time, we have continued to develop the BaMS instrument in anticipation that it would eventually find a home on a NASA planetary mission. Gooding proposed BaMS as a geochemistry instrument on MESUR. More recently, an LPI workshop has recommended that BaMS be included in a three-instrument payload on the next (1996?) lunar lander.

  6. Antiferroelectric-to-paraelectric transition in BaFCl

    NASA Astrophysics Data System (ADS)

    Sundarakkannan, B.; Kesavamoorthy, R.; Adelene Nisha, J.; Sridharan, V.; Sivakumar, T.

    1998-05-01

    Thermoanalytical investigations are carried out on the flux-grown BaFCl crystals. An endothermic peak at 725 °C and 1.2% weight loss in the temperature range from 730 to 860 °C is observed in differential thermal analysis and thermogravimetric analysis measurements. Heating rate dependency of the endotherm peak position and that of weight loss onset temperature indicate that these two processes are independent from one another. Endotherm is attributed to the antiferroelectric to paraelectric transition in BaFCl. High-temperature Raman scattering, high-temperature x-ray diffraction (XRD) measurements and thermomechanical analysis show that BaFCl has no structural transition from 25 to 800 °C. Our results indicate order-disorder type transition. We propose the origin of the dipole to be the displacement of a Ba ion center from the nonpolar site, viz. anionic cage charge center. Weight loss is attributed to the evolution of halides with the activation energy of 1.57 eV. The weight loss results in the shrinkage of the unit cell as determined by XRD, leading to the shifting of the endotherm peak to 823 °C. The signature of defects produced by the evolution of halide is seen in optical absorption spectra.

  7. Backscatter Mossbauer Spectrometer (BaMS) for extraterrestrial applications

    NASA Technical Reports Server (NTRS)

    Agresti, D. G.; Shelfer, T. D.; Pimperl, M. M.; Wills, E. L.; Shen, M. H.; Morris, R. V.

    1993-01-01

    Mossbauer spectroscopy is a nuclear gamma resonance technique particularly well suited to the study of materials that contain iron (Fe-57). It can provide information on the oxidation state of iron as well as the type and proportion of iron-containing mineral species in a sample of interest. Iron Mossbauer spectroscopy (FeMS) has been applied to samples believed to have come from Mars (SNC meteorites) and has been helpful in refining the choice among putative Martian surface materials by suggesting a likely nanophase component of the Martian regolity. FeMS spectrum of a Martial analogue material (Hawaiian palagonite) is shown; it is dominated by ferric-bearing phases and shows evidence of a nanophase component. FeMS has also been applied to lunar materials. It can be used to measure the maturity of lunar surface material and has been proposed as a prospector for lunar ilmenite, an oxygen resource mineral. Several years ago we suggested a backscatter Mossbauer spectrometer (BaMS) for a Mars rover mission. Backscatter design was selected as most appropriate for in-situ application because no sample preparation is required. Since that time, we have continued to develop the BaMS instrument in anticipation that it would eventually find a home on a NASA planetary mission. Gooding proposed BaMS as a geochemistry instrument on MESUR. More recently, an LPI workshop has recommended that BaMS be included in a three-instrument payload on the next (1996?) lunar lander.

  8. AMiBA: Array for Microwave Background Anisotropy

    NASA Astrophysics Data System (ADS)

    Lo, K. Y.; Chiueh, T.; Martin, R. N.

    2000-12-01

    As part of a 4-year US\\ 15 million Cosmology and Particle Astrophysics (CosPA) Research Excellence Initiative in Taiwan, AMiBA - a 19-element dual-channel 85-105 GHz interferometer array is being specifically built to survey for high redshift clusters of galaxies via the Sunyaev-Zeldovich Effect. In addition, the AMiBA will have full polarization capabilities in order to probe the polarization properties of the Cosmic Microwave Background. The AMiBA, to be sited on Mauna Kea in Hawaii or in Chile, will reach a sensitivity of 1.5 mJy or 7\\mu$K in 1 hour. The project involves scientific and technical collaborations with the Australia Telescope National Facilities (ATNF), the Canadian Institute of Theoretical Astrophysics (CITA), the Physics departments of the Carnegie-Mellon University (CMU) and the University of Pennsylvania (UPenn). The construction of the AMiBA is scheduled to be completed in 2003. Current status of the project will be discussed.

  9. Measurements of Form Factors with the BaBar Experiment

    SciTech Connect

    Li, Selina Z.; /SLAC

    2011-08-25

    Selected recent results on measurements of form factors by the BaBar Collaboration are reviewed, including e{sup +}e{sup -} {yields} {eta}{prime}{gamma}, leptonic and semileptonic charm decays from data collected at or near the {Upsilon}(4S) resonance.

  10. LaBaNiO4: a Fermi glass

    NASA Astrophysics Data System (ADS)

    Schilling, A.; Dell'Amore, R.; Karpinski, J.; Bukowski, Z.; Medarde, M.; Pomjakushina, E.; Müller, K. A.

    2009-01-01

    Polycrystalline samples of LaSr1-xBaxNiO4 show a crossover from a state with metallic transport properties for x = 0 to an insulating state as x\\to 1 . The end member LaBaNiO4 with a nominal nickel Ni 3d7 configuration might therefore be regarded as a candidate for an antiferromagnetic insulator. However, we do not observe any magnetic ordering in LaBaNiO4 down to 1.5 K, and despite its insulating transport properties several other physical properties of LaBaNiO4 resemble those of metallic LaSrNiO4. Based on an analysis of electrical and thermal-conductivity data as well as magnetic-susceptibility and low-temperature specific-heat measurements, we suggest that LaBaNiO4 is a Fermi glass with a finite electron density of states at the Fermi level but these states are localized.

  11. Complete Genome Sequence of the Methanogen Methanoculleus bourgensis BA1 Isolated from a Biogas Reactor

    PubMed Central

    Maus, Irena; Wibberg, Daniel; Winkler, Anika; Pühler, Alfred; Schnürer, Anna

    2016-01-01

    Methanoculleus bourgensis BA1, a hydrogenotrophic methanogen, was isolated from a laboratory-scale biogas reactor operating under an elevated ammonium concentration. Here, the complete genome sequence of M. bourgensis BA1 is reported. The availability of the BA1 genome sequence enables detailed comparative analyses involving other Methanoculleus spp. representing important members of microbial biogas communities. PMID:27340059

  12. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  13. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  14. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  15. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  16. Core-corona PSt/P(BA-AA) composite particles by two-stage emulsion polymerization

    NASA Astrophysics Data System (ADS)

    Xie, Delong; Ren, Xiaolin; Zhang, Xinya; Liao, Shijun

    2016-03-01

    Raspberry-shaped composite particles with polystyrene (PSt) as core and poly(n-butyl acrylate-co-acrylic acid) (P(BA-AA)) as corona were synthesized via emulsion polymerization. The random copolymer, P(BA-AA), was pre-prepared and used as a polymeric surfactant, its emulsifying properties adjusted by changing the mass ratio of BA and AA. The morphology of the resulting core-corona composite particles, P(St/P(BA-AA)), could be regulated and controlled by varying the concentrations of P(BA-AA) or the mass ratio of BA:AA in P(BA-AA). The experimental results indicate that 3.0-6.0 wt% of P(BA-AA) is required to obtain stable composite emulsions, and P(BA-AA) with a mass ratio of BA:AA = 1:2 is able to generate distinct core-corona structures. A mechanism of composite particle formation is proposed based on the high affinity between the PSt core and the hydrophobic segments of P(BA-A). The regular morphology of the colloidal film is expected to facilitate potential application of core-corona particles in the field of light scattering. Furthermore, the diversity of core-corona particles can be expanded by replacing P(BA-AA) corona particles with other amphiphilic particles.

  17. Superconductivity in Al-substituted Ba8Si46 clathrates

    NASA Astrophysics Data System (ADS)

    Li, Yang; Garcia, Jose; Chen, Ning; Liu, Lihua; Li, Feng; Wei, Yuping; Bi, Shanli; Cao, Guohui; Feng, Z. S.

    2013-05-01

    There is a great deal of interest vested in the superconductivity of Si clathrate compounds with sp3 network, in which the structure is dominated by strong covalent bonds among silicon atoms, rather than the metallic bonding that is more typical of traditional superconductors. A joint experimental and theoretical investigation of superconductivity in Al-substituted type-I silicon clathrates is reported. Samples of the general formula Ba8Si46-xAlx, with different values of x were prepared. With an increase in the Al composition, the superconducting transition temperature TC was observed to decrease systematically. The resistivity measurement revealed that Ba8Si42Al4 is superconductive with transition temperature at TC = 5.5 K. The magnetic measurements showed that the bulk superconducting Ba8Si42Al4 is a type II superconductor. For x = 6 sample Ba8Si40Al6, the superconducting transition was observed down to TC = 4.7 K which pointed to a strong suppression of superconductivity with increasing Al content as compared with TC = 8 K for Ba8Si46. Suppression of superconductivity can be attributed primarily to a decrease in the density of states at the Fermi level, caused by reduced integrity of the sp3 hybridized networks as well as the lowering of carrier concentration. These results corroborated by first-principles calculations showed that Al substitution results in a large decrease of the electronic density of states at the Fermi level, which also explains the decreased superconducting critical temperature within the BCS framework. The work provided a comprehensive understanding of the doping effect on superconductivity of clathrates.

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

    SciTech Connect

    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.

  19. Stellar Laboratories: 3. New Ba 5, Ba 6, and Ba 7 Oscillator Strengths and the Barium Abundance in the Hot White Dwarfs G191-B2B and RE 0503-289

    NASA Technical Reports Server (NTRS)

    Rauch, T.; Werner, K.; Quinet, P.; Kruk, Jeffrey Walter

    2014-01-01

    Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims. Reliable Ba 5-7 oscillator strengths are used to identify Ba lines in the spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and to determine their photospheric Ba abundances. Methods. We newly calculated Ba v-vii oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Ba lines exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results. For the first time, we identified highly ionized Ba in the spectra of hot white dwarfs. We detected Ba vi and Ba vii lines in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of RE 0503-289. The Ba vi/Ba vii ionization equilibrium is well reproduced with the previously determined effective temperature of 70 000 K and surface gravity of log g=7.5. The Ba abundance is 3.5 +/- 0.5 × 10(exp-4) (mass fraction, about 23 000 times the solar value). In the FUSE spectrum of G191-B2B, we identified the strongest Ba vii line (at 993.41 Å) only, and determined a Ba abundance of 4.0 +/- 0.5 × 10(exp-6) (about 265 times solar). Conclusions. Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Ba vi-vii line profiles in two white dwarfs' (G191-B2B and RE 0503-289) far-ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed to determine the photospheric Ba abundance of these two stars precisely.

  20. Co{sub 2}FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers

    SciTech Connect

    Rogge, J.; Schmalhorst, J.; Hütten, A.; Hetaba, W.

    2015-07-15

    We succeed to integrate BaO as a tunneling barrier into Co{sub 2}FeAl based magnetic tunnel junctions (MTJs). By means of Auger electron spectroscopy it could be proven that the applied annealing temperatures during BaO deposition and afterwards do not cause any diffusion of Ba neither into the lower Heusler compound lead nor into the upper Fe counter electrode. Nevertheless, a negative tunnel magnetoresistance (TMR) ratio of -10% is found for Co{sub 2}FeAl (24 nm) / BaO (5 nm) / Fe (7 nm) MTJs, which can be attributed to the preparation procedure and can be explained by the formation of Co- and Fe-oxides at the interfaces between the Heusler and the crystalline BaO barrier by comparing with theory. Although an amorphous structure of the BaO barrier seems to be confirmed by high-resolution transmission electron microscopy (TEM), it cannot entirely be ruled out that this is an artifact of TEM sample preparation due to the sensitivity of BaO to moisture. By replacing the BaO tunneling barrier with an MgO/BaO double layer barrier, the electric stability could effectively be increased by a factor of five. The resulting TMR effect is found to be about +20% at room temperature, although a fully antiparallel state has not been realized.

  1. Superconducting EuBa 2Cu 3O 7-δ and YbBa 2Cu 3O 7-δ produced by oxidation of microcrystalline precursor alloys

    NASA Astrophysics Data System (ADS)

    Weiss, F.; Yavari, A. R.; Rouault, A.; Hadar, R.; Senateur, J. P.; Desre, P.

    1988-06-01

    EuBa2Cu3 and YbBa2Cu3 microcrystalltne alloys obtained by rapid solidification have been oxidized completely in flowing oxygen at a temperature higher than 900° C with subsequent slow cooling and have yield the high temperature oxides EuBa2Cu37-δ and YbBa2Cu3O7-δ. The onset of superconductivity occured at 92 K in the case of Eu and at 89 K in the case of Yb. The resistivity in the normal state ( ρ at 100 K) is lower than in sintered powder materials Sue to a better compaction and to a better intergrain coupling.

  2. The effects of BaSO₄ loading on OPC cementing system for encapsulation of BaSO₄ scale from oil and gas industry.

    PubMed

    Hussein, O; Utton, C; Ojovan, M; Kinoshita, H

    2013-10-15

    The BaSO4 scales obtained from piping decontamination from oil and gas industries are most often classified as low level radioactive waste. These wastes could be immobilised by stable cement matrix to provide higher safety of handling, transportation, storage and disposal. However, the information available for the effects of the basic formulation such as waste loading on the fundamental properties is still limited. The present study investigated the effect of BaSO4 loading and water content on the properties of OPC-BaSO4 systems containing fine BaSO4 powder and coarse granules. The BaSO4 with different particle size had a marked effect on the compressive strength due to their different effects on hydration products formed. Introduction of fine BaSO4 powder resulted in an increased formation of CaCO3 in the system, which significantly contributed to the compressive strength of the products. Amount of water was important to control the CaCO3 formation, and water to cement ratio of 0.53 was found to be a good level to maintain a low porosity of the products both for fine BaSO4 powder and coarse BaSO4 granule. BaSO4 loading of up to 60 wt% has been achieved satisfying the minimum compressive strength of 5 MPa required for the radioactive wasteforms.

  3. Growth and transport properties of Y-Ba-Cu-O/Pr-Ba-Cu-O superlattices

    SciTech Connect

    Lowndes, D.H.; Norton, D.P.; Budai, J.D.; Christen, D.K.; Klabunde, C.E.; Warmack, R.J.; Pennycook, S.J.

    1990-01-01

    The pulsed-laser deposition method has been used to fabricate epitaxial, nonsymmetric M(Y) {times} N(Pr) superlattices in which YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) layers either M = 1,2,3,4,8, or 16 c-axis unit cells thick are separated by insulating PrBa{sub 2}Cu{sub 3}O{sub 7-x} (PBCO) layers N unit cells thick (N = 1 to {approximately}32). The zero-resistance superconducting transition temperature, T{sub c0}, initially decreases rapidly with increasing PBCO layer thickness, but then saturates at T{sub c0} {approximately} 19 K, 54 K, 71 K, or 80 K, or structures containing 1-,2-,3-, or 4-cell-thick YBCO layers, respectively. Critical current density measurements carried out on structures with 16- or 32-cell thick YBCO layers show that the magnitude of J{sub c}(H = 0) {approximately} 1-2 MA/cm{sup 2}, as well as the magnetic field dependence and the anisotropy of J{sub c}(H) all are in good agreement with corresponding measurements on thicker, single-layer YBCO films. Thus, there is no evidence of an enhanced J{sub c}(H) due to the multi-layered structure, for the layer thickness investigated to date. The systematic variation of T{sub c0}, as a function of the YBCO and PBCO layer thickness, is discussed in light of other recent experiments and theoretical model calculations. The superlattices' structural and compositional order are characterized using x-ray diffraction, transmission electron microscopy, and scanning tunneling microscopy, and details of the pulsed-laser deposition process are reported. 42 refs., 7 figs.

  4. The quasi-binary phase diagram BaF2-BaBr2 and its relation to the x-ray storage phosphor BaFBr : Eu2+

    NASA Astrophysics Data System (ADS)

    Kolb, R.; Schlapp, M.; Hesse, S.; Schmechel, R.; von Seggern, H.; Fasel, C.; Riedel, R.; Ehrenberg, H.; Fuess, H.

    2002-08-01

    In order to understand the formation and stoichiometry of the x-ray storage phosphor BaFBr : Eu2+, the phase diagram of the quasi-binary BaF2-BaBr2 system has been investigated. The phase diagram was obtained by means of differential thermal analysis and temperature controlled x-ray diffraction experiments. The resulting phase diagram indicates that BaFBr forms a compound with no detectable solid solubility for neither BaF2 nor BaBr2. Experiments to obtain non-stoichiometric BaFBr via the synthesis route using BaF2 and NH4Br as proposed in the literature could not be verified. It will be shown that the type of colour centre created during x-ray irradiation is related to the non-stoichiometry of the starting compositions before sintering. A surplus of either barium fluoride or barium bromide during sintering allows the controlled formation of F(Br-)- and F(F-)-centres, respectively.

  5. Unexpected size distribution of Ba(H2O)n clusters: why is the intensity of the Ba(H2O)1 cluster anomalously low?

    PubMed

    Cabanillas-Vidosa, Iván; Rossa, Maximiliano; Pino, Gustavo A; Ferrero, Juan C

    2011-08-07

    An experimental and theoretical study on the reactivity of neutral Ba atoms with water clusters has been conducted to unravel the origin of the irregular intensity pattern observed in one-photon ionization mass spectra of a Ba(H(2)O)(n)/BaOH(H(2)O)(n-1) (n = 1-4) cluster distribution, which was generated in a laser vaporization-supersonic expansion source. The most remarkable irregular feature is the finding for n = 1 of a lower intensity for the Ba(+)(H(2)O)(n) peak with respect to that of BaOH(+)(H(2)O)(n-1), which is opposite to the trend for n = 2-4. Rationalization of the data required consideration of a distinct behavior of ground-state and electronically excited state Ba atoms in inelastic and reactive Ba + (H(2)O)(n) encounters that can occur in the cluster source. Within this picture, the generation of Ba(H(2)O)(n) (n > 1) association products results from stabilizing collisions with atoms of the carrier gas, which are favored by intramolecular vibrational redistribution that operates on the corresponding collision intermediates prior to stabilization; the latter is unlikely to occur for Ba + (H(2)O) encounters. Overall, this interpretation is consistent with additional in-source laser excitation and quenching experiments, which aimed to explore qualitatively the effect of perturbing the Ba atom electronic state population distribution on the observed intensity pattern, as well as with the energetics of various possible reactions for the Ba + H(2)O system that derive from high level ab initio calculations.

  6. Superconductivity in the Graphite Intercalation Compound BaC(6).

    PubMed

    Heguri, Satoshi; Kawade, Naoya; Fujisawa, Takumi; Yamaguchi, Akira; Sumiyama, Akihiko; Tanigaki, Katsumi; Kobayashi, Mototada

    2015-06-19

    Among many two-dimensional (2D) high T(C) superconductors, graphite intercalation compounds (GICs) are the most famous intercalation family, which are classified as typical electron-phonon mediated superconductors. We show unambiguous experimental facts that BaC(6), the superconductivity of which has been missing for many years so far among various alkaline earth metal (Ca, Sr, and Ba) intercalted GICs, exhibits superconductivity at T(C)=65  mK. By adding this finding as the additional experimental point, a complete figure displaying the relationship between T(C) and interlayer distance (d) for GICs is now provided, and their possible superconducting mechanisms raised so far are revisited. The present study settles a long-running debate between theories and experiments on the superconductivity in the first stage GICs.

  7. BaTMAn: Bayesian Technique for Multi-image Analysis

    NASA Astrophysics Data System (ADS)

    Casado, J.; Ascasibar, Y.; García-Benito, R.; Guidi, G.; Choudhury, O. S.; Bellocchi, E.; Sánchez, S. F.; Díaz, A. I.

    2016-12-01

    Bayesian Technique for Multi-image Analysis (BaTMAn) characterizes any astronomical dataset containing spatial information and performs a tessellation based on the measurements and errors provided as input. The algorithm iteratively merges spatial elements as long as they are statistically consistent with carrying the same information (i.e. identical signal within the errors). The output segmentations successfully adapt to the underlying spatial structure, regardless of its morphology and/or the statistical properties of the noise. BaTMAn identifies (and keeps) all the statistically-significant information contained in the input multi-image (e.g. an IFS datacube). The main aim of the algorithm is to characterize spatially-resolved data prior to their analysis.

  8. Superconductivity in the Graphite Intercalation Compound BaC 6

    NASA Astrophysics Data System (ADS)

    Heguri, Satoshi; Kawade, Naoya; Fujisawa, Takumi; Yamaguchi, Akira; Sumiyama, Akihiko; Tanigaki, Katsumi; Kobayashi, Mototada

    2015-06-01

    Among many two-dimensional (2D) high TC superconductors, graphite intercalation compounds (GICs) are the most famous intercalation family, which are classified as typical electron-phonon mediated superconductors. We show unambiguous experimental facts that BaC 6 , the superconductivity of which has been missing for many years so far among various alkaline earth metal (Ca, Sr, and Ba) intercalted GICs, exhibits superconductivity at TC=65 mK . By adding this finding as the additional experimental point, a complete figure displaying the relationship between TC and interlayer distance (d ) for GICs is now provided, and their possible superconducting mechanisms raised so far are revisited. The present study settles a long-running debate between theories and experiments on the superconductivity in the first stage GICs.

  9. Thermoelectric properties of topological insulator BaSn2

    NASA Astrophysics Data System (ADS)

    Guo, San-Dong; Qiu, Liang

    2017-01-01

    Recently, \\text{BaS}{{\\text{n}}2} has been predicted to be a strong topological insulator by the first-principle calculations. It is well known that topological insulators have a close connection to thermoelectric materials, such as the \\text{B}{{\\text{i}}2}\\text{T}{{\\text{e}}3} family. In this work, we investigate thermoelectric properties of \\text{BaS}{{\\text{n}}2} by the first-principles calculations combined with the Boltzmann transport theory. The electronic part is carried out by a modified Becke and Johnson (mBJ) exchange potential, including spin-orbit coupling (SOC), while the phonon part is performed using a generalized gradient approximation (GGA). It was found that the electronic transport coefficients between the in-plane and cross-plane directions showed strong anisotropy, while lattice-lattice thermal conductivities demonstrated almost complete isotropy. Calculated results revealed a very low lattice thermal conductivity for \\text{BaS}{{\\text{n}}2} , and the corresponding average lattice thermal conductivity at room temperature is 1.69 \\text{W}~{{\\text{m}}-1}~{{\\text{K}}-1} , which is comparable or lower than those of lead chalcogenides and bismuth-tellurium systems as classic thermoelectric materials. Due to the complicated scattering mechanism, calculating the scattering time τ is challenging. By using an empirical τ ={{10}-14} s, the n-type figure of merit ZT is greater than 0.40 in wide temperature ranges. Experimentally, it is possible to attain better thermoelectric performance by strain or tuning size parameters. This work indicates that \\text{BaS}{{\\text{n}}2} may be a potential thermoelectric material, which can stimulate further theoretical and experimental work.

  10. Superconductivity in noncentrosymmetric BaAl4 derived structures

    NASA Astrophysics Data System (ADS)

    Kneidinger, F.; Salamakha, L.; Bauer, E.; Zeiringer, I.; Rogl, P.; Blaas-Schenner, C.; Reith, D.; Podloucky, R.

    2014-07-01

    Ternary intermetallics Ep-T-X, crystallizing in ordered variants of the BaAl4 structure type, have been investigated systematically with respect to their formation and stability. For this, a comprehensive overview of the BaAl4 derivative structure types including group-subgroup relations was established. Special emphasis was laid on compounds where inversion symmetry is missing in the respective crystal structures and where superconductivity is observed at low temperatures. EpTX3 compounds crystallize in the noncentrosymmetric BaNiSn3 structure type (space-group I4mm; a ≈0.4 and c ≈1 nm), an ordered ternary derivative of BaAl4. Superconductivity below 3 K was found for seven members of this series, as evidenced from heat capacity and electrical resistivity measurements. Although the Rashba-like spin-orbit coupling in noncentrosymmetric systems can enable a mixture of spin-singlet and spin-triplet pairs in the superconducting condensate, the experimental data basically indicate a predominant s-wave superconducting state in all of these compounds. For this family of compounds, fully relativistic density functional theory (DFT) calculations of the electronic structure and phonon properties were done. Despite the different size of spin-orbit coupling depending on the actual choice of elements for Ep, T, and X that result in different spin-orbit splittings of the Fermi surfaces, the experimental observation of a prevalent spin-singlet pairing in the superconducting phases of the EpTX3 compounds is supported.

  11. Analysis of Jupiter’s Oval BA: A streamlined approach

    NASA Astrophysics Data System (ADS)

    Sussman, Michael G.; Chanover, Nancy J.; Simon-Miller, Amy A.; Vasavada, Ashwin R.; Beebe, Reta F.

    2010-11-01

    We present a novel method of constructing streamlines to derive wind speeds within jovian vortices and demonstrate its application to Oval BA for 2001 pre-reddened Cassini flyby data, 2007 post-reddened New Horizons flyby data, and 1998 Galileo data of precursor Oval DE. Our method, while automated, attempts to combine the advantages of both automated and manual cloud tracking methods. The southern maximum wind speed of Oval BA does not show significant changes between these data sets to within our measurement uncertainty. The northern maximum does appear to have increased in strength during this time interval, which likely correlates with the oval's return to a symmetric shape. We demonstrate how the use of closed streamlines can provide measurements of vorticity averaged over the encircled area with no a priori assumptions concerning oval shape. We find increased averaged interior vorticity between pre- and post-reddened Oval BA, with the precursor Oval DE occupying a middle value of vorticity between these two.

  12. Electronic States of IC60BA and PC71BM

    NASA Astrophysics Data System (ADS)

    Sheng, Chun-Qi; Wang, Peng; Shen, Ying; Li, Wen-Jie; Zhang, Wen-Hua; Zhu, Jun-Fa; Lai, Guo-Qiao; Li, Hong-Nian

    2013-11-01

    We investigate the electronic states of IC60BA and PC71BM using first-principles calculations and photoelectron spectroscopy (PES) measurements. The energy level structures for all possible isomers are reported and compared with those of C60, C70 and PC61BM. The attachment of the side chains can raise the LUMO energies and decrease the HOMO-LUMO gaps, and thus helps to increase the power-conversion efficiency of bulk heterojunction solar cells. In the PES studies, we prepared IC60BA and PC71BM films on Si:H(111) substrates to construct adsorbate/substrate interfaces describable with the integer charge-transfer (ICT) model. Successful measurements then revealed that one of the most important material properties for an electron acceptor, the energy of the negative integer charge-transfer state (EICT-), is 4.31 eV below the vacuum level for PC71BM. The EICT- of IC60BA is smaller than 4.14 eV.

  13. Analysis of Jupiter's Oval BA: A Streamlined Approach

    NASA Technical Reports Server (NTRS)

    Sussman, Michael G.; Chanover, Nancy J.; Simon-Miller, Amy A.; Vasavada, Ashwin R.; Beebe, Reta F.

    2010-01-01

    We present a novel method of constructing streamlines to derive wind speeds within jovian vortices and demonstrate its application to Oval BA for 2001 pre-reddened Cassini flyby data, 2007 post-reddened New Horizons flyby data, and 1998 Galileo data of precursor Oval DE. Our method, while automated, attempts to combine the advantages of both automated and manual cloud tracking methods. The southern maximum wind speed of Oval BA does not show significant changes between these data sets to within our measurement uncertainty. The northern maximum dries appear to have increased in strength during this time interval, tvhich likely correlates with the oval's return to a symmetric shape. We demonstrate how the use of closed streamlines can provide measurements of vorticity averaged over the encircled area with no a priori assumptions concerning oval shape. We find increased averaged interior vorticity between pre- and post-reddened Oval BA, with the precursor Oval DE occupying a middle value of vorticity between these two.

  14. Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl: Interesting size effects originated from the tetrahedral anions

    SciTech Connect

    Pan, Ming-Yan; Xia, Sheng-Qing Liu, Xiao-Cun; Tao, Xu-Tang

    2014-11-15

    Two new barium chalcogenides, Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl, were synthesized by using high temperature solid-state reactions and their structures were determined by single-crystal X-ray diffraction technique. Despite the similar chemical formula, the structures of Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl are subtly different due to the size effects originated from the tetrahedral anions. Ba{sub 3}GeS{sub 5} crystallizes in the orthorhombic space group Pnma (no. 62) with cell parameters of a=12.0528(9) Å, b=9.5497(7) Å and c=8.5979(6) Å, while Ba{sub 3}InS{sub 4}Cl adopts a different tetragonal system (space group: I4/mcm, no. 140, a=b=8.3613(6) Å, c=14.3806(18) Å). The measured optical band gap of Ba{sub 3}GeS{sub 5} is 3.0 eV, a little smaller than the value of 3.42 eV in Ba{sub 3}InS{sub 4}Cl. Theoretical calculations by Wien2k are provided as well in order to better understand these results. - Graphical abstract: The polyhedral structure view for Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl in which Ba, S and Cl atoms are plotted in purple, red and green spheres. - Highlights: • Two new barium chalcogenides, Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl, were synthesized from the BaCl{sub 2}-flux reactions. • Their crystal structures feature discrete [MS{sub 4}] tetrahedra which embody interesting size effects. • Both compounds exhibit a band gap around 3.0 eV. • They are thermally stable up to 1073 K.

  15. Structural and chemical characterization of BaTiO{sub 3} nanorods

    SciTech Connect

    Zagar, K.; Recnik, A.; Sturm, S.; Gajovic, A.; Ceh, M.

    2011-03-15

    Research highlights: {yields} Polycrystalline BaTiO{sub 3} nanorods were synthesized with EPD into AAO templates. {yields} Nanorods are composed of crystalline, nanosized grains with pseudo-cubic structure. {yields} Integrowth of hexagonal BaTiO{sub 3} polymorph within pseudo-cubic structure was observed. -- Abstract: An electron-microscopy investigation was performed on BaTiO{sub 3} nanorods that were processed by sol-gel electrophoretic deposition (EPD) into anodic aluminium oxide (AAO) membranes. The BaTiO{sub 3} nanorods grown within the template membranes had diameters ranging from 150 to 200 nm, with an average length of 10-50 {mu}m. By using various electron-microscopy techniques we showed that the processed BaTiO{sub 3} nanorods were homogeneous in their chemical composition. The BaTiO{sub 3} nanorods were always polycrystalline and were composed of well-crystallized, defect-free, pseudo-cubic BaTiO{sub 3} grains, ranging from 10 to 30 nm. No intergranular phases were observed between the BaTiO{sub 3} grains. A low-temperature hexagonal polymorph that is coherently intergrown with the BaTiO{sub 3} perovskite matrix was also observed as a minor phase. When annealing the AAO templates containing the BaTiO{sub 3} sol in an oxygen atmosphere the presence of the hexagonal polymorph was diminished.

  16. Calculated g -factors of 5 d double perovskites Ba2NaOsO6 and Ba2YOsO6

    NASA Astrophysics Data System (ADS)

    Ahn, Kyo-Hoon; Pajskr, Karel; Lee, Kwan-Woo; Kuneš, Jan

    2017-02-01

    Using Wannier functions to represent the density functional results we calculate the hybridization corrections to the orbital momentum operator in the Os 5 d shell of the Mott insulators Ba2NaOsO6 and Ba2YOsO6 . The g -factors are obtained by evaluating the spin and orbital momentum operators in the atomic ground states of the Os ion. While the hybridization corrections play a minor role in the d3 ion of Ba2YOsO6 with a dominant spin moment, they are instrumental for the observation of the nonzero g -factor of the d1 ions of Ba2NaOsO6 . In addition, we analyze the exchange interactions in Ba2YOsO6 and find them to be consistent with the reported magnetic structure.

  17. XANES and micro-Raman spectroscopy study of the barium titanosilicates BaTiSi2O7 and BaTiSi4O11

    NASA Astrophysics Data System (ADS)

    Viani, A.; Pollastri, S.; Macova, P.; Palermo, A.; Peréz-Estébanez, M.; Gualtieri, A. F.

    2016-04-01

    The coordination environment around Ti4+ in the photoluminescent compound BaTiSi2O7 and in BaTiSi4O11 was investigated with X-ray absorption near-edge structure spectroscopy and micro-Raman spectroscopy. The presence of VTi in TiO5 pyramidal units with one short Ti-O bond involving the apical oxygen was detected in both compounds. Interpretation of the vibrational signal from the silicate framework suggested that BaTiSi4O11 is a metasilicate containing building units of SiO4 tetrahedra, which are larger than in other barium titanosilicates. These results confirmed the same structural environment of Ti4+ as recently disclosed by structure refinement of BaTiSi2O7 and provided new insights into the unknown structure of BaTiSi4O11 in the light of the study of its physical properties as potential functional material.

  18. Electronic properties of BaCuChF (Ch=S,Se,Te) surfaces and BaCuSeF/ZnPc interfaces

    NASA Astrophysics Data System (ADS)

    Zakutayev, Andriy; Tate, Janet; Platt, Heather A. S.; Keszler, Douglas A.; Hein, Corinna; Mayer, Thomas; Klein, Andreas; Jaegermann, Wolfram

    2010-05-01

    BaCuChF (Ch=S,Se,Te) surfaces and BaCuSeF interfaces with zinc phthalocyanine (ZnPc) were studied by photoelectron spectroscopy. BaCuChF compounds oxidize when exposed to ambient atmosphere. Se capping layers were studied as a means to produce representative surfaces for photoelectron spectroscopic measurements. Decapped BaCuSeF surfaces remain O-free and C-free when the Se layer is evaporated but they become F-deficient. The resulting surfaces have work functions of 4.85 eV and Fermi levels located 0.25 eV above the valence band maximum. In situ stepwise deposition of ZnPc on a BaCuSeF film surface produced a chemically inert interface with a hole-injection barrier of 0.11 eV.

  19. Advective excess Ba transport as shown from sediment and trap geochemical signatures

    SciTech Connect

    Fagel, N.; Andre, L.; Dehairs, F.

    1999-08-01

    The authors report the results of a geochemical study of sediment and trap material. Major and trace elements (Zr, Ba, rare earth elements, and Th) were analyzed on bulk sedimentary material collected along the NE Atlantic margin. The aim is to test the widespread use of Ba-barite as a proxy for paleoproductivity in a continental margin area. This environment is of great interest because atmospheric-oceanic exchanges are important. In sediments, the geochemical signatures remain close to an upper crust reference, with flat shale-normalized rare earth elements patterns and constant elementary ratios. The calculated biogenic fraction of Ba or excess Ba (20--45%) remains lower than the excess Ba record in trap material (80--99%). The evolution of the geochemical signature along the margin reflects variable dilution of a detrital Post Archean Australian Shale-like component by a biogenic carbonaceous seawater-derived component. The trap material displays a wide range of variation in its trace element content (e.g., Ba {approximately}150--3,000 ppm, Zr {approximately}2--100 ppm), except for the abyssal site, which is characterized by constant signature. In the two other sites, all of the trace element contents increase with water depth and present pronounced seasonal changes at each sampled water depth. The amount of excess Ba also increases in the deepest traps, and its evolution throughout the year mimics the change of the other analyzed trace elements. In contrast, its relationships with particulate organic carbon are not obvious. In terms of fluxes, two periods of enhanced excess Ba fluxes are observed: (1) excess Ba flux increases with the detrital-like elements like Th especially during winter, and (2) excess Ba flux is enhanced without any change for the other trace elements during spring. To explain the first case, a supply through lateral advection is proposed. Such transient input of significant excess Ba flux will have a great impact on the yearly averaged

  20. Laser-induced synthesis of BaMoO4 nanocolloidal suspension and its optical properties

    NASA Astrophysics Data System (ADS)

    Ryu, Jeong Ho; Kim, Kang Min; Mhin, Sung Wook; Park, Gyeong Seon; Eun, Jong Won; Shim, Kwang Bo; Lim, Chang Sung

    2008-08-01

    Pulsed laser ablation in a liquid phase was successfully employed to synthesize a barium molybdate (BaMoO4) nanocolloidal suspension. The nanocolloidal suspension was composed of well-dispersed and horizontally assembled BaMoO4 aggregates. The BaMoO4 aggregates showed predominantly elliptically shaped nanorods with sizes between 100 and 200 nm. The preferential elliptical growth was rationalized from the viewpoint of the intrinsic structure of BaMoO4. The optical properties of the prepared BaMoO4 colloidal nanoparticles were investigated using Raman spectroscopy, UV vis spectroscopy and photoluminescence (PL) spectrophotometry. The optical band gap was estimated by Tauc and Menth’s law. The PL emission feature was decomposed into several individual Gaussian components, which could be interpreted by a Jahn Teller splitting effect on the [MoO4]2- tetrahedron of the BaMoO4 colloidal nanoparticles.

  1. Water adsorption induced in-plane domain switching on BaTiO{sub 3} surface

    SciTech Connect

    Li, X.; Bai, Y.; Su, Y. J.; Wang, B. C.

    2015-09-07

    In this study, the influences of the adsorption of water molecules on the changes in the atomic and electric structures of BaTiO{sub 3} surface were investigated using ab initio calculation. Water molecules are molecularly and dissociatively adsorbed on the BaTiO{sub 3} surface, which makes electrons transfer from water molecules to the BaTiO{sub 3} surface. The redistribution of electrons in the BaTiO{sub 3} surface layers weakens the Ba-O interactions and strengthens the Ti-O interactions, so that the Ti atom shifts in TiO{sub 2} plane, i.e., an in-plane domain switching. The adsorption of water molecules on BaTiO{sub 3} surfaces also results in a reduction in the surface rumpling.

  2. Electrical and Optical Property of Ferroelectric BaTiO3:Eu

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon; Grichener, Alexander; Jensen, Jacob; Choi, Sang H.

    2005-01-01

    We studied various electrical and optical properties of Europium (1 atomic %) incorporated BaTiO3 film on n-Si(100) substrate. The thin film structure was analyzed by X-ray diffraction. Film thickness and optical refractive index were measured with an ellipsometer. P-E hysteresis measurement shows the remnant polarization of 37 micro C/sq cm in BaTiO3:Eu film. C-V measurements on the pure BaTiO3 film show recovery of capacitance across sweeping voltage ranges with a narrow transition zone due to the polarization change. On the other hand, C-V and I-V measurements on the BaTiO3:Eu film show that Europium incorporation increases positively charged states in the BaTiO3 layer such that BaTiO3:Eu/n-Si interface behaves like a leaky p-n junction.

  3. Growth of single crystals of BaFe12O19 by solid state crystal growth

    NASA Astrophysics Data System (ADS)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-10-01

    Single crystals of BaFe12O19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe12O19 are buried in BaFe12O19+1 wt% BaCO3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe12O19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe12O19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth.

  4. Interfacial reactions and microstructure of BaTiO 3 films prepared using fluoride precursor method

    NASA Astrophysics Data System (ADS)

    Fujihara, Shinobu; Schneller, Theodor; Waser, Rainer

    2004-01-01

    Interfacial reactions of BaF 2 and TiO 2 were investigated in preparing BaTiO 3 thin films using a fluoride precursor method. Trifluoroacetate solutions were prepared from barium acetate, titanium tetraisopropoxide (TTIP), and trifluoroacetic acid (TFA, CF 3COOH) with additives such as water and acetylacetone. The solutions were deposited on platinized Si wafers by spin-coating, were pyrolysed at 400 °C in air and were finally heated typically at 700 °C in a water vapor atmosphere. The perovskite BaTiO 3 phase was obtained although a small portion of BaF 2 remained unreacted. Thus, the films were characterized as the mixture of BaTiO 3, BaF 2, and amorphous TiO 2. Influence of the solution chemistry on the phase evolution and microstructure was examined in order to discuss the reaction pathway of the perovskite phase.

  5. Enhancement of p-type conductivity in nanocrystalline BaTiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Guo, Xin; Pithan, Christian; Ohly, Christian; Jia, Chun-Lin; Dornseiffer, Jügen; Haegel, Franz-Hubert; Waser, Rainer

    2005-02-01

    Undoped BaTiO3 ceramic samples with an average grain size of ˜35nm were prepared and the electrical properties investigated. The defect structure is dominated by acceptor impurities; therefore, the conductivity of nanocrystalline BaTiO3 is of p-type. Comparing with microcrystalline BaTiO3, the conductivity of nanocrystalline BaTiO3 is about 1 to 2 orders of magnitude higher and the activation energy remarkably lower, which is ascribed to a greatly reduced oxidation enthalpy in nanocrystalline BaTiO3 (˜0.3 versus ˜0.92eV for microcrystalline BaTiO3).

  6. Dimension effects on the dielectric properties of fine BaTiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Hou, Zhi-Wen; Kang, Ai-Guo; Ma, Wei-Qing; Zhao, Xiao-Long

    2014-11-01

    It is found that the core-shell structured grains are easy to produce for fine grain doped BaTiO3 ceramics in the sintering process. We study the influence of the core-shell structure on the Curie—Weiss temperature and dielectric properties of BaTiO3 ceramics by using effective medium approximation (EMA). Considering the second approximation, the dielectric properties of fine grain doped BaTiO3 ceramics are consistent with experimental data.

  7. Ba{sub 2}TeO: A new layered oxytelluride

    SciTech Connect

    Besara, T.; Ramirez, D.; Sun, J.; Whalen, J.B.; Tokumoto, T.D.; McGill, S.A.; Singh, D.J.; Siegrist, T.

    2015-02-15

    Single crystals of the new semiconducting oxytelluride phase, Ba{sub 2}TeO, were synthesized from barium oxide powder and elemental tellurium in a molten barium metal flux. Ba{sub 2}TeO crystallizes in tetragonal symmetry with space group P4/nmm (#129), a=5.0337(1) Å, c=9.9437(4) Å, Z=2. The crystals were characterized by single crystal x-ray diffraction, heat capacity and optical measurements. The optical measurements along with electronic band structure calculations indicate semiconductor behavior with a band gap of 2.93 eV. Resistivity measurements show that Ba{sub 2}TeO is highly insulating. - Graphical abstract: Starting from a simple stacking of rocksalt layers, the final structure of Ba{sub 2}TeO can be obtained by accommodation of structural strain via atom displacements. Density of states calculations and optical absorbance measurements show that Ba{sub 2}TeO has a band gap of 2.93 eV, indicative of semiconductor behavior. - Highlights: • Single crystal synthesis of a new layered oxytelluride, Ba{sub 2}TeO. • The structure features inverse PbO-type BaO layers and NaCl-type BaTe layers. • Optical absorbance show Ba{sub 2}TeO to be a semiconductor with a 2.93 eV gap. • Density of states indicate a small hybridization between Te 5p and Ba 5d states. • The BaTe (BaO) layers dominate the heat capacity at low (high) temperatures.

  8. Reflection Asymmetric Shapes in the Neutron-Rich 140,143Ba Isotopes

    NASA Astrophysics Data System (ADS)

    Zhu Sheng-jiang (S, J. Zhu; Wang, Mu-ge; J, H. Hamilton; A, V. Ramayya; B, R. S. Babu; W, C. Ma; Long, Gui-lu; Deng, Jing-kang; Zhu, Ling-yan; Li, Ming; T, N. Ginter; J, Komicki; J, D. Cole; R, Aryaeinejad; Y, K. Dardenne; M, W. Drigert; J, O. Rasmussen; Ts, Yu Oganessian; M, A. Stoyer; S, Y. Chu; K, E. Gregorich; M, F. Mohar; S, G. Prussin; I, Y. Lee; N, R. Johnson; F, K. McGowan

    1997-08-01

    Level schemes for the neutron-rich 140,143Ba nuclei have been determined by study of prompt γ-rays in spontaneous fission of 252Cf. The level pattern and enhanced E1 transitions between π = + and π = - bands show reflection asymmetric shapes with simplex quantum number s = +1 in 140Ba and s = ±i in 143Ba, respectively. The octupole deformation stability with spin variation has been discussed.

  9. Light Sensitive Lattice Defects In BaTiO3 Containing Fe

    NASA Astrophysics Data System (ADS)

    Possenriede, Ewald; Schirmer, Ortwin F.; Godefroy, Genevieve; Maillard, Alain

    1989-01-01

    Electron spin resonance spectra, which can consistently be explained by the models Fe4+ - Vo and Fe5+ - vBa, have been observed with BaTiO3 containing Fe. Also Fe3+ and - Fe3+ - Vo have been identified. All these centers as well as several unidentified ones are observed to change their charge states under illumination. They thus are possibly in involved in photorefractive processes in BaTiO3 containing Fe.

  10. Piezoelectric and Dielectric Properties of Multilayered BaTiO3/(Ba,Ca)TiO3/CaTiO3 Thin Films.

    PubMed

    Zhu, Xiao Na; Gao, Ting Ting; Xu, Xing; Liang, Wei Zheng; Lin, Yuan; Chen, Chonglin; Chen, Xiang Ming

    2016-08-31

    Highly oriented multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films were fabricated on Nb-doped (001) SrTiO3 (Nb:STO) substrates by pulsed laser deposition. The configurations of multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films are designed with the thickness ratio of 1:1:1 and 2:1:1 and total thickness ∼300 nm. Microstructural characterization by X-ray diffraction indicates that the as-deposited thin films are highly c-axis oriented and large in-plane strain is determined in BaTiO3 and CaTiO3 layers. Piezoresponse force microscopy (PFM) studies reveal an intense in-plane polarization component, whereas the out-of-plane shows inferior phase contrast. The optimized combination is found to be the BaTiO3-(Ba0.85Ca0.15)TiO3-CaTiO3 structure with combination ratio 2:1:1, which displays the largest domain switching amplitude under DC electric field, the largest room-temperature dielectric constant ∼646, a small dielectric loss of 0.03, and the largest dielectric tunability of ∼50% at 400 kV/cm. These results suggest that the enhanced dielectric and tunability performance are greatly associated with the large in-plane polarization component and domain switching.

  11. From Ba3Ta5O14N to LaBa2Ta5O13N2: Decreasing the optical band gap of a photocatalyst

    NASA Astrophysics Data System (ADS)

    Anke, B.; Bredow, T.; Pilarski, M.; Wark, M.; Lerch, M.

    2017-02-01

    Yellow LaBa2Ta5O13N2 was successfully synthesized as phase-pure material crystallizing isostructurally to previously reported Ba3Ta5O14N and mixed-valence Ba3TaV4TaIVO15. The electronic structure of LaBa2Ta5O13N2 was studied theoretically with the range-separated hybrid method HSE06. The most stable structure was obtained when lanthanum was placed on 2a and nitrogen on 4h sites confirming Pauling's second rule. By incorporating nitrogen, the measured band gap decreases from ∼3.8 eV for the oxide via 2.74 eV for Ba3Ta5O14N to 2.63 eV for the new oxide nitride, giving rise to an absorption band well in the visible-light region. Calculated fundamental band gaps confirm the experimental trend. The atom-projected density of states has large contributions from N2p orbitals close to the valence band edge. These are responsible for the observed band gap reduction. Photocatalytic hydrogen formation was investigated and compared with that of Ba3Ta5O14N revealing significantly higher activity for LaBa2Ta5O13N2 under UV-light.

  12. Structure and stability of BaTiSi₂O₇.

    PubMed

    Viani, Alberto; Palermo, Andrea; Zanardi, Stefano; Demitri, Nicola; Petrícek, Václav; Varini, Federico; Belluso, Elena; Ståhl, Kenny; Gualtieri, Alessandro Francesco

    2015-04-01

    Due to their optical, photo-luminescence (PL), and afterglow properties, barium titanosilicates are compounds of great interest for functional materials and light-emitting devices. Among them, BaTiSi2O7 (BTS2) is certainly one of the most intriguing; it displays peculiar properties (e.g. PL orange emission) whose exhaustive explanation has been hampered to date by the lack of a structure model. In this work, BTS2 and the related compound BaTiSi4O11 (BTS4) were synthesized through conventional solid-state reaction methods. BTS2 invariably shows complex twinning patterns. Thus, its structure solution and Rietveld structure refinement were attempted using synchrotron powder diffraction. BTS2 was found to be an intergrowth of monoclinic and triclinic crystals. The monoclinic phase has the space group P21/n and unit cell a = 7.9836 (3), b = 10.0084 (4), c = 7.4795 (3) Å, and β = 100.321 (3)°, whereas the triclinic phase has the space group P\\bar 1 and unit cell a = 7.99385 (4), b = 10.01017 (5), c = 7.47514 (3) Å, α = 90.084 (8), β = 100.368 (8) and γ = 89.937 (9)°. These lattices can be seen as a distortion of that of tetragonal synthetic β-BaVSi2O7 with Ti in place of V. The structure models obtained from this study confirm the presence of fivefold coordinated Ti atoms in a distorted pyramidal configuration. The proposed solution supports existing theories for the explanation of the PL orange colour in BTS2.

  13. Enhanced 77 K vortex-pinning in Y Ba2Cu3O7-x films with Ba2Y TaO6 and mixed Ba2Y TaO6 + Ba2Y NbO6 nano-columnar inclusions with irreversibility field to 11 T

    NASA Astrophysics Data System (ADS)

    Rizzo, F.; Augieri, A.; Angrisani Armenio, A.; Galluzzi, V.; Mancini, A.; Pinto, V.; Rufoloni, A.; Vannozzi, A.; Bianchetti, M.; Kursumovic, A.; MacManus-Driscoll, J. L.; Meledin, A.; Van Tendeloo, G.; Celentano, G.

    2016-06-01

    Pulsed laser deposited thin Y Ba2Cu3O7-x (YBCO) films with pinning additions of 5 at. % Ba2Y TaO6 (BYTO) were compared to films with 2.5 at. % Ba2Y TaO6 + 2.5 at. % Ba2Y NbO6 (BYNTO) additions. Excellent magnetic flux-pinning at 77 K was obtained with remarkably high irreversibility fields greater than 10 T (YBCO-BYTO) and 11 T (YBCO-BYNTO), representing the highest ever achieved values in YBCO films.

  14. Induced antiferromagnetism in Mn doped BaMgF{sub 4}

    SciTech Connect

    Manikandan, M. Muthukumaran, A. Venkateswaran, C.

    2014-04-24

    Pure and Mn doped BaMgF{sub 4} samples have been synthesized by the hydrothermal method. X-ray diffraction (XRD) pattern of both the samples reveal the formation of pure BaMgF{sub 4} phase. High resolution scanning electron micrographs (HRSEM) show rectangular shape particles. At room temperature, the undoped BaMgF{sub 4} shows diamagnetic behavior where as the 5% Mn doped BaMgF{sub 4} exhibits antiferromagnetic hysteresis loop. The possible reason for room temperature antiferromagnetism and the role of dopant ion have been investigated.

  15. Low-Temperature Synthesis, Structure, and Stability of Ba 2+ yCu 3O 6

    NASA Astrophysics Data System (ADS)

    Brosha, Eric L.; Garzon, Fernando H.; Raistrick, Ian D.; Davies, Peter K.

    1996-02-01

    Single-phase powders of Ba2Cu3O6have been prepared at 620°C under 1 atm of oxygen using freeze-dried nitrate precursors. Calcinations utilizing a precursor with a 1:1 Ba:Cu stoichiometry produced a two-phase mixture of BaO2+ Ba2Cu3O6and confirmed the stable, oxidized barium cuprate exists with a metal ion ratio close to 2:3. Diffraction studies suggest that Ba2Cu3O6(Ba0.67CuO2) crystallizes in a structure closely related to the linear chain KCuO2and NaCuO2cuprates. It is proposed that the reduction of copper and accompanying loss of oxygen observed above 620°C are accommodated by an increase in the Ba content of the structure and the formation of Ba2+yCu3O6with 0 ≤y≤ 0.25. Above 710°C, the high-yend member is metastable with respect to BaCuO2, although it decomposes slowly even at elevated temperatures.

  16. Method of forming superconducting Tl-Ba-Ca-Cu-O films

    DOEpatents

    Wessels, Bruce W.; Marks, Tobin J.; Richeson, Darrin S.; Tonge, Lauren M.; Zhang, Jiming

    1993-01-01

    A method of forming a superconducting Tl-Ba-Ca-Cu-O film is disclosed, which comprises depositing a Ba-Ca-Cu-O film on a substrate by MOCVD, annealing the deposited film and heat-treating the annealed film in a closed circular vessel with TlBa.sub.2 Ca.sub.2 Cu.sub.3 O.sub.x and cooling to form said superconducting film of TlO.sub.m Ba.sub.2 Ca.sub.n-1 Cu.sub.n O.sub.2n+2, wherein m=1,2 and n=1,2,3.

  17. A teleost complement factor Ba possesses antimicrobial activity and inhibits bacterial infection in fish.

    PubMed

    Li, Xue-Peng; Sun, Li

    2017-01-24

    Complement factor B (Bf) is a component of the complement system. Following activation of the alternative pathway of the complement system, factor B is cleaved into Ba and Bb fragments. In fish, the Bf of rainbow trout is known to act as a C3 convertase, but the function of the Ba fragment is essentially unknown. In this study, we examined the expression patterns of tongue sole Cynoglossus semilaevis Bf (named CsBf) and the biological activity of the Ba fragment of CsBf (named CsBa). CsBf possesses the conserved domains of Bf and shares 39.9%-56.4% sequence identities with other fish Bf. CsBf expression was high in liver, muscle, and heart, and low in intestine, blood, and kidney. Bacterial infection significantly induced CsBf expression in kidney, spleen, and liver in a time-dependent manner. Recombinant CsBa (rCsBa) exhibited apparent binding capacities to bacteria and tongue sole peripheral blood leukocytes, and binding of rCsBa to bacteria inhibited bacterial growth. When overexpressed in tongue sole, CsBa significantly reduced bacterial dissemination in fish tissues. Together these results indicate for the first time that a fish Ba possesses antibacterial effect as well as immune cell-binding capacity, and thus probably plays a role in host immune defense against bacterial infection.

  18. Low-lying Collective States in {sup 136}Ba

    SciTech Connect

    Scheck, M.; Mukhopadhyay, S.; Crider, B.; Choudry, S. N.; Elhami, E.; Peters, E. E.; McEllistrem, M. T.; Orce, J. N.; Yates, S. W.

    2009-01-28

    Low-lying collective states in {sup 136}Ba were investigated with (n,n'{gamma}) techniques, including Doppler-shift attenuation lifetime measurements. The level spins, lifetimes, branching ratios, multipole-mixing ratios and transition strengths reveal candidates for symmetric-phonon states up to third order. The 2{sub ms}{sup +} mixed-symmetry state was confirmed as unfragmented and a candidate for a [2{sub 1}{sup +} x 2{sub ms}{sup +}]{sub 3}{sup +} two-phonon mixed-symmetry state is proposed.

  19. Flux Creep in Sintered Superconducting Y-Ba-Cu-O

    NASA Astrophysics Data System (ADS)

    Matsushita, Teruo; Funaba, Seiji; Nagamatsu, Yoshiyuki; Ni, Baorong; Funaki, Kazuo; Yamafuji, Kaoru

    1989-09-01

    The flux creep rate in sintered superconducting Y-Ba-Cu-O was measured at 77 K and in fields of up to 0.1 T. The pinning potential mainly caused by flux pinning inside grains was 0.25 eV at B{=}50 mT and decreased monotonically with increasing magnetic field. The obtained results can be explained by the theoretical model with observed intragrain current density. This theoretical model suggests that the flux creep at high fields is notable even if a superconducting wire with the critical current density of 2× 1010 A/m2 at B{=}5 T is realized.

  20. Thin film processing of photorefractive BaTiO3

    NASA Technical Reports Server (NTRS)

    Schuster, Paul R.

    1993-01-01

    During the period covered by this report, October 11, 1991 through October 10, 1992, the research has progressed in a number of different areas. The sol-gel technique was initially studied and experimentally evaluated for depositing films of BaTiO3. The difficulties with the precursors and the poor quality of the films deposited lead to the investigation of pulsed laser deposition as an alternative approach. The development of the pulsed laser deposition technique has resulted in continuous improvements to the quality of deposited films of BaTiO3. The initial depositions of BaTiO3 resulted in amorphous films, however, as the pulsed laser deposition technique continued to evolve, films were deposited in the polycrystalline state, then the textured polycrystalline state, and most recently heteroepitaxial films have also been successfully deposited on cubic (100) oriented SrTiO3 substrates. A technique for poling samples at room temperature and in air is also undergoing development with some very preliminary but positive results. The analytical techniques, which include x-ray diffraction, ferroelectric analysis, UV-Vis spectrophotometry, scanning electron microscopy with x-ray compositional analysis, optical and polarized light microscopy, and surface profilometry have been enhanced to allow for more detailed evaluation of the samples. In the area of optical characterization, a pulsed Nd:YAG laser has been incorporated into the experimental configuration. Now data can also be acquired within various temporal domains resulting in more detailed information on the optical response of the samples and on their photorefractive sensitivity. The recent establishment of collaborative efforts with two departments at Johns Hopkins University and the Army Research Lab at Fort Belvoir has also produced preliminary results using the metallo-organic decomposition technique as an alternative method for thin film processing of BaTiO3. RF and DC sputtering is another film deposition

  1. Syntheses, crystal structures and characterizations of BaZn(SeO{sub 3}){sub 2} and BaZn(TeO{sub 3})Cl{sub 2}

    SciTech Connect

    Jiang Hailong; Feng Meiling; Mao Jianggao . E-mail: mjg@ms.fjirsm.ac.cn

    2006-06-15

    Two new barium zinc selenite and tellurite, namely, BaZn(SeO{sub 3}){sub 2} and BaZn(TeO{sub 3})Cl{sub 2}, have been synthesized by the solid state reaction. The structure of BaZn(SeO{sub 3}){sub 2} features double chains of [Zn(SeO{sub 3}){sub 2}]{sup 2-} anions composed of four- and eight-member rings which are alternatively along a-axis. The double chains of [Zn{sub 2}(TeO{sub 3}){sub 2}Cl{sub 3}]{sup 3-} anions in BaZn(TeO{sub 3})Cl{sub 2} are formed by Zn{sub 3}Te{sub 3} rings in which each tellurite group connects with three ZnO{sub 3}Cl tetrahedra. BaZn(SeO{sub 3}){sub 2} and BaZn(TeO{sub 3})Cl{sub 2} are wide bandgap semiconductors based on optical diffuse reflectance spectrum measurements. -- Graphical abstract: Two new barium zinc selenite and tellurite, namely, BaZn(SeO{sub 3}){sub 2} and BaZn(TeO{sub 3})Cl{sub 2}, have been synthesized by solid state reaction. The structure of BaZn(SeO{sub 3}){sub 2} features 1D double chains of [Zn(SeO{sub 3}){sub 2}]{sup 2-} anions composed of four- and eight-member rings which are alternatively along a-axis. The 1D double chains of [Zn{sub 2}(TeO{sub 3}){sub 2}Cl{sub 3}]{sup 3-} anions in BaZn(TeO{sub 3})Cl{sub 2} are formed by Zn{sub 3}Te{sub 3} rings in which each tellurite group connects with one ZnO{sub 3}Cl and two ZnO{sub 2}Cl{sub 2} tetrahedra. BaZn(SeO{sub 3}){sub 2} and BaZn(TeO{sub 3})Cl{sub 2} are wide bandgap semiconductors based on optical diffuse reflectance spectrum measurements.

  2. Thin films sputtered from Ba{sub 2}NdFeNb{sub 4}O{sub 15} multiferroic targets on BaFe{sub 12}O{sub 19} coated substrates

    SciTech Connect

    Bodeux, Romain; Michau, Dominique; Maglione, Mario; Josse, Michaël

    2016-09-15

    Highlights: • Synthesis of Ba{sub 2}NdFeNb{sub 4}O{sub 15}/BaFe{sub 12}O{sub 19} (BaM) heterostructures by RF magnetron sputtering. • Growth of TTB layer were retained regardless of the underlayer (Pt bottom electrode or BaM). • Dielectric and magnetic properties were obtained from the Pt/TTB/BaM/Pt stacks. - Abstract: Ba{sub 2}NdFeNb{sub 4}O{sub 15} tetragonal tungsten bronze (TTB)/BaFe{sub 12}O{sub 19} (BaM) hexaferrite bilayers have been grown by RF magnetron sputtering on Pt/TiO{sub 2}/SiO{sub 2}/Si (PtS) substrates. The BaM layer is textured along (0 0 1) while the TTB layer is multioriented regardless of the PtS or BaM/PtS substrate. Dielectric properties of TTB films are similar to those of bulk, i.e., ε ∼ 150 and a magnetic hysteresis loop is obtained from TTB/BaM bilayers, thanks to the BaM component. This demonstrates the possibility of transferring to 2 dimensional structures the composite multiferroic system TTB/BaM previously identified in 3 dimensional bulk ceramics.

  3. [Effect of PEG400 on the luminescent Eu(BA)3/SiO2].

    PubMed

    Zeng, Dong-ming; Li, Yan-hua; Fu, Chang-cheng; Liu, You-nian; Shu, Wan-gen

    2007-02-01

    Rare earth organic complexes combined with inorganic compounds can enhanced thermal stability, but inorganic compounds matrix has great influence on the luminescence characteristic of rare earth organic complexes. The luminescence characteristic of organic and inorganic compound material was improved by PEG doping in the material. Eu(BA)3/SiO2 and Eu(BA)3/PEG400-SiO2 were synthesized by Sol-Gel method. The result of luminescence analysis showed that the excitation spectra and emission spectra of Eu(BA)3 accorded with those of Eu(BA)3/SiO2 and Eu(BA)3/PEG400-SiO2, but the luminescence intensity of Eu(BA)3/SiO2 was improved by PEG400-SiO2 in SiO2 gel. This was because PEG400 as a hard Lewis base, could be combined with rare earth ion and increase the luminescence intensity of Eu(BA)3. It was shown that the amount of PEG400 in Eu(BA)3/SiO2 had influence on luminescence intensity of Eu(BA)3, namely there was better luminescence intensity in Eu(BA)3/SiO2 with increment of the PEG400 addition, but when the amount of PEG400 exceeded 50 wt% of that of SiO2, the luminescence intensity of Eu(BA)3 hardly increased. When the amount of PEG400 exceed 15 wt% of that of SiO2, PEG400 had little influence on the content of water and hydroxy in the matrix, as verified by IR spectrum. The surface characteristic of SiO2 gel was investigated by atomic force microscopy (AFM).

  4. Towards a sub 15-dBA optical micromachined microphone.

    PubMed

    Kim, Donghwan; Hall, Neal A

    2014-05-01

    Micromachined microphones with grating-based optical-interferometric readout have been demonstrated previously. These microphones are similar in construction to bottom-inlet capacitive microelectromechanical-system (MEMS) microphones, with the exception that optoelectronic emitters and detectors are placed inside the microphone's front or back cavity. A potential advantage of optical microphones in designing for low noise level is the use of highly-perforated microphone backplates to enable low-damping and low thermal-mechanical noise levels. This work presents an experimental study of a microphone diaphragm and backplate designed for optical readout and low thermal-mechanical noise. The backplate is 1 mm × 1 mm and is fabricated in a 2-μm-thick epitaxial silicon layer of a silicon-on-insulator wafer and contains a diffraction grating with 4-μm pitch etched at the center. The presented system has a measured thermal-mechanical noise level equal to 22.6 dBA. Through measurement of the electrostatic frequency response and measured noise spectra, a device model for the microphone system is verified. The model is in-turn used to identify design paths towards MEMS microphones with sub 15-dBA noise floors.

  5. Mid-IR Atmospheric Tracers of Jupiter's Storm Oval BA

    NASA Astrophysics Data System (ADS)

    Shannon, Matthew J.; Orton, G.; Fletcher, L.

    2010-10-01

    The 2005-2006 reddening of a major anticyclonic storm, known as Oval BA, in Jupiter's turbulent atmosphere may well be a paradigm for the formation of red-colored vortices on the giant planets, including Jupiters Great Red Spot. Mid-infrared observations can be effectively used to determine physical and chemical properties of the atmosphere, and we present the results of mid-infrared thermal imaging observations, collected from NASAs Infrared Telescope Facility (IRTF) in Hawaii, ESOs Very Large Telescope (VLT) in Chile and the NAOJ Subaru Telescope in Hawaii between spring of 2005 and summer of 2006. These address the role of atmospheric tracers, including cloud opacity, the ammonia gas content, and the variation of the fraction of para- to ortho-hydrogen from local thermal equilibrium in assessing the rate of upwelling. These properties were retrieved with the Oxford-developed code, Nemesis, with the purpose of providing constraints on dynamical models in an effort to identify the mechanism for the color change. The most obvious change is that the temperature gradient from the inner to the outer part of Oval BA increased over the time of the color change, indicating a strengthening of the intensity of the vortex.

  6. DIRC - The Particle Identification System for BaBar

    SciTech Connect

    Leith, David

    2002-08-19

    I have the pleasure of reporting on the status of the DIRC particle identification sub-system(2) of the BaBar Detector, running at the asymmetric B Factory at SLAC. The acronym DIRC stands for ''Detection of Internally Reflected Cherenkov Light.'' This device grows out of our group's experience with ring-imaging Cherenkov devices founded on a long partnership with Tom Ypsilantis and in particular with the CRID device for the SLD experiment. Blair Ratcliff had the brilliant idea of using the totally internally reflected Cherenkov light created in quartz bars, and transported out to the photon detectors by those same quartz bars, to provide excellent {pi}, K, p particle identification in the momentum range important for the B Factory. His naming of this new instrument was aptly ''CRID'' spelled backwards. The detailed design, building and commissioning of the DIRC sub-system was the work of a large international collaboration of French and U.S. groups. The device has proven to be a very robust detector, with the promised performance essentially fully realized, and is being effectively utilized in almost all of the current BaBar physics analysis.

  7. thermodynamics of nitrogen in BaO-TiOx melts

    NASA Astrophysics Data System (ADS)

    Tomioka, Katsutomo; Suito, Hideaki

    1993-02-01

    Using a gas-slag-metal equilibration technique, nitrogen contents in BaO-TiO^ slags and nitrogen and titanium contents in liquid Cu were measured at 1823, 1873, and 1923 K under controlled partial pressures of oxygen (@#@ PO 2 = 10-11.5 ≈ 10-13.7 atm) and nitrogen (@#@ PN 2 = 0.9 atm). The nitride capacity, C(N) [=(mass pct N) · PO2/3/4, (mass pct Ti3+)/(mass pct Ti4+) ratio, and solubility of TiN in BaO-TiO2-TiO1.5 slags were obtained as a function of slag com-position (@#@ XBaO = 0.20 = 0.43) and temperature. Activity coefficients of TiN were estimated, using the values for activity coefficients of Ti in liquid Cu which were calculated from the results of a TiN saturation experiment. Free energy of dissolution of nitrogen into liquid Cu was derived as °GGN o = 32,400 + 46.17 ± 1400 (J/g · atom).

  8. Aging Studies of 2nd Generation BaBar RPCs

    SciTech Connect

    Band, H.R.; /SLAC

    2007-09-25

    The BaBar detector, operating at the PEPII B factory of the Stanford Linear Accelerator Center (SLAC), installed over 200 2nd generation Resistive Plate Chambers (RPCs) in 2002. The streamer rates produced by backgrounds and signals from normal BaBar running vary considerably (0.1- >20 Hz/cm2) depending on the layer and position of the chambers, thus providing a broad spectrum test of RPC performance and aging. The lowest rate chambers have performed very well with stable efficiencies averaging 95%. Other chambers had rate-dependant inefficiencies due to Bakelite drying which were reversed by the introduction of humidified gases. RPC inefficiencies in the highest rate regions of the higher rate chambers have been observed and also found to be rate dependant. The inefficient regions grow with time and have not yet been reduced by operation with humidified input gas. Three of these chambers were converted to avalanche mode operation and display significantly improved efficiencies. The rate of production of HF in the RPC exhaust gases was measured in avalanche and streamer mode RPCs and found to be comparable despite the lower current of the avalanche mode RPCs.

  9. Evidence for extinct 135Cs from Ba isotopes in Allende CAIs?

    NASA Astrophysics Data System (ADS)

    Bermingham, K. R.; Mezger, K.; Desch, S. J.; Scherer, E. E.; Horstmann, M.

    2014-05-01

    The abundance and distribution of isotopes throughout the Solar System can be used to constrain the number and type of nucleosynthetic events that contributed material to the early nebula. Barium is particularly well suited to quantifying the degree of isotope heterogeneity in the Solar System because it comprises seven stable isotopes that were synthesized by three different nucleosynthetic processes (s-, r-, and p-processes), all of which contributed material to the Solar System. There is also potential contribution to 135Ba from short-lived radioisotope 135Cs, conclusive evidence for which is yet to be reported. Four Allende (CV3) Ca,Al-rich inclusions (CAI 1, CAI 2, CAI 4, CAI 5) and one Allende dark inclusion (DI) were analyzed for Ba isotope variability. Two CAIs (CAI 2 and CAI 5) display 135Ba excesses that are not accompanied by 137Ba anomalies. Calcium-aluminum-rich inclusion 1 displays a 135Ba excess that is possibly coupled with a 137Ba excess, and the remaining refractory inclusions (CAI 2 and DI) have terrestrial Ba isotope compositions. These Ba isotope data are presented in conjunction with published whole rock Ba isotope data from individual Allende CAIs. The enrichment in 135Ba and absence of coupled 137Ba excesses in CAI 2 and CAI 5 is interpreted to indicate that the anomalies are not purely nucleosynthetic in origin but also contain contributions (16-48 ppm) from the decay of short-lived 135Cs. The majority of Allende CAIs studied to date may also have similar contributions from 135Cs on the basis of higher than expected 135Ba excesses if the Ba isotope anomalies were purely nucleosynthetic in origin. The 135Ba anomalies appear not to be coupled with superchondritic Cs/Ba, which may imply that the contribution to 135Ba did not occur via in situ decay of live 135Cs. However, it is feasible that the CAIs had a superchondritic Cs/Ba during decay of 135Cs, but Cs was subsequently removed from the system during aqueous alteration on the parent body

  10. Multi-colony calibrations of coral Ba/Ca with a contemporaneous in situ seawater barium record

    NASA Astrophysics Data System (ADS)

    LaVigne, Michèle; Grottoli, Andréa G.; Palardy, James E.; Sherrell, Robert M.

    2016-04-01

    The coral skeleton barium to calcium ratio (Ba/Cacoral), a proxy for seawater barium concentrations (BaSW), has been interpreted as a tracer of upwelling based on the characteristic "nutrient like" depth profile of BaSW. However, in some tropical regions, such as the Gulf of Panamá, substantial influence of terrestrial runoff inputs and differences between the vertical distribution of BaSW and that of the major nutrients (nitrate and phosphate) in the upper water column can complicate the interpretation of Ba/Cacoral as an upwelled nutrient proxy. In the Gulf of Panamá, contemporaneous Ba/Cacoral records from multiple colonies of Porites lobata, Pavona gigantea, and Pavona clavus corals record a nearly twofold change in surface water BaSW as a 20-70% increase in skeletal Ba/Ca with excellent correlation among Ba/Ca records from co-located colonies (r = 0.86-0.99). These results provide, for the first time, an absolute calibration of the coral Ba proxy with a contemporaneous BaSW record. Compiling the Ba/Cacoral records from three co-located colonies of each species into taxon-specific composite regressions reveals strong statistically significant correlations with the BaSW time-series record (p < 0.001). Differences among taxa in regression slope, y-intercept, and average distribution coefficient, as well as a demonstration of the application of the P. clavus calibration to a previously published Ba/Cacoral record, emphasize the necessity of using taxon-specific calibrations to reconstruct changes in BaSW with accuracy. These results support the application of Ba/Cacoral to reconstruct past changes in absolute BaSW concentrations, adding an important tool to the collection of geochemical proxies for reconstructing surface ocean biogeochemical processes in the past.

  11. Characterization of novel BaZnSnO thin films by solution process and applications in thin film transistors

    SciTech Connect

    Li, Jun; Huang, Chuan-Xin; Zhang, Jian-Hua; Zhu, Wen-Qing; Jiang, Xue-Yin; Zhang, Zhi-Lin

    2015-08-15

    Graphical abstract: This work reports the Ba content on thin film transistor based on a novel BaZnSnO semiconductor using solution process. - Highlights: • No reports about BaZnSnO thin film using solution process. • BaZnSnO thin film transistor (TFT) was firstly fabricated. • BaZnSnO-TFT shows a acceptable performace. • Influence of Ba content on BaZnSnO-TFT. - Abstract: A novel BaZnSnO semiconductor is fabricated using solution process and the influence of Ba addition on the structure, the chemical state of oxygen and electrical performance of BaZnSnO thin films are investigated. A high performance BaZnSnO-based thin film transistor with 15 mol% Ba is obtained, showing a saturation mobility of 1.94 cm{sup 2}/V s, a threshold voltage of 3.6 V, an on/off current ratio of 6.2 × 10{sup 6}, a subthreshold swing of 0.94 V/decade, and a good bias stability. Transistors with solution processed BaZnSnO films are promising candidates for the development of future large-area, low-cost and high-performance electronic devices.

  12. Microstructures and properties of superconducting Y-ErBaCuO thin films obtained from disordered Y-ErBaF2Cu films

    NASA Technical Reports Server (NTRS)

    Cikmach, P.; Diociaiuti, M.; Fontana, A.; Giovannella, C.; Iannuzzi, M.; Lucchini, C.; Merlo, V.; Messi, R.; Paoluzi, L.; Scopa, L.

    1991-01-01

    The preparation procedure used to obtain superconducting thin films by radio frequency magnetron sputtering of a single mosaic target is described in detail. The single mosaic target is composed of (Y-Er), BaF2, and Cu.

  13. Molecular recognition at methyl methacrylate/n-butyl acrylate (MMA/nBA) monomer unit boundaries of phospholipids at p-MMA/nBA copolymer surfaces.

    PubMed

    Yu, Min; Urban, Marek W; Sheng, Yinghong; Leszczynski, Jerzy

    2008-09-16

    Lipid structural features and their interactions with proteins provide a useful vehicle for further advances in membrane proteins research. To mimic one of potential lipid-protein interactions we synthesized poly(methyl methacrylate/ n-butyl acrylate) (p-MMA/nBA) colloidal particles that were stabilized by phospholipid (PLs). Upon the particle coalescence, PL stratification resulted in the formation of surface localized ionic clusters (SLICs). These entities are capable of recognizing MMA/nBA monomer interfaces along the p-MMA/nBA copolymer backbone and form crystalline SLICs at the monomer interface. By utilizing attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy and selected area electron diffraction (SAD) combined with ab initio calculations, studies were conducted that identified the origin of SLICs as well as their structural features formed on the surface of p-MMA/nBA copolymer films stabilized by 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) PL. Specific entities responsible for SLIC formation are selective noncovalent bonds of anionic phosphate and cationic quaternary ammonium segments of DLPC that interact with two neighboring carbonyl groups of nBA and MMA monomers of the p-MMA/nBA polymer backbone. To the best of our knowledge this is the first example of molecular recognition facilitated by coalescence of copolymer colloidal particles and the ability of PLs to form SLICs at the boundaries of the neighboring MMA and nBA monomer units of the p-MMA/nBA chain. The dominating noncovalent bonds responsible for the molecular recognition is a combination of H-bonding and electrostatic interactions.

  14. Microstructures and properties of superconducting Y-Er-BaCu-O thin films obtained from disordered Y-Er-BaF2-Cu films

    NASA Technical Reports Server (NTRS)

    Cikmach, P.; Diociaiuti, M.; Fontana, A.; Giovannella, C.; Iannuzzi, M.; Lucchini, C.; Messi, R.; Paoluzi, L.; Scopa, L.; Tripodi, P.

    1990-01-01

    Since the first reports on superconducting thin films obtained by evaporating BaF2, Cu and Y(sup 1), or Yb or Er(sup 2), several others have followed. All these reports describe thin films prepared by means of molecular beam cells or electron guns. Researchers show that films with similar properties can be obtained by radio frequency sputtering of a single mosaic target composed by Y-Er, BaF2 and Cu. Process steps are described.

  15. PrBa{sub 2}Cu{sub 3}O{sub 7}: A new superconductor

    SciTech Connect

    Blackstead, H.A.; Dow, J.D.

    1995-10-01

    PrBa{sub 2}Cu{sub 3}O{sub 7} superconducts, provided Pr is kept off Ba-sites - experimentally confirming the prediction of the oxygen model and indicating that superconductivity originates in the chains, not in the planes.

  16. Single crystalline BaTiO3 thin films synthesized using ion implantation induced layer transfer

    NASA Astrophysics Data System (ADS)

    Park, Young-Bae; Diest, Kenneth; Atwater, Harry A.

    2007-10-01

    Layer transfer of BaTiO3 thin films onto silicon-based substrates has been investigated. Hydrogen and helium ions were co-implanted to facilitate ion-implantation-induced layer transfer of films from BaTiO3 single crystals. From thermodynamic equilibrium calculations, we suggest that the dominant species during cavity nucleation and growth are H2, H+, H2O, Ba2+ and Ba-OH, and that the addition of hydrogen to the Ba-Ti-O system can effectively suppress volatile oxide formation during layer transfer and subsequent annealing. After ion implantation, BaTiO3 layers contain microstructural defects and hydrogen precipitates in the lattice, but after layer transfer, the single crystal is found to be stoichiometric. Using direct wafer bonding and layer splitting, single crystal BaTiO3 thin films were transferred onto amorphous Si3N4 and Pt substrates. Micro-Raman spectroscopy indicated that the density of defects generated by ion implantation in BaTiO3 can be significantly reduced during post-transfer annealing, returning the transferred layer to its single crystal state. Characterization using piezoresponse force microscopy shows that the layer transferred thin films are ferroelectric, with domain structures and piezoresponse characteristics similar to that of bulk crystals.

  17. Benzo(A)pyrene (BaP) treatment results in complete infertility in female pigeons

    SciTech Connect

    Hough, J.L.; Darrow, D.; Eaton, J.; Baird, M.B. )

    1991-03-11

    BaP is a carcinogenic polycyclic aromatic hydrocarbon (PAH) and a common environmental pollutant. Show Racer and White Carneau female pigeons injected weekly with BaP for 3 for 5 months were completely infertile, with ovaries appearing necrotic or oxidized. Fertility in benzo(e)pyrene (BeP, a noncarcinogenic PAH) treated birds was the same as for corn oil treated controls, as was embryo development. Thus, infertility in BaP treated birds appears to be related to its structure-carcinogenic potential. There was no readily apparent affect of BaP treatment on testes from male birds. In order to determine whether BaP metabolites covalently bind to DNA in the ovaries of these birds, pigeons were injected with BaP or BeP, controls were injected with corn oil. Animals were sacrificed 24h later, the ovaries or testes removed, and the DNA isolated and analyzed for PAH-DNA adducts by {sup 32}P-post labeling assay. One major and one minor PAH-DNA adduct was found in ovaries and testes from BaP treated birds. However, no PAH adducts were found in BeP treated or control animals. Thus, problems with fertility may arise because of the alteration in DNA by BaP metabolite binding in ovaries where rapid cell growth occurs during egg production.

  18. Synthesis and characterization of barium silicide (BaSi2) nanowire arrays for potential solar applications.

    PubMed

    Pokhrel, Ankit; Samad, Leith; Meng, Fei; Jin, Song

    2015-11-07

    In order to utilize nanostructured materials for potential solar and other energy-harvesting applications, scalable synthetic techniques for these materials must be developed. Herein we use a vapor phase conversion approach to synthesize nanowire (NW) arrays of semiconducting barium silicide (BaSi2) in high yield for the first time for potential solar applications. Dense arrays of silicon NWs obtained by metal-assisted chemical etching were converted to single-crystalline BaSi2 NW arrays by reacting with Ba vapor at about 930 °C. Structural characterization by X-ray diffraction and high-resolution transmission electron microscopy confirm that the converted NWs are single-crystalline BaSi2. The optimal conversion reaction conditions allow the phase-pure synthesis of BaSi2 NWs that maintain the original NW morphology, and tuning the reaction parameters led to a controllable synthesis of BaSi2 films on silicon substrates. The optical bandgap and electrochemical measurements of these BaSi2 NWs reveal a bandgap and carrier concentrations comparable to previously reported values for BaSi2 thin films.

  19. The Acquisition of the BA Construction by English-Speaking Learners of Chinese

    ERIC Educational Resources Information Center

    Xu, Hongying

    2012-01-01

    This study examined the acquisition of the BA construction by English-speaking learners of Chinese. The BA construction is a unique yet important grammar phenomenon in Chinese. Whether second language (L2) learners of Chinese are able to understand and use this construction correctly and appropriately may affect the overall success of their…

  20. Extraction of potassium from biotite by Ba2+/K+ ion exchange and the structural transformation

    NASA Astrophysics Data System (ADS)

    Meng, Peng; Li, Ziqian; Huang, Zhiliang; Chen, Changlian

    2016-06-01

    Potassium has been extracted successfully from biotite by Ba2+/K+ ion exchange. The potassium release rate increased along S-curve versus reaction time. The maximum of potassium release rate was about 96 %. Powder X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy were used to characterize the obtained samples to reveal the exchanging behavior and structural transformation. The results showed that after treated with Ba(NO3)2 four times the original biotite transformed to vermiculite-type hydrated Ba-mica. The (001) basal plane was expanded from 1.000 nm of biotite to 1.221 nm of hydrated Ba-mica. Because of the "vacancy effect," the Ba2+ has two different statuses, causing the structural water vibration of vermiculite-type hydrated Ba-mica split. The edge of vermiculite-type hydrated Ba-mica was crimped compared with the flat edge of original biotite. The (001) basal plane of dehydrated Ba-mica was also split, supporting the "vacancy effect."

  1. Band gap tuning of lead-substituted BaSnO3 for visible light photocatalysis

    NASA Astrophysics Data System (ADS)

    Borse, Pramod H.; Joshi, Upendra A.; Ji, Sang Min; Jang, Jum Suk; Lee, Jae Sung; Jeong, Euh Duck; Kim, Hyun Gyu

    2007-01-01

    The Pb substitution effect was investigated experimentally and theoretically on the crystal structure of BaSnO3 and on the photo-oxidation activity of H2O. The chemically doped Pb in BaSnO3 induced a concentration-dependent redshift of the experimental band gap (BG). The BaPb0.8Sn0.2O3 system produced 32μmol /h of O2 under λ ⩾420nm photons, but no O2 for BaSnO3. The DFT calculations of BaPbxSn1-xO3 (x =0,0.5,1) by using generalized approximation, implying the BG alteration and the photocatalytic activity of BaPbxSn1-xO3, are due to the induced Pb 6s orbital in the BG of BaSnO3. Thus Pb modified the insulating nature of BaSnO3 to semiconducting and semimetallic.

  2. 49 CFR 178.51 - Specification 4BA welded or brazed steel cylinders.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification 4BA welded or brazed steel cylinders... FOR PACKAGINGS Specifications for Cylinders § 178.51 Specification 4BA welded or brazed steel...) Cylindrical type cylinders must be of circumferentially welded or brazed construction. (b) Steel. The...

  3. 49 CFR 178.51 - Specification 4BA welded or brazed steel cylinders.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Specification 4BA welded or brazed steel cylinders... FOR PACKAGINGS Specifications for Cylinders § 178.51 Specification 4BA welded or brazed steel...) Cylindrical type cylinders must be of circumferentially welded or brazed construction. (b) Steel. The...

  4. 49 CFR 178.51 - Specification 4BA welded or brazed steel cylinders.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification 4BA welded or brazed steel cylinders... FOR PACKAGINGS Specifications for Cylinders § 178.51 Specification 4BA welded or brazed steel...) Cylindrical type cylinders must be of circumferentially welded or brazed construction. (b) Steel. The...

  5. 49 CFR 178.51 - Specification 4BA welded or brazed steel cylinders.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Specification 4BA welded or brazed steel cylinders... FOR PACKAGINGS Specifications for Cylinders § 178.51 Specification 4BA welded or brazed steel...) Cylindrical type cylinders must be of circumferentially welded or brazed construction. (b) Steel. The...

  6. A facile method for the preparation of Eu{sup 2+}-doped nanocrystalline BaFCl

    SciTech Connect

    Wang, Xianglei; Liu, Zhiqiang; Stevens-Kalceff, Marion A.; Riesen, Hans

    2013-10-15

    Graphical abstract: - Highlights: • A facile co-precipitation method for the preparation of Eu{sup 2+}-doped BaFCl. • Reduction of Eu{sup 3+} to Eu{sup 2+} by zinc granular under nitrogen flow. • Photoluminescence and cathodoluminescence spectroscopy of the as-prepared BaFCl:Eu{sup 2+}. • Temperature dependent photoluminescence properties of Eu{sup 2+} ions in BaFCl. - Abstract: A facile method for the preparation of Eu{sup 2+}-doped BaFCl is reported. The method is based on the co-precipitation of aqueous solutions of BaCl{sub 2} and NH{sub 4}F to yield BaFCl. The doping by europium in the 2+ oxidation state is realized by the reduction of Eu{sup 3+} to Eu{sup 2+} employing granular zinc in the BaCl{sub 2} solution under nitrogen. Powder X-ray diffraction and electron microscopy have been used to confirm the BaFCl phase and photoluminescence, in the temperature range of 2.5–290 K, and room-temperature cathodoluminescence spectra have been measured to characterize the Eu{sup 2+} ions in the sample.

  7. High-k perovskite gate oxide BaHfO3

    NASA Astrophysics Data System (ADS)

    Kim, Young Mo; Park, Chulkwon; Ha, Taewoo; Kim, Useong; Kim, Namwook; Shin, Juyeon; Kim, Youjung; Yu, Jaejun; Kim, Jae Hoon; Char, Kookrin

    2017-01-01

    We have investigated epitaxial BaHfO3 as a high-k perovskite dielectric. From x-ray diffraction measurement, we confirmed the epitaxial growth of BaHfO3 on BaSnO3 and MgO. We measured optical and dielectric properties of the BaHfO3 gate insulator; the optical bandgap, the dielectric constant, and the breakdown field. Furthermore, we fabricated a perovskite heterostructure field effect transistor using epitaxial BaHfO3 as a gate insulator and La-doped BaSnO3 as a channel layer on SrTiO3 substrate. To reduce the threading dislocations and enhance the electrical properties of the channel, an undoped BaSnO3 buffer layer was grown on SrTiO3 substrates before the channel layer deposition. The device exhibited a field effect mobility value of 52.7 cm2 V-1 s-1, a Ion/Ioff ratio higher than 107, and a subthreshold swing value of 0.80 V dec-1. We compare the device performances with those of other field effect transistors based on BaSnO3 channels and different gate oxides.

  8. The solubility of BaCO3(cr) (witherite) in CO2-H2O solutions between 0 and 90°C, evaluation of the association constants of BaHCO3+(aq) and BaCO30(aq) between 5 and 80°C, and a preliminary evaluation of the thermodynamic properties of Ba2+(aq)

    USGS Publications Warehouse

    Busenberg, Eurybiades; Plummer, L. Niel

    1986-01-01

    Problems in the thennodynamic selections of Ba compounds are considered. Newer data require the revision of ΔfH° and ΔfG° of Ba2+(aq) to −532.5 and −555.36 kJ · mol−1, respectively, for agreement with solubility data.

  9. 17 CFR 240.15Ba1-7 - Registration of successor to municipal advisor.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Registration of successor to municipal advisor. 240.15Ba1-7 Section 240.15Ba1-7 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules...

  10. 17 CFR 240.15Ba1-4 - Withdrawal from municipal advisor registration.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Withdrawal from municipal advisor registration. 240.15Ba1-4 Section 240.15Ba1-4 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules...

  11. Ba/Ca coral-based proxy of tropical hydrology: Yucatan Peninsula case study

    NASA Astrophysics Data System (ADS)

    Gonneea, M. E.; Cohen, A. L.; Charette, M. A.

    2011-12-01

    The barium/calcium ratio (Ba/Ca) in corals growing on fringing reefs of the Yucatan Peninsula is a potentially powerful tool with which to reconstruct seasonally resolved, multicentury-long records of precipitation (both seasonally-forced as well as episodic events). The Yucatan Peninsula is a carbonate platform with minimal surface flow, thus groundwater is the major vector for freshwater transport to the coast. The basic premise for this work is that elements enriched in groundwater (such as Ba) are delivered via submarine groundwater discharge (SGD) to the coastal waters of the Yucatan Peninsula and that the magnitude of SGD is positively correlated with precipitation. Delivery of Ba enriched groundwater elevates coastal Ba concentrations and high/low rainfall events are recorded as high/low Ba/Ca ratios in the coral skeleton. Recent quantification of groundwater discharge to coastal waters of the Yucatan Peninsula showed that discharge was three times higher at the end of the wet season relative to the dry season. This strongly suggests that precipitation drives the delivery of fresh groundwater to coastal waters (and the reef). The Ba/Ca ratio of seawater is linearly dependent on salinity, thus this is an excellent tracer of terrestrially source fresh water. Initial Ba/Ca data generated from two corals (Siderastrea spp.) collected live on the Yucatan reefs demonstrate a positive correlation with rainfall; both corals record Hurricane Isadore as a substantial Ba/Ca spike in the 2002 annual growth band.

  12. Luminescence and Site Occupancy of Eu2+ in Ba2 Ca(BO3)2

    NASA Astrophysics Data System (ADS)

    Li, Pan-Lai; Wang, Zhi-Jun; Yang, Zhi-Ping; Guo, Qing-Lin

    2011-01-01

    A green phosphor Ba2Ca(BO3)2:Eu2+ was synthesized by a high temperature solid-state reaction method under a reductive atmosphere. The luminescence and site occupancy of Eu2+ in Ba2Ca(BO3)2 are investigated. Ba2Ca(BO3)2:Eu2+ shows one green band (537 nm) under 400 nm near ultraviolet excitation which is suitable for UV LED. Ca2+ and Ba2+ ions in Ba2Ca(BO3)2 are replaced by Eu2+ ions, the Ba2Ca(BO3)2:Eu2+ shows a dissymmetrical emission band. The influence of Eu2+ doping concentrations on the emission intensity of Ba2Ca(BO3)2:Eu2+ is studied. It is found that the emission intensity is influenced by the Eu2+ concentration and reaches the maximum value at 2% Eu2+. According to the Dexter theory, the concentration quenching mechanisms of Eu2+ in Ba2Ca(BO3)2 are the d-dinteraction.

  13. Crystal Structures at Atomic Resolution of the Perovskite-Related GdBaMnFeO5 and Its Oxidized GdBaMnFeO6.

    PubMed

    García-Martín, Susana; Manabe, Keisuke; Urones-Garrote, Esteban; Ávila-Brande, David; Ichikawa, Noriya; Shimakawa, Yuichi

    2017-02-06

    Perovskite-related GdBaMnFeO5 and the corresponding oxidized phase GdBaMnFeO6, with long-range layered-type ordering of the Ba and Gd atoms have been synthesized. Oxidation retains the cation ordering but drives a modulation of the crystal structure associated with the incorporation of the oxygen atoms between the Gd layers. Oxidation of GdBaMnFeO5 increases the oxidation state of Mn from 2+ to 4+, while the oxidation state of Fe remains 3+. Determination of the crystal structure of both GdBaMnFeO5 and GdBaMnFeO6 is carried out at atomic resolution by means of a combination of advanced transmission electron microscopy techniques. Crystal structure refinements from synchrotron X-ray diffraction data support the structural models proposed from the TEM data. The oxidation states of the Mn and Fe atoms are evaluated by means of EELS and Mössbauer spectroscopy, which also reveals the different magnetic behavior of these oxides.

  14. Direct spectroscopic evidence for completely filled Cu 3d shell in BaCu2As2 and α-BaCu2Sb2

    DOE PAGES

    Wu, S. F.; Richard, P.; van Roekeghem, A.; ...

    2015-06-08

    In this study, we use angle-resolved photoemission spectroscopy to extract the band dispersion and the Fermi surface of BaCu2As2 and α-BaCu2Sb2. While the Cu 3d bands in both materials are located around 3.5 eV below the Fermi level, the low-energy photoemission intensity mainly comes from As 4p states, suggesting a completely filled Cu 3d shell. The splitting of the As 3d core levels and the lack of pronounced three-dimensionality in the measured band structure of BaCu2As2 indicate a surface state likely induced by the cleavage of this material in the collapsed tetragonal phase, which is consistent with our observation ofmore » a Cu+1 oxidation state. However, the observation of Cu states at similar energy in α-BaCu2Sb2 without the pnictide-pnictide interlayer bonding characteristic of the collapsed tetragonal phase suggests that the short interlayer distance in BaCu2As2 follows from the stability of the Cu+1 rather than the other way around. In conclusion, our results confirm the prediction that BaCu2As2 is an sp metal with weak electronic correlations.« less

  15. New insights into the application of the valence rules in Zintl phases—Crystal and electronic structures of Ba{sub 7}Ga{sub 4}P{sub 9}, Ba{sub 7}Ga{sub 4}As{sub 9}, Ba{sub 7}Al{sub 4}Sb{sub 9}, Ba{sub 6}CaAl{sub 4}Sb{sub 9}, and Ba{sub 6}CaGa{sub 4}Sb{sub 9}

    SciTech Connect

    He, Hua; Stoyko, Stanislav; Bobev, Svilen

    2016-04-15

    Crystals of three new ternary pnictides—Ba{sub 7}Al{sub 4}Sb{sub 9}, Ba{sub 7}Ga{sub 4}P{sub 9}, and Ba{sub 7}Ga{sub 4}As{sub 9} have been prepared by reactions of the respective elements in molten Al or Pb fluxes. Single-crystal X-ray diffraction studies reveal that the three phases are isotypic, crystallizing in the orthorhombic Ba{sub 7}Ga{sub 4}Sb{sub 9}-type structure (space group Pmmn, Pearson symbol oP40, Z=2), for which only the prototype is known. The structure is based on TrPn{sub 4} tetrahedra (Tr=Al, Ga; Pn=P, As, Sb), connected in an intricate scheme into 1D-ribbons. Long interchain Pn–Pn bonds (d{sub P–P}>3.0 Å; d{sub As–As}>3.1 Å; d{sub Sb–Sb}>3.3 Å) account for the realization of 2D-layers, separated by Ba{sup 2+} cations. Applying the classic valance rules to rationalize the bonding apparently fails, and Ba{sub 7}Ga{sub 4}Sb{sub 9} has long been known as a metallic Zintl phase. Earlier theoretical calculations, both empirical and ab-initio, suggest that the possible metallic properties originate from filled anti-bonding Pn–Pn states, and the special roles of the “cations” in this crystal structure. To experimentally probe this hypothesis, we sought to synthesize the ordered quaternary phases Ba{sub 6}CaTr{sub 4}Sb{sub 9} (Tr=Al, Ga). Single-crystal X-ray diffraction work confirms Ba{sub 6.145(3)}Ca{sub 0.855}Al{sub 4}Sb{sub 9} and Ba{sub 6.235(3)}Ca{sub 0.765}Ga{sub 4}Sb{sub 9}, with Ca atoms preferably substituting Ba on one of the three available sites. The nuances of the five crystal structures are discussed, and the chemical bonding in Ba{sub 7}Ga{sub 4}As{sub 9} is interrogated by tight-binding linear muffin-tin orbital calculations. - Graphical abstract: The new Zintl phases—Ba{sub 7}Al{sub 4}Sb{sub 9}, Ba{sub 7}Ga{sub 4}P{sub 9}, and Ba{sub 7}Ga{sub 4}As{sub 9}, and their quaternary variants Ba{sub 6}CaTr{sub 4}Sb{sub 9} (Tr=Al, Ga)—crystallize in the Ba{sub 7}Ga{sub 4}Sb{sub 9} structure type. The structures are based

  16. Electron-relaxation-mode interaction in BaTiO3:Nb

    NASA Astrophysics Data System (ADS)

    Maglione, M.; Belkaoumi, M.

    1992-02-01

    Dielectric relaxation was previously reported in BaTiO3 and BaTiO3:Fe single crystals at radio frequencies [M. Maglione et al., Phys. Rev. B 40, 11 441 (1989)]. We have measured the dielectric dispersion in four BaTiO3:Nb samples (xNb<0.3 at. %) as a function of frequency (10BaTiO3:Nb enhances drastically the relaxation step at all temperatures. In the rhombohedral phase of BaTiO3:Nb (T<180 K), an unusual slowing down of the relaxation motion is measured. The relaxation time increases to more than 10-2 s at 20 K while the relaxation step is temperature independent. The precursor effect of this slowing down is a maximum in the dc conductivity. A simple electron-relaxation-mode coupling model may explain such behavior.

  17. Structural, optical and electrical properties of GdAlO3:Eu3+Ba2+

    NASA Astrophysics Data System (ADS)

    Selvalakshmi, T.; Tamilarasi, S.; Bose, A. Chandra

    2015-06-01

    Effect of Ba2+ ions concentration on the photoluminescence of GdAlO3:Eu3+ Ba2+ phosphor is investigated. The phosphors are synthesized by citrate-based sol-gel method and the formation of orthorhombic phase GdAlO3 is confirmed by XRD analysis. Kubelka-Munk function is used to estimate the band gap and the value varies with concentration of Ba2+ is observed. Photoluminescence spectra show a strong red emission peak at 616 nm corresponding to5D0→7F2 transition and its intensity increase with the addition of Ba2+ ions. The presence of Eu3+ and Ba2+ ions in GdAlO3 strongly influences the dielectric property of GdAlO3.

  18. The Structural Disorder and Lattice Stability of (Ba,Sr)(Co,Fe)O3 Complex Perovskites

    SciTech Connect

    S.N.Rashkeev

    2011-05-01

    The structural disorder and lattice stability of complex perovskite (Ba,Sr)(Co,Fe)O3, a promising cathode material for solid oxide fuel cells and oxygen permeation membranes, is explored by means of first principles DFT calculations. It is predicted that Ba and Sr ions easily exchange their lattice positions (A-cation disorder) similarly to Co and Fe ions (B-cation disorder). The cation antisite defects (exchange of A- and B-type cations) have a relatively high formation energy. The BSCF is predicted to exist in an equilibrium mixture of several phases and can decompose exothermically into the Ba- and Co-rich hexagonal (Ba,Sr)CoO3 and Sr- and Fe-rich cubic (Ba,Sr)FeO3 perovskites.

  19. The Ba813 chromosomal DNA sequence effectively traces the whole Bacillus anthracis community.

    PubMed

    Ramisse, V; Patra, G; Vaissaire, J; Mock, M

    1999-08-01

    Plasmid genes that are responsible for virulence of Bacillus anthracis are important targets for the DNA-based detection of anthrax. We evaluated the distribution of the Ba813 chromosomal DNA sequence (Ba813) within closely related Bacillus species. Ba813 was systematically identified from 47 strains or isolates of B. anthracis tested, thus indicating its reliability as a tracer for that species. From the 60 strains of closely related Bacillus spp. examined, three bona fide B. cereus and one bona fide B. thuringiensis were found to harbour Ba813. This marker was also detected in Bacillus sp. isolates that were present at high levels in soil samples collected in a place where an anthrax outbreak had occurred. The significance and the possible function of the Ba813 locus is discussed.

  20. Structure of periodic crystals and quasicrystals in ultrathin films of Ba-Ti-O

    DOE PAGES

    Cockayne, Eric; Mihalkovič, Marek; Henley, Christopher L.

    2016-01-07

    Here, we model the remarkable thin-film Ba-Ti-O structures formed by heat treatment of an initial perovskite BaTiO3 thin film on a Pt(111) surface. All structures contain a rumpled Ti-O network with all Ti threefold coordinated with O, and with Ba occupying the larger. mainly Ti7O7, pores. The quasicrystal structue is a simple decoration of three types of tiles: square, triangle and 30° rhombus, with edge lengths 6.85 Å, joined edge-to-edge in a quasicrystalline pattern; observed periodic crystals in ultrathin film Ba-Ti-O are built from these and other tiles. Simulated STM images reproduce the patterns seen experimentally, and identify the brightmore » protrusions as Ba atoms. The models are consistent with all experimental observations.« less

  1. Nanocrystalline BaTiO3 powder via ambient conditions sol process (Prop.2001-071)

    SciTech Connect

    Payzant, E Andrew; Wang, X.; Hu, Michael Z.; Blom, Douglas Allen

    2005-01-01

    Nanocrystalline BaTiO{sub 3} particles have been prepared by ambient condition sol (ACS) process starting from soluble precursors of barium and titanium yielding a mixed oxide/hydroxide gel. The gel was peptized and crystallized in water under a refluxing condition. Higher initial pH and Ba/Ti ratio led to smaller crystallite sizes of BaTiO{sub 3} powders. Organic mineralizer, tetramethylammonium hydroxide (TMAH), can adsorb on the BaTiO{sub 3} nuclei and inhibited further growth of the particles. Adding a polymer during BaTiO{sub 3} synthesis led to a smaller particle size and increased redispersibility of the particles in water.

  2. Bound-bound transitions in the emission spectra of Ba+-He excimer

    NASA Astrophysics Data System (ADS)

    Moroshkin, P.; Kono, K.

    2016-05-01

    We present an experimental and theoretical study of the emission and absorption spectra of the Ba+ ions and Ba+*He excimer quasimolecules in the cryogenic Ba-He plasma. We observe several spectral features in the emission spectrum, which we assign to the electronic transitions between bound states of the excimer correlating to the 6 2P3 /2 and 5 2D3 /2 ,5 /2 states of Ba+. The resulting Ba+(5 2DJ) He is a metastable electronically excited complex with orbital angular momentum L =2 , thus expanding the family of known metal-helium quasimolecules. It might be suitable for high-resolution spectroscopic studies and for the search for new polyatomic exciplex structures.

  3. BaSnO3 perovskite nanoparticles for high efficiency dye-sensitized solar cells.

    PubMed

    Kim, Dong Wook; Shin, Seong Sik; Lee, Sangwook; Cho, In Sun; Kim, Dong Hoe; Lee, Chan Woo; Jung, Hyun Suk; Hong, Kug Sun

    2013-03-01

    The synthesis of highly crystalline perovskite BaSnO3 nanoparticles for use as photoanode materials in dye-sensitized solar cells (DSSCs) is reported, and the photovoltaic properties of DSSCs based on BaSnO3 nanoparticles (BaSnO3 cells) are demonstrated. The resulting DSSCs exhibit remarkably rapid charge collection and a DSSC fabricated with a BaSnO3 film thickness of 43 µm leads to a high energy conversion efficiency of 5.2 %, which is one of the highest reported for ternary oxide-based DSSCs. More importantly, the BaSnO3 cells show superior charge collection in nanoparticle films compared to TiO2 cells and could offer a breakthrough in the efficiencies of DSSCs.

  4. Structure of periodic crystals and quasicrystals in ultrathin films of Ba-Ti-O

    SciTech Connect

    Cockayne, Eric; Mihalkovič, Marek; Henley, Christopher L.

    2016-01-07

    Here, we model the remarkable thin-film Ba-Ti-O structures formed by heat treatment of an initial perovskite BaTiO3 thin film on a Pt(111) surface. All structures contain a rumpled Ti-O network with all Ti threefold coordinated with O, and with Ba occupying the larger. mainly Ti7O7, pores. The quasicrystal structue is a simple decoration of three types of tiles: square, triangle and 30° rhombus, with edge lengths 6.85 Å, joined edge-to-edge in a quasicrystalline pattern; observed periodic crystals in ultrathin film Ba-Ti-O are built from these and other tiles. Simulated STM images reproduce the patterns seen experimentally, and identify the bright protrusions as Ba atoms. The models are consistent with all experimental observations.

  5. On the existence of a homologous series of Ba mCu m+nO y oxides with the cubic structure of the BaCuO 2 oxide

    NASA Astrophysics Data System (ADS)

    Klinkova, L. A.; Nikolaichik, V. I.; Barkovskii, N. V.; Fedotov, V. K.

    2010-12-01

    Phase relations have been studied in the BaO-CuO x system in the range of 42.0-83.0 mol.% CuO at P(O 2) = 21 kPa (air) by visual polythermal analysis (VPA), powder X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TGA), chemical analysis (CA), and electron diffraction (ED) with simultaneous elemental analysis (EA) in a transmission electron microscope (TEM). The existence of discrete crystallization fields of barium-copper oxides of cation compositions Ba 4Cu 5O y, Ba 5Cu 6O y, Ba 7Cu 8O y, Ba 12Cu 13O y, and Ba 24Cu 25O y, which have the cubic structure of the BaCuO 2 oxide, is revealed in the studied region of the system. The oxides may be represented as members of a Ba mCu m+nO y homologous series. The BaCuO 2 oxide does not exist in the subsolidus region and does not have its own crystallization field. The oxygen-deficient oxide BaCuO 1.78 of the cation composition (Ba:Cu) 1:1 with the BaCuO 2 cubic structure is found in melted samples of the 50.0 mol.% CuO composition quenched at 1020-1060 °С.

  6. Ba/Ca Ratios in North Pacific Bamboo Corals Record Changes in Intermediate Water Biogeochemistry

    NASA Astrophysics Data System (ADS)

    Serrato Marks, G.; LaVigne, M.; Hill, T. M.; Sauthoff, W.; Guilderson, T. P.; Roark, E. B.; Dunbar, R. B.

    2015-12-01

    Trace elemental ratios preserved in the skeleton of bamboo corals, which live for hundreds of years at >500m depth, have been utilized as archives of deep-ocean conditions. However, it was previously unclear whether trace element data from these corals were internally reproducible and could therefore be used as reliable climate proxies. This study tests the internal reproducibility of Ba/Ca in the calcite of nine bamboo corals to further develop a new proxy for dissolved Ba in seawater (BaSW). Trace element LA-ICP-MS data were collected along three replicate radii of varying lengths of the calcitic internodes of well-dated corals collected live from the Gulf of Alaska (720m and 643m) and the California Margin (870m, 1012m, 1295m, 1500m, 1521m, 1954m, and 2054m; samples from 1295-1521m are not yet dated). Data were aligned using visible bands measured with a petrographic microscope to account for irregular growth. Ba/Ca data filtered with a 50μm (1.5-2 year) moving average were reproducible within each coral to 2.9 ± 2.1% (n=3 radii/coral, 9 corals), suggesting that regional geochemical signals are recorded as reproducible Ba/Ca signals on >annual timescales. Coral Ba/Ca presents an excellent proxy for BaSW, which has been found to be correlated with refractory nutrients (e.g. silicate) and oxygen minima. Increasing BaSW with depth and increased variability near 1000m suggests that BaSW is not constant with depth or with time. Several factors, including barite saturation state, particulate organic carbon (POC) remineralization rate, and particle sinking time, may be involved in the observed changes in BaSW. Further examination of such mechanisms could provide new insights into modern changes in deep-sea biogeochemistry.

  7. Dual preparation of hydrophobic and hydrophilic BaWO{sub 4}:Eu phosphors

    SciTech Connect

    Cho, Young-Sik; Huh, Young-Duk

    2016-06-15

    Highlights: • Red-emitting BaWO{sub 4}:Eu phosphors were prepared in hexane-water bilayer system. • The hydrophobic nanometer-sized BaWO{sub 4}:Eu phosphors were obtained in hexane. • The hydrophilic micrometer-sized BaWO{sub 4}:Eu dendrites were obtained in water. - Abstract: BaWO{sub 4}:Eu phosphors were prepared by performing a solvothermal reaction in a water–hexane bilayer system. A barium oleate (and europium oleate) complex was obtained in hexane via a phase transfer reaction involving Ba{sup 2+} (and Eu{sup 3+}) ions in an aqueous solution of sodium oleate. The outer surfaces of the nanometer-sized BaWO{sub 4}:Eu phosphors were capped by the long alkyl chain of oleate; therefore, the hydrophobic nanometer-sized BaWO{sub 4}:Eu phosphors preferentially dissolved in the hexane layer. The micrometer-sized BaWO{sub 4}:Eu phosphors were obtained in the water layer. The BaWO{sub 4}:Eu phosphors prepared in hexane and water yielded sharp strong absorption and emission peaks at 464 and 615 nm, respectively, due to the {sup 7}F{sub 0} → {sup 5}D{sub 2} and the {sup 5}D{sub 0} →{sup 7} F{sub 2} transitions of the Eu{sup 3+} ions. The BaWO{sub 4}:Eu phosphors are good candidate red-emitting phosphors for use in InGaN blue-emitting diodes, which have an emission wavelength of 465 nm.

  8. The Ba II [lambda]4554 resonance line and solar granulation

    NASA Astrophysics Data System (ADS)

    Olshevsky, V. L.; Shchukina, N. G.

    We present the results of an investigation of the impact of NLTE effects and of granulation inhomogeneities on the solar Ba II [lambda]4554 Å line. Our analysis is based on both the classical one-dimensional (1D) solar atmosphere models and on the new generation of three-dimensional (3D) hydrodynamical models. We show that NLTE and 3D effects have to be taken into account for reliable diagnostics of the solar atmosphere using this line. We analyse the influence of different parameters on the line shape. It turns out to be most sensitive to collisional broadening and barium abundance. Uncertainties in the oscillator strength, micro- and macroturbulence (in 1D-case) have a secondary importance. We have derived the barium abundance assuming NLTE. We find ABa = 2.16 in good agreement with the recent result of Asplund et al. (2005).

  9. Investigation of structural, mechanical, electronic, optical, and dynamical properties of cubic BaLiF3, BaLiH3, and SrLiH3

    NASA Astrophysics Data System (ADS)

    Yalcin, Battal G.; Salmankurt, Bahadır; Duman, Sıtkı

    2016-03-01

    The structural, mechanical, electronic, optical, and dynamical properties of BaLiF3, BaLiH3, and SrLiH3 cubic perovskite materials are theoretically investigated by using first principles calculations. Obtained results are in reasonable agreement with other available theoretical and experimental studies. The considered materials are found to be mechanically stable in the cubic structure. We found that all materials are brittle. The modified Becke-Johnson (mBJ) exchange potential has been used here to obtain an accurate band order. The calculated band-gap energy value of BaLiF3 (8.26 eV) within the mBJ potential agrees very well with the experimentally reported value of 8.41 eV. In order to have a deeper understanding of the bonding mechanism and the effect of atomic relaxation on the electronic band structure, the total and partial density of states have also been calculated. We have investigated the fundamental optical properties, such as the real ɛ 1(ω) and imaginary ɛ 2(ω) parts of the dielectric function, absorption coefficient α(ω), reflectivity R(ω), and refractive index n(ω) in the energy range from 0 to 40 eV within the mBJ potential. The band-gap energy obtained from the absorption spectrum is around 8.76, 3.99, and 3.31 eV for BaLiF3, BaLiH3, and SrLiH3 crystals, respectively. It should be noted that BaLiF3 could be a strong potential candidate as a laser material for the development of a vacuum-ultraviolet light emitting diode once direct transition is confirmed by experimental studies. Finally, we have calculated the lattice dynamical properties of BaLiF3, BaLiH3, SrLiH3, and SrLiF3 crystals. The full phonon dispersion curves of these materials are reported for the first time. Our results clearly indicate that the materials are dynamically stable, except for SrLiF3, in the cubic structure. The obtained zone-center phonon frequencies of BaLiF3, BaLiH3, and SrLiH3 accord very well with previous experimental measurements.

  10. The new barium zinc mercurides Ba3ZnHg10 and BaZn0.6Hg3.4 - Synthesis, crystal and electronic structure

    NASA Astrophysics Data System (ADS)

    Schwarz, Michael; Wendorff, Marco; Röhr, Caroline

    2012-12-01

    The title compounds Ba3ZnHg10 and BaZn0.6Hg3.4 were synthesized from stoichiometric ratios of the elements in Ta crucibles. Their crystal structures, which both represent new structure types, have been determined using single crystal X-ray data. The structure of Ba3ZnHg10 (orthorhombic, oP28, space group Pmmn, a=701.2(3), b=1706.9(8), c=627.3(3)pm, Z=2, R1=0.0657) contains folded 44 Hg nets, where the meshes form the bases of flat rectangular pyramids resembling the structure of BaAl4. The flat pyramids are connected via Hg-Zn/Hg bonds, leaving large channels at the folds, in which Ba(1) and Hg(2) atoms alternate. Whereas the remaining Hg/Zn atoms form a covalent 3D network of three- to five-bonded atoms with short M-M distances (273-301 pm; CN 9-11), the Hg(2) atoms in the channels adopt a comparatively large coordination number of 12 and increased distances (317-348 pm) to their Zn/Hg neighbours. In the structure of BaZn0.6Hg3.4 (cubic, cI320, space group I4bar3d, a=2025.50(7) pm, Z=64, R1=0.0440), with a chemical composition not much different from that of Ba3ZnHg10, the Zn/Hg atoms of the mixed positions M(1/2) are arranged in an slightly distorted primitive cubic lattice with a 4×4×4 subcell relation to the unit cell. The 24 of the originating 64 cubes contain planar cis tetramers Hg(5,6)4 with Hg in a nearly trigonal planar or tetrahedral coordination. In another 24 of the small cubes, two opposing faces are decorated by Hg(3,4)2 dumbbells, two by Ba(2) atoms respectively. The third type of small cubes are centered by Ba(1) atoms only. The complex 3D polyanionic Hg/Zn network thus formed is compared with the Hg partial structure in Rb3Hg20 applying a group-subgroup relation. Despite their different overall structures, the connectivity of the negatively charged Hg atoms, the rather metallic Zn bonding characteristic (as obtained from FP-LAPW band structure calculations) and the coordination number of 16 for all Ba cations relate the two title compounds.

  11. Draft genome sequence of Bacillus pumilus BA06, a producer of alkaline serine protease with leather-dehairing function.

    PubMed

    Zhao, Chuan-Wu; Wang, Hai-Yan; Zhang, Yi-Zheng; Feng, Hong

    2012-12-01

    Bacillus pumilus BA06 was isolated from the proteinaceous soil and produced an extracellular alkaline protease with leather-dehairing function. The genome of BA06 was sequenced. The comparative genome analysis indicated that strain BA06 is different in genome from the other B. pumilus strains, with limited insertions, deletions, and rearrangements.

  12. 17 CFR 240.15Ba1-2 - Registration of municipal advisors and information regarding certain natural persons.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Affiliated Securities Associations § 240.15Ba1-2 Registration of municipal advisors and information regarding... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Registration of municipal advisors and information regarding certain natural persons. 240.15Ba1-2 Section 240.15Ba1-2 Commodity...

  13. Organogenic responses of Pinus pinea cotyledons to hormonal treatments: BA metabolism and cytokinin content.

    PubMed

    Moncaleán, P; Alonso, P; Centeno, M L; Cortizo, M; Rodríguez, A; Fernández, B; Ordás, R J

    2005-01-01

    Isolated cotyledons from mature Pinus pinea L. embryos were cultured in vitro in a factorial combination of 4.4, 10 and 44.4 microM N6-benzyladenine (BA) for 2, 4, 8, 16 and 35 days to optimize shoot regeneration. Incubation of explants in 44.4 microM BA for 4 days, in place of the standard incubation in 4.4 microM BA for 35 days, reduced the entire culture period to 4 weeks. Shortening the culture period had no significant effect on the caulogenic response or the number of buds formed per cotyledon. To establish the relationship between key moments in the caulogenic process induced by 4.4 microM BA and the endogenous concentrations of the active forms of BA and other isoprenoid-type cytokinins (CKs), we examined uptake, metabolism and amount of BA, as well as the amounts of zeatin, dihydrozeatin and their ribosides in P. pinea cotyledons after 1, 2, 6, 12 and 24 h, and 2, 4, 8, 16 and 35 days of exposure to 8-[14C]BA. Uptake and release of BA were associated with water movement between explants and the medium during the first 8 days of culture. The interconvertible forms of BA were the main metabolites formed in the tissues. Inactivation of BA as a result of conjugation or oxidation was insignificant. The endogenous concentration of BA + N6-benzyladenosine was 20-fold higher than the exogenously applied BA during the competence acquisition phase (Days 0-3). The concentration of isoprenoid-type CKs also increased 16-fold and then decreased during this time. Induction of shoot buds (Days 4-8) was characterized by a second peak of BA uptake by explants that triggered the synthesis of N6-benzyladenosine-5 -monophosphate and by the maintenance of isoprenoid-type CKs. Reestablishment of CK homeostasis marked the shift from the induction phase to the shoot development phase in this organogenic process (Days 8-12).

  14. The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA

    PubMed Central

    Sayapathi, Balachandar S; Su, Anselm Ting; Koh, David

    2014-01-01

    Background: Development of noise-induced hearing loss is reliant on a few factors such as frequency, intensity, and duration of noise exposure. The occurrence of this occupational malady has doubled from 120 million to 250 million in a decade. Countries such as Malaysia, India, and the US have adopted 90 dBA as the permissible exposure limit. According to the US Occupational Safety and Health Administration (OSHA), the exposure limit for noise is 90 dBA, while that of the US National Institute of Occupational Safety and Health (NIOSH) is 85 dBA for 8 hours of noise exposure. Objectives: This study aimed to assess the development of hearing threshold levels beyond 25 dBA on adoption of 85 dBA as the permissible exposure limit compared to 90 dBA. Patients and Methods: This is an intervention study done on two automobile factories. There were 203 employees exposed to noise levels beyond the action level. Hearing protection devices were distributed to reduce noise levels to a level between the permissible exposure limit and action level. The permissible exposure limits were 90 and 85 dBA in factories 1 and 2, respectively, while the action levels were 85 and 80 dBA, respectively. The hearing threshold levels of participants were measured at baseline and at first month of postshift exposure of noise. The outcome was measured by a manual audiometer. McNemar and chi-square tests were used in the statistical analysis. Results: We found that hearing threshold levels of more than 25 dBA has changed significantly from pre-intervention to post-intervention among participants from both factories (3000 Hz for the right ear and 2000 Hz for the left ear). There was a statistically significant association between participants at 3000 Hz on the right ear at ‘deteriorated’ level ( χ² (1) = 4.08, φ = - 0.142, P = 0.043), whereas there was worsening of hearing threshold beyond 25 dBA among those embraced 90 dBA. Conclusions: The adoption of 85 dBA as the permissible exposure

  15. First principles investigations of structural, elastic, dielectric and piezoelectric properties of { Ba,Sr,Pb } TiO3, { Ba,Sr,Pb } ZrO3 and { Ba,Sr,Pb } { Zr,Ti } O3 ceramics

    NASA Astrophysics Data System (ADS)

    Akgenc, Berna; Tasseven, Cetin; Cagin, Tahir

    2015-03-01

    We use first-principle density-functional study of structural, anisotropic mechanical, dielectric and piezoelectric properties of {Ba,Sr,Pb}TiO3, {Ba,Sr,Pb}ZrO3 and {Ba,Sr,Pb}{Zr,Ti}O3 alloys in cubic perovskite structures at zero temperature. Because there is significant interest in finding new piezoelectrics that do not contain toxic elements such as lead. In this study, we compare piezoelectric response of those alloys to synthesize outstanding piezoelectric materials. In perovskite structures, the spontaneous polarization is due to enormous values of Born effective charges computed by linear response within density functional perturbation theory, which are much larger than predicted nominal charge. We deeply investigated the effects of composition, order and site defects structure on piezoelectric constants.

  16. Graphene oxide-BaGdF5 nanocomposites for multi-modal imaging and photothermal therapy.

    PubMed

    Zhang, Hao; Wu, Huixia; Wang, Jun; Yang, Yan; Wu, Dongmei; Zhang, Yingjian; Zhang, Yang; Zhou, Zhiguo; Yang, Shiping

    2015-02-01

    By using a solvothermal method in the presence of polyethylene glycol (PEG), BaGdF5 nanoparticles are firmly attached on the surface of graphene oxide (GO) nanosheets to form the GO/BaGdF5/PEG nanocomposites. The resulting GO/BaGdF5/PEG shows low cytotoxicity, positive magnetic resonance (MR) contrast effect and better X-ray attenuation property than Iohexol, which enables effective dual-modality MR and X-ray computed tomography (CT) imaging of the tumor model in vivo. The enhanced near-infrared absorbance, good photothermal stability and efficient tumor passive targeting of GO/BaGdF5/PEG result in the highly efficient photothermal ablation of tumor in vivo after intravenous injection of GO/BaGdF5/PEG and the following 808-nm laser irradiation (0.5 W/cm(2)). The histological and biochemical analysis data reveal no perceptible toxicity of GO/BaGdF5/PEG in mice after treatment. These results indicate potential application of GO/BaGdF5/PEG in dual-modality MR/CT imaging and photothermal therapy of cancers.

  17. Crystal chemical and quantum chemical studies of Ba(Sr)-Nb oxide compounds

    NASA Technical Reports Server (NTRS)

    Zubkov, V. G.; Turzhevsky, S. A.; Pereliaev, V. A.; Liechtenstein, A. I.; Gubanov, V. A.

    1990-01-01

    The information available on the BaO(SrO)-NbO-NbO2 system with the niobium atom in the lower oxidation degree is very limited. Very few compounds have been found previously in this system. They are BaNbO3, SrxNbO3(0,7=x=1), Ba2Nb2O9, SrNb8O14; and some suggestions on the BaNb8O14 existence have been made also. At the same time Nb-based oxide compounds could be quite interesting in the search of new noncopper high T(sub c) superconductors Researchers studied Ba(Sr) NbxO2x-2 and Ba2(Sr2)-NbxO2x-1 compositions in the phase diagram of BaO(SrO)-NbO-NbO2 system. The synthesis of the materials was carried out in vacuum at the temperatures of 1000 to 1500 C. Barium carbonate and niobium pentoxide were used as initial components. X-ray analysis was carried out.

  18. Hemostatic effects of recombinant DisBa-01, a disintegrin from Bothrops alternatus.

    PubMed

    Kauskot, Alexandre; Cominetti, Marcia R; Ramos, Oscar H P; Bechyne, Iga; Renard, Jean-Marie; Hoylaerts, Marc F; Crepin, Michel; Legrand, Chantal; Selistre-de-Araujo, Heloisa S; Bonnefoy, Arnaud

    2008-05-01

    A monomeric RGD-disintegrin was recently identified from a cDNA library from the venom gland of Bothrops alternatus. The corresponding 12 kDa-recombinant protein, DisBa-01, specifically interacted with alpha(v)beta3 integrin and displayed potent anti-metastatic and anti-angiogenic properties. Here, the interaction of DisBa-01 with platelet alphaIIb beta3 integrin and its effects on hemostasis and thrombosis were investigated. DisBa-01 bound to Chinese Hamster Ovary (CHO) cells expressing beta3 or alphaIIb beta3 and promoted their adhesion and the adhesion of resting platelets onto glass coverslips. The disintegrin inhibited the binding of FITC-fibrinogen and FITC-PAC-1 to ADP-stimulated platelets and inhibited ADP-, TRAP- and collagen-induced aggregation of murine, rabbit or human platelets. In a flow chamber assay, DisBa-01 inhibited and reverted platelet adhesion to immobilized fibrinogen. DisBa-01 inhibited the phosphorylation of FAK following platelet activation. The intravenous injection of DisBa-01 in C57Bl6/j mice, prolonged tail bleeding time as well as thrombotic occlusion time in mesenteric venules and arterioles following vessel injury with FeCl3. In conclusion, DisBa-01 antagonizes the platelet alphaIIb beta3 integrin and potently inhibits thrombosis.

  19. Thermodynamic stability of radiogenic Ba in CsAlSi2O6 pollucite

    NASA Astrophysics Data System (ADS)

    Jaffe, John; van Ginhoven, Renée; Jiang, Weilin

    2013-03-01

    Pollucite, a zeolite-like nanoporous aluminosilicate structure with nominal composition CsAlSi2O6, has been suggested as a nuclear waste storage form for fission-product radioactive isotopes of cesium, especially 137Cs. One factor affecting the long-term stability of this waste form is the valence change associated with the beta decay that converts Cs into barium. We have used first-principles density functional total energy calculations to evaluate the thermodynamic stability of pollucite with Ba replacing Cs at regular lattice sites with respect to the precipitation of Ba, Cs or their oxides. We included small clusters of substitutional BaCs as well as localized complexes of BaCs with compensating electron donor defects, specifically Cs vacancies and interstitial oxygen. We conclude that Cs-Ba pollucite is thermodynamically stable against precipitation of Cs or its oxide, but that partial precipitation of Ba or BaO may be thermodynamically favored under some conditions. Even this change may be kinetically limited, however. Fuel Cycle Research and Development, U.S. Department of Energy Waste Form Campaign

  20. Effects of induced optical tunable and ferromagnetic behaviors of Ba doped nanocrystalline LaB6.

    PubMed

    Bao, Lihong; Qi, Xiaoping; Tana; Chao, Lumen; Tegus, O

    2016-07-28

    Multiple nanocrystalline rare-earth hexaborides La1-xBaxB6 have been synthesized via a single step solid-state reaction. The Ba doping effects on crystal structure, grain morphology, magnetic and optical absorption properties were investigated using XRD, FESEM, HRTEM, SQUID magnetometry and optical measurements. The results show that all the Ba-doped hexaborides crystallize in the CsCl-type single phase, indicating the Ba atoms occupied the lattice sites of LaB6. The optical absorption results indicate that the absorption valleys of LaB6 are red-shifted from 622 nm to 780 nm when the Ba doping content increases to x = 0.8. The first-principle calculation results reveal that Ba doping reduces the total kinetic energy of the electrons of LaB6, which lead to the absorption valleys moving toward a higher wavelength. Meanwhile, the band gap of BaB6 obtained from optical absorption is in good agreement with the theoretical calculation results. The magnetic measurements results showed that Ba doping lead to room-temperature ferromagnetism of LaB6 due to the different ionic radii of La(3+) and Ba(2+) causing intrinsic crystal defects, which is directly observed experimentally by HRTEM. This is the first time that we have found the tunable optical and ferromagnetic behavior of Ba doped nanocrystalline LaB6. Thus, nanocrystalline La1-xBaxB6, as multi-functional materials, should open up a new route to extend the optical and magnetic applications of LaB6 nanopowder.

  1. Possible octupole deformation in Cs and Ba nuclei from their differential radii

    SciTech Connect

    Sheline, R.K.; Jain, A.K.; Jain, K.

    1988-12-01

    The odd-even staggering of the differential radii of Fr and Ra and the Cs and Ba nuclei is compared. This staggering is inverted in the region of known octupole deformation in the Fr and Ra nuclei. The normal staggering is eliminated in the Cs nuclei and attenuated in the Ba nuclei for neutron numbers 85--88. This fact is used to suggest the possible existence of octupole deformation and its neutron number range in the Cs and Ba nuclear ground states.

  2. Electron Diffraction Studies of Superconductors of the K-Ba System and Related Oxides

    NASA Astrophysics Data System (ADS)

    Nikolaichik, V. I.; Klinkova, L. A.

    The application of transmission electron microscopy in combination with physical-chemical methods has made it possible to discover a large number of discrete oxides of ordered structures in the Ba-Bi-O system, which is the parent system for the K-Ba-Bi-O superconducting system. Cation-ordered superconductors Ba1-xKxBiO3 with the crystalline structure of a non-cubic and layered nature have been synthesized. This result removes the crystallographic contradiction between bismuthate and cuprate superconductors that provides support to the existence of a common non-magnetic pairing mechanism.

  3. Direct writing of three-dimensional woodpile BaTiO3 structures

    NASA Astrophysics Data System (ADS)

    Li, Jijiao; Li, Bo; Wu, Hongya; Zhou, Ji

    2014-05-01

    Barium titanate (BaTiO3) woodpile structures with designed, three-dimensional (3D) geometry have been fabricated by direct-writing assembly techniques. Concentrated BaTiO3 inks with suitable rheological properties were prepared to enable the fabrication of the complex 3D structures. It was demonstrated that BaTiO3 inks with a total solids volume fraction of 0.41 are shear thinning and have a high storage modulus 1 × 105Pa with a yield stress of 300 Pa. Additionally, the woodpile lattice structures exhibited an excellent self-supporting feature.

  4. First-principles calculations of low coverage growth of Ba on Si(001)

    NASA Astrophysics Data System (ADS)

    Ashman, C. R.; Foerst, C. J.; Bloechl, P. E.

    2007-03-01

    Ba is of interest to the semiconductor industry for it's possible use in replacement gate oxide materials and for possible use in a buffer layer between Si(001) and Ba containing dielectric materials. Thus it is of importance to understand the initial stages of growth. This paper reports state-of-the-art electronic structure calculations on the deposition of Barium on the technologically relevant, (001) orientated silicon surface. We identify the surface reconstructions from zero to one monolayer and relate them to previous theoretical studies of low coverage Ba growth and Sr growth.

  5. BaSTI: An updated, advanced and VO-compliant database of stellar evolution predictions

    NASA Astrophysics Data System (ADS)

    Pietrinferni, A.; Molinaro, M.; Cassisi, S.; Pasian, F.; Salaris, M.; Pelusi, D.; Manzato, P.; Vuerli, C.

    2014-11-01

    Stellar evolution model databases, spanning a wide ranges of masses and initial chemical compositions, are nowadays a major tool to study Galactic and extragalactic stellar populations. We describe here the current status of the widely used BaSTI (A Bag of Stellar Tracks and Isochrones) database. We focus in particular on the efforts devoted to port BaSTI to a VO-compliant environment, the BaSTI Web portal that enables users to retrieve data tables and run a range of web tools to facilitate the theoretical analysis of observations, and planned future developments within the framework of the Italian Virtual Observatory project.

  6. Vibrational spectra of (BaF2)n (n=1-6) clusters

    NASA Astrophysics Data System (ADS)

    Pandey, Ratnesh K.; Waters, Kevin; Nigam, Sandeep; Pandey, Ravindra; Pandey, Avinash C.

    2016-05-01

    The vibrational properties of alkaline-earth metal fluoride clusters (BaF2)n (n=1-6) are investigated in the framework of density functional theory. The calculated Raman and Infrared (IR) spectra reveals shift in Raman and IR peak position towards lower frequency region with the increase in the cluster size. Further the calculated spectra have been compared with the experimental vibrational spectra of bulk BaF2 crystal. Even though the smaller size cluster lacks translational symmetry, the structural and vibrational characteristic of (BaF2)5-6 are nearer to bulk counterpart.

  7. Climate, productivity, and intermediate water nutrients: new records from bamboo coral Ba/Ca

    NASA Astrophysics Data System (ADS)

    Lavigne, M.; Hill, T. M.; Spero, H. J.; Guilderson, T. P.

    2010-12-01

    A geochemical nutrient proxy from deep-sea corals would provide decadal to centennial scale records of intermediate-water nutrient dynamics. Such records could be used to determine how intermediate water masses (300-2000m) are affected by decadal scale climate change (e.g. Pacific Decadal Oscillation) via carbon cycling, export production, and intermediate water-mass circulation/ventilation. Because seawater barium (BaSW ) has a nutrient-like distribution in the water-column (similar to silicate), Ba/Ca records have been used to trace upwelled nutrient supply in shallow water surface corals isolated from terrestrial barium sources. Here we show the first calibration of a nutrient proxy from skeletal barium preserved in the calcitic internodes of bamboo corals. Our calibration was calculated from a depth transect (500-2000m) of Isidella and Keratoisis corals spanning a silicate and (BaSW ) gradient on the California Margin (Ba/Ca coral (µmol/mol) = 0.117 BaSW (nmol/kg ) + 0.835; R2 = 0.88; n = 29). The strong linear correlation between Ba/Ca coral and BaSW suggests that coral Ba/Ca is a reliable recorder of seawater barium (and, therefore, silicate). We find a distribution coefficient (DBa) for bamboo coral Ba/Ca of 1.3±0.1, similar to that of other corals (surface and deep-sea dwelling) and inorganic calcium carbonate precipitation experiments (DBa = 1.2-1.5). This implies that, as true for other carbonates, Ba incorporation is primarily driven by ionic substitution and holds promise as a globally applicable nutrient proxy in bamboo corals. High-resolution Ba/Ca timeseries records sampled via LA-ICP-MS in two co-located California Margin corals (Pioneer Seamount; 830m; 37°22’27”N) co-vary with ~decadal-scale variations in silicate and nitrate measured at 500m depth (CalCOFI line 80 sta. 60; 34°8’60”N). This suggests that high-resolution records of bamboo coral Ba/Ca can be used to reconstruct broad changes in intermediate water nutrients driven by

  8. The ordered double perovskite PrBaCo2O6: Synthesis, structure, and magnetism

    NASA Astrophysics Data System (ADS)

    Motin Seikh, Md.; Pralong, V.; Lebedev, O. I.; Caignaert, V.; Raveau, B.

    2013-07-01

    The stoichiometric layered perovskite cobaltite PrBaCo2O6 has been synthesized using an oxidative reaction of PrBaCo2O5.80 by sodium hypochlorite. The ferromagnetic properties of this oxide, which exhibits the highest TC of 210 K among the "112" layered cobaltites, are interpreted by double exchange mechanism. In contrast, the creation of oxygen vacancies in this framework leads for the oxides PrBaCo2O5+δ (0.80 ≤ δ < 1) to a strong competition between ferromagnetism and antiferromagnetism due to the appearance of superexchange Co3+—O—Co3+ antiferromagnetic interactions.

  9. Ferroelectric switching induced magnetic anisotropy in Fe/BaTiO3 bilayers

    NASA Astrophysics Data System (ADS)

    Duan, Chun-Gang; Jaswal, S. S.; Tsymbal, E. Y.

    2007-03-01

    Ferromagnetic/ferroelectric heterostructures have recently attracted significantly interest due to their potential applications in multifunctional electronic devices. We have recently predicted a magnetoelectric effect at the Fe/BaTiO3 interface induced by ferroelectric polarization reversal [1]. In this report, calculations are being carried out on the magnetic anisotropy of Fe/BaTiO3 films. Preliminary results show that the ferroelectric switching of the BaTiO3 has appreciable effect on the magnetic anisotropy of magnetic Fe films. This should be of interest in multiferroic device applications. [1] Chun-gang Duan, S. S. Jaswal, E. Y. Tsymbal, Phys. Rev. Lett. 97, 047201 (2006).

  10. Addendum: Safety Standards for Gua sha (press-stroking) and Ba guan (cupping).

    PubMed

    Nielsen, Arya; Kligler, Ben; Koll, Brian S

    2014-06-01

    Our previous article Safety Standards for Gua sha (press-stroking) and Baguan (cupping) discussed the risk of transfer of blood-borne pathogens with Gua sha and Ba guan, identified Gua sha and Ba guan 'instrument criticality' as semi-critical and offered recommendations for safe practice based on hospital disinfection standards. Based on the article's feedback, we feel the need to clarify that Gua sha and Ba guan instruments, if intended for reuse, must undergo high level disinfection (HLD) or, in the case of 'wet-cupping', sterilization. We update our recommendations to be amenable to both private practice and education settings.

  11. Nonstoichiometry and decomposition of La 1+ zBa 2- zCu 3O y and La 4BaCu 5O 13- w

    NASA Astrophysics Data System (ADS)

    Lindemer, T. B.; Specht, E. D.; MacDougall, C. S.; Taylor, G. M.; Pye, S. L.

    1993-10-01

    The temperature ( T, K) and oxygen pressure ( pO 2, Pa) dependence of oxygen content in La 1+ zBa 2- zCu 3O y (123) and La 4BaCu 5O 13- w (415) were determined over the ranges 10 Pa to 0.1 MPa O 2, 0.0≤ z≤0.7 and 523≤ T≤1223 K. The data for each phase were correlated with chemical thermodynamic representations. For La 1+ zBa 2- zCu 3O y, the T- z- y- pO 2 behavior was modeled as a solution of LaBa 2Cu 3O 7- x and 415. The experimental data demonstrated 7- x values <6 at high temperatures, while they exceed 6.99 only at temperatures approaching ambient at 0.1 MPa O 2. These two characteristics are not known to occur in the lanthanide and Y analogues. The T- z- pO 2 dependence of high-temperature decomposition was determined and, in conjunction with X-ray analysis, permitted construction of the phase diagram lying between LaBa 2Cu 3O 7- x and 415. Effects of residual carbonate content were also determined.

  12. Genomics-based high-resolution mapping of the BaMMV/BaYMV resistance gene rym11 in barley (Hordeum vulgare L.).

    PubMed

    Lüpken, Thomas; Stein, Nils; Perovic, Dragan; Habekuss, Antje; Krämer, Ilona; Hähnel, Urs; Steuernagel, Burkhard; Scholz, Uwe; Zhou, Rounan; Ariyadasa, Ruvini; Taudien, Stefan; Platzer, Matthias; Martis, Mihaela; Mayer, Klaus; Friedt, Wolfgang; Ordon, Frank

    2013-05-01

    Soil-borne barley yellow mosaic virus disease, caused by different strains of Barley yellow mosaic virus (BaYMV) and Barley mild mosaic virus (BaMMV), is one of the most important diseases of winter barley (Hordeum vulgare L.) in Europe and East Asia. The recessive resistance gene rym11 located in the centromeric region of chromosome 4HL is effective against all so far known strains of BaMMV and BaYMV in Germany. In order to isolate this gene, a high-resolution mapping population (10,204 meiotic events) has been constructed. F2 plants were screened with co-dominant flanking markers and segmental recombinant inbred lines (RILs) were tested for resistance to BaMMV under growth chamber and field conditions. Tightly linked markers were developed by exploiting (1) publicly available barley EST sequences, (2) employing barley synteny to rice, Brachypodium distachyon and sorghum and (3) using next-generation sequencing data of barley. Using this approach, the genetic interval was efficiently narrowed down from the initial 10.72 % recombination to 0.074 % recombination. A marker co-segregating with rym11 was developed providing the basis for gene isolation and efficient marker-assisted selection.

  13. The role of Area 10 (BA10) in human multitasking and in social cognition: a lesion study.

    PubMed

    Roca, María; Torralva, Teresa; Gleichgerrcht, Ezequiel; Woolgar, Alexandra; Thompson, Russell; Duncan, John; Manes, Facundo

    2011-11-01

    A role for rostral prefrontal cortex (BA10) has been proposed in multitasking, in particular, the selection and maintenance of higher order internal goals while other sub-goals are being performed. BA10 has also been implicated in the ability to infer someone else's feelings and thoughts, often referred to as theory of mind. While most of the data to support these views come from functional neuroimaging studies, lesion studies are scant. In the present study, we compared the performance of a group of frontal patients whose lesions involved BA10, a group of frontal patients whose lesions did not affect this area (nonBA10), and a group of healthy controls on tests requiring multitasking and complex theory of mind judgments. Only the group with lesions involving BA10 showed deficits on multitasking and theory of mind tasks when compared with control subjects. NonBA10 patients performed more poorly than controls on an executive function screening tool, particularly on measures of response inhibition and abstract reasoning, suggesting that theory of mind and multitasking deficits following lesions to BA10 cannot be explained by a general worsening of executive function. In addition, we searched for correlations between performance and volume of damage within different subregions of BA10. Significant correlations were found between multitasking performance and volume of damage in right lateral BA10, and between theory of mind and total BA10 lesion volume. These findings stress the potential pivotal role of BA10 in higher order cognitive functions.

  14. Crystal structure of the solid solution Ba8.35Pb0.65(B3O6)6.

    PubMed

    Zhao, Wenwu

    2017-03-01

    Single crystals of lead barium borate, Ba8.35Pb0.65(B3O6)6, octabarium lead(II) hexa-kis-(triborate), have been obtained by spontaneous nucleation from a high-temperature melt. Its three-dimensional structure is constructed on the basis of a BaO9 polyhedron, a (Pb/Ba)O6 octa-hedron (occupancy ratio Pb:Ba = 0.216:0.784) and a condensed B3O6 ring anion. In the crystal, the planar B3O6 anions are stacked in an alternating fashion with Ba and (Pb/Ba) atoms along [001]. A comparison is made with the structures of related solid solutions in the system Ba/Pb/B/O.

  15. Crystal structure of the solid solution Ba8.35Pb0.65(B3O6)6

    PubMed Central

    Zhao, Wenwu

    2017-01-01

    Single crystals of lead barium borate, Ba8.35Pb0.65(B3O6)6, octabarium lead(II) hexa­kis­(triborate), have been obtained by spontaneous nucleation from a high-temperature melt. Its three-dimensional structure is constructed on the basis of a BaO9 polyhedron, a (Pb/Ba)O6 octa­hedron (occupancy ratio Pb:Ba = 0.216:0.784) and a condensed B3O6 ring anion. In the crystal, the planar B3O6 anions are stacked in an alternating fashion with Ba and (Pb/Ba) atoms along [001]. A comparison is made with the structures of related solid solutions in the system Ba/Pb/B/O. PMID:28316806

  16. Surface Relaxations, Surface Energies and Electronic Structures of BaSnO3 (001) Surfaces: Ab Initio Calculations

    NASA Astrophysics Data System (ADS)

    Slassi, A.; Hammi, M.; El Rhazouani, O.

    2017-02-01

    The surface relaxations, surface energies and electronic structures of BaO- and SnO2-terminated BaSnO3 (001) surfaces have been studied by employing the first-principles density functional theory. For both terminations, we find that the upper-layer Ba and Sn atoms move inward, whereas upper-layer O atoms move outward from the surface. Moreover, the largest relaxations are occurred on the first-layer atoms of both terminations. The surface rumpling of BaO-terminated BaSnO3 (001) is slightly less than that of the SnO2-terminated BaSnO3 (001) surface. The surface energies show that both terminated surfaces are energetically stable and favorable. Finally, the surface band gap is slightly decreased for the BaO termination, while it is dramatically decreased for the SnO2 termination.

  17. Barium isotope fractionation during experimental formation of the double carbonate BaMn[CO3](2) at ambient temperature.

    PubMed

    Böttcher, Michael E; Geprägs, Patrizia; Neubert, Nadja; von Allmen, Katja; Pretet, Chloé; Samankassou, Elias; Nägler, Thomas F

    2012-09-01

    In this study, we present the first experimental results for stable barium (Ba) isotope ((137)Ba/(134)Ba) fractionation during low-temperature formation of the anhydrous double carbonate BaMn[CO(3)](2). This investigation is part of an ongoing work on Ba fractionation in the natural barium cycle. Precipitation at a temperature of 21±1°C leads to an enrichment of the lighter Ba isotope described by an enrichment factor of-0.11±0.06‰ in the double carbonate than in an aqueous barium-manganese(II) chloride/sodium bicarbonate solution, which is within the range of previous reports for synthetic pure BaCO (3) (witherite) formation.

  18. Physicochemical properties of high-temperature solutions of the systems BaO-B/sub 2/O/sub 3/-Fe/sub 2/O/sub 3/ and BaO-B/sub 2/O/sub 3/-BaF/sub 2/-Fe/sub 2/O/sub 3/ suitable for the growth of BaFe/sub 12/O/sub 19/ single crystals

    SciTech Connect

    Peshev, P.; Varadinov, R.; Nikolov, V. )

    1989-08-01

    The systems BaO-B/sub 2/O/sub 3/-Fe/sub 2/O/sub 3/ and BaO-B/sub 2/O/sub 3/-BaF/sub 2/-Fe/sub 2/O/sub 3/ have been investigated and the concentration and temperature regions of stability of the Ba Fe/sub 12/O/sub 19/ phase in them are determined with a view to choosing suitable solvents and growth conditions of barium hexaferrite single crystals. The temperature dependencies of the dynamic viscosity of solutions of these systems are studied. It is shown that solutions containing BaF/sub 2/ have considerably lower viscosity values. The density and volatility of the solutions at their saturation temperatures are determined. On the basis of the data obtained, an appropriate solvent composition from the system BaO-B/sub 2/O/sub 3/-BaF/sub 2/ is proposed.

  19. Uptake, metabolism and macromolecular binding of benzo(a)pyrene (BaP) metabolites in channel catfish

    SciTech Connect

    Elskus, A.A.; McElroy, A.E.

    1995-12-31

    Polynuclear aromatic hydrocarbons (PAH), such as BaP, are contaminants with demonstrated carcinogenicity, yet little is known about the fate of PAH metabolites in aquatic organisms. Some invertebrates actively metabolize BaP to hydroxylated and conjugated forms, becoming BaP metabolite-rich prey items for fish. The authors examined the fate of BaP metabolites acquired by fish through diet. Channel catfish, Ictaluruspunctatus, were fed a single dose (2.5 umoles/kg fish) of either {sup 3}H-parent BaP or individual {sup 3}H-BaP metabolites: 3-hydroxy, 9-hydroxy, 9-sulfate or 9-glucuronidated BaP. After 24 hrs fish were killed, and samples of intestinal mucosa, bile, liver and muscle immediately frozen at {minus}80 C. Mean (n = 3--5) percent of dose retained was lowest for conjugated BaP (3.7%), 2--4 times higher for hydroxylated BaP (8.9%), and 5 times higher for parent BaP (18.9%). Differences were also observed between the distributions of individual metabolites in tissues. Radioactivity derived from parent and hydroxylated BaP was several fold higher in intestinal mucosa and bile than in liver or muscle. In contrast, radioactivity derived from conjugated BaP metabolites was more evenly distributed between all four tissues. These data demonstrate that in fish (1) dietary BaP metabolites are absorbed by the intestine, and they or their metabolites are transported to and absorbed by major tissue reservoirs (liver, muscle), (2) conjugated metabolites are less readily absorbed and/or retained than parent or hydroxylated BaP, and (3) some differences in metabolic fate exist between metabolites from the same class. DNA, RNA and protein adducts, as well as metabolite profiles, are being determined in liver and intestine.

  20. Critical currents and pinning forces in a-axis oriented EuBa2Cu3O7/PrBa2Cu3O7 superlattices

    NASA Astrophysics Data System (ADS)

    Vélez, M.; Martín, J. I.; Vicent, J. L.

    1995-11-01

    a-axis oriented EuBa2Cu3O7/PrBa2Cu3O7 (EBCO/PBCO) superlattices have been grown by dc sputtering. The critical current (JC) behavior is modified by the pinning force arising from the insulating PrBa2Cu3O7 layers, which in a-axis oriented superlattices are perpendicular to the Cu-O planes. Depending on the EBCO and PBCO layer thicknesses the pinning forces deviate from the usual scaling laws as a function of temperature observed in single films. When B is perpendicular to the sample, an exponential dependence of JC(B) appears as the PBCO thickness is increased (coupling is reduced), and also as the thickness of the EBCO layer is reduced.

  1. Liquidus Diagram of the Ba-Y-Cu-O System in the Vicinity of the Ba2YCu3O6+x Phase Field

    PubMed Central

    Wong-Ng, Winnie; Cook, Lawrence P.

    1998-01-01

    This paper describes the melting equilibria in the vicinity of the high Tc phase Ba2YCu3O6+x, including evidence for two Ba-Y-Cu-O immiscible liquids. Melting equilibria have been investigated in purified air using a combination of differential thermal analysis (DTA), thermogravimetric analysis (TGA), powder x-ray diffraction (XRD), MgO wick entrapment of liquid for analysis, scanning electron microscopy (SEM) coupled with energy dispersive x-ray analysis (EDS), and hydrogen reduction for determination of copper oxidation state. For relatively barium-rich compositions, it was necessary to prepare the starting materials under controlled atmosphere conditions using BaO. A liquidus diagram was derived from quantitative data for the melts involved in various melting reactions. In general the 1/2(Y2O3) contents of the melts participating in these equilibria were low (mole fraction <4 %). The primary phase field of Ba2YCu3O6+x occurs at a mole fraction of <2.0 % 1/2Y2O3 and lies very close along the BaO-CuOx edge, extending from a mole fraction of ≈43 % CuO to a mole fraction of ≈76 % CuO. It is divided by a liquid miscibility gap and extends on either side about this gap. The topological sequence of melting reactions associated with the liquidus is presented as a function of temperature. Implications for the growth of Ba2YCu3O6+x crystals are discussed. PMID:28009382

  2. The electronic structure of the high-symmetry perovskite iridate Ba2IrO4

    NASA Astrophysics Data System (ADS)

    Moser, S.; Moreschini, L.; Ebrahimi, A.; Dalla Piazza, B.; Isobe, M.; Okabe, H.; Akimitsu, J.; Mazurenko, V. V.; Kim, K. S.; Bostwick, A.; Rotenberg, E.; Chang, J.; Rønnow, H. M.; Grioni, M.

    2014-01-01

    We report angle-resolved photoemission (ARPES) measurements, density functional and model tight-binding calculations on Ba2IrO4 (Ba-214), an antiferromagnetic (TN = 230 K) insulator. Ba-214 does not exhibit the rotational distortion of the IrO6 octahedra that is present in its sister compound Sr2IrO4 (Sr-214), and is therefore an attractive reference material to study the electronic structure of layered iridates. We find that the band structures of Ba-214 and Sr-214 are qualitatively similar, hinting at the predominant role of the spin-orbit interaction in these materials. Temperature-dependent ARPES data show that the energy gap persists well above TN, and favor a Mott over a Slater scenario for this compound.

  3. Crystal and electronic structures of metallic Ba2Pd5Ge4.

    PubMed

    Saparov, Bayrammurad; Parker, David S; Sefat, Athena S

    2012-11-07

    Crystals of a new intermetallic germanide Ba(2)Pd(5)Ge(4) have been grown out of a binary PdGe flux. Single crystal X-ray diffraction reveals that the compound crystallizes in a novel structure type in the Cmca space group, with a = 10.9296(9) Å, b = 14.1639(12) Å, and c = 5.8808(5) Å at 173(2) K. This structure type features a three-dimensional [Pd(5)Ge(4)] network made of distorted tetrahedral and square planar PdGe(4) units, with Ba atoms filling the voids. The magnetic susceptibility and the electrical resistivity measurements show that Ba(2)Pd(5)Ge(4) is a Pauli paramagnet and a metal with the room temperature resistivity value of ρ(300 K) ≈ 0.096 mΩ cm. The band structure calculations confirm that Ba(2)Pd(5)Ge(4) is a good metal with no magnetic instability.

  4. Pyroelectric response of spray-deposited BaTiO3 thin film

    NASA Astrophysics Data System (ADS)

    Peale, Robert E.; Oladeji, Isaiah O.; Smith, Evan M.; Vasilyev, Vladimir; Alhasan, Sarmad Fawzi Hamza; Abouelkhair, Hussain; Todorovski, Dalibor; Kimani, Martin; Cleary, Justin W.

    2016-09-01

    Pyroelectric photoresponse of aqueous spray deposited thin films containing BaTiO3 nano-crystals is reported. X-ray diffraction data indicate the presence of hexagonal BaTiO3 nano-crystals with 20 nm crystalline domains in a matrix of some as yet unidentified nano-crystalline material. When the film is annealed at 600 C, the X-ray pattern changes significantly and indicates a conversion to one of the non-hexagonal phases of BaTiO3 as well as a complete change in the matrix. With suitable amplifier, the measured photoresponse was 40V/W. Ferroelectric hysteresis on a film with significant presence of hexagonal BaTiO3 shows saturated polarization which is about 5-times smaller than for the bulk tetragonal phase. A potential application is a patternable infrared detector for photonic and plasmonic devices, such as chip-scale spectral sensors.

  5. Ba{sub 2}TeO as an optoelectronic material: First-principles study

    SciTech Connect

    Sun, Jifeng; Shi, Hongliang; Du, Mao-Hua; Singh, David J.; Siegrist, Theo

    2015-05-21

    The band structure, optical, and defects properties of Ba{sub 2}TeO are systematically investigated using density functional theory with a view to understanding its potential as an optoelectronic or transparent conducting material. Ba{sub 2}TeO crystallizes with tetragonal structure (space group P4/nmm) and with a 2.93 eV optical bandgap [Besara et al., J. Solid State Chem. 222, 60 (2015)]. We find relatively modest band masses for both electrons and holes suggesting applications. Optical properties show infrared-red absorption when doped. This could potentially be useful for combining wavelength filtering and transparent conducting functions. Furthermore, our defect calculations show that Ba{sub 2}TeO is intrinsically p-type conducting under Ba-poor condition. However, the spontaneous formation of the donor defects may constrain the p-type transport properties and would need to be addressed to enable applications.

  6. Pressure dependence of electronic properties of BaI{sub 2}

    SciTech Connect

    Kumar, Pradeep; Vedeshwar, Agnikumar G.

    2015-08-28

    We present Density Functional Theoretical (DFT) calculations of the electronic properties of scintillator material BaI{sub 2} under pressure which were carried out using Perdew-Burke-Ernzerhof genralized gradient approximation. We found that BaI{sub 2} is a direct band gap material with band gap calculated as 3.35 eV. The pressure effect on BaI{sub 2} indicates a linear monotonously decreasing band gap and increasing valence band width with pressure. We have observed the shifting of band extrema from the Γ point with pressure. The pressure coefficient of band gap is found to be −0.047 eV/GPa. The interatomic ionicity factor of BaI{sub 2} is found to be 0.51. Trends in bonding and ionicity under pressure are also discussed.

  7. Anomalous properties and nature of Ba 1-xK xBiO 3 superconductivity

    NASA Astrophysics Data System (ADS)

    Golovashkin, A. I.; Anshukova, N. V.; Ivanova, L. I.; Rusakov, A. P.

    1994-12-01

    On the base of temperature dependencies of the specific heat in magnetic fields, thermal expansion and magnetic properties of high quality high-T c Ba 1-xK xBiO 3 ( x = 0,38 - 0,40) it was found that H c2(T) had anomalous upward curvature up to fields 20T and coefficient of thermal expansion was negative at low temperatures. The results contradict the picture of simple electron-phonon coupling. We have presented a model of the electronic ordering in Ba 1-xK xBiO 3 which drives the system to the dielectric-metal phase transition with doping. It was shown that electronic spectrum peculiarities near the Brillouin zone boundary determine the anomalous properties and upward curvature of H c2(T) in BaKBiO. The mechanism of BaKBiO superconductivity is discussed.

  8. Consequences of Ca multisite occupation for the conducting properties of BaTiO3

    NASA Astrophysics Data System (ADS)

    Zulueta, Y. A.; Dawson, J. A.; Leyet, Y.; Anglada-Rivera, J.; Guerrero, F.; Silva, R. S.; Nguyen, Minh Tho

    2016-11-01

    In combination with the dielectric modulus formalism and theoretical calculations, a newly developed defect incorporation mode, which is a combination of the standard A- and B-site doping mechanisms, is used to explain the conducting properties in 5 mol% Ca-doped BaTiO3. Simulation results for Ca solution energies in the BaTiO3 lattice show that the new oxygen vacancy inducing mixed mode exhibits low defect energies. A reduction in dc conductivity compared with undoped BaTiO3 is witnessed for the incorporation of Ca. The conducting properties of 5 mol% Ca-doped BaTiO3 are analyzed using molecular dynamics and impedance spectroscopy. The ionic conductivity activation energies for each incorporation mode are calculated and good agreement with experimental data for oxygen migration is observed. The likely existence of the proposed defect configuration is also analyzed on the basis of these methods.

  9. Electronic structures and optical spectra of BaO from first principles

    SciTech Connect

    Wu, Chang-Wei; Pan, Bo; Wang, Neng-Ping

    2015-08-21

    We present the results of first-principles study for the electronic structure and optical absorption spectrum of the alkaline-earth metal oxide BaO. The quasiparticle band structure is evaluated within the Hedin's GW approximation [Phys. Rev. 139, A796 (1965)]. Thereafter, the electron-hole interaction is taken into consideration and the Bethe-Salpeter equation for the electron-hole two-particle Green function is solved. The calculated quasiparticle band gap of BaO is 4.1 eV, which is in good agreement with the experimental result. The calculated optical absorption spectrum of BaO is also in agreement with the experimental data. In particular, the calculated excitation energy for the lowest exciton peak in the optical absorption spectrum of BaO reproduces very well the corresponding experimental result.

  10. Electronic structures and optical spectra of BaO from first principles

    NASA Astrophysics Data System (ADS)

    Wu, Chang-Wei; Pan, Bo; Wang, Neng-Ping

    2015-08-01

    We present the results of first-principles study for the electronic structure and optical absorption spectrum of the alkaline-earth metal oxide BaO. The quasiparticle band structure is evaluated within the Hedin's GW approximation [Phys. Rev. 139, A796 (1965)]. Thereafter, the electron-hole interaction is taken into consideration and the Bethe-Salpeter equation for the electron-hole two-particle Green function is solved. The calculated quasiparticle band gap of BaO is 4.1 eV, which is in good agreement with the experimental result. The calculated optical absorption spectrum of BaO is also in agreement with the experimental data. In particular, the calculated excitation energy for the lowest exciton peak in the optical absorption spectrum of BaO reproduces very well the corresponding experimental result.

  11. Synthesis, crystal structure, and photocatalytical properties of Ba3Ta5O14N

    NASA Astrophysics Data System (ADS)

    Anke, B.; Bredow, T.; Soldat, J.; Wark, M.; Lerch, M.

    2016-01-01

    Light yellow Ba3TaV5O14N was successfully synthesized as phase-pure material crystallizing isostructurally to well-known mixed-valence Ba3TaV4TaIVO15. The electronic structure of Ba3Ta5O14N was studied theoretically with a hybrid Hartree-Fock-DFT method. The most stable structure was obtained when nitrogen atoms were placed at 4 h sites having fourfold coordination. By incorporating nitrogen, the band gap decreases from ∼3.8 eV commonly known for barium tantalum(V) oxides to 2.8 eV for the oxide nitride, giving rise to an absorption band well in the visible-light region. Ba3Ta5O14N was also tested for photocatalytic hydrogen formation.

  12. First-principles calculations on the four phases of BaTiO3.

    PubMed

    Evarestov, Robert A; Bandura, Andrei V

    2012-04-30

    The calculations based on linear combination of atomic orbitals basis functions as implemented in CRYSTAL09 computer code have been performed for cubic, tetragonal, orthorhombic, and rhombohedral modifications of BaTiO(3) crystal. Structural and electronic properties as well as phonon frequencies were obtained using local density approximation, generalized gradient approximation, and hybrid exchange-correlation density functional theory (DFT) functionals for four stable phases of BaTiO(3). A comparison was made between the results of different DFT techniques. It is concluded that the hybrid PBE0 [J. P. Perdew, K. Burke, M. Ernzerhof, J. Chem. Phys. 1996, 105, 9982.] functional is able to predict correctly the structural stability and phonon properties both for cubic and ferroelectric phases of BaTiO(3). The comparative phonon symmetry analysis in BaTiO(3) four phases has been made basing on the site symmetry and irreducible representation indexes for the first time.

  13. Metallic behavior of GaAs/BaTiO3 heterostructure

    NASA Astrophysics Data System (ADS)

    Yuan, Mengqi; Wang, Jianli; Pu, Long; Tang, Gang; Guo, Sandong

    2016-07-01

    The integration of III-V semiconductors on functional perovskite-oxide can lead to new material properties and new device applications by combining the rich properties of perovskite-oxides together with the superior optical and electronic properties of III-V semiconductors. The structural and electronic properties of the surface and interface of the GaAs/BaTiO3 are studied using first-principles calculations. We point out the energetically favorable GaAs/BaTiO3 interfaces according to the GaAs initial adsorption on the BaTiO3(001) substrate. Our calculations predict the existence of the metallic behavior at the GaAs/BaTiO3 interfaces.

  14. Yttrium enrichment and improved magnetic properties in partially melted Y-Ba-Cu-O materials

    NASA Technical Reports Server (NTRS)

    Alterescu, Sidney; Hojaji, Hamid; Barkatt, Aaron; Michael, Karen A.; Hu, Shouxiang

    1990-01-01

    The yttrium-rich compositions in the Y-Ba-Cu-O system were mapped out in a systematic manner to quantify their magnetic properties and to correlate them with the microstructure and phase composition as determined by scanning electron microscopy and X-ray diffraction analysis. It is found that the microstructure of Y-Ba-Cu-O compositions is a sensitive function of both their composition and processing conditions. Measurements of magnetic susceptibility and maximum (low-field) and remanent magnetization for the system Y:Ba:Cu = x:2:3 show highest values for x = 2. The corresponding structures involve numerous small crystals of Y2BaCuO5 (211) embedded in highly ordered assemblages of continous YBa2Cu3O(7-y) (123) layers.

  15. BaMBa: towards the integrated management of Brazilian marine environmental data

    PubMed Central

    Meirelles, Pedro Milet; Gadelha, Luiz M. R.; Francini-Filho, Ronaldo Bastos; de Moura, Rodrigo Leão; Amado-Filho, Gilberto Menezes; Bastos, Alex Cardoso; Paranhos, Rodolfo Pinheiro da Rocha; Rezende, Carlos Eduardo; Swings, Jean; Siegle, Eduardo; Asp Neto, Nils Edvin; Leitão, Sigrid Neumann; Coutinho, Ricardo; Mattoso, Marta; Salomon, Paulo S.; Valle, Rogério A.B.; Pereira, Renato Crespo; Kruger, Ricardo Henrique; Thompson, Cristiane; Thompson, Fabiano L.

    2015-01-01

    A new open access database, Brazilian Marine Biodiversity (BaMBa) (https://marinebiodiversity.lncc.br), was developed in order to maintain large datasets from the Brazilian marine environment. Essentially, any environmental information can be added to BaMBa. Certified datasets obtained from integrated holistic studies, comprising physical–chemical parameters, -omics, microbiology, benthic and fish surveys can be deposited in the new database, enabling scientific, industrial and governmental policies and actions to be undertaken on marine resources. There is a significant number of databases, however BaMBa is the only integrated database resource both supported by a government initiative and exclusive for marine data. BaMBa is linked to the Information System on Brazilian Biodiversity (SiBBr, http://www.sibbr.gov.br/) and will offer opportunities for improved governance of marine resources and scientists’ integration. Database URL: http://marinebiodiversity.lncc.br PMID:26454874

  16. Ba2TeO as an optoelectronic material: First-principles study

    DOE PAGES

    Sun, Jifeng; Shi, Hongliang; Du, Mao-Hua; ...

    2015-05-21

    The band structure, optical and defects properties of Ba2TeO are systematically investigated using density functional theory with a view to understanding its potential as an optoelectronic or transparent conducting material. Ba2TeO crystallizes with tetragonal structure (space group P4/nmm) and with a 2.93 eV optical band gap1. We find relatively modest band masses for both electrons and holes suggesting applications. Optical properties show a infrared-red absorption when doped. This could potentially be useful for combining wavelength filtering and transparent conducting functions. Furthermore, our defect calculations show that Ba2TeO is intrinsically p-type conducting under Ba-poor condition. However, the spontaneous formation of themore » donor defects may constrain the p-type transport properties and would need to be addressed to enable applications.« less

  17. Ba2TeO as an optoelectronic material: First-principles study

    SciTech Connect

    Sun, Jifeng; Shi, Hongliang; Du, Mao-Hua; Siegrist, Theo; Singh, David J.

    2015-05-21

    The band structure, optical and defects properties of Ba2TeO are systematically investigated using density functional theory with a view to understanding its potential as an optoelectronic or transparent conducting material. Ba2TeO crystallizes with tetragonal structure (space group P4/nmm) and with a 2.93 eV optical band gap1. We find relatively modest band masses for both electrons and holes suggesting applications. Optical properties show a infrared-red absorption when doped. This could potentially be useful for combining wavelength filtering and transparent conducting functions. Furthermore, our defect calculations show that Ba2TeO is intrinsically p-type conducting under Ba-poor condition. However, the spontaneous formation of the donor defects may constrain the p-type transport properties and would need to be addressed to enable applications.

  18. The BaBar Gas Bubbler Upgrade and Evaluation

    SciTech Connect

    Gan, Yu; Young, C.; /SLAC

    2005-12-15

    The Instrumented Flux Return region (muon and K{sub L} detection barrel) of the BaBar detector at SLAC requires careful monitoring of the gas flow through the detector array. This is currently done by a system of digital gas bubblers which monitor the flow rate by using photogate technology to detect the presence of bubbles formed by gas flowing through an internal oil chamber. Recently, however, a design flaw was discovered in these bubblers. Because the bubblers are connected directly to the detector array with no filter, during rises in atmospheric pressure or a drop in the gas flow rate (e.g. when the gas system is shut off for maintenance), the oil in this chamber could be forced backwards into the detector tubes. To compensate for this problem, we upgraded the existing gas bubbler systems by installing metal traps into the old gas lines to capture the oil. This installation was followed by an evaluation of the retro-fitted bubblers during which we determined a relationship between the bubble counting rate and the actual gas flow rate, but encountered recurring problems with baseline fluctuations and unstable bubble counting rates. Future work will involve the study of how these instabilities develop, and whether or not they can be mitigated.

  19. Measurements of the CKM Angle Alpha at BaBar

    SciTech Connect

    Stracka, Simone; /Milan U. /INFN, Milan

    2012-04-04

    The authors present improved measurements of the branching fractions and CP-asymmetries fin the B{sup 0} {yields} {pi}{sup +}{pi}{sup -}, B{sup 0} {yields} {pi}{sup 0}{pi}{sup 0}, and B{sup +} {yields} {rho}{sup +}{rho}{sup 0} decays, which impact the determination of {alpha}. The combined branching fractions of B {yields} K{sub 1}(1270){pi} and B {yields} K{sub 1}(1400){pi} decays are measured for the first time and allow a novel determination of {alpha} in the B{sup 0} {yields} {alpha}{sub 1}(1260){sup {+-}}{pi}{sup {-+}} decay channel. These measurements are performed using the final dataset collected by the BaBar detector at the PEP-II B-factory. The primary goal of the experiments based at the B factories is to test the Cabibbo-Kobayashi-Maskawa (CKM) picture of CP violation in the standard model of electroweak interactions. This can be achieved by measuring the angles and sides of the Unitarity Triangle in a redundant way.

  20. Radiation damage in BaF[sub 2] crystals

    SciTech Connect

    Woody, C.L.; Kierstead, J.A.; Levy, P.W.; Stoll, S.

    1991-01-01

    The effects of radiation damage and recovery have been studied in BaF[sub 2] crystals exposed to [sup 60]Co radiation. The change in optical transmission and scintillation light output have been measured as a function of dose up to 4.7 [times] 10[sup 6] rad. Although some crystals exhibit a small change in transmission, a greater change in scintillation light output is observed. Several 25 cm long crystals whichhave been irradiated show large changes in both transmission and light output. Recovery from radiation damage has been studied as a function of time and exposure to UV light. A long lived radiation induced phosphorescence has been observed in all irradiated samples which is distinct from the standard fast and slow scintillation emissions. The emission spectrum of the phosphorescence has been measured and shown a peakat [approximately]330 nm, near the region of the slow scintillation component. Results are given on the dependence of the decay time of the phosphorescence with dose.

  1. Radiation damage in BaF{sub 2} crystals

    SciTech Connect

    Woody, C.L.; Kierstead, J.A.; Levy, P.W.; Stoll, S.

    1991-12-31

    The effects of radiation damage and recovery have been studied in BaF{sub 2} crystals exposed to {sup 60}Co radiation. The change in optical transmission and scintillation light output have been measured as a function of dose up to 4.7 {times} 10{sup 6} rad. Although some crystals exhibit a small change in transmission, a greater change in scintillation light output is observed. Several 25 cm long crystals whichhave been irradiated show large changes in both transmission and light output. Recovery from radiation damage has been studied as a function of time and exposure to UV light. A long lived radiation induced phosphorescence has been observed in all irradiated samples which is distinct from the standard fast and slow scintillation emissions. The emission spectrum of the phosphorescence has been measured and shown a peakat {approximately}330 nm, near the region of the slow scintillation component. Results are given on the dependence of the decay time of the phosphorescence with dose.

  2. 137 Ba Double Gamma Decay Measurement with GAMMASPHERE

    SciTech Connect

    Merchán, E.; Moran, K.; Lister, C. J.; Chowdhury, P.; McCutchan, E. A.; Greene, J. P.; Zhu, S.; Lauritsen, T.; Carpenter, M. P.; Shearman, R.

    2015-05-28

    The study of the electromagnetic moments (EM), and decay probability, provides detailed information about nuclear wave functions. The well-know properties of EM interactions are good for extracting information about the motion of nucleons. Higher order EM processes always occur, but are usually too weak to be measured. In the case of a 0+ → 0+ transitions, where a single gamma transition is forbidden, the simultaneous emission of two γ-rays has been studied. An interesting opportunity to further investigate 2-photon emission phenomena is by using a standard 137Cs source populating, via β-decay, the Jπ = 11/2- isomeric state at 662 keV in 137Ba. In this case, two photon process can have contributions from quadrupole-quadrupole or dipole-octupole multipolarities in direct competition with the high multipolarity M4 decay. Since the yield of the double gamma decay is around six orders of magnitude less than the first order transition, very good statistics are needed in order to observe the phenomena and great care must be taken to suppress the first-order decay. The Gammasphere array is ideal since its configuration allows a good coverage of the angular distribution and the Compton events can be suppressed. Nevertheless the process to understand and eliminate the Compton background is a challenge. Geant4 simulations were carried out to help understand and correct for those factors.

  3. 137 Ba Double Gamma Decay Measurement with GAMMASPHERE

    DOE PAGES

    Merchán, E.; Moran, K.; Lister, C. J.; ...

    2015-05-28

    The study of the electromagnetic moments (EM), and decay probability, provides detailed information about nuclear wave functions. The well-know properties of EM interactions are good for extracting information about the motion of nucleons. Higher order EM processes always occur, but are usually too weak to be measured. In the case of a 0+ → 0+ transitions, where a single gamma transition is forbidden, the simultaneous emission of two γ-rays has been studied. An interesting opportunity to further investigate 2-photon emission phenomena is by using a standard 137Cs source populating, via β-decay, the Jπ = 11/2- isomeric state at 662 keVmore » in 137Ba. In this case, two photon process can have contributions from quadrupole-quadrupole or dipole-octupole multipolarities in direct competition with the high multipolarity M4 decay. Since the yield of the double gamma decay is around six orders of magnitude less than the first order transition, very good statistics are needed in order to observe the phenomena and great care must be taken to suppress the first-order decay. The Gammasphere array is ideal since its configuration allows a good coverage of the angular distribution and the Compton events can be suppressed. Nevertheless the process to understand and eliminate the Compton background is a challenge. Geant4 simulations were carried out to help understand and correct for those factors.« less

  4. Theoretical study of Ge/ BaTiO 3 Interfaces

    NASA Astrophysics Data System (ADS)

    Fredrickson, Kurt; Demkov, Alexander

    2011-03-01

    It has been shown (McKee et al., Phys. Rev. Lett. 81, 3014 (1998), and R. McKee, et al., Science 293 , 468 (2001)) that perovskite oxides SrTi O3 and BaTi O3 (BTO) can be grown epitaxially on Si and Ge, respectively. It would be interesting to achieve the reverse, i.e. to grow for example, Ge on BTO. It is not clear, however, whether one can achieve wetting of BTO by Ge. Theoretically, the energy of the Ge (001) surface is estimated to be anywhere between 591 and 1700 erg/cm2 and the surface energy of BTO is in the range of 1083-1496 erg/cm2 depending on termination and environment. The missing piece of information is the energy of the Ge/BTO interface. We examine five possible Ge/BTO interface structures and calculate their energies using density functional theory to determine which one has the lowest energy, and whether wetting can be achieved.

  5. Surface electronic structures of Ba overlayers on W(100), W(110), and W(111)

    NASA Astrophysics Data System (ADS)

    Ibrahim, Z. A.; Lee, M. J. G.

    2007-10-01

    The total energy distributions (TEDs) in field emission (FE) and photofield emission (PFE) and the work functions have been measured at room temperature for Ba adsorbed on W(100), W(110), and W(111) in the range of coverage from 0 to 1 ML (monolayer). We observe two initial state peaks and three final state peaks on W(100)/Ba , six initial state peaks and one final state peak on W(110)/Ba , and two initial state peaks and two final state peaks on W(111)/Ba . We extend the full-potential linear augmented plane wave method for the electronic structures of periodic lattices to calculate the emission current in FE and surface PFE at a metal-adsorbate-vacuum interface. Our calculations account for the energies of all of the initial state features observed experimentally in FE and surface PFE from clean W(100), in PFE and angle-resolved inverse photoemission spectroscopy from W(100)/Ba at 1 ML, and for all of the peaks observed in FE, surface PFE, and photoemission from W(110)/Ba at 0.6 ML and from W(111)/Ba at 1 ML. The dz2 -like surface states of the Swanson hump [L. W. Swanson and L. C. Crouser, Phys. Rev. Lett. 16, 389 (1966)] of clean W(100) hybridize with s -like states of the c(2×2) overlayer and are shifted by -1.60eV to yield a prominent peak in PFE. An isolated Ba c(2×2) layer is found to be weakly metallic; the metallicity is greatly enhanced when it is adsorbed on a W(100) substrate. The TEDs in PFE from the atomically less dense overlayer W(110)/Ba (2×2) are dominated by substrate-overlayer interactions, while those from the atomically denser overlayer W(111)/Ba (1×1) are dominated by interactions within the overlayer. Our results yield evidence that above 1/3 ML Ba coverage on W(111), which corresponds to a commensurate (31/2×31/2)R30° overlayer, the interstitial sites fill in randomly to form a commensurate (1×1) overlayer at 1 ML coverage.

  6. NO2 uptake under practically relevant conditions on BaO/Pt(111)

    SciTech Connect

    Mudiyanselage, Kumudu; Szanyi, János

    2012-02-01

    The formation of nitrites and nitrates (Ba(NOx)2) under practically relevant conditions (PNO2 up to 1.0 Torr and T = 500 K) and their thermal decomposition on BaO (>20 monolayer equivalent (MLE))/Pt(1 1 1) were studied using temperature programmed desorption (TPD), infrared reflection absorption (IRA), and Xray photoelectron (XP) spectroscopies. The exposure of BaO to 1.0 × 10-8 Torr NO2 at 500 K leads to the formation of a Ba(NOx)2 layer with small, disordered crystalline nitrate clusters. Under these conditions (PNO2 = 1.0 × 10-8 Torr and T = 500 K) only the top portion of the BaO layer converts to Ba(NOx)2 and the nitrites in this Ba(NOx)2 layer stay without converting completely to nitrates even after 100 min of NO2 exposure. In the thermal decomposition of Ba(NOx)2, first nitrites decompose, releasing NO and then the decomposition of nitrates occurs via two pathways releasing NO2 and NO + O2. At 500 K and PNO2 ≥ 1.0 × 10-7 Torr, first NO2 reacts with BaO to form small disordered crystalline Ba(NO3)2 particles and then these particles agglomerate to form large, well-ordered (bulk-like) crystalline nitrates as the NO2 exposure increases. The thermal decomposition of these well-ordered, bulk-like crystalline nitrate aggregates occurs in two steps releasing NO2 and NO + O2 in each step in two different temperature regions. NO2 pressure ≥1.0 × 10-5 Torr is required for the complete oxidation of initially formed nitrites to nitrates and the full nitration of the BaO layer at 500 K sample temperature. We gratefully acknowledge the US Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by

  7. Bulk superconductivity in Tl 2Ba 2CaCu 2O 8 and TlBa 2Ca 2Cu 3O 9 phases

    NASA Astrophysics Data System (ADS)

    Sulpice, A.; Giordanengo, B.; Tournier, R.; Hervieu, M.; Maignan, A.; Martin, C.; Michel, C.; Provost, J.

    1988-09-01

    Well-crystallized Tl 2Ba 2CaCu 2O 8 phases have been observed superconducting or normal below 108 K depending on their stoichiometry. This observation is an evidence that a (Cu IL&.zbnd;O -) mixed valence induced by vacancies or substitution on different sites gives rise to superconductivity in this phase. The new phase TlBa 2Ca 2CuO 9 which intrinsically contains a mixed valence has been observed as having a sharp transition to bulk superconductivity in the Meissner effect at a critical temperature of 120 K. This temperature is much higher than the recently observed one.

  8. Crystallography and Physical Properties of BaCo2As2, Ba0.94K0.06Co2As2, and Ba0.78K0.22Co2As2

    SciTech Connect

    Anand, V K; Quirinale, Dante G; Lee, Yongbin; Harmon, Bruce N; Furukawa, Yuji; Ogloblichev, V V; Huq, A; Abernathy, D L; Stephens, P W; McQueeney, Robert J; Kreyssig, Aandreas; Goldman, Alan I; Johnston, David C

    2014-08-01

    The crystallographic and physical properties of polycrystalline and single crystal samples of BaCo2As2 and K-doped Ba{1-x}K{x}Co2As2 (x = 0.06, 0.22) are investigated by x-ray and neutron powder diffraction, magnetic susceptibility chi, magnetization, heat capacity Cp, {75}As NMR and electrical resistivity rho measurements versus temperature T. The crystals were grown using both Sn flux and CoAs self-flux, where the Sn-grown crystals contain 1.6-2.0 mol% Sn. All samples crystallize in the tetragonal ThCr2Si2-type structure (space group I4/mmm). For BaCo2As2, powder neutron diffraction data show that the c-axis lattice parameter exhibits anomalous negative thermal expansion from 10 to 300 K, whereas the a-axis lattice parameter and the unit cell volume show normal positive thermal expansion over this T range. No transitions in BaCo2As2 were found in this T range from any of the measurements. Below 40-50 K, we find rho ~ T^2 indicating a Fermi liquid ground state. A large density of states at the Fermi energy D(EF) ~ 18 states/(eV f.u.) for both spin directions is found from low-T Cp(T) measurements, whereas the band structure calculations give D(EF) = 8.23 states/(eV f.u.). The {75}As NMR shift data versus T have the same T dependence as the chi(T) data, demonstrating that the derived chi(T) data are intrinsic. The observed {75}As nuclear spin dynamics are consistent with the presence of ferromagnetic and/or stripe-type antiferromagnetic spin fluctuations. The crystals of Ba{0.78}K{0.22}Co2As2 were grown in Sn flux and show properties very similar to those of undoped BaCo2As2. On the other hand, the crystals from two batches of Ba{0.94}K{0.06}Co2As2 grown in CoAs self-flux show evidence of weak ferromagnetism at T < 10 K with small ordered moments at 1.8 K of 0.007 and 0.03 muB per formula unit, respectively.

  9. Exploring the potential of semiconducting BaSi2 for thin-film solar cell applications

    NASA Astrophysics Data System (ADS)

    Suemasu, Takashi; Usami, Noritaka

    2017-01-01

    Semiconducting barium disilicide (BaSi2), which is composed of earth-abundant elements, has attractive features for thin-film solar cell applications. Both a large absorption coefficient comparable to copper indium gallium diselenide and a minority-carrier diffusion length much larger than the grain size of BaSi2 can be used to improve solar cell properties. In this review article, we explore the potential of semiconducting BaSi2 film for thin-film solar cell applications. We start by describing its crystal and energy band structure, followed by discussing thin-film growth techniques and the optical and electrical properties of BaSi2 films. We use a first-principles calculation based on density-functional theory to calculate the position of the Fermi level to predict the carrier type of impurity-doped BaSi2 films using either a group 13 or 15 element, and compare the calculated results with the experimental ones. Special attention was paid to the minority-carrier properties, such as minority-carrier lifetime, minority-carrier diffusion length, and surface passivation. The potential variations across the grain boundaries measured by Kelvin-probe force microscopy allowed us to detect a larger minority-carrier diffusion length in BaSi2 on Si(1 1 1) compared with BaSi2 on Si(0 0 1). Finally, we demonstrate the operation of p-BaSi2/n-Si heterojunction solar cells and discuss prospects for future development.

  10. Evidence for superconductivity above 40 K in the La-Ba-Cu-O compound system

    NASA Technical Reports Server (NTRS)

    Chu, C. W.; Hor, P. H.; Meng, R. L.; Gao, L.; Huang, Z. J.

    1987-01-01

    An apparent superconducting transition with an onset temperature above 40 K has been detected under pressure in the La-Ba-Cu-O compound system synthesized directly from a solid-state reaction of La2O3, CuO, and BaCO3 followed by a decomposition of the mixture in a reduced atmosphere. The experiment is described and the results of effects of magnetic field and pressure are discussed.

  11. Superconductivity in the Sn-Ba-Sr-Y-Cu-O system

    NASA Technical Reports Server (NTRS)

    Aleksandrov, K. S.; Khrustalev, B. P.; Krivomazov, S. N.; Petrov, M. I.; Vasilyev, A. D.; Zwegintsev, S. A.

    1991-01-01

    After the discovery of high-T(sub c) superconductivity in the La-Ba-Cu-O compound, several families of superconducting oxides were synthesized. Here, researchers report the results of the search for superconductivity in the compounds based on tin which has a lone electron pair like Bi, Tl, and Pb. The following compounds were synthesized: Sn1Ba1Sr1Cu3O(sub x), Sn1Ba1Ca1Cu3O(sub x), Sn1Ba1Mg1Cu3O(sub x), Sn1Sr1Ca1Cu3O(sub x), Sn1Sr1Mg1Cu3O(sub x), and Sn1Ca1Mg1Cu3O(sub x). The initial components were oxides and carbonates of the appropriate elements. A standard firing-grinding procedure was used. Final heating was carried out at 960 C during 12 hours. Then the samples were cooled inside the furnace. All the synthesis cycles were carried out in air atmosphere. Among the synthesized compounds only Sn1Ba1Sr1Cu3O(sub x) showed remarkable conductivity. Other compounds were practically dielectrics. Presence of a possible superconductivity in Sn1Ba1Sr1Cu3O(sub x) was defined by using the Meissner effect. At low temperature a deviation from paramagnetic behavior is observed. The hysteresis loops obtained at lower temperature undoubtly testify to the presence of a superconductive phase in the sample. However, the part of the superconductive phase in the Sn1Ba1Sr1Cu3O(sub x) ceramic turned out to be small, less than 2 percent, which agrees with the estimation from magnetic data. In order to increase the content of the superconductive phase, two-valent cations Ba and Sr were partially substituted by univalent (K) and three-valent ones (Y).

  12. Superconductivity in the Sn-Ba-Sr-Y-Cu-O system

    NASA Technical Reports Server (NTRS)

    Aleksandrov, K. S.; Khrustalev, B. P.; Krivomazov, S. N.; Petrov, M. I.; Vasilyev, A. D.; Zwegintsev, S. A.

    1990-01-01

    Since Bednorz and Muller discovered high-T(sub c) superconductivity in the La-Ba-Cu-O compound, several families of superconducting oxides have been synthesized. Here, researchers report the results of search for superconductivity in the compounds based on tin, which has a lone electron pair like Bi, Tl, Pb. The following compounds were synthesized: Sn1Ba1Sr1Cu3Ox, Sn1Ba1Ca1Cu3Ox, Sn1Ba1Mg1Cu3Ox, Sn1Sr1Ca1Cu3Ox, Sn1Sr1Mg1Cu3Ox, Sn1Ca1Mg1Cu3Ox. The initial components were oxides and carbonates of the appropriate elements. Standard firing-grinding procedure was used. Final heating was carried out at 960 C during 12 hours. Then the samples were cooled inside the furnace. All the synthesis cycles were carried out in air atmosphere. Among the synthesized compounds only Sn1Ba1Sr1Cu3Ox showed remarkable conductivity. Other compounds were practically dielectrics. Presence of a possible superconductivity in Sn1Ba1Sr1Cu3Ox was defined by using the Meissner effect. At low temperature a deviation from paramagnetic behavior is observed. The hysteresis loops obtained at lower temperatures undoubtly testify to the presence of a superconductive phase in the sample. However, the part of the superconductive phase in the Sn1Ba1Sr1Cu3Ox ceramic turned out to be small, less than 2 percent, which agrees with the estimation from magnetic data. In order to increase the content of the superconductive phase two-valent cations Ba, Sr were partially substituted by univalent (K) and three-valent ones (Y).

  13. The relationship of structure to superconductivity in the Pr-Ba-Cu-O system

    SciTech Connect

    Minseo, Park

    1994-05-10

    The relation of structure to lack of superconductivity in Pr-Ba-Cu-O was systematically investigated. First, the phase equilibria of this system was studied to find the processing parameters which maximize the cation-site ordering between Pr and Ba ions. Second, a comparative study between superconducting Nd-Ba-Cu-0 and non- superconducting Pr-Ba-Cu-0 was performed by forming solid-solution Nd- Pr-Ba-Cu-0. The relation between structure and superconductivity in Ndb1-xPrxBa2Cu3O7-δ is investigated. Tc decreases monotonically with increasing x and superconductivity disappears at around x=0.3-0.4. Tc is enhanced by 10K when the sample is processed at an oxygen partial pressure (PO2) of 0.01 atm, followed by oxygenation at 450C. Depression of (Tc) as a function of x and PO 2 is explained in terms of a charge-transfer model. It is suggested that destruction of superconductivity in the RE1-xPrxBa2CU3O7-δ (RE=rare-earth) system can be viewed as disruption of four-fold planar coordinated Cu ions in the chain-site due to permanent occupation of extra Pr ions on Ba sites.

  14. Reactive Atmosphere Processing of BaTiO(3) and Origins of Its Photorefractive Effect

    DTIC Science & Technology

    1989-04-01

    samples of BaTi03 ....... 3-17 3-2 bsorption coefficient at 4416 A for Ea .......................................... 3-20 3-3 Transition metal impurities...in BaTi0 3 , measured by spark source emission spectroscopy ..................................... 3-22 3-4 Electronic properties of first-row...impurities was determined by both secondary ion mass spectroscopy (SIMS) and spark source emission spectroscopy (Burgess Analytical Labs, North Adams

  15. Nuclear electric dipole moments for the lowest 1/2+ states in Xe and Ba isotopes

    NASA Astrophysics Data System (ADS)

    Yoshinaga, N.; Higashiyama, K.; Arai, R.; Teruya, E.

    2014-04-01

    The electric dipole moments for the lowest 1/2+ states of Xe and Ba isotopes are calculated in terms of the nuclear shell model, which includes two-body nucleon interactions violating parity and time-reversal invariance. Using the wave functions thus obtained, the nuclear electric dipole moments arising from the intrinsic nucleon electric dipole moments and also from asymmetric charge distribution are calculated. The upper limits for the nuclear electric dipole moments of Xe and Ba isotopes are estimated.

  16. Mesoporous BaSnO3 layer based perovskite solar cells.

    PubMed

    Zhu, Liangzheng; Shao, Zhipeng; Ye, Jiajiu; Zhang, Xuhui; Pan, Xu; Dai, Songyuan

    2016-01-18

    One of the limitations of TiO2 based perovskite solar cells is the poor electron mobility of TiO2. Here, perovskite oxide BaSnO3 is used as a replacement. It has a higher electron mobility and the same perovskite structure as the light harvesting materials. After optimization, devices based on BaSnO3 showed the best performance of 12.3% vs. 11.1% for TiO2.

  17. Picosecond Nd:BaY2F8 laser discretely tunable around 1 μm

    NASA Astrophysics Data System (ADS)

    Agnesi, A.; Pirzio, F.; Reali, G.; Toncelli, A.; Tonelli, M.

    2010-09-01

    Passive mode-locking of a diode-pumped Nd:BaY2F8 (Nd:BaYF) was achieved on four lines in the range 1040-1074 nm, employing a semiconductor saturable absorber mirror (SAM). Nearly Fourier-limited pulses with durations of 2.6 to 7.2 ps and output power ≈50 mW were generated in a dispersion-controlled resonator using a single prism for wavelength selection, tuning and dispersion management.

  18. Local environment analysis of Fe ions in BaMgSiO4

    NASA Astrophysics Data System (ADS)

    Kase, Junya; Shingaki, Yoshihiro; Inaba, Yuta; Meguro, Kazune; Murata, Hidenobu; Okajima, Toshihiro; Yamamoto, Tomoyuki

    2016-08-01

    Polycrystalline Fe-doped BaMgSiO4 is synthesized by the conventional solid state reaction method, which shows strong photochromism. Photochromic property of the synthesized specimens is investigated by measuring the diffuse reflectance spectrum. Local environment of doped Fe ions in BaMgSiO4 has been studied by the analysis of the X-ray absorption near-edge structure (XANES) spectrum with the aid of the first-principles calculations.

  19. Structure and magnetic properties of Zn-Ti-substituted Ba-ferrite particles for magnetic recording

    NASA Astrophysics Data System (ADS)

    Wang, C. S.; Wei, F. L.; Lu, M.; Han, D. H.; Yang, Z.

    1998-03-01

    The formation process of Zn-Ti-doped Ba-ferrite particles was investigated by the X-ray diffraction technique, transmission electron microscope and magnetic measurements. The effects of heating temperature Th and the Zn-Ti substitution x on the microstructure and magnetic properties of BaFe 12-2 xZn xTi x O 19 particles with x=0.10-0.80 were studied. The temperature dependence of magnetic properties of these particles was measured.

  20. BaCO3 mediated modifications in structural and magnetic properties of natural nanoferrites

    NASA Astrophysics Data System (ADS)

    Widanarto, W.; Jandra, M.; Ghoshal, S. K.; Effendi, M.; Cahyanto, W. T.

    2015-04-01

    Preparing M-type barium hexaferrite and improving the magnetic response of natural ferrites by incorporating barium carbonate (BaCO3) is ever-demanding. Series of barium carbonate doped ferrites with composition (100-x)Fe3O4·xBaCO3 (x=0, 10, 20, 30 wt%) are prepared through solid state reaction method and sintered gradually at temperatures of 800 and 1000 °C. Nanoparticles of natural ferrite and commercial BaCO3 are used as raw materials. Impacts of BaCO3 on structural and magnetic properties of these synthesized ferrites are inspected. The obtained ferrites are characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) at room temperature. Uniform barium hexaferrite particles in terms of both morphology and size are not achieved. The average crystallite size of BaFe12O19 is observed to be within 30-600 nm. The sintering process results phase transformation from Fe3O4 (magnetite) to α-Fe2O3 (hematite) and the formation of hexagonal barium ferrite crystals. The occurrence of barium crystal is found to enhance with the increase of BaCO3 concentrations up to 20 wt% and suddenly drop at 30 wt%. Saturation and remanent magnetization of the doped ferrites are significantly augmented up to 16.37 and 8.92 emu g-1, respectively compared to their pure counterpart. Furthermore, the coercivity field is slightly decreased as BaCO3 concentrations are increased. BaCO3 mediated improvements in the magnetic response of natural ferrites are demonstrated.

  1. Synthesis and photoactivity enhancement of Ba doped Bi{sub 2}WO{sub 6} photocatalyst

    SciTech Connect

    Li, Wen Ting; Huang, Wan Zhen; Zhou, Huan; Yin, Hao Yong; Zheng, Yi Fan; Song, Xu Chun

    2015-04-15

    Highlights: • The Ba-doped Bi{sub 2}WO{sub 6} photocatalyst have been synthesized by a hydrothermal route. • The photocatalytic activity of Bi{sub 2}WO{sub 6} was greatly enhanced by Ba-doping. • The effect of Ba on the catalytic activity of Bi{sub 2}WO{sub 6} was studied and discussed. - Abstract: In this study, Bi{sub 2}WO{sub 6} doped with different barium contents were successfully prepared by a simple hydrothermal route at 180 °C for 12 h. The as-synthesized samples were characterized in detailed by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffusere flectance spectroscopy (UV–vis DRS) and Brunauer–Emmet–Teller (BET) theory. Their photocatalytic activities were evaluated by photodegradation of Rhodamine B (RhB) under simulated solar light. As a result, the photocatalytic properties were enhanced after Ba doping and the Ba-doped Bi{sub 2}WO{sub 6} with R{sub Ba} = 0.15 showed the highest photocatalytic activities of 96.3% RhB was decomposed in 50 min. Close investigation revealed that the proper Ba doped into Bi{sub 2}WO{sub 6} could not only increases its BET surface area, decrease its crystalline size, but also act as electron traps and facilitate the separation of photogenerated electron–hole pairs. The mechanism of enhanced photocatalytic activities of Ba-doped Bi{sub 2}WO{sub 6} were further investigated.

  2. Photoluminescent BaMoO{sub 4} nanopowders prepared by complex polymerization method (CPM)

    SciTech Connect

    Azevedo Marques, Ana Paula de . E-mail: apamarques@liec.ufscar.br; Melo, Dulce M.A. de; Paskocimas, Carlos A.; Pizani, Paulo S.; Joya, Miryam R.; Leite, Edson R.; Longo, Elson

    2006-03-15

    The BaMoO{sub 4} nanopowders were prepared by the Complex Polymerization Method (CPM). The structure properties of the BaMoO{sub 4} powders were characterized by FTIR transmittance spectra, X-ray diffraction (XRD), Raman spectra, photoluminescence spectra (PL) and high-resolution scanning electron microscopy (HR-SEM). The XRD, FTIR and Raman data showed that BaMoO{sub 4} at 300 deg. C was disordered. At 400 deg. C and higher temperature, BaMoO{sub 4} crystalline scheelite-type phases could be identified, without the presence of additional phases, according to the XRD, FTIR and Raman data. The calculated average crystallite sizes, calculated by XRD, around 40 nm, showed the tendency to increase with the temperature. The crystallite sizes, obtained by HR-SEM, were around of 40-50 nm. The sample that presented the highest intensity of the red emission band was the one heat treated at 400 deg. C for 2 h, and the sample that displayed the highest intensity of the green emission band was the one heat treated at 700 deg. C for 2 h. The CPM was shown to be a low cost route for the production of BaMoO{sub 4} nanopowders, with the advantages of lower temperature, smaller time and reduced cost. The optical properties observed for BaMoO{sub 4} nanopowders suggested that this material is a highly promising candidate for photoluminescent applications.

  3. Recent increase in Ba concentrations as recorded in a South Pole ice core

    NASA Astrophysics Data System (ADS)

    Korotkikh, Elena V.; Mayewski, Paul A.; Dixon, Daniel; Kurbatov, Andrei V.; Handley, Michael J.

    2014-06-01

    Here we present high-resolution (∼9.4 samples/year) records of Ba concentrations for the period from 1541 to 1999 A.D. obtained from an ice core recovered at the South Pole (US ITASE-02-6) site. We note a significant increase in Ba concentration (by a factor of ∼23) since 1980 A.D. The Ba crustal enrichment factor (EFc) values rise from ∼3 before 1980 A.D. to ∼32 after 1980 A.D. None of the other measured major and trace elements reveal such significant increases in concentrations and EFc values. Comparison with previously reported Antarctic Ba records suggests that significant increases in Ba concentrations at South Pole since 1980 A.D. are most likely caused by local source pollution. The core was collected in close proximity to Amundsen-Scott South Pole Station; therefore activities at the station, such as diesel fuel burning and intense aircraft activity, most likely caused the observed increase in Ba concentrations and its EFc values in the South Pole ice core record.

  4. The (3×2) phase of Ba adsorption on Si(001)-2×1

    NASA Astrophysics Data System (ADS)

    Hu, X.; Yao, X.; Peterson, C. A.; Sarid, D.; Yu, Z.; Wang, J.; Marshall, D. S.; Droopad, R.; Hallmark, J. A.; Ooms, W. J.

    2000-01-01

    The initial stages and surface structures of the (3×2) phase of Ba adsorption on an Si(100)-2×1 surface held at 900°C have been studied by low-energy electron diffraction, Auger electron spectroscopy, and ultra-high vacuum scanning tunneling microscopy (STM). At low coverages (<{1}/{6} ML), the Ba atoms form atomic chains across the Si dimer rows by occupying valley bridge sites, as well as on fourfold sites by replacing Si dimers and exhibiting a local (3×2) phase, with the 3×-phase along the Si dimer row direction. Two different configurations for the (3×2) phase, namely, mono- and dimer-Ba models, are proposed based on the STM images. Below a coverage of {1}/{6} ML, the (3×2) phase is formed by single Ba atoms at fourfold sites by replacing original Si dimers. For a Ba coverage of {1}/{3} ML, the (3×2) phase is formed by buckled Ba dimers, as revealed by high-resolution STM images.

  5. High-pressure synthesis and superconductivity of a new binary barium germanide BaGe3.

    PubMed

    Fukuoka, Hiroshi; Tomomitsu, Yusuke; Inumaru, Kei

    2011-07-04

    A new binary barium germanide BaGe(3) was prepared by high-pressure and high-temperature reactions using a Kawai type multi-anvil press. It crystallizes in a hexagonal unit cell with a = 6.814(1) Å, c = 5.027(8) Å, and V = 202.2(5) Å(3) (the space group P6(3)/mmc, No. 194). The unit cell contains two layers along the c axis composed of Ba atoms and Ge(3) triangular units. The triangular units stack along the c axis to form 1D columns in which the adjacent Ge(3) units turn to opposite directions. The columns, therefore, can be described as the face-sharing stacking of elongated Ge(6) octahedra. Each Ba atom is surrounded by six columns. BaGe(3) is metallic and shows superconductivity at 4.0 K. The band structure calculations revealed that there are four conduction bands mainly composed of Ge 4p and Ba 5d orbitals. From Fermi surface analysis, we confirmed that three of them have a large contribution of Ge 4pz orbitals in the vicinity of the Fermi level and show a simple 1D appearance. The remaining one contains Ge 4px, 4py, and Ba 5d contributions and shows a 2D property.

  6. Synthesis and luminescent properties of novel BaGd2O4:Eu3+ scintillating phosphor.

    PubMed

    Sun, Xin-Yuan; Wang, Wen-Feng; Sun, Shou-Qiang; Lin, Liang-Wu; Li, De-Yi; Zhou, Ling-Ping

    2013-01-01

    BaGd2-x O4:xEu(3+) and Ba1-y Gd1.79-2y Eu0.21 Na3y O4 phosphors were synthesized at 1300°C in air by conventional solid-state reaction method. Phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence excitation (PLE) spectra, photoluminescence (PL) spectra and thermoluminescence (TL) spectra. Optimal PL intensity for BaGd2-x O4 :xEu(3+) and Ba1-y Gd1.79-2y Eu0.21 Na3y O4 phosphors at 276 nm excitation were found to be x = 0.24 and y = 0.125, respectively. The PL intensity of Eu(3+) emission could only be enhanced by 1.3 times with incorporation of Na(+) into the BaGd2 O4 host. Enhanced luminescence was attributed to the flux effect of Na(+) ions. However, when BaGd2 O4:Eu(3+) phosphors were codoped with Na(+) ions, the induced defects confirmed by TL spectra impaired the emission intensity of Eu(3+) ions.

  7. Photoluminescent BaMoO 4 nanopowders prepared by complex polymerization method (CPM)

    NASA Astrophysics Data System (ADS)

    de Azevedo Marques, Ana Paula; de Melo, Dulce M. A.; Paskocimas, Carlos A.; Pizani, Paulo S.; Joya, Miryam R.; Leite, Edson R.; Longo, Elson

    2006-03-01

    The BaMoO 4 nanopowders were prepared by the Complex Polymerization Method (CPM). The structure properties of the BaMoO 4 powders were characterized by FTIR transmittance spectra, X-ray diffraction (XRD), Raman spectra, photoluminescence spectra (PL) and high-resolution scanning electron microscopy (HR-SEM). The XRD, FTIR and Raman data showed that BaMoO 4 at 300 °C was disordered. At 400 °C and higher temperature, BaMoO 4 crystalline scheelite-type phases could be identified, without the presence of additional phases, according to the XRD, FTIR and Raman data. The calculated average crystallite sizes, calculated by XRD, around 40 nm, showed the tendency to increase with the temperature. The crystallite sizes, obtained by HR-SEM, were around of 40-50 nm. The sample that presented the highest intensity of the red emission band was the one heat treated at 400 °C for 2 h, and the sample that displayed the highest intensity of the green emission band was the one heat treated at 700 °C for 2 h. The CPM was shown to be a low cost route for the production of BaMoO 4 nanopowders, with the advantages of lower temperature, smaller time and reduced cost. The optical properties observed for BaMoO 4 nanopowders suggested that this material is a highly promising candidate for photoluminescent applications.

  8. Luminescence and scintillation properties of BaF2sbnd Ce transparent ceramic

    NASA Astrophysics Data System (ADS)

    Luo, Junming; Sahi, Sunil; Groza, Michael; Wang, Zhiqiang; Ma, Lun; Chen, Wei; Burger, Arnold; Kenarangui, Rasool; Sham, Tsun-Kong; Selim, Farida A.

    2016-08-01

    Cerium doped Barium Fluoride (BaF2sbnd Ce) transparent ceramic was fabricated and its luminescence and scintillation properties were studied. The photoluminescence shows the emission peaks at 310 nm and 323 nm and is related to the 5d-4f transitions in Ce3+ ion. Photo peak at 511 keV and 1274 keV were obtained with BaF2sbnd Ce transparent ceramic for Na-22 radioisotopes. Energy resolution of 13.5% at 662 keV is calculated for the BaF2sbnd Ce transparent ceramic. Light yield of 5100 photons/MeV was recorded for BaF2sbnd Ce(0.2%) ceramic and is comparable to its single crystal counterpart. Scintillation decay time measurements shows fast component of 58 ns and a relatively slow component of 434 ns under 662 keV gamma excitation. The slower component in BaF2sbnd Ce(0.2%) ceramic is about 200 ns faster than the STE emission in BaF2 host and is associated with the dipole-dipole energy transfer from the host matrix to Ce3+ luminescence center.

  9. Ferroelectric and ferromagnetic properties in BaTiO{sub 3} thin films on Si (100)

    SciTech Connect

    Singamaneni, Srinivasa Rao Prater, John T.; Punugupati, Sandhyarani; Hunte, Frank; Narayan, Jagdish

    2014-09-07

    In this paper, we report on the epitaxial integration of room temperature lead-free ferroelectric BaTiO{sub 3} thin (∼1050 nm) films on Si (100) substrates by pulsed laser deposition technique through a domain matching epitaxy paradigm. We employed MgO and TiN as buffer layers to create BaTiO{sub 3}/SrRuO{sub 3}/MgO/TiN/Si (100) heterostructures. C-axis oriented and cube-on-cube epitaxial BaTiO{sub 3} is formed on Si (100) as evidenced by the in-plane and out-of-plane x-ray diffraction, and transmission electron microscopy. X-ray photoemission spectroscopic measurements show that Ti is in 4(+) state. Polarization hysteresis measurements together with Raman spectroscopy and temperature-dependent x-ray diffraction confirm the room temperature ferroelectric nature of BaTiO{sub 3}. Furthermore, laser irradiation of BaTiO{sub 3} thin film is found to induce ferromagnetic-like behavior but affects adversely the ferroelectric characteristics. Laser irradiation induced ferromagnetic properties seem to originate from the creation of oxygen vacancies, whereas the pristine BaTiO{sub 3} shows diamagnetic behavior, as expected. This work has opened up the route for the integration of room temperature lead-free ferroelectric functional oxides on a silicon platform.

  10. Electrical and magnetic properties of hexagonal BaTiO3-δ

    NASA Astrophysics Data System (ADS)

    Kolodiazhnyi, T.; Belik, A. A.; Wimbush, S. C.; Haneda, H.

    2008-02-01

    The electrical resistivity, Hall coefficient, and magnetic susceptibility of n -type hexagonal BaTiO3-δ (hex-BaTiO3-δ) have been measured in the 5-400K temperature range. Above 200K this compound undergoes a transition from an insulating to a semiconducting state. Below 140K Hall effect data indicate the existence of an energy gap of approximately 43meV separating the localized electron ground state from the conduction band. Magnetic measurements reveal a strong magnetic anomaly in hex-BaTiO3-δ with a maximum in the susceptibility at around 160-200K . This anomaly is quite similar to that of the hexagonal BaMg1/3Ru2/3O3 which may indicate that the electron ground state in hex-BaTiO3-δ is comprised of spin singlet Ti3+-Ti3+ dimers. We further propose that the thermal dissociation of these dimers is responsible for the change in the electron transport mechanism in hex-BaTiO3-δ .

  11. Characterization of BaCl 2 scintillation crystal at low temperature

    NASA Astrophysics Data System (ADS)

    Kim, M. J.; Kim, H. J.; Park, H.; Kim, Sunghwan; Kim, Jung-in

    2011-03-01

    A BaCl 2 scintillation crystal was grown by the Czochralski method. The grown crystal was cut to a size of 10×10×5 mm 3. The scintillation properties of the crystal such as pulse height spectra, energy resolution, and fluorescence decay time were measured with a 137Cs (662 keV) γ-ray source at room temperature. We measured the temperature dependence of the scintillation light yield and decay time with a bi-alkali photomultiplier tube for the BaCl 2 crystal. The BaCl 2 crystal was cooled down with compressed helium gas from room temperature to 10 K. We measured the light yield and decay time changes of the BaCl 2 crystal from 10 K to room temperature. The light yield of the BaCl 2 at 200 K was four times higher than that at room temperature. The decay time increases as temperature decreases. The BaCl 2 scintillation crystal has a low light yield but a fast decay time so that it can be a calorimeter candidate for high energy physics experiments.

  12. Synthesis, crystal structure, bonding, and properties of (Ba6O)(OsN3)2.

    PubMed

    Schmidt, Carsten L; Wedig, Ulrich; Dinnebier, Robert; Jansen, Martin

    2008-11-13

    The new barium nitridoosmate oxide (Ba(6)O)(OsN(3))(2) was prepared by reacting elemental barium and osmium (3:1) in nitrogen at 815-830 degrees C. The crystal structure of (Ba(6)O)(OsN(3))(2) as determined by laboratory powder X-ray diffraction (R3, No 148: a = b = 8.112(1) A, c = 17.390(1) A, V = 991.0(1) A(3), Z = 3), consists of sheets of trigonal OsN(3) units and trigonal-antiprismatic Ba(6)O groups, and is structurally related to the "313 nitrides" AE(3)MN(3) (AE = Ca, Sr, Ba, M = V-Co, Ga). Density functional calculations, using a hybrid functional, likewise indicate the existence of oxygen in the Ba(6) polyhedra. The oxidation state 4+ of osmium is confirmed, both by the calculations and by XPS measurements. The bonding properties of the OsN(3)(5-) units are analyzed and compared to the Raman spectrum. The compound is paramagnetic from room temperature down to T = 10 K. Between room temperature and 100 K it obeys the Curie-Weiss law (mu = 1.68 mu(B)). (Ba(6)O)(OsN(3))(2) is semiconducting with a good electronic conductivity at room temperature (8.74x10(-2) ohms(-1) cm(-1)). Below 142 K the temperature dependence of the conductivity resembles that of a variable-range hopping mechanism.

  13. Atomistic description for temperature-driven phase transitions in BaTiO3

    NASA Astrophysics Data System (ADS)

    Qi, Y.; Liu, S.; Grinberg, I.; Rappe, A. M.

    2016-10-01

    Barium titanate (BaTiO3) is a prototypical ferroelectric perovskite that undergoes the rhombohedral-orthorhombic-tetragonal-cubic phase transitions as the temperature increases. In this paper, we develop a classical interatomic potential for BaTiO3 within the framework of the bond-valence theory. The force field is parametrized from first-principles results, enabling accurate large-scale molecular dynamics (MD) simulations at finite temperatures. Our model potential for BaTiO3 reproduces the temperature-driven phase transitions in isobaric-isothermal ensemble (N P T ) MD simulations. This potential allows for the analysis of BaTiO3 structures with atomic resolution. By analyzing the local displacements of Ti atoms, we demonstrate that the phase transitions of BaTiO3 exhibit a mix of order-disorder and displacive characters. Besides, from a detailed observation of structural dynamics during phase transition, we discover that the global phase transition is associated with changes in the equilibrium value and fluctuations of each polarization component, including the ones already averaging to zero, Contrary to the conventional understanding that temperature increase generally causes bond-softening transition, the x -polarization component (the one which is polar in both the orthorhombic and the tetragonal phases) exhibits a bond-hardening character during the orthorhombic-to-tetragonal transition. These results provide further insight about the temperature-driven phase transitions in BaTiO3.

  14. Photoresponse properties of BaSi2 film grown on Si (100) by vacuum evaporation

    NASA Astrophysics Data System (ADS)

    Thi Trinh, Cham; Nakagawa, Yoshihiko; Hara, Kosuke O.; Takabe, Ryota; Suemasu, Takashi; Usami, Noritaka

    2016-07-01

    We have succeeded in the observation of high photoresponsivity of orthorhombic BaSi2 film grown on crystalline Si by a vacuum evaporation method, raising the prospect of its promising application in high-efficiency thin-film solar cells. Photocurrent was observed at photon energies larger than 1.28 eV, which corresponds to the band gap of evaporated BaSi2 film, indicating that the photoresponsivity originates from the BaSi2 film. The effect of the substrate temperature on the film’s properties was also investigated. The films grown at a substrate temperature larger than 500 °C are single-phase polycrystalline BaSi2 films, while those grown at a substrate temperature of 400 °C is a mixture of phases. We confirmed that undoped evaporated BaSi2 films are an n-type material with high carrier concentration. High carrier lifetime of 4.8 and 2.7 μs can be found for the films grown at 500 °C and 400 °C, respectively. BaSi2 film grown at a substrate temperature of 500 °C, which is crack-free and single-phase, shows the best photoresponsivity. The maximum value of photocurrent was obtained at photon energy of 1.9 eV, corresponding to an external quantum efficiency of 22% under reverse applied voltage of 2 V.

  15. Preparation, characterization and magnetic properties of the BaFe12O19 @ chitosan composites

    NASA Astrophysics Data System (ADS)

    Li, Lei; Zhang, Zunju; Xie, Yu; Zhao, Jie

    2016-07-01

    The BaFe12O19 @ chitosan composites are synthesized by the crosslinking reaction through chitosan and glutaraldehyde onto the surface of BaFe12O19. The structures of the samples were characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The shape and size were observed by scanning electron microscopy and transmission electron microscopy. These results showed that chitosan has been decorated onto the surface of BaFe12O19, and the chitosan-glutaraldehyde Schiff-base composites have also been formed within the chitosan layers. Then, the magnetic properties of the samples were tested with the vibrating sample magnetometer. The magnetic saturation (MS), residual magnetization (Mr) and coercive force (Hc) values of the BaFe12O19 @ chitosan Schiff-base composite have achieved 44.94 emu/g, 27.82 emu/g and 3580.7 Oe, respectively. Compared with single BaFe12O19, the MS, and Mr of the BaFe12O19 @ chitosan composites decreases 12.31 emu/g and 8.58 emu/g, respectively. Finally, based on the experimental results, the probable formation mechanism of this composite has been investigated.

  16. Synthesis of Y1Ba2Cu3O(sub x) superconducting powders by intermediate phase reaction

    NASA Technical Reports Server (NTRS)

    Moore, C.; Fernandez, J. F.; Recio, P.; Duran, P.

    1990-01-01

    One of the more striking problems for the synthesis of the Y1Ba2Cu3Ox compound is the high-temperature decomposition of the BaCO3. This compound is present as raw material or as an intermediate compound in chemical processes such as amorphous citrate, coprecipitation oxalate, sol-gel process, acetate pyrolisis, etc. This fact makes difficult the total formation reaction of the Y1Ba2Cu3Ox phase and leads to the presence of undesirable phases such as the BaCuO2 phase, the 'green phase', Y2BaCuO5 and others. Here, a new procedure to overcome this difficulty is studied. The barium cation is previously combined with yttrium and/or copper to form intermediate compounds which can react between them to give Y1Ba2Cu3Ox. BaY2O4 and BaCu2O3 react according to the equation BaY2O4+3BaCu2O3 yields 2Y1Ba2Cu3Ox. BaY2O4 is a stable compound of the Y2O3-BaO system; BaCu2O3 is an intimate mixture of BaCuO2 and uncombined CuO. The reaction kinetics of these phases have been established between 860 and 920 C. The phase evolution has been determined. The crystal structure of the Y1Ba2Cu3Ox obtained powder was studied. According to the results obtained from the kinetics study the Y1Ba2Cu3Ox the synthesis was performed at temperatures of 910 to 920 C for short treatment times (1 to 2 hours). Pure Y1Ba2Cu3Ox was prepared, which develops orthorombic type I structure despite of the cooling cycle. Superconducting transition took place at 91 K. The sintering behavior and the superconducting properties of sintered samples were studied. Density, microstructure and electrical conductivity were measured. Sintering densities higher than 95 percent D(sub th) were attained at temperatures below 940 C. Relatively fine grained microstructure was observed, and little or no-liquid phase was detected.

  17. Cage-forming compounds in the Ba-Rh-Ge system: from thermoelectrics to superconductivity.

    PubMed

    Falmbigl, M; Kneidinger, F; Chen, M; Grytsiv, A; Michor, H; Royanian, E; Bauer, E; Effenberger, H; Podloucky, R; Rogl, P

    2013-01-18

    Phase relations and solidification behavior in the Ge-rich part of the phase diagram have been determined in two isothermal sections at 700 and 750 °C and in a liquidus projection. A reaction scheme has been derived in the form of a Schulz-Scheil diagram. Phase equilibria are characterized by three ternary compounds: τ(1)-BaRhGe(3) (BaNiSn(3)-type) and two novel phases, τ(2)-Ba(3)Rh(4)Ge(16) and τ(3)-Ba(5)Rh(15)Ge(36-x), both forming in peritectic reactions. The crystal structures of τ(2) and τ(3) have been elucidated from single-crystal X-ray intensity data and were found to crystallize in unique structure types: Ba(3)Rh(4)Ge(16) is tetragonal (I4/mmm, a = 0.65643(2) nm, c = 2.20367(8) nm, and R(F) = 0.0273), whereas atoms in Ba(5)Rh(15)Ge(36-x) (x = 0.25) arrange in a large orthorhombic unit cell (Fddd, a = 0.84570(2) nm, b = 1.4725(2) nm, c = 6.644(3) nm, and R(F) = 0.034). The body-centered-cubic superstructure of binary Ba(8)Ge(43)□(3) was observed to extend at 800 °C to Ba(8)Rh(0.6)Ge(43)□(2.4), while the clathrate type I phase, κ(I)-Ba(8)Rh(x)Ge(46-x-y)□(y), reveals a maximum solubility of x = 1.2 Rh atoms in the structure at a vacancy level of y = 2.0. The cubic lattice parameter increases with increasing Rh content. Clathrate I decomposes eutectoidally at 740 °C: κ(I) ⇔ (Ge) + κ(IX) + τ(2). A very small solubility range is observed at 750 °C for the clathrate IX, κ(IX)-Ba(6)Rh(x)Ge(25-x) (x ∼ 0.16). Density functional theory calculations have been performed to derive the enthalpies of formation and densities of states for various compositions Ba(8)Rh(x)Ge(46-x) (x = 0-6). The physical properties have been investigated for the phases κ(I), τ(1), τ(2), and τ(3), documenting a change from thermoelectric (κ(I)) to superconducting behavior (τ(2)). The electrical resistivity of κ(I)-Ba(8)Rh(1.2)Ge(42.8)□(2.0) increases almost linearly with the temperature from room temperature to 730 K, and the Seebeck coefficient is negative

  18. Preparation of LTCC materials with adjustable permittivity based on BaO–B{sub 2}O{sub 3}–SiO{sub 2}/BaTiO{sub 3} system

    SciTech Connect

    Wang, Kai-tuo; He, Yan; Liang, Zhong-yuan; Cui, Xue-min

    2015-05-15

    Graphical abstract: The dielectric constant (ϵ) of the sintered BaO–B{sub 2}O{sub 3}–SiO{sub 2}/BaTiO{sub 3} glass/ceramics (the sintered samples with line shrinkage of 10%) changed from 5 to 30 and the dielectric losses (tanδ) was lower than 0.05 at 100 MHz with the amount of BaTiO{sub 3} additive increment from 60 wt% to 90 wt% fraction. - Highlights: • The ϵ of BaO–B{sub 2}O{sub 3}–SiO{sub 2} glass can be adjusted from 5 to 30 by adding BaTiO{sub 3}. • The influence factors on dielectric are the secondary phase and microstructure. • BaO–B{sub 2}O{sub 3}–SiO{sub 2}/BaTiO{sub 3} system can fabricate LTCC when BaTiO{sub 3} located in 60–80 wt%. - Abstract: This paper studied the preparation and characterization of LTCC (low temperature co-fired ceramics) materials based on BaO–B{sub 2}O{sub 3}–SiO{sub 2}/BaTiO{sub 3} glass–ceramics, where the sintering temperature was about 900 °C and dielectric constant was effectively adjustable from 5 to 30 by changing the BaTiO{sub 3} fraction from 60 wt% to 90 wt%. X-ray diffractometer (XRD), scanning electron microscopy (SEM) were used to examine the effect of different amounts additive on the dielectric properties of this LTCC system and the crystal structure change. The results indicated that BaTiO{sub 3} can be used as a dielectric additive aim to adjust the permittivity of BaO–B{sub 2}O{sub 3}–SiO{sub 2} glass, which the main influence factors on dielectric are the contents of the secondary phase, the BaTiO{sub 3} phase fraction and the porous structure of the sintered body. Therefore, the microstructure and dielectric property of BaO–B{sub 2}O{sub 3}–SiO{sub 2}/BaTiO{sub 3} glass–ceramics composites could be controlled by adjusting the content of BaTiO{sub 3} additive.

  19. Search for compounds of the NaBaR(BO{sub 3}){sub 2} family (R = La, Nd, Gd, and Yb) and the new NaBaYb(BO{sub 3}){sub 2} orthoborate

    SciTech Connect

    Svetlyakova, T. N. Kokh, A. E.; Kononova, N. G.; Fedorov, P. P.; Rashchenko, S. V.; Maillard, A.

    2013-01-15

    A search for compounds of the NaBaR(BO{sub 3}){sub 2} composition (where R = La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, or Yb{sup 3+}) is performed by solid state synthesis and spontaneous crystallization. A new compound, NaBaYb(BO{sub 3}){sub 2}, is found in this series. It crystallizes in space group R3{sup -} and belongs to the family of sublayer complex orthoborates with isolated BO{sub 3} groups NaBaR(BO{sub 3}){sub 2} (R = Y, Sc, and Yb). Theoretical X-ray powder diffraction patterns of NaBaY(BO{sub 3}){sub 2}, NaBaSc(BO{sub 3}){sub 2}, and NaBaYb(BO{sub 3}){sub 2} are calculated based on single-crystal data.

  20. On the quasi-1D magnetic behavior of Ba 2MnCoAl 2F 14, Ba 2MnCuAl 2F 14 and related compounds

    NASA Astrophysics Data System (ADS)

    le Lirzin, A.; Darriet, J.; Georges, R.; Soubeyroux, J. L.

    1992-02-01

    Two new fluorides Ba 2MnCoAl 2F 14 and Ba 2MnCoAl 2F 14, isostructural with the natural compound usovite Ba 2CaMgAl 2F 14, have been synthesized. The nuclear structures of both compounds, refined from neutron diffraction data, give evidence for strongly disordered bimetallic chains MnCu or MnCo along the b-axis: two new theoretical treatments are suggested in order to account for the magnetic behavior of each compound but, due to their intrinsic limitations, they are in fact applied here to solid solutions between the parent compound and BaMnAlF 7, namely Ba 2Mn 1+ yCu 1- yAl2F14 and Ba 2Mn1+ yCo1- yAl 2F 14, leading to a rather good agreement with the measured values of the susceptibilities.

  1. Malignant intraperitoneal mesothelioma-Başkent University experience

    PubMed Central

    Macuks, Ronalds; Özdemir, Halis; Dursun, Polat; Özen, Özlem Işıksaçan; Haberal, Nihan; Ayhan, Ali

    2011-01-01

    Objective To evaluate diagnostic and treatment results of malignant intraperitoneal mesothelioma in one setting. Materials and Method: 12 patients treated for malignant peritoneal mesothelioma from January 2007 to June 2009 in Başkent University Ankara Hospital, Department of Gynaecology and Obstetrics were evaluated. In a retrospective observational study design tumour stage, grade, differentiation, time from first symptoms, pleural involvement, peritoneal cancer index, surgical cytoreduction, chemotherapeutic regimen, number of cycles, disease free survival and overall survival were evaluated. Disease free survival, overall survival, time until first symptoms were researched. Results The main presenting symptom was abdominal distension. Primary cytoreductive surgery followed by chemotherapy was performed in 9 patients. In 6 patients completeness of cytoreductive score below 2 was achieved. As a first line chemotherapy the most often used was cisplatin in combination with pemetrexed. Themean time from first symptoms until the diagnosis was 1.9 months. Disease free survival of 4.4±1.0 months after completing particular treatment and overall 1-year survival of 85.7 % was observed. No correlations between first symptoms (0.27, p=0.52), time until the diagnosis (−0.29, p=0.44) and overall survival were observed. Similarly, correlations between peritoneal cancer index (0.25, p=0.67), prior surgical score (−.45, p=0.37), completeness of cytoreduction score (0.61, p=0.27) and overall survival were not observed. Conclusions Because of the low number of patients and different treatment approaches data from a particular patient setting are inconclusive, but from the literature there is evidence that patients with malignant intraperitoneal mesothelioma should undergo optimal cytoreduction and receive a combination of cisplatin and pemetrexed as a first line chemotherapy for intravenous or cisplatin in different chemotherapy regimens using the intraperitoneal

  2. Second Phase (BaGeO3, BaSiO3) Nanocolumns in YBa2Cu3O7-x Films

    NASA Astrophysics Data System (ADS)

    Varanasi, C. V.; Reichart, J.; Burke, J.; Wang, H.; Susner, M.; Sumption, M.; Barnes, P. N.

    2010-04-01

    YBa2Cu3O7-x (YBCO) films with BaGeO3 (BGeO), BaSiO3 (BSiO) second phase additions were processed by pulsed laser deposition. Sectored targets with BGO or BSiO wedges as well as pre-mixed targets of YBCO, BGeO or BSiO with appropriate compositions were used to deposit YBCO+BGeO and YBCO+BSiO films on (100) single crystal LaAlO3 substrates. The cross-sectional transmission electron micrographs showed the presence of 20 nm diameter nanocolumns in the YBCO films of both the compositions. However, the critical transition temperature (Tc) of the films was found to significantly decrease. As a result, the critical current density (Jc) in applied magnetic fields was suppressed. The YBCO+BGeO and YBCO+BSiO films made with lower concentrations of additions showed slight improvement in Tc indicating that the substitution of Ge and Si in the lattice is possibly responsible for the Tc depression. This study shows that in addition to the ability to form nanocolumns, the chemical compatibility of BaSnO3 (BSO) and BaZrO3 (BZO) as observed in YBCO+BSO and YBCO+BZO is critical to process high Jc YBCO films.

  3. Electrical properties of ferroelectric BaTi{sub 2}O{sub 5} and dielectric Ba{sub 6}Ti{sub 17}O{sub 40} ceramics

    SciTech Connect

    Beltran, Hector; Gomez, Beatriz; Maso, Nahum; Cordoncillo, Eloisa; Escribano, Purificacion; West, Anthony R.

    2005-04-15

    Single phase powders of BaTi{sub 2}O{sub 5} and Ba{sub 6}Ti{sub 17}O{sub 40} were made by a sol-gel method with final heating at 1100-1200 deg. C. Ceramic samples were prepared and fired at temperatures in the range 1100-1300 deg. C. Both sets were highly insulating, with conductivities of, e.g., 10{sup -6}-10{sup -7} S cm{sup -1} at 600 deg. C and activation energies for conduction in the range 1.75-1.86 eV. BaTi{sub 2}O{sub 5} compositions are ferroelectric with a permittivity maximum dependent on firing conditions: {epsilon}{sub max}{sup '}=122 at 450 deg. C on firing at 1100 deg. C; and {epsilon}{sub max}{sup '}=130 at 475 deg. C on firing at 1225 deg. C. Ba{sub 6}Ti{sub 17}O{sub 40} is a dielectric with {epsilon}{sup '}{approx}57-55 over the range 40-400 deg. C.

  4. High-pressure BaCrO{sub 3} polytypes and the 5H–BaCrO{sub 2.8} phase

    SciTech Connect

    Arévalo-López, Angel M.; Paul Attfield, J.

    2015-12-15

    Polytypism of BaCrO{sub 3} perovskites has been investigated at 900–1100 °C and pressures up to 22 GPa. Hexagonal 5H, 4H, and 6H perovskites are observed with increasing pressure, and the cubic 3C perovskite (a=3.99503(1) Å) is observed in bulk form for the first time at 19–22 GPa. An oxygen-deficient material with limiting composition 5H–BaCrO{sub 2.8} is synthesised at 1200 °C under ambient pressure. This contains double tetrahedral Cr{sup 4+} layers and orders antiferromagnetically below 260 K with a (0 0 1/2) magnetic structure. - Graphical abstract: Hexagonal 5H, 4H, and 6H perovskites polytypes of BaCrO{sub 3} are observed with increasing pressure and the cubic 3C perovskite is stabilised in bulk form for the first time at 19–22 GPa. Oxygen-deficient 5H–BaCrO{sub 2.8} synthesised at ambient pressure contains double tetrahedral Cr{sup 4+} layers and orders antiferromagnetically below 260 K with a (0 0 1/2) magnetic structure.

  5. Multilayer pinning in a-axis-oriented EuBa2Cu3O7/PrBa2Cu3O7 superconducting superlattices

    NASA Astrophysics Data System (ADS)

    Martin, J. I.; Velez, M.; Vicent, J. L.

    1995-08-01

    a-axis EuBa2Cu3O7/PrBa2Cu3O7 superlattices and a-axis films have been grown by dc sputtering to study the interplay between the natural material anisotropy (Cu-O planes) and the artificial layered structure (PrBa2Cu3O7 layers). These a-axis-oriented superlattices are unique because, in comparison with c-axis superlattices, they allow one to separate both effects: in c-axis multilayers Cu-O planes and the artificial layers are parallel whereas in a-axis multilayers the intrinsic and the artificial layers are perpendicular to each other. When B is parallel to the substrate plane, the superlattices show an enhancement of the pinning force in comparison with the behavior of the films that is controlled by the EuBa2Cu3O7 layer thickness. If B is perpendicular to the substrate plane, the flux motion presents a log B dependence of the activation energy up to at least, 40-unit-cell-thick layers.

  6. Local manifestations of a static magnetoelectric effect in nanostructured BaTiO3-BaFe12O9 composite multiferroics.

    PubMed

    Trivedi, Harsh; Shvartsman, Vladimir V; Lupascu, Doru C; Medeiros, Marco S A; Pullar, Robert C; Kholkin, Andrei L; Zelenovskiy, Pavel; Sosnovskikh, Andrey; Shur, Vladimir Ya

    2015-03-14

    A study on magnetoelectric phenomena in the barium titanate-barium hexaferrite (BaTiO3-BaFe12O19) composite system, using high resolution techniques including switching spectroscopy piezoresponse force microscopy (SSPFM) and spatially resolved confocal Raman microscopy (CRM), is presented. It is found that both the local piezoelectric coefficient and polarization switching parameters change on the application of an external magnetic field. The latter effect is rationalized by the influence of magnetostrictive stress on the domain dynamics. Processing of the Raman spectral data using principal component analysis (PCA) and self-modelling curve resolution (SMCR) allowed us to achieve high resolution phase distribution maps along with separation of average and localized spectral components. A significant effect of the magnetic field on the Raman spectra of the BaTiO3 phase has been revealed. The observed changes are comparable with the classical pressure dependent studies on BaTiO3, confirming the strain mediated character of the magnetoelectric coupling in the studied composites.

  7. Nuclear structure of even 120-136Ba under the framework of IBM, IVBM and new method (SEF)

    NASA Astrophysics Data System (ADS)

    Al-Jubbori, Mushtaq A.; Kassim, Huda H.; Sharrad, Fadhil I.; Hossain, I.

    2016-11-01

    The positive and negative-state bands of even-even 120-136Ba nuclei have been studied. The energy levels for the ground-state band of 120-136Ba have been calculated using Interacting Boson Model (IBM), Interacting Vector Boson Model (IVBM) and a new method called Semi-Empirical Formula (SEF). The negative parity band of even-even 120-136Ba isotopes has been also calculated using (IVBM) and (SEF). The γ and β-bands of even-even 120-136Ba isotopes have been calculated using IBM and SEF. The parameters of the best fit to the measured data are determined. The reduced transition probabilities B (E 2) of these nuclei was calculated. The critical points have been determined for 134,136Ba isotopes. The potential energy surfaces for even-even Ba isotopes are studied using the simplified form of Interacting Boson Model (IBM) with an intrinsic coherent state.

  8. In vitro anticancer potential of BaCO3 nanoparticles synthesized via green route.

    PubMed

    Nagajyothi, P C; Pandurangan, Muthuraman; Sreekanth, T V M; Shim, Jaesool

    2016-03-01

    Green synthesis of nanoparticles is a growing research area because of their potential applications in nanomedicine. Barium carbonate nanoparticles (BaCO3 NPs) were synthesized using an aqueous extract of Mangifera indica seed as a reducing agent. These particles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Transmission electron microscopy (TEM), selected area electron diffraction (SAED), Energy-dispersive-X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) analysis. HR-TEM images are confirmed that green synthesized BaCO3 NPs have spherical, triangular and uneven shapes. EDX analysis confirmed the presence of Ba, C and O. The peaks at 2θ of 19.45, 23.90, 24.29, 27.72, 33.71, 34.08, 34.60, 41.98, 42.95, 44.18, 44.85, and 46.78 corresponding to (110), (111), (021), (002), (200), (112), (130), (221), (041), (202), (132) and (113) showed that BaCO3 NPs average size was ~18.3 nm. SAED pattern confirmed that BaCO3 NPs are crystalline nature. BaCO3 NPs significantly inhibited cervical carcinoma cells, as evidenced by cytotoxicity assay. Immunofluorescence and fluorescence assays showed that BaCO3 NPs increased the expression and activity of caspase-3, an autocatalytic enzyme that promotes apoptosis. According to the results, green synthesis route has great potential for easy, rapid, inexpensive, eco-friendly and efficient development of novel multifunctional nanoparticles for the treatment of cancer.

  9. Adsorption of Ba2+ by Ca-exchange clinoptilolite tuff and montmorillonite clay.

    PubMed

    Chávez, M L; de Pablo, L; García, T A

    2010-03-15

    The adsorption of barium by Ca-exchanged clinoptilolite and montmorillonite is presented. The kinetics of adsorption of Ba(2+) were evaluated contacting 1g portion of each adsorber with 100mL 0.1N BaCl(2) for 200 h. Adsorption by Ca-clinoptilolite is defined by second-order kinetics of rate constant K(v) 8.232 x 10(-2) g mg(-1)h(-1) and maximum removal of 71.885 mg g(-1). It is a two-stage process initiated by a rapid uptake of Ba(2+) followed by more moderate kinetics. The adsorption isotherms were determined contacting 0.2g of each adsorber with 10 mL 0.1-0.005N BaCl(2)+CaCl(2) solution, Ba(2+)/Ca(2+) ratio 1, for periods of 7 days for the tuff and 2 days for the clay. The equilibrium adsorption is described by the Langmuir model, of equilibrium constant K 0.0151 L mg(-1) and maximum adsorption of 15.29 mg g(-1). The adsorption of Ba(2+) by Ca-exchanged montmorillonite also follows a second-order reaction of rate constant K(v) 3.179 x 10(-2) g mg(-1)h(-1), and calculated separation of 36.74 mg g(-1); the Langmuir isotherm is defined by the constant K 0.034 L mg(-1) and maximum adsorption of 15.29 mg g(-1). X-ray diffraction shows that the exchange of Ba(2+) modifies the d(001) of Ca-montmorillonite from 15.4 to 12.4A.

  10. Structure and magnetic properties of the cubic oxide fluoride BaFeO{sub 2}F

    SciTech Connect

    Berry, Frank J.; Coomer, Fiona C.; Hancock, Cathryn; Helgason, Orn; Moore, Elaine A.; Slater, Peter R.; Wright, Adrian J.; Thomas, Michael F.

    2011-06-15

    Fluorination of the parent oxide, BaFeO{sub 3-{delta}}, with polyvinylidine fluoride gives rise to a cubic compound with a=4.0603(4) A at 298 K. {sup 57}Fe Moessbauer spectra confirmed that all the iron is present as Fe{sup 3+}. Neutron diffraction data showed complete occupancy of the anion sites, indicating a composition BaFeO{sub 2}F, with a large displacement of the iron off-site. The magnetic ordering temperature was determined as T{sub N}=645{+-}5 K. Neutron diffraction data at 4.2 K established G-type antiferromagnetism with a magnetic moment per Fe{sup 3+} ion of 3.95 {mu}{sub B}. However, magnetisation measurements indicated the presence of a weak ferromagnetic moment that is assigned to the canting of the antiferromagnetic structure. {sup 57}Fe Moessbauer spectra in the temperature range 10-300 K were fitted with a model of fluoride ion distribution that retains charge neutrality of the perovskite unit cell. - Graphical abstract: The cubic oxide fluoride of composition BaFeO{sub 2}F has been synthesised and characterised. Highlights: > Fluorination of BaFeO{sub 3-{delta}} with polyvinylidene fluoride gives a cubic oxide fluoride of composition BaFeO{sub 2}F. > BaFeO{sub 2}F adopts a canted antiferromagnetic structure and is different from the related phase of composition SrFeO{sub 2}F. > A model of fluoride ion distribution about iron in BaFeO{sub 2}F has been explored.

  11. Thermal expansion and structural complexity of Ba silicates with tetrahedrally coordinated Si atoms

    NASA Astrophysics Data System (ADS)

    Gorelova, Liudmila A.; Bubnova, Rimma S.; Krivovichev, Sergey V.; Krzhizhanovskaya, Maria G.; Filatov, Stanislav K.

    2016-03-01

    Thermal expansion of Ba silicates with tetrahedrally coordinated Si atoms in the temperature range of 25-1100 °C had been studied by high-temperature X-ray powder diffraction. The volume thermal expansion coefficients (TECs) are in the range 41-50×10-6 °C-1 with an average value of <αV > = 45 ×10-6 °C-1. In the structures with chain and layered silicate anions, thermal expansion is anisotropic: the direction of maximal TEC is parallel to the extension of the zweier chains of silicate tetrahedra, which are strained owing to the interactions with Ba2+. The strain is released during thermal expansion due to the increasing effective size of Ba2+ induced by thermal vibrations. Information-theoretic analysis of the structural and topological complexities of Ba silicates indicates that their structural complexity is a function of the topological complexity of their silicate anions. The latter displays a non-linear behaviour with increasing SiO2 content (=the increasing degree of polymerization and increasing dimensionality): it starts from simple topologies, reaches a maximum at topologies of intermediate complexity, and ends up at simple topologies again. The specificity of the interactions of Ba2+ with the silicate anions results in higher complexity of high-temperature α-BaSi2O5 compared to that of low-temperature β-BaSi2O5. This uncommon behaviour may be explained by the vibrational advantages provided by flatter and more complex silicate layers in the α-phase, which overcome negative differences in configurational entropies of the two modifications apparent in the differences of their structural Shannon information.

  12. Stabilisation des phases monocristallines quadratique et cubique dans BaTiO3

    NASA Astrophysics Data System (ADS)

    Amami, J.; Goutaudier, C.; Trabelsi-Ayadi, M.; Boulon, G.

    2004-12-01

    Single crystals of Ba1-xYbxTiO3 and Ba1-xSrxTiO3 with tetragonal structure were grown by the floating zone (FZ) method using an LHPG (Laser Heated Pedestal Growth) technique. The grown crystals, typically 1 mm in diameter and 8 mm in length, were yellowish transparent. Substitution of more than 2.5 at % Sr for Ba in BaTiO3 and addition of 3 to 5 at % Ln (Ln= Yb, Eu), were effective in preventing the formation of the hexagonal phase. The Eu3+ emission spectra recorded at room temperature demonstrate a significant intensity enhancement of the 5D0 → 7F1 magnetic dipolar transition compared to the 5D0 → 7F2 electric dipolar transition. Les fibres monocristallines de Ba1-xYbxTiO3 et Ba1-xSrxTiO3 de structure quadratique ont été préparées par la méthode de la zone flottante (FZ) en utilisant la technique LHPG (Laser Heated Pedestal Growth). Les échantillons élaborés, de dimensions 1mm x 8 mm, sont jaunâtres et transparentes. La substitution du baryum par plus de 2,5 mol% de Sr dans BaTiO3 et le dopage de 3 à 5 mol% de Ln (Ln = Yb, Eu) évitent la formation de la phase hexagonale. Le spectre d’émission de Eu3+ enregistré à température ambiante montre le changement de structure traduit par la forte intensité de la transition dipolaire magnétique 5D0 → 7F1 comparée à celle de la transition dipolaire électrique 5D0 → 7F2.

  13. Barium isotope fractionation during witherite (BaCO3) dissolution, precipitation and at equilibrium

    NASA Astrophysics Data System (ADS)

    Mavromatis, Vasileios; van Zuilen, Kirsten; Purgstaller, Bettina; Baldermann, Andre; Nägler, Thomas F.; Dietzel, Martin

    2016-10-01

    This study examines the behavior of Ba isotope fractionation between witherite and fluid during mineral dissolution, precipitation and at chemical equilibrium. Experiments were performed in batch reactors at 25 °C in 10-2 M NaCl solution where the pH was adjusted by continuous bubbling of a water saturated gas phase of CO2 or atmospheric air. During witherite dissolution no Ba isotope fractionation was observed between solid and fluid. In contrast, during witherite precipitation, caused by a pH increase, a preferential uptake of the lighter 134Ba isotopomer in the solid phase was observed. In this case, the isotope fractionation factor αwitherite-fluid is calculated to be 0.99993 ± 0.00004 (or Δ137/134Bawitherite-fluid ≈ -0.07 ± 0.04‰, 2 sd). The most interesting feature of this study, however, is that after the attainment of chemical equilibrium, the Ba isotope composition of the aqueous phase is progressively becoming lighter, indicating a continuous exchange of Ba2+ ions between witherite and fluid. Mass balance calculations indicate that the detachment of Ba from the solid is not only restricted to the outer surface layer of the solid, but affects several (∼7 unit cells) subsurface layers of the crystal. This observation comes in excellent agreement with the concept of a dynamic system at chemical equilibrium in a mineral-fluid system, denoting that the time required for the achievement of isotopic equilibrium in the witherite-fluid system is longer compared to that observed for chemical equilibrium. Overall, these results indicate that the isotopic composition of Ba bearing carbonates in natural environments may be altered due to changes in fluid composition without a net dissolution/precipitation to be observed.

  14. Novel perovskite-related barium tungstate Ba 11W 4O 23

    NASA Astrophysics Data System (ADS)

    Hong, Seung-Tae

    2007-11-01

    Ba 11W 4O 23 was synthesized at 1300 °C, followed by quenching with liquid nitrogen. The crystal structure, which was known to be cryolite-related but has remained unclear, was initially determined by single-crystal X-ray diffraction for the isostructural Ru-substituted compound Ba 11(W 3.1Ru 0.9)O 22.5, which was discovered during exploratory synthesis in the Ba-Ru-O system. The structure of Ba 11W 4O 23 was refined by a combined powder X-ray and neutron Rietveld method ( Fd-3 m, a=17.1823(1) Å, Z=8, Rp=3.09%, Rwp=4.25%, χ2=2.8, 23 °C). The structure is an example of A-site vacancy-ordered 4×4×4 superstructure of a simple perovskite ABO 3, and it may be written as (Ba 1.75□ 0.25)BaWO 5.75□ 0.25, emphasizing vacancies on both metal and anion sites. The local structure of one of two asymmetric tungsten ions is the WO 6 octahedron, typical of perovskite. The other tungsten, however, is surrounded by oxygen and anionic vacancies statistically distributed over three divided sites to form 18 partially occupied oxygen atoms (˜30% on average), represented as WO 18/3. The A-site cation-vacancies are ordered at the 8a ( {1}/{8}, {1}/{8}, {1}/{8}) site in between adjoining WO 18/3 polyhedra which form 1-D arrangements along [110] and equivalent directions. In situ high-temperature XRD data have shown that the quenched Ba 11W 4O 23 at room temperature is isostructural to the high-temperature phase at 1100 °C.

  15. Study of the structural, electronic, and magnetic properties of the barium-rich iron(IV) oxides, Ba(2)FeO(4) and Ba(3)FeO(5).

    PubMed

    Delattre, James L; Stacy, Angelica M; Young, Victor G; Long, Gary J; Hermann, Raphaël; Grandjean, Fernande

    2002-06-03

    Crystals of Ba(2)FeO(4) and Ba(3)FeO(5), grown from a "self-sealing" KOH-Ba(OH)(2) flux, have been characterized by single-crystal X-ray diffraction, Mössbauer spectroscopy, and magnetic measurements. Ba(2)FeO(4) forms nonmerohedral twinned crystals with the monoclinic space group P2(1)/n, a = 6.034(2) A, b = 7.647(2) A, c = 10.162(3) A, beta = 92.931(6) degrees, and Z = 4. Ba(3)FeO(5) crystallizes in the orthorhombic space group Pnma, with a = 10.301(1) A, b = 8.151(1) A, c = 7.611(1) A, and Z = 4. While both compounds feature discrete FeO(4)(4-) tetrahedra, the anion found in Ba(2)FeO(4) has shorter Fe-O bonds and is significantly distorted relative to the Ba(3)FeO(5) anion. An iron valence of 4+ was confirmed by magnet susceptibility measurements and by the low-temperature isomer shifts of -0.152 and -0.142 mm/s relative to alpha-iron for Ba(2)FeO(4) and Ba(3)FeO(5), respectively.

  16. Comparison of rheological, mechanical, electrical properties of HDPE filled with BaTiO3 with different polar surface tension

    NASA Astrophysics Data System (ADS)

    Su, Jun; Zhang, Jun

    2016-12-01

    In this work, three types of coupling agents: isopropyl trioleic titanate (NDZ105), vinyltriethoxysilane (SG-Si151), 3-aminopropyltriethoxysilane (KH550) were applied to modify the surface tension of Barium titanate (BaTiO3) particles. The Fourier transform infrared (FT-IR) spectra confirm the chemical adherence of coupling agents to the particle surface. The long hydrocarbon chains in NDZ105 can cover the particle surface and reduce the polar surface tension of BaTiO3 from 37.53 mJ/m2 to 7.51 mJ/m2, turning it from hydrophilic to oleophilic properties. The short and non-polar vinyl groups in SG-Si151 does not influence the surface tension of BaTiO3, but make BaTiO3 have both hydrophilic and oleophilic properties. The polar amino in KH550 can keep BaTiO3 still with hydrophilic properties. It is found that SG-Si151 modified BaTiO3 has the lowest interaction with HDPE matrix, lowering the storage modulus of HDPE composites to the greatest extent. As for mechanical properties, the polar amino groups in KH550 on BaTiO3 surface can improve the adhesion of BaTiO3 with HDPE matrix, which increases the elongation at break of HDPE composites to the greatest extent. In terms of electrical properties, the polar amino groups on surface of BaTiO3 can boost the dielectric properties of HDPE/BaTiO3 composites and decrease the volume resistivity of HDPE/BaTiO3 composites. The aim of this study is to investigate how functional groups affect the rheological, mechanical and electrical properties of HDPE composites and to select a coupling agent to produce HDPE/BaTiO3 composites with low dielectric loss, high dielectric constant and elongation at break.

  17. Jumping the gun: Smoking constituent BaP causes premature primordial follicle activation and impairs oocyte fusibility through oxidative stress

    SciTech Connect

    Sobinoff, A.P.; Pye, V.; Nixon, B.; Roman, S.D.; McLaughlin, E.A.

    2012-04-01

    Benzo(a)pyrene (BaP) is an ovotoxic constituent of cigarette smoke associated with pre-mature ovarian failure and decreased rates of conception in IVF patients. Although the overall effect of BaP on female fertility has been documented, the exact molecular mechanisms behind its ovotoxicity remain elusive. In this study we examined the effects of BaP exposure on the ovarian transcriptome, and observed the effects of in vivo exposure on oocyte dysfunction. Microarray analysis of BaP cultured neonatal ovaries revealed a complex mechanism of ovotoxicity involving a small cohort of genes associated with follicular growth, cell cycle progression, and cell death. Histomorphological and immunohistochemical analysis supported these results, with BaP exposure causing increased primordial follicle activation and developing follicle atresia in vitro and in vivo. Functional analysis of oocytes obtained from adult Swiss mice treated neonatally revealed significantly increased levels of mitochondrial ROS/lipid peroxidation, and severely reduced sperm-egg binding and fusion in both low (1.5 mg/kg/daily) and high (3 mg/kg/daily) dose treatments. Our results reveal a complex mechanism of BaP induced ovotoxicity involving developing follicle atresia and accelerated primordial follicle activation, and suggest short term neonatal BaP exposure causes mitochondrial leakage resulting in reduced oolemma fluidity and impaired fertilisation in adulthood. This study highlights BaP as a key compound which may be partially responsible for the documented effects of cigarette smoke on follicular development and sub-fertility. -- Highlights: ► BaP exposure up-regulates canonical pathways linked with follicular growth/atresia. ► BaP causes primordial follicle activation and developing follicle atresia. ► BaP causes oocyte mitochondrial ROS and lipid peroxidation, impairing fertilisation. ► Short term neonatal BaP exposure compromises adult oocyte quality.

  18. 17 CFR 240.15Ba1-8 - Books and records to be made and maintained by municipal advisors.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Books and records to be made and maintained by municipal advisors. 240.15Ba1-8 Section 240.15Ba1-8 Commodity and Securities... Securities Associations § 240.15Ba1-8 Books and records to be made and maintained by municipal advisors....

  19. Phase transition behavior of hydrogen bonded liquid crystal (6BA)2-(BPy) x as studied by 2H NMR

    NASA Astrophysics Data System (ADS)

    Mizuno, M.; Tabota, K.; Oigawa, T.; Miyatou, T.; Kumagai, Y.; Ohashi, R.; Ida, T.

    2016-12-01

    The thermal properties and the orientational order of hydrogen-bonded liquid crystals (6BA)2-(BPy)0.4 and (6BA)2-(BPy)0.3 (6BA: 4- n-hexylbenzoicacid, BPy: 4,4'-bipyridine) were investigated by DSC and 2H NMR. On cooling, isotropic liquid - liquid crystal phase transition temperatures were T C= 409 and 405 K for (6BA)2-(BPy)0.4 and (6BA)2-(BPy)0.3, respectively. Thermal anomalies in the liquid crystal phase were observed at T LC1= 402 and T LC2= 375 K for (6BA)2-(BPy)0.4 and at T LC1= 398 and T LC2= 375 K for (6BA)2-(BPy)0.3. For (6BA)2-(BPy)0.4, only the smectic component was created above T LC1. In addition, the nematic component was created below T LC1. The nematic component gradually changed to the smectic component with decreasing temperature and only the smectic component was observed below T LC2. For (6BA)2-(BPy)0.3, only the nematic component was created above T LC2. The phase transition from the nematic phase to the smectic phase took place at around T LC2.

  20. Work Function Reduction by BaO: Growth of Crystalline Barium Oxide on Ag(001) and Ag(111) Surfaces

    SciTech Connect

    Droubay, Timothy C.; Kong, Lingmei; Chambers, Scott A.; Hess, Wayne P.

    2015-02-01

    Ultrathin films of barium oxide were grown on Ag(001) and Ag(111) using the evaporation of Ba metal in an O2 atmosphere by molecular beam epitaxy. Ultraviolet photoemission spectroscopy reveals that films consisting of predominantly BaO or BaO2 result in Ag(001) work function reductions of 1.74 eV and 0.64 eV, respectively. On the Ag(001) surface, Ba oxide growth is initiated by two-dimensional nucleation of epitaxial BaO, followed by a transition to three-dimensional dual-phase nucleation of epitaxial BaO and BaO2. Three-dimensional islands of primarily BaO2(111) nucleate epitaxially on the Ag(111) substrate leaving large patches of Ag uncovered. We find no indication of chemical reaction or charge transfer between the films and the Ag substrates. These data suggest that the origin of the observed work function reduction is largely due to a combination of BaO surface relaxation and an electrostatic compressive effect.

  1. Liquidus projection of the Ag-Ba-Ge system and melting points of clathrate type-I compounds

    NASA Astrophysics Data System (ADS)

    Zeiringer, I.; Grytsiv, A.; Brož, P.; Rogl, P.

    2012-12-01

    The liquidus and solidus projection has been constructed for the Ag-Ba-Ge system up to 33.3 at% Ba, using electron micro probe analysis (EPMA), X-ray powder diffraction (XRD) and differential thermal analysis (DSC/DTA). Eight different primary crystallization regions were found: (Ge), Ba8AgxGe46-x-y□y (κI) (□ is a vacancy), Ba6AgxGe25-x (κIx), BaGe2, Ba(Ag1-xGex)2 (τ1), BaAg2-xGe2+x (τ2) BaAg5 and (Ag). The ternary invariant reactions have been determined for the region investigated and are the basis for a Schulz-Scheil diagram. The second part of this work provides a comprehensive compilation of melting points of ternary A8TxM46-x and quaternary (A=Sr, Ba, Eu; T=Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga; M=Si, Ge, Sn) clathrate type-I compounds and decomposition temperatures of inverse clathrate type-I Ge38{P,As,Sb}8{Cl,Br,I}8, Si46-xPxTey and tin based compounds.

  2. Al substituted Ba ferrite films with high coercivity and excellent squareness for low noise perpendicular recording layer

    NASA Astrophysics Data System (ADS)

    Feng, J.; Matsushita, N.; Watanabe, K.; Nakagawa, S.; Naoe, M.

    1999-04-01

    Al substituted BaM (Al-BaM) ferrite films with composition of BaAlxFe12-xO19 (x=0,1,2) were deposited using facing targets sputtering apparatus on SiOx/Si wafers with a Pt seed layer. A postannealing process is necessary to crystallize the films. It was confirmed that the substrate temperature Ts is also one of the important parameters for the magnetic properties of the postannealed films. Al-BaM ferrite films exhibit the Ts dependence of magnetic properties different from that of simple BaM ones. With increase of the Al content x in Al-BaM ferrite films, 4πMs decreased, while Hc and the anisotropy field HA increased. It was found that acicular shape grains formed more easily in Al-BaM ferrite films than in simple BaM ones. The squareness S⊥ increased largely by substitution of Al for Fe. The Al-BaM ferrite films with high Hc⊥ (˜3 kOe) and large S⊥(˜0.9) may be applicable as perpendicular magnetic recording layers with low noise level.

  3. Electric control of magnetism at the Fe/BaTiO3 interface

    NASA Astrophysics Data System (ADS)

    Radaelli, G.; Petti, D.; Plekhanov, E.; Fina, I.; Torelli, P.; Salles, B. R.; Cantoni, M.; Rinaldi, C.; Gutiérrez, D.; Panaccione, G.; Varela, M.; Picozzi, S.; Fontcuberta, J.; Bertacco, R.

    2014-03-01

    Interfacial magnetoelectric coupling is a viable path to achieve electrical writing of magnetic information in spintronic devices. For the prototypical Fe/BaTiO3 system, only tiny changes of the interfacial Fe magnetic moment upon reversal of the BaTiO3 dielectric polarization have been predicted so far. Here, by using X-ray magnetic circular dichroism in combination with high-resolution electron microscopy and first principles calculations, we report on an undisclosed physical mechanism for interfacial magnetoelectric coupling in the Fe/BaTiO3 system. At this interface, an ultrathin oxidized iron layer exists, whose magnetization can be electrically and reversibly switched on and off at room temperature by reversing the BaTiO3 polarization. The suppression/recovery of interfacial ferromagnetism results from the asymmetric effect that ionic displacements in BaTiO3 produces on the exchange coupling constants in the interfacial-oxidized Fe layer. The observed giant magnetoelectric response holds potential for optimizing interfacial magnetoelectric coupling in view of efficient, low-power spintronic devices.

  4. Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2.

    PubMed

    Liu, Jinyu; Hu, Jin; Cao, Huibo; Zhu, Yanglin; Chuang, Alyssa; Graf, D; Adams, D J; Radmanesh, S M A; Spinu, L; Chiorescu, I; Mao, Zhiqiang

    2016-07-28

    Layered compounds AMnBi2 (A = Ca, Sr, Ba, or rare earth element) have been established as Dirac materials. Dirac electrons generated by the two-dimensional (2D) Bi square net in these materials are normally massive due to the presence of a spin-orbital coupling (SOC) induced gap at Dirac nodes. Here we report that the Sb square net in an isostructural compound BaMnSb2 can host nearly massless Dirac fermions. We observed strong Shubnikov-de Haas (SdH) oscillations in this material. From the analyses of the SdH oscillations, we find key signatures of Dirac fermions, including light effective mass (~0.052m0; m0, mass of free electron), high quantum mobility (1280 cm(2)V(-1)S(-1)) and a π Berry phase accumulated along cyclotron orbit. Compared with AMnBi2, BaMnSb2 also exhibits much more significant quasi two-dimensional (2D) electronic structure, with the out-of-plane transport showing nonmetallic conduction below 120 K and the ratio of the out-of-plane and in-plane resistivity reaching ~670. Additionally, BaMnSb2 also exhibits a G-type antiferromagnetic order below 283 K. The combination of nearly massless Dirac fermions on quasi-2D planes with a magnetic order makes BaMnSb2 an intriguing platform for seeking novel exotic phenomena of massless Dirac electrons.

  5. Structural instability in BaZrO3 crystals: Calculations and experiment

    NASA Astrophysics Data System (ADS)

    Lebedev, A. I.; Sluchinskaya, I. A.

    2013-09-01

    The phonon spectrum of cubic barium zirconate is calculated from first principles using the density functional theory. An unstable R 25 phonon mode observed in the phonon spectrum indicates an instability of the BaZrO3 structure with respect to the oxygen octahedra rotations. It is shown that the symmetry of the ground-state structure of the crystal is I4/ mcm. The local structure of BaZrO3 is studied by the EXAFS spectroscopy at the Ba L III absorption edge at 300 K to search for the instability predicted by calculations. Anomalously high values of the Debye-Waller factor for the Ba-O atomic pairs (σ{1/2} ˜ 0.015 Å2) are attributed to the appearance of this structural instability. The average amplitude of the octahedra rotations caused by thermal vibrations is estimated from the measured σ{1/2} value to be ˜4° at 300 K. The closeness of the calculated energies of various distorted phases resulting from the condensation of the R 25 mode suggests a possible formation of the structural glass state in BaZrO3 as the temperature is lowered. It explains the origin of the disagreement between the results of calculations and diffraction experiments.

  6. Lattice dynamics of BaFe2X3(X=S,Se) compounds

    DOE PAGES

    Popović, Z. V.; Šćepanović, M.; Lazarević, N.; ...

    2015-02-27

    We present the Raman scattering spectra of the S=2 spin ladder compounds BaFe₂X₃ (X=S,Se) in a temperature range between 20 and 400 K. Although the crystal structures of these two compounds are both orthorhombic and very similar, they are not isostructural. The unit cell of BaFe₂S₃ (BaFe₂Se₃) is base-centered Cmcm (primitive Pnma), giving 18 (36) modes to be observed in the Raman scattering experiment. We have detected almost all Raman active modes, predicted by factor group analysis, which can be observed from the cleavage planes of these compounds. Assignment of the observed Raman modes of BaFe₂S(Se)₃ is supported by themore » lattice dynamics calculations. The antiferromagnetic long-range spin ordering in BaFe₂Se₃ below TN=255K leaves a fingerprint both in the A1g and B3g phonon mode linewidth and energy.« less

  7. Superconductivity in the ternary iridium-arsenide BaIr2As2

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Chuan; Ruan, Bin-Bin; Yu, Jia; Pan, Bo-Jin; Mu, Qing-Ge; Liu, Tong; Chen, Gen-Fu; Ren, Zhi-An

    2017-03-01

    Here we report the synthesis and discovery of superconductivity in a novel ternary iridium-arsenide compound BaIr2As2. The polycrystalline BaIr2As2 sample was first synthesized by a high temperature and high pressure method. Crystal structural analysis indicates that BaIr2As2 crystallizes in the ThCr2Si2-type layered tetragonal structure with space group I4/mmm (No. 139), and the lattice parameters were refined to be a = 4.052(9) Å and c = 12.787(8) Å. By the electrical resistivity and magnetic susceptibility measurements we found type-II superconductivity in the new BaIr2As2 compound with a T c (critical temperature) of 2.45 K, and an upper critical field μ 0 H c2(0) about 0.2 T. Low temperature specific heat measurements gave a Debye temperature of about 202 K and a distinct specific jump with ΔC e /γT c = 1.36, which is close to the value of BCS weak coupling limit and confirms the bulk superconductivity in this new BaIr2As2 compound.

  8. Ba4Ga2Se8: A ternary selenide containing chains and discrete Se22- units

    NASA Astrophysics Data System (ADS)

    Yin, Wenlong; Iyer, Abishek K.; Lin, Xinsong; Mar, Arthur

    2016-05-01

    The ternary selenide Ba4Ga2Se8 has been synthesized by reaction of BaSe, Ga2Se3, and Se at 1023 K. Single-crystal X-ray diffraction analysis revealed a monoclinic structure (space group P21/c, Z=4, a=13.2393(5) Å, b=6.4305(2) Å, c=20.6432(8) Å, β=104.3148(6)°) featuring one-dimensional chains of corner-sharing Ga-centered tetrahedra and discrete Se22- anionic units, with charge-compensating Ba2+ cations located between them. The UV/vis/NIR diffuse reflectance spectrum reveals an optical band gap of 1.63(2) eV, which is consistent with the black color of the crystals and agrees with a calculated gap of 1.51 eV obtained from band structure calculations. The presence of the Se22- units narrows the band gap in Ba4Ga2Se8 relative to other Ba-Ga-Se phases.

  9. Significant increase of Curie temperature in nano-scale BaTiO{sub 3}

    SciTech Connect

    Li, Yueliang; Liao, Zhenyu; Fang, Fang; Zhu, Jing; Wang, Xiaohui; Li, Longtu

    2014-11-03

    The low Curie temperature (T{sub c} = 130 °C) of bulk BaTiO{sub 3} greatly limits its applications. In this work, the phase structures of BaTiO{sub 3} nanoparticles with sizes ranging from 2.5 nm to 10 nm were studied at various temperatures by using aberration-corrected transmission electron microscopy (TEM) equipped with an in-situ heating holder. The results implied that each BaTiO{sub 3} nanoparticle was composed of different phases, and the ferroelectric ones were observed in the shells due to the complicated surface structure. The ferroelectric phases in BaTiO{sub 3} nanoparticles remained at 600 °C, suggesting a significant increase of T{sub c}. Based on the in-situ TEM results and the data reported by others, temperature-size phase diagrams for BaTiO{sub 3} particles and ceramics were proposed, showing that the phase transition became diffused and the T{sub c} obviously increased with decreasing size. The present work sheds light on the design and fabrication of advanced devices for high temperature applications.

  10. Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2

    PubMed Central

    Liu, Jinyu; Hu, Jin; Cao, Huibo; Zhu, Yanglin; Chuang, Alyssa; Graf, D.; Adams, D. J.; Radmanesh, S. M. A.; Spinu, L.; Chiorescu, I.; Mao, Zhiqiang

    2016-01-01

    Layered compounds AMnBi2 (A = Ca, Sr, Ba, or rare earth element) have been established as Dirac materials. Dirac electrons generated by the two-dimensional (2D) Bi square net in these materials are normally massive due to the presence of a spin-orbital coupling (SOC) induced gap at Dirac nodes. Here we report that the Sb square net in an isostructural compound BaMnSb2 can host nearly massless Dirac fermions. We observed strong Shubnikov-de Haas (SdH) oscillations in this material. From the analyses of the SdH oscillations, we find key signatures of Dirac fermions, including light effective mass (~0.052m0; m0, mass of free electron), high quantum mobility (1280 cm2V−1S−1) and a π Berry phase accumulated along cyclotron orbit. Compared with AMnBi2, BaMnSb2 also exhibits much more significant quasi two-dimensional (2D) electronic structure, with the out-of-plane transport showing nonmetallic conduction below 120 K and the ratio of the out-of-plane and in-plane resistivity reaching ~670. Additionally, BaMnSb2 also exhibits a G-type antiferromagnetic order below 283 K. The combination of nearly massless Dirac fermions on quasi-2D planes with a magnetic order makes BaMnSb2 an intriguing platform for seeking novel exotic phenomena of massless Dirac electrons. PMID:27466151

  11. Synthesis and functionality of the storage phosphor BaFBr:Eu{sup 2+}

    SciTech Connect

    Hesse, S.; Zimmermann, J.; Seggern, H. von; Meng, X.; Fasel, C.; Riedel, R.

    2009-03-15

    The present paper relates to a method for synthesizing the photostimulable storage phosphor BaFBr:Eu{sup 2+} that features high stimulation characteristics for use in image plates. All previous synthesis routes consist of a multistep process whereas the presented route is a one-step synthesis. Starting compounds are BaCO{sub 3}, NH{sub 4}F, and NH{sub 4}Br, as well as EuF{sub 3} where the ammonium compounds are highly volatile at temperatures below 300 deg. C. Their reaction products initiate the decomposition of BaCO{sub 3} and form BaFBr. The incorporation of F-centers and europium ions occurs at temperature exceeding 550 deg. C. The individual reaction steps are monitored by simultaneous thermal analysis (thermogravimetry/differential thermal analysis) and the gaseous reaction products are detected by in situ mass spectroscopy. Intermediate and final products are characterized by x-ray diffraction techniques to determine the involved phases. Photoluminescence spectra reveal the typical emission peak of Eu{sup 2+} accompanied by a redshifted emission band at 470 nm, which was assigned to oxygen incorporated into the BaFBr lattice. The synthesized powders exhibit small grain sizes well suited for the use in image plates.

  12. Precipitation method for barium metaborate (BaB2O4) synthesis from borax solution

    NASA Astrophysics Data System (ADS)

    Akşener, Eymen; Figen, Aysel Kantürk; Pişkin, Sabriye

    2013-12-01

    In this study, barium metaborate (BaB2O4, BMB) synthesis from the borax solution was carried out. BMB currently is used in production of ceramic glazes, luminophors, oxide cathodes as well as additives to pigments for aqueous emulsion paints and also β-BaB2O4 single crystals are the best candidate for fabrication of solid-state UV lasers operating at a wavelength of 200 nm due to excellent nonlinear optical properties. In the present study, synthesis was carried out from the borax solution (Na2B4O7ṡ10H2O, BDH) and barium chloride (BaCI2ṡ2H2O, Ba) in the glass-batch reactor with stirring. The effect of, times (5-15 min), molar ratio [stoich.ration (1.0:2.0), 1.25:2.0, 1.5:2.0, 2.5:2:0, 3.0:2.0, 3.5:2.0,4.0:2.0, 5.0:2.0] and also crystallization time (2-6 hour) on the BMB yield (%) was investigated at 80 °C reaction temperature. It is found that, BMB precipitation synthesis with 90 % yield can be performed from 0.50 molar ration (BDH:Ba), under 80 °C, 15 minute, and 6 hours crystallization time. The structural properties of BMB powders were characterized by using XRD, FT-IR and DTA-TG instrumental analysis technique.

  13. Synthesis and structure of the Zintl compounds Na 2BaTt 4 (Tt = Si, Ge)

    NASA Astrophysics Data System (ADS)

    Huang, B.; Corbett, J. D.

    1999-10-01

    The isotypic title compounds ate obtained from reactions of stoichiometric mixtures of the elements in welded Ta containers at 700-800 °C. The structure of Na 2BaSi 4 was determined by single-crystal X-ray diffraction (orthorhombic, Ima2 (No. 46), Z = 8, a = 9.524, b = 17.980(3), c = 8.570(3) Å). The compound crystallizes in a novel structure type with Na + and Ba 2+ cations and two crystallographically-independent isolated Si 44- anions. The anions are nearly regular tetrahedra with bond distances of 2.385(3) to 2.448(4) Å and bond angles between 59.2 and 61.7°. The overall structure may be described as a distorted face-centered-cubic array of Si 44- anions in which Na + and Ba 2+ atoms occupy all tetrahedral and octahedral holes in an ordered way. The result is closely related to the topology of f.c.c. Li 3Bi type but with ordering of the two cations. Magnetic measurements showed that Na 2BaSi 4 is diamagnetic, and its family can be formulated in terms of oxidation states as Zintl phases (Na +) 2Ba 2+(Tt 44-).

  14. Structural and electrical transport properties of proficient Ba-Pb nanoferrites

    NASA Astrophysics Data System (ADS)

    Haq, A.; Anis-ur-Rehman, M.; Malik, Muhammad Ali

    2012-03-01

    The excellent combination of magnetic and dielectric properties of hexaferrites makes these materials suitable for use in high-frequency applications. Ba-Pb nanocrystalline ferrites having the general formula Ba1-xPbxFe12O19 (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were prepared by the co-precipitation method. X-ray powder diffraction (XRD) patterns of all prepared samples indicated the formation of the required phase. The crystallite size, lattice parameters and porosities of samples were measured from XRD data. Scanning electron microscopy was carried out to observe the morphology of the synthesized Ba-Pb ferrites. Temperature-dependent dc electrical resistivity, dielectric constant, dielectric loss tangent and the ac electrical conductivity of nanocrystalline Ba ferrites were investigated as a function of frequency and Pb concentration. The effect of Pb doping on dielectric and electric properties of Ba nanoferrites was explained on the basis of cation distribution in the crystal structure.

  15. Electric control of magnetism at the Fe/BaTiO₃ interface.

    PubMed

    Radaelli, G; Petti, D; Plekhanov, E; Fina, I; Torelli, P; Salles, B R; Cantoni, M; Rinaldi, C; Gutiérrez, D; Panaccione, G; Varela, M; Picozzi, S; Fontcuberta, J; Bertacco, R

    2014-03-03

    Interfacial magnetoelectric coupling is a viable path to achieve electrical writing of magnetic information in spintronic devices. For the prototypical Fe/BaTiO₃ system, only tiny changes of the interfacial Fe magnetic moment upon reversal of the BaTiO₃ dielectric polarization have been predicted so far. Here, by using X-ray magnetic circular dichroism in combination with high-resolution electron microscopy and first principles calculations, we report on an undisclosed physical mechanism for interfacial magnetoelectric coupling in the Fe/BaTiO₃ system. At this interface, an ultrathin oxidized iron layer exists, whose magnetization can be electrically and reversibly switched on and off at room temperature by reversing the BaTiO₃ polarization. The suppression/recovery of interfacial ferromagnetism results from the asymmetric effect that ionic displacements in BaTiO₃ produces on the exchange coupling constants in the interfacial-oxidized Fe layer. The observed giant magnetoelectric response holds potential for optimizing interfacial magnetoelectric coupling in view of efficient, low-power spintronic devices.

  16. Hybrid molecular beam epitaxy for the growth of stoichiometric BaSnO{sub 3}

    SciTech Connect

    Prakash, Abhinav Dewey, John; Yun, Hwanhui; Jeong, Jong Seok; Mkhoyan, K. Andre; Jalan, Bharat

    2015-11-15

    Owing to its high room-temperature electron mobility and wide bandgap, BaSnO{sub 3} has recently become of significant interest for potential room-temperature oxide electronics. A hybrid molecular beam epitaxy (MBE) approach for the growth of high-quality BaSnO{sub 3} films is developed in this work. This approach employs hexamethylditin as a chemical precursor for tin, an effusion cell for barium, and a radio frequency plasma source for oxygen. BaSnO{sub 3} films were thus grown on SrTiO{sub 3} (001) and LaAlO{sub 3} (001) substrates. Growth conditions for stoichiometric BaSnO{sub 3} were identified. Reflection high-energy electron diffraction (RHEED) intensity oscillations, characteristic of a layer-by-layer growth mode were observed. A critical thickness of ∼1 nm for strain relaxation was determined for films grown on SrTiO{sub 3} using in situ RHEED. Scanning transmission electron microscopy combined with electron energy-loss spectroscopy and energy dispersive x-ray spectroscopy confirmed the cube-on-cube epitaxy and composition. The importance of precursor chemistry is discussed in the context of the MBE growth of BaSnO{sub 3}.

  17. Hydrothermal synthesis of BaTiO 3 nanoparticles using a supercritical continuous flow reaction system

    NASA Astrophysics Data System (ADS)

    Hayashi, Hiromichi; Noguchi, Takio; Islam, Nazrul M.; Hakuta, Yukiya; Imai, Yusuke; Ueno, Nobuhiko

    2010-06-01

    Highly crystalline BaTiO 3 nanoparticle was synthesized rapidly by hydrothermal reaction in supercritical water using a continuous flow reactor. The reactants of TiO 2 sol (or TiCl 4)/Ba(NO 3) 2 mixed solution and KOH solution were used as starting materials and that was heated quickly up to 400 °C under the pressure of 30 MPa for 8 ms as reaction time. The XRD results revealed that the crystal phase of the obtained particles was cubic BaTiO 3, indicating that the hydrothermal reaction in supercritical water was successfully proceeded under present reaction conditions. Primarily particle size of the BaTiO 3 nanoparticle was determined by means of BET surface area, as small as less than 10 nm with decreasing the reaction pH. In contrast, dispersed particle size in solution measured by DLS (dynamic light scattering) technique decreased from 260 to 90 nm with increasing the reactants concentration. Aggregation of BaTiO 3 nanoparticles might be depressed in the presence of coexisting nitrate anions.

  18. Structural transformation and vibrational properties of BaO2 at high pressures

    NASA Astrophysics Data System (ADS)

    Efthimiopoulos, I.; Kunc, K.; Karmakar, S.; Syassen, K.; Hanfland, M.; Vajenine, G.

    2010-10-01

    The tetragonal ambient-pressure phase of BaO2 ( CaC2 -type, space group I4/mmm ) with sixfold coordination of Ba atoms and O2 dumbbells was found to transform reversibly to an orthorhombic modification (space group Cmmm ) near 33 GPa. The eight-coordinated high-pressure phase represents a new structure type. It is related to the CsCl-type structure but can also be viewed as a distorted variant of the hexagonal AlB2 type, suggesting possible polymerization of the isolated O2 dumbbells to a two-dimensional network at higher pressure. In addition to in situ x-ray diffraction, Raman measurements were performed to study the lattice dynamics of the BaO2 phases under pressure. The experimental observations are compared to the results of ab initio calculations of the structural stability and dynamical properties. Raman spectra of barium monoxide BaO are reported in the Appendix; these results were found useful for the interpretation of the Raman scattering of BaO2 .

  19. Thermoelectric properties of BaSi2, SrSi2, and LaSi

    NASA Astrophysics Data System (ADS)

    Hashimoto, Kohsuke; Kurosaki, Ken; Imamura, Yasushi; Muta, Hiroaki; Yamanaka, Shinsuke

    2007-09-01

    We studied the thermoelectric properties of BaSi2, SrSi2, and LaSi. The polycrystalline samples were prepared by spark plasma sintering (SPS). The electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ) were measured above room temperature. The power factor (S2/ρ) is quite low (below 10-5 Wm-1 K-2 over the whole temperature range) for BaSi2 and LaSi, while relatively high (1.19×10-3 Wm-1 K-2 at 331 K) for SrSi2. BaSi2 exhibits quite low κ. The κ values at room temperature are 1.56, 5.25, and 6.71 Wm-1 K-1 for BaSi2, SrSi2, and LaSi, respectively. The maximum values of the dimensionless figure of merit, ZT =S2T/ρ/κ, are 0.01 at 954 K for BaSi2, 0.09 at 417 K for SrSi2, and 0.002 at 957 K for LaSi.

  20. Thick barium hexaferrite (Ba-M) films prepared by electron-beam evaporation for microwave application

    NASA Astrophysics Data System (ADS)

    Wane, I.; Bessaudou, A.; Cosset, F.; Célérier, A.; Girault, C.; Decossas, J. L.; Vareille, J. C.

    2000-03-01

    Hexagonal ferrites such as barium or strontium hexaferrites have many existing and potential applications. Among these are microwave devices. In this paper we present the results of Ba-M thick ferrite films deposited on silicon (1 0 0) by electron-beam evaporation. To increase adhesion and reduce cracks, the films are also deposited on thin (#1 μm) metallic underlayers. The influence of deposition rate and post-deposition annealing on crystallographic structure, magnetic properties, morphology and chemical composition has been investigated. The deposition pressure was equal to 0.46 Pa and substrate temperature was kept at 200°C. The results show that, before annealing, the films do not crystallise under the bulk phase of BaFe 12O 19 (Ba-M) and magnetic measurements show no hysteresis curve. On the other hand, films annealed at 850°C for 2 h in oxygen atmosphere are magnetic and crystallise in the Ba-M phase. The coercive fields of these films range between 160 and 360 kA/m. The saturation magnetisation of the annealed films varies between 0.15 and 0.21 T. The EDX analysis shows that the Fe/Ba atomic ratio depends on the deposition rate. The SEM study shows homogeneous film surfaces and small grains size.

  1. Synthesis of transparent BaTiO3 nanoparticle/polymer composite film using DC field

    NASA Astrophysics Data System (ADS)

    Kondo, Yusuke; Okumura, Yasuko; Oi, Chifumi; Sakamoto, Wataru; Yogo, Toshinobu

    2008-10-01

    Transparent BaTiO3 nanoparticle/polymer composite films were synthesized from titanium-organic film and barium ion in aqueous solution under direct current (DC) field. Titanium-organic precursor was synthesized from titanium isopropoxide, acetylacetone and methacrylate derivative. The UV treatment was effective to increase the anti-solubility of the titanium-organic film during DC processing. BaTiO3 nanoparticles were crystallized in the precursor films on stainless substrates without high temperature process, as low as 40°C. The crystallite size of BaTiO3 increased with increasing reaction temperature from 40 to 50 °C at 3.0 V/cm. BaTiO3 nanoparticles also grew in size with increasing reaction time from 15 min to 45 min at 3.0 V/cm and 50 °C. Transparent BaTiO3 nanoparticle/polymer films were synthesized on stainless substrates at 3.0 V/cm and 50°C for 45 min.

  2. Structure and Thermophysical Properties of Molten BaGe Using Electrostatic Levitation Technique

    NASA Astrophysics Data System (ADS)

    Ishikura, Akiko; Mizuno, Akitoshi; Watanabe, Masahito; Masaki, Tadahiko; Ishikawa, Takehiko; Yoda, Shinichi

    2008-12-01

    BaGe alloys with two compositions near their eutectic point form open framework structures called the clathrate structure. These BaGe compounds with the clathrate structure can be made by rapid solidification from their liquid state. However, the formation mechanism of the clathrate structure has not been clarified due to lack of information on their liquid-state structure and properties. Since BaGe alloy melts have very high reactivity, it is difficult to measure the thermophysical properties of them by ordinary methods using a container. Therefore, a containerless technique must be used to measure the thermophysical properties of BaGe melts. Using the electrostatic levitation (ESL) technique as a containerless technique, the thermophysical properties (density, surface tension, and viscosity) of BaGe melts around the eutectic composition were measured in order to clarify the formation mechanism of the clathrate structure, and also the structure of them was observed by using the high-energy X-ray diffraction method combined with ESL. From experimental results, it was observed that the short-range order based on the clathrate structure exists even in the liquid state at the clathrate-forming compositions.

  3. The solubility of (Ba,Sr)SO 4 precipitates: Thermodynamic equilibrium and reaction path analysis

    NASA Astrophysics Data System (ADS)

    Felmy, Andrew R.; Rai, Dhanpat; Moore, Dean A.

    1993-09-01

    The solubility of (Ba,Sr)SO 4 precipitates, varying in SrSO 4 mole fraction from 0.05-0.90, was investigated at room temperature with an equilibration period extending to almost three years. The data show that on or before 315 days of equilibration the precipitates reach a reversible equilibrium with the aqueous solution. The reversibility of this equilibrium was verified both by the attainment of steady-state concentrations with time and by heating the samples to perturb the equilibrium and then observing the slow return to the initial equilibrium state. The dissolution of the (Ba,Sr)SO 4 precipitates does not, in general, follow limiting reaction paths as defined by the Lippmann solutus or stoichiometric dissolution curves. In addition, activity coefficient calculations for the BaSO 4 and SrSO 4 components of the solid phase, using either total bulk analysis or near-surface analysis of the component mole fractions, do not satisfy the Gibbs-Duhem equation, demonstrating that a single solid-solution phase does not control both the aqueous Ba and Sr concentrations. Instead, our long-term equilibration data can be explained by the unavoidable formation of small amounts of barite and substitution of Sr into a solid-solution phase with the BaSO 4 component of the solid-solution phase never reaching thermodynamic equilibrium with the aqueous phase.

  4. Large linear magnetoresistance in a new Dirac material BaMnBi2

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Yan; Yu, Qiao-He; Xia, Tian-Long

    2016-10-01

    Dirac semimetal is a class of materials that host Dirac fermions as emergent quasi-particles. Dirac cone-type band structure can bring interesting properties such as quantum linear magnetoresistance and large mobility in the materials. In this paper, we report the synthesis of high quality single crystals of BaMnBi2 and investigate the transport properties of the samples. BaMnBi2 is a metal with an antiferromagnetic transition at T N = 288 K. The temperature dependence of magnetization displays different behavior from CaMnBi2 and SrMnBi2, which suggests the possible different magnetic structure of BaMnBi2. The Hall data reveals electron-type carriers and a mobility μ(5 K) = 1500 cm2/V·s. Angle-dependent magnetoresistance reveals the quasi-two-dimensional (2D) Fermi surface in BaMnBi2. A crossover from semiclassical MR ˜ H 2 dependence in low field to MR ˜ H dependence in high field, which is attributed to the quantum limit of Dirac fermions, has been observed in magnetoresistance. Our results indicate the existence of Dirac fermions in BaMnBi2. Project supported by the National Natural Science Foundation of China (Grant No. 11574391), the Fundamental Research Funds for the Central Universities, and the Research Funds of Renmin University of China (Grant No. 14XNLQ07).

  5. Dielectric relaxation and polaronic conduction in epitaxial BaFe12O19 hexaferrite thin film

    NASA Astrophysics Data System (ADS)

    Tang, Rujun; Zhou, Hao; Zhao, Run; Jian, Jie; Wang, Han; Huang, Jijie; Fan, Meng; Zhang, Wei; Wang, Haiyan; Yang, Hao

    2016-03-01

    The dielectric properties of epitaxial BaFe12O19 hexaferrite thin film have been investigated as a function of frequency (50 Hz  -  2 MHz) and temperature (100-375 K). The frequency dependent permittivity, impedance ({{Z}\\prime \\prime} ) and modulus ({{M}\\prime \\prime} ) spectra show that the dielectric responses of BaFe12O19 thin film are thermally activated. The activation energy of BaFe12O19 film (E a) is much smaller than that of the polycrystalline bulk BaFe12O19. In addition, E a increases with increasing temperature and there is a distribution of relaxation time in the sample. The scaling behavior of {{Z}\\prime \\prime} and {{M}\\prime \\prime} spectra of the sample further suggest that the distribution of relaxation time is temperature independent at low temperatures (<250 K) and temperature dependent at high temperatures. The temperature dependent dc conductivity shows that small polaron hopping is the most probable conduction mechanism for BaFe12O19 film.

  6. Innovative treatment trains of bottom ash (BA) from municipal solid waste incineration (MSWI) in Germany.

    PubMed

    Holm, Olaf; Simon, Franz-Georg

    2017-01-01

    The industrial sector of bottom ash (BA) treatment from municipal solid waste incineration (MSWI) in Germany is currently changing. In order to increase the recovery rates of metals or to achieve a higher quality of mineral aggregates derived from BA, new procedures have been either implemented to existing plants or completely new treatment plants have been built recently. Three treatment trains, which are designated as entire sequences of selected processing techniques of BA, are introduced and compared. One treatment train is mainly characterized by usage of a high speed rotation accelerator whereas another is operating completely without crushing. In the third treatment train the BA is processed wet directly after incineration. The consequences for recovered metal fractions and the constitution of remaining mineral aggregates are discussed in the context of legislative and economical frameworks. Today the recycling or disposal options of mineral residues still have a high influence on the configuration and the operation mode of the treatment trains of BA despite of the high value of recovered metals.

  7. BaTiO3 and polypropylene nanocomposites for capacitor applications

    NASA Astrophysics Data System (ADS)

    Dong, Daxuan; Tang, Longxiang; Zhu, Lei; Lee, Je; Case Western Reserve University Collaboration; Agiltron, Inc Collaboration

    2013-03-01

    A novel strategy to uniformly disperse 70-nm BaTiO3 ferroelectric nanoparticles in a dielectric polypropylene (PP) matrix is developed in order to achieve high dielectric constant and high energy density for capacitor applications. By modifying BaTiO3 surface with a bis-phosphonic acid-terminated polyhedral oligomeric selsisquioxane (POSS), a nanocomposite with BaTiO3@POSS uniformly dispersed in PP matrix was achieved. The nanocomposite film containing a high nanoparticle content of 30 vol.% exhibited a high dielectric constant of 32 and a breakdown voltage of 220 MV/m, but with a high energy loss. Improvement of this nanocomposite by understanding the interfacial polarization is carried out in this work. The dielectric constant difference between BaTiO3 and PP can generate interfacial polarization and subsequent internal conduction in BaTiO3 particles upon bipolar polarization. Reduction of this internal conduction mechanism will significantly reduce the hysteresis loss in polymer nanodielectrics.

  8. Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2

    NASA Astrophysics Data System (ADS)

    Liu, Jinyu; Hu, Jin; Cao, Huibo; Zhu, Yanglin; Chuang, Alyssa; Graf, D.; Adams, D. J.; Radmanesh, S. M. A.; Spinu, L.; Chiorescu, I.; Mao, Zhiqiang

    2016-07-01

    Layered compounds AMnBi2 (A = Ca, Sr, Ba, or rare earth element) have been established as Dirac materials. Dirac electrons generated by the two-dimensional (2D) Bi square net in these materials are normally massive due to the presence of a spin-orbital coupling (SOC) induced gap at Dirac nodes. Here we report that the Sb square net in an isostructural compound BaMnSb2 can host nearly massless Dirac fermions. We observed strong Shubnikov-de Haas (SdH) oscillations in this material. From the analyses of the SdH oscillations, we find key signatures of Dirac fermions, including light effective mass (~0.052m0 m0, mass of free electron), high quantum mobility (1280 cm2V‑1S‑1) and a π Berry phase accumulated along cyclotron orbit. Compared with AMnBi2, BaMnSb2 also exhibits much more significant quasi two-dimensional (2D) electronic structure, with the out-of-plane transport showing nonmetallic conduction below 120 K and the ratio of the out-of-plane and in-plane resistivity reaching ~670. Additionally, BaMnSb2 also exhibits a G-type antiferromagnetic order below 283 K. The combination of nearly massless Dirac fermions on quasi-2D planes with a magnetic order makes BaMnSb2 an intriguing platform for seeking novel exotic phenomena of massless Dirac electrons.

  9. Antiperovskite Chalco-Halides Ba3(FeS4)Cl, Ba3(FeS4)Br, and Ba3(FeSe4)Br with Spin Super-Super Exchange

    PubMed Central

    Zhang, Xian; Liu, Kai; He, Jian-Qiao; Wu, Hui; Huang, Qing-Zhen; Lin, Jian-Hua; Lu, Zhong-Yi; Huang, Fu-Qiang

    2015-01-01

    Perovskite-related materials have received increasing attention for their broad applications in photovoltaic solar cells and information technology due to their unique electrical and magnetic properties. Here we report three new antiperovskite chalco-halides: Ba3(FeS4)Cl, Ba3(FeS4)Br, and Ba3(FeSe4)Br. All of them were found to be good solar light absorbers. Remarkably, although the shortest Fe-Fe distance exceeds 6 Å, an unexpected anti-ferromagnetic phase transition near 100 K was observed in their magnetic susceptibility measurement. The corresponding complex magnetic structures were resolved by neutron diffraction experiments as well as investigated by first-principles electronic structure calculations. The spin-spin coupling between two neighboring Fe atoms along the b axis, which is realized by the Fe-S···S-Fe super-super exchange mechanism, was found to be responsible for this magnetic phase transition. PMID:26525136

  10. Superconductivity and structural distortion in BaPt2As2

    NASA Astrophysics Data System (ADS)

    Jiang, W. B.; Guo, C. Y.; Weng, Z. F.; Wang, Y. F.; Chen, Y. H.; Chen, Y.; Pang, G. M.; Shang, T.; Lu, X.; Yuan, H. Q.

    2015-01-01

    We report the synthesis of BaPt2As2 single crystals and the discovery of superconductivity and a structural phase transition in this compound by measuring the electrical resistivity, magnetic susceptibility and specific heat as well as the x-ray diffraction at low temperatures. BaPt2As2 crystallizes in the CaBe2Ge2-type tetragonal structure (P4/nmm) at room temperature and undergoes a first-order structural transition at TS ≃ 275 K, which is likely to be associated with a charge-density-wave (CDW) instability. BCS-like superconductivity with two subsequent transitions Tc1 ≃ 1.67 K and Tc2 ≃ 1.33 K is observed. Our results demonstrate that BaPt2As2 may serve as a new system for studying the interplay of superconductivity and the CDW order.

  11. Fresnoite Ba2TiSi2O8: A novel stimulated Raman scattering active crystal

    NASA Astrophysics Data System (ADS)

    Shen, Chuanying; Wang, Duanliang; Zhang, Huaijin; Wang, Jiyang; Boughton, Robert I.

    2016-12-01

    Large Ba2TiSi2O8 crystals were successfully grown by the Czochralski technique. The stimulated Raman scattering properties of the Ba2TiSi2O8 crystals were investigated for the first time, and the first (558 nm) and second (587 nm) Stokes lines were generated in an ultracavity single-pass configuration excited by 532 nm picosecond pulses. The output energy and conversion efficiency of the scattering process as functions of pump energy were studied, and the highest conversion efficiency was found to be 31.8%. The experiments indicate that Ba2TiSi2O8 is a novel active crystal suitable for solid-state Raman laser applications.

  12. Enhanced flux pinning in GdBaCuO bulk superconductors by Zr dopants

    NASA Astrophysics Data System (ADS)

    Xu, C.; Hu, A.; Ichihara, M.; Sakai, N.; Izumi, M.; Hirabayashi, I.

    2007-10-01

    We, respectively, fabricated GdBa2Cu3O7-δ (Gd123) single domain superconductors by melt growth process in air with Gd2Ba4CuZrOx (GdZr2411) and nanosize ZrO2 dopants. The microstructures and superconducting properties were investigated by scanning/transmission electron microscopy (SEM/TEM) and SQUID. GdZr2411 and BaZrO3 particles with the average size of 50 nm were observed in the GdZr2411 and nanosize ZrO2 doped Gd123 bulks by TEM, respectively. Critical current density (Jc) was enhanced up to 100,000 A/cm2 at 77 K and self-field with 0.4 mol% nano-sized ZrO2. The present study also showed that small amount GdZr2411 dopants (8 mol%, ratio to Gd123) were effective to induce a δTc-type pinning.

  13. High-mobility BaSnO{sub 3} grown by oxide molecular beam epitaxy

    SciTech Connect

    Raghavan, Santosh; Schumann, Timo; Kim, Honggyu; Zhang, Jack Y.; Cain, Tyler A.; Stemmer, Susanne

    2016-01-01

    High-mobility perovskite BaSnO{sub 3} films are of significant interest as new wide bandgap semiconductors for power electronics, transparent conductors, and as high mobility channels for epitaxial integration with functional perovskites. Despite promising results for single crystals, high-mobility BaSnO{sub 3} films have been challenging to grow. Here, we demonstrate a modified oxide molecular beam epitaxy (MBE) approach, which supplies pre-oxidized SnO{sub x}. This technique addresses issues in the MBE of ternary stannates related to volatile SnO formation and enables growth of epitaxial, stoichiometric BaSnO{sub 3}. We demonstrate room temperature electron mobilities of 150 cm{sup 2} V{sup −1} s{sup −1} in films grown on PrScO{sub 3}. The results open up a wide range of opportunities for future electronic devices.

  14. Superconductivity and structural distortion in BaPt2As2.

    PubMed

    Jiang, W B; Guo, C Y; Weng, Z F; Wang, Y F; Chen, Y H; Chen, Y; Pang, G M; Shang, T; Lu, X; Yuan, H Q

    2015-01-21

    We report the synthesis of BaPt2As2 single crystals and the discovery of superconductivity and a structural phase transition in this compound by measuring the electrical resistivity, magnetic susceptibility and specific heat as well as the x-ray diffraction at low temperatures. BaPt2As2 crystallizes in the CaBe2Ge2-type tetragonal structure (P4/nmm) at room temperature and undergoes a first-order structural transition at TS ≃ 275 K, which is likely to be associated with a charge-density-wave (CDW) instability. BCS-like superconductivity with two subsequent transitions Tc1 ≃ 1.67 K and Tc2 ≃ 1.33 K is observed. Our results demonstrate that BaPt2As2 may serve as a new system for studying the interplay of superconductivity and the CDW order.

  15. Far-Infrared Study of BaTi4O9 Microwave Dielectric Ceramics

    NASA Astrophysics Data System (ADS)

    Huang, Xianli; Wang, Fuping; Song, Ying

    2006-02-01

    In this work, lattice vibrations in BaTi4O9 ceramic were investigated using far-infrared spectra (FIRS), which were transformed by Kramers-Kronig relations into the real and imaginary parts of permittivity spectra. Curve fitting of reflectance spectra shows that 32 vibration modes were observed, among which transverse vibrations at lower frequencies (stretching and bending vibration modes involving A-site cations and TiO6 octahedra) account for most dielectric loss. An evaluation of dielectric constants and quality factors using an extrapolation method was accomplished. The calculated dielectric constants agree well with the measured ones, while the calculated dielectric losses are about half the measured ones, indicating that noneigen elements such as defects and pores exist and play an important role in BaTi4O9 ceramics. A multimode behavior of vibration modes involving Ba-sites was proposed as the origin of dielectric loss.

  16. Ba2TeO: A new layered oxytelluride

    SciTech Connect

    Besara, T.; Ramirez, D.; Sun, J.; Whalen, J. B.; Tokumoto, T. D.; McGill, S. A.; Singh, D. J.; Siegrist, T.

    2015-02-01

    For single crystals of the new semiconducting oxytelluride phase, Ba2TeO, we synthesized from barium oxide powder and elemental tellurium in a molten barium metal flux. Ba2TeO crystallizes in tetragonal symmetry with space group P4/nmm (#129), a=5.0337(1) Å, c=9.9437(4) Å, Z=2. The crystals were characterized by single crystal x-ray diffraction, heat capacity and optical measurements. Moreover, the optical measurements along with electronic band structure calculations indicate semiconductor behavior with a band gap of 2.93 eV. Resistivity measurements show that Ba2TeO is highly insulating.

  17. Solvent removes downhole NORM-contaminated BaSO{sub 4} scale

    SciTech Connect

    Ford, W.G.F.; Gadeken, L.L.; Callahan, T.J.; Jackson, D.

    1996-04-22

    A research project in Canada recently demonstrated that a solvent can remove barium sulfate (BaSO{sub 4}) scales, and all radioactive material is left downhole, eliminating costly NORM disposal. Each year, scale precipitation costs operators millions of dollars in maintenance, treatment, and lost production. Scale contaminated with naturally occurring radioactive material (NORM) creates further problems because NORM scales fall under strict and expensive disposal guidelines. Highly insoluble BaSO{sub 4} scales can be difficult to treat because radioactive materials often incorporate into the scale as it forms. BaSO{sub 4} scales have had to be removed by mechanical scraping or reaming, which is troublesome and costly. The strict regulations concerning disposal of NORM scale add to the costs of the treatment. This paper describes an innovative handling and disposal method for these NORM materials.

  18. Photovoltaic properties of ferroelectric BaTiO3 thin films RF sputter deposited on silicon

    NASA Technical Reports Server (NTRS)

    Dharmadhikari, V. S.; Grannemann, W. W.

    1982-01-01

    Ferroelectric thin films of BaTiO3 have been successfully deposited on n-type silicon substrates at temperatures above 500 C by RF sputtering in an O2/Ar atmosphere. Analysis by X-ray diffraction patterns show that films deposited at room temperature are amorphous. At temperatures above 500 C, crystalline BaTiO3 films with a tetragonal structure are obtained. The polarization-electric field (P-E) hysteresis loops and a broad peak in the dielectric constant versus temperature curve at Curie point indicate that the RF sputtered BaTiO3 films are ferroelectric. An anomalous photovoltaic effect is observed in these thin films which is related to the remanent polarization of the material. The results on open-circuit and short-circuit measurements provide an important basis for a better understanding of the role of photovoltaic field, photovoltaic current, and the pyroelectric properties in photoferroelectric domain switching.

  19. Spectroscopic and theoretical studies of the low-lying states of BaO{sup +}

    SciTech Connect

    Bartlett, Joshua H.; VanGundy, Robert A.; Heaven, Michael C.

    2015-07-28

    The BaO{sup +} cation is of interest from the perspectives of electronic structure and the potential for cooling to ultra-cold temperatures. Spectroscopic data for the ion have been obtained using a two-color photoionization technique. The ionization energy for BaO was found to be 6.8123(3) eV. The ground state of BaO{sup +} was identified as X{sup 2}Σ{sup +}, and both vibrational and rotational constants were determined. Vibrationally resolved spectra were recorded for A{sup 2}Π, the first electronically excited state. These data yielded the term energy, vibrational frequency, and the spin-orbit interaction constant. Relativistic electronic structure calculations were carried out using multi-reference configuration interaction (MRCI), coupled cluster and density functional theory methods. Transition moments for the pure vibrational and A{sup 2}Π-X{sup 2}Σ{sup +} transitions were predicted using the MRCI method.

  20. The School of Posture as a postural training method for Paraíba Telecommunications Operators.

    PubMed

    Cardia, M C; Soares Màsculo, F

    2001-01-01

    This work proposes to show the experience of posture training accomplished in the Paraíba State Telecommunication Company, using the knowledge of the Back School. The sample was composed of 12 operators, employees of the company, representing 31% of this population. The model applied in TELPA (Paraíba Telecommunication Company, Brazil) was based on the models of Sherbrooke, Canada, and of the School of Posture of Paraìba Federal University. Fifty-eight point four percent of participants showed a reduction of column pain, 25% improved the quality of the rest and the received training was considered enough for the learning of correct postures at work in 75% of the cases. The whole population approved of the training, and 83.3% of the cases considered that this training influenced their lives very positively.

  1. A General Reliability Model for Ni-BaTiO3-Based Multilayer Ceramic Capacitors

    NASA Technical Reports Server (NTRS)

    Liu, Donhang

    2014-01-01

    The evaluation of multilayer ceramic capacitors (MLCCs) with Ni electrode and BaTiO3 dielectric material for potential space project applications requires an in-depth understanding of their reliability. A general reliability model for Ni-BaTiO3 MLCC is developed and discussed. The model consists of three parts: a statistical distribution; an acceleration function that describes how a capacitor's reliability life responds to the external stresses, and an empirical function that defines contribution of the structural and constructional characteristics of a multilayer capacitor device, such as the number of dielectric layers N, dielectric thickness d, average grain size, and capacitor chip size A. Application examples are also discussed based on the proposed reliability model for Ni-BaTiO3 MLCCs.

  2. A General Reliability Model for Ni-BaTiO3-Based Multilayer Ceramic Capacitors

    NASA Technical Reports Server (NTRS)

    Liu, Donhang

    2014-01-01

    The evaluation for potential space project applications of multilayer ceramic capacitors (MLCCs) with Ni electrode and BaTiO3 dielectric material requires an in-depth understanding of the MLCCs reliability. A general reliability model for Ni-BaTiO3 MLCCs is developed and discussed in this paper. The model consists of three parts: a statistical distribution; an acceleration function that describes how a capacitors reliability life responds to external stresses; and an empirical function that defines the contribution of the structural and constructional characteristics of a multilayer capacitor device, such as the number of dielectric layers N, dielectric thickness d, average grain size r, and capacitor chip size A. Application examples are also discussed based on the proposed reliability model for Ni-BaTiO3 MLCCs.

  3. Preparation and photophysical properties of rhombic dodecahedral perovskite-type BaSnO3

    NASA Astrophysics Data System (ADS)

    Guo, Fu-an; Li, Guoqiang; Yang, Na; Wang, Wanling; Zhang, Weifeng

    2012-06-01

    BaSnO3 grains with a rhombic dodecahedron shape have been synthesized via a facile modified hydrothermal approach. The structure and morphology evolution during hydrothermal treatment have been investigated with X-ray diffraction, scanning electron microscopy, and Raman and Fourier transform infrared spectroscopy. The sample with the single-phase of BaSnO3 can be obtained at the hydrothermal temperature of 24 °C, and the grain size grows with an increasing temperature from 10 to 15 μm below 270 °C. But the grain size decreases sharply to 4 μm when the temperature reaches 280 °C. The optical absorption and surface photovoltage spectroscopy analysis indicate that controlling the size and shape is of great importance in tuning photophysical properties of BaSnO3 powders.

  4. Pyroelectric, piezoelectric, and dielectric properties of beta-BaB2O4 single crystal

    NASA Astrophysics Data System (ADS)

    Guo, R.; Bhalla, A. S.

    1989-12-01

    Results are presented on measurements of dielectric and pyroelectric properties of single-crystal beta-BaB2O4 in the temperature range between 50 and -190 C, and of piezoelectric properties at room temperature. The piezoelectric and electromechanical coupling coefficients of this material were found to be rather low, indicating that beta-BaB2O4 is not suitable for piezoelectric transducer applications. On the other hand, the calculated pyroelectric figure of merit p/K was found to remain constant (compared to the p/K of many ferroelectric materials, in which p/K value decreases with the decrease in temperature), making the beta-BaB2O4 an attractive candidate for some device applications.

  5. Reentrant spin glass behavior in antiferromagnetic single crystalline Ba 6Mn 24O 48 nanoribbons

    NASA Astrophysics Data System (ADS)

    Zhang, Xianke; Tang, Shaolong; Li, Yulong; Du, Youwei

    2010-04-01

    Single crystalline Ba 6Mn 24O 48 nanoribbons with diameters ranging from one hundred nanometers to a few hundred nanometers and length up to tens of microns are synthesized via a facile molten salt method. These nanoribbons are characterized by a range of methods including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The magnetic properties of Ba 6Mn 24O 48 nanoribbons are investigated by the zero-field-cooled (ZFC), field-cooled (FC) magnetization, and ac susceptibility. Upon cooling, we find the reentrant spin glass (RSG) behavior in these nanoribbons, i.e., paramagnetic (PM), antiferromagnetic (AFM), and spin glass (SG). The RSG behavior might be due to the surface spin disorder, geometrical frustration and Mn 3+/Mn 4+ mixture in Ba 6Mn 24O 48 nanoribbons.

  6. Limited Streamer Tubes for the BaBar Instrumented Flux Return Upgrade

    SciTech Connect

    Lu, C.; /Princeton U.

    2005-10-11

    Starting from the very beginning of their operation the efficiency of the RPC chambers in the BaBar Instrumented Flux Return (IFR) has suffered serious degradation. After intensive investigation, various remediation efforts had been carried out, but without success. As a result the BaBar collaboration decided to replace the dying barrel RPC chambers about two years ago. To study the feasibility of using the Limited Streamer Tube (LST) as the replacement of RPC we carried out an R&D program that has resulted in BaBar's deciding to replace the barrel RPC's with LST's. In this report we summarize the major detector R&D results, and leave other issues of the IFR system upgrade to the future publications.

  7. AMiBA: Cluster Sunyaev-Zel’dovich Effect Observations with the Expanded 13-element Array

    NASA Astrophysics Data System (ADS)

    Lin, Kai-Yang; Nishioka, Hiroaki; Wang, Fu-Cheng; Locutus Huang, Chih-Wei; Liao, Yu-Wei; Proty Wu, Jiun-Huei; Koch, Patrick M.; Umetsu, Keiichi; Chen, Ming-Tang; Chan, Shun-Hsiang; Chang, Shu-Hao; Lucky Chang, Wen-Hsuan; Cheng, Tai-An; Duy, Hoang Ngoc; Fu, Szu-Yuan; Han, Chih-Chiang; Ho, Solomon; Ho, Ming-Feng; Ho, Paul T. P.; Huang, Yau-De; Jiang, Homin; Kubo, Derek Y.; Li, Chao-Te; Lin, Yu-Chiung; Liu, Guo-Chin; Martin-Cocher, Pierre; Molnar, Sandor M.; Nunez, Emmanuel; Oshiro, Peter; Pai, Shang-Ping; Raffin, Philippe; Ridenour, Anthony; Shih, Chia-You; Stoebner, Sara; Teo, Giap-Siong; Yeh, Jia-Long Johnny; Williams, Joshua; Birkinshaw, Mark

    2016-10-01

    The Yuan-Tseh Lee Array for Microwave Background Anisotropy (AMiBA) is a co-planar interferometer array operating at a wavelength of 3 mm to measure the Sunyaev-Zel’dovich effect (SZE) of galaxy clusters at arcminute scales. The first phase of operation—with a compact 7-element array with 0.6 m antennas (AMiBA-7)—observed six clusters at angular scales from 5\\prime to 23\\prime . Here, we describe the expansion of AMiBA to a 13-element array with 1.2 m antennas (AMiBA-13), its subsequent commissioning, and cluster SZE observing program. The most noticeable changes compared to AMiBA-7 are (1) array re-configuration with baselines ranging from 1.4 m to 4.8 m, allowing us to sample structures between 2\\prime and 10\\prime , (2) 13 new lightweight carbon-fiber-reinforced plastic (CFRP) 1.2 m reflectors, and (3) additional correlators and six new receivers. Since the reflectors are co-mounted on and distributed over the entire six-meter CFRP platform, a refined hexapod pointing error model and phase error correction scheme have been developed for AMiBA-13. These effects—entirely negligible for the earlier central close-packed AMiBA-7 configuration—can lead to additional geometrical delays during observations. Our correction scheme recovers at least 80 ± 5% of the point-source fluxes. We, therefore, apply an upward correcting factor of 1.25 to our visibilities to correct for phase decoherence, and a ±5% systematic uncertainty is added in quadrature with our statistical errors. We demonstrate the absence of further systematics with a noise level consistent with zero in stacked uv-visibilities. From the AMiBA-13 SZE observing program, we present here maps of a subset of 12 clusters with signal-to-noise ratios above five. We demonstrate combining AMiBA-7 with AMiBA-13 observations on Abell 1689, by jointly fitting their data to a generalized Navarro-Frenk-White model. Our cylindrically integrated Compton-y values for five radii are consistent with results from

  8. Final Report: BaBar Detector and Experimental at SLAC, September 30, 1998 - September 29, 1999

    SciTech Connect

    Judd, Dennis J.

    2000-01-20

    The Prairie View A&M University High Energy Physics Group with its contingent of three undergraduates physics majors, joined the BaBar Collaboration at SLAC in September 1994. BaBar is the experiment and detector running in the PEP-II ring at SLAC as part of the Asymmetric B Factory project there to study CP violation and heavy flavor physics. The focus of our effort before this year was with the Muon/Neutral Hadron Detector/Instrumented Flux Return (IFD) subgroup within the BaBar collaboration, and particularly with the GEANT simulation of the IFR. With the GEANT3 simulation essentially frozen, and the GEANT4 full simulation of the IFR done, we have decided to redirect our efforts toward other areas.

  9. Superconductivity in the Tl-Ca-Ba-Cu-O System:. Synthesis, Characterization and Mechanism

    NASA Astrophysics Data System (ADS)

    Ganguli, A. K.; Swamy, K. S. Nanjunda; Subbanna, G. N.; Rajumon, M. K.; Sarma, D. D.; Rao, C. N. R.

    Synthesis and characterization of some of the members of the Tl-Ca-Ba-Cu-O system are presented. Tc in both the TlCan-1Ba2CunO2n+3 and Tl2Can-1Ba2CunO2n+4 series increase with the number of Cu-O layers, n; Tc in the latter series with two Tl-O layers are generally higher than in the former with a single Tl-O layer. Tl in the cuprates is in the 3+ state while Cu is in the 1+ and 2+ states, showing the importance of oxygen holes. The concentration of these holes seems to increase with the number of Tl-O layers.

  10. Electrical properties of Y-Ba-Na-Cu-O high Tc superconductors thin films

    NASA Astrophysics Data System (ADS)

    Verdyan, A.; Lapsker, I.; Azoulay, J.; Sackler, Raymond; Sackler, Beverly

    1993-04-01

    Y-Ba-Na-Cu-O high Tc superconductors thin films deposited on MgO substrate by resistive evaporation technique were found to have improved electrical properties as compared to pure Y-Ba-Cu-O thin films similarly prepared. A simple conventional inexpensive vacuum system housing a single resistively tungsten heated source was used for the deposition. Pulverized mixture of Y, BaF 2, NaF and Cu in the appropriate atomic proportion was evaporated onto the substrates whose temperature was held constant at 400°C during the evaporation. In situ heat treatment has been carried out at 700°C under oxygen partial pressure of 7 pa. The films thus obtained were found to have the normal superconductors orthorhombic phase at room temperature without any further ex situ heat treatment. The films were characterized and analyzed by x-ray diffraction auger electron spectroscopy and four point dc electrical measurements.

  11. Microstructure and magnetism in barium strontium titanate (BSTO)-barium hexaferrite (BaM) multilayers

    SciTech Connect

    Frey, N.A.; Heindl, R.; Srinath, S.; Srikanth, H. . E-mail: sharihar@cas.usf.edu; Dudney, N.J.

    2005-08-11

    High quality multilayers of barium ferrite (BaM) and barium strontium titanate (BSTO) were grown in optimized conditions on thermally oxidized Si(1 0 0) and Al{sub 2}O{sub 3} substrates using magnetron sputtering. As-grown films were amorphous and different annealing procedures were explored to stabilize crystalline phases. BSTO and BaM phases were identified using X-ray diffraction and cross-sectional scanning electron micrographs showed sharp interfaces between BSTO and BaM layers. Magnetic hysteresis loops obtained at various temperatures and field orientations showed a large coercivity ({approx}2500 Oe) consistent with the hard magnetic hexaferrite component. Hysteresis loops also revealed the distinct influence of magnetocrystalline and shape anisotropies at different temperature ranges.

  12. On the subject of the Ba overabundance in the open clusters stars

    NASA Astrophysics Data System (ADS)

    Mishenina, T. V.; Korotin, S. A.; Carraro, G.; Kovtyukh, V. V.; Yegorova, I. A.

    2016-01-01

    For eight distant open clusters, namely Ruprecht 4, Ruprecht 7, Berkeley 25, Berkeley 73, Berkeley 75, NGC 6192, NGC 6404, and NGC 6583, we determined the yttrium and barium abundances using the UVES, VLT spectra (ESO, Chile). The stars of one young cluster (Ruprecht 7) demonstrate significant barium overabundance(∼0.55 dex) that can not be due to the determination error. We have considered the Ba abundance determination errors due to LTE approach, saturation of the lines, synthetic and observed barium line fitting, and the causes of the Ba overabundance associated with the Galactic disc enrichment or the origin of open clusters. Possible explanation for this overabundance can be the origin of n-capture elements enrichment of the clusters (galactic or extragalactic) or additional sources of the Ba production.

  13. Momentum-resolved electronic structure of the superconductor parent compound BaBiO3

    NASA Astrophysics Data System (ADS)

    Plumb, N. C.; Ristic, Z.; Park, J.; Wang, Z.; Matt, C. E.; Xu, N.; Lv, B. Q.; Gawryluk, D.; Pomjakushina, E.; Conder, K.; Wang, Y.; Johnston, S.; Mesot, J.; Shi, M.; Radovic, M.

    We use in situ angle-resolved photoemission to study thin films of BaBiO3, a parent compound of bismuthate superconductors with Tc up to 30 K. By simple electron counting, BaBiO3 should be metallic. However, in analogy with many unconventional and high-Tc superconductor families, it is instead insulating, and superconductivity emerges with doping. Our experiments reveal a folded band structure consistent with known BiO6 breathing distortions. However, charge ordering often thought to accompany the distortions is virtually nonexistent. The data combined with DFT calculations indicate that states near EF are primarily oxygen-derived. Hence BaBiO3 appears to be characterized by negative charge transfer energy. This can account for the seeming discrepancy between the atomic structure and ''missing'' charge order. It should also be relevant for understanding the doping evolution and superconductivity in bismuthates.

  14. Growth of BaWO4 fishbone-like nanostructures in w/o microemulsion.

    PubMed

    Zhang, Xu; Xie, Yi; Xu, Fen; Tian, Xiaobo

    2004-06-01

    BaWO(4) fishbone-like nanostructures with fourfold structural symmetry have been successfully grown in w/o microemulsion. The BaWO(4) fishbone-like nanostructures have four rows of nanorods, epitaxially grown on the stem and perpendicular to the stem. The obtained samples are characterized by means of XRD, TEM, HRTEM, and SEM. It is found that the water content has a large influence on the size of the product and the molar ratio between cations and anions plays an important role in the morphology of the product. It is assumed that site-selective surfactant adsorption may be responsible for the formation of the BaWO(4) fishbone-like nanostructures.

  15. Particle morphology as a control of permeation in polymer films obtained from MMA/nBA colloidal dispersions.

    PubMed

    Lestage, David J; Urban, Marek W

    2004-07-20

    The combination of precision-controlled weight loss measurements and spectroscopic surface FT-IR analysis allowed us to identify unique behaviors of poly(methyl methacrylate) (p-MMA). When MMA and n-butyl acrylate (nBA) are polymerized into p-MMA and p-nBA homopolymer blends, MMA/nBA random copolymers, and p-MMA/p-nBA core-shell morphologies, a controlled mobility and stratification of low molecular weight components occurs in films formed from coalesced colloidal dispersions. Due to different affinities toward water, p-MMA and p-nBA are capable of releasing water at different rates, depending upon particle morphological features of initial dispersions. As coalescence progresses, water molecules are released from the high free volume p-nBA particles, whereas p-MMA retains water molecules for the longest time due to its hydrophilic nature. As a result, water losses at extended coalescence times are relatively small for p-MMA. MMA/nBA copolymer and p-MMA/p-nBA blends follow the same trends, although the magnitudes of changes are not as pronounced. The p-MMA/p-nBA core-shell behavior resembles that of p-nBA homopolymer, which is attributed to significantly lower content of the p-MMA component in particles. Annealing of coalesced colloidal films at elevated temperatures causes migration of SDOSS to the F-A interface, but for films containing primarily p-nBA, reverse diffusion back into the bulk is observed. These studies illustrate that the combination of different particle morphologies and temperatures leads to controllable permeation processes through polymeric films.

  16. Crystallography and physical properties of BaCo2As2,Ba0.94K0.06Co2As2, and Ba0.78K0.22Co2As2

    NASA Astrophysics Data System (ADS)

    Anand, V. K.; Quirinale, D. G.; Lee, Y.; Harmon, B. N.; Furukawa, Y.; Ogloblichev, V. V.; Huq, A.; Abernathy, D. L.; Stephens, P. W.; McQueeney, R. J.; Kreyssig, A.; Goldman, A. I.; Johnston, D. C.

    2014-08-01

    The crystallographic and physical properties of polycrystalline and single-crystal samples of BaCo2As2 and K-doped Ba1-xKxCo2As2 (x=0.06,0.22) are investigated by x-ray and neutron powder diffraction, magnetic susceptibility χ, magnetization, heat capacity Cp,As75 nuclear magnetic resonance (NMR), and electrical resistivity ρ measurements versus temperature T. The crystals were grown using both Sn flux and CoAs self-flux, where the Sn-grown crystals contain 1.6-2.0 mol% Sn. All samples crystallize in the tetragonal ThCr2Si2-type structure (space group I4/mmm). For BaCo2As2, powder neutron diffraction data show that the c-axis lattice parameter exhibits anomalous negative thermal expansion from 10 K to 300 K, whereas the a axis lattice parameter and the unit cell volume show normal positive thermal expansion over this T range. No transitions in BaCo2As2 were found in this T range from any of the measurements. Below 40-50 K, we find ρ ∝T2, indicating a Fermi liquid ground state. A large density of states at the Fermi energy D (EF)≈18 states/(eV f.u.) for both spin directions is found from low-T Cp(T) measurements, whereas the band-structure calculations give D (EF)=8.23 states/(eV f.u.). The enhancement of the former value above the latter is inferred to arise from electron-electron correlations and the electron-phonon interaction. The derived intrinsic χ (T) monotonically increases with decreasing T, with anisotropy χab>χc. The 75As-NMR shift data versus T have the same T dependence as the derived χ (T) data, demonstrating that the derived χ (T) data are intrinsic. The observed 75As nuclear spin dynamics rule out the presence of Néel-type antiferromagnetic electronic spin fluctuations, but are consistent with the presence of ferromagnetic and/or stripe-type antiferromagnetic spin fluctuations. The crystals of Ba0.78K0.22Co2As2 were grown in Sn flux and show properties very similar to those of undoped BaCo2As2. On the other hand, the crystals from two

  17. Deficit in Complex Sequence Processing after a Virtual Lesion of Left BA45

    PubMed Central

    Clerget, Emeline; Andres, Michael; Olivier, Etienne

    2013-01-01

    Although the contribution of Broca's area to motor cognition is generally accepted, its exact role remains controversial. A previous functional imaging study has suggested that Broca's area implements hierarchically organised motor behaviours and, in particular, that its anterior (Brodmann area 45, BA45) and posterior (BA44) parts process, respectively, higher and lower-level hierarchical elements. This function of Broca's area could generalize to other cognitive functions, including language. However, because of the correlative nature of functional imaging data, the causal relationship between Broca's region activation and its behavioural significance cannot be ascertained. To circumvent this limitation, we used on-line repetitive transcranial magnetic stimulation to disrupt neuronal processing in left BA45, left BA44 or left dorsal premotor cortex, three areas that have been shown to exhibit a phasic activation when participants performed hierarchically organised motor behaviours. The experiment was conducted in healthy volunteers performing the same two key-press sequences as those used in a previous imaging study, and which differed in terms of hierarchical organisation. The performance of the lower-order hierarchical task (Experiment #1) was unaffected by magnetic stimulation. In contrast, in the higher-order hierarchical task (Experiment #2, “superordinate” task), we found that a virtual lesion of the anterior part of Broca's area (left BA45) delayed the processing of the cue initiating the sequence in an effector-independent way. Interestingly, in this task, the initiation cue only informed the subjects about the rules to be applied to produce the appropriate response but did not allow them to anticipate the entire motor sequence. A second important finding was a RT decrease following left PMd virtual lesions in the superordinate task, a result compatible with the view that PMd plays a critical role in impulse control. The present study therefore

  18. Diamagnetic vortex barrier stripes in underdoped BaFe2(As1-xPx) 2

    NASA Astrophysics Data System (ADS)

    Yagil, A.; Lamhot, Y.; Almoalem, A.; Kasahara, S.; Watashige, T.; Shibauchi, T.; Matsuda, Y.; Auslaender, O. M.

    2016-08-01

    We report magnetic force microscopy (MFM) measurements on underdoped BaFe2(As1 -xPx)2 (x =0.26 ) that show enhanced superconductivity along stripes parallel to twin boundaries. These stripes of enhanced diamagnetic response repel superconducting vortices and act as barriers for them to cross. The width of the stripes is hundreds of nanometers, on the scale of the penetration depth, well within the inherent spatial resolution of MFM and implying that the width is set by the interaction of the superconductor with the MFM's magnetic tip. Unlike similar stripes observed previously by scanning SQUID in the electron doped Ba (Fe1 -xCox)2As2 , the stripes in the isovalently doped BaFe2(As1 -xPx)2 disappear gradually when we warm the sample towards the superconducting transition temperature. Moreover, we find that the stripes move well below the reported structural transition temperature in BaFe2(As1 -xPx)2 and that they can be much denser than in the Ba (Fe1 -xCox)2As2 study. When we cool in finite magnetic field we find that some vortices appear in the middle of stripes, suggesting that the stripes may have an inner structure, which we cannot resolve. Finally, we use both vortex decoration at higher magnetic field and deliberate vortex dragging by the MFM magnetic tip to obtain bounds on the strength of the interaction between the stripes and vortices. We find that this interaction is strong enough to play a significant role in determining the critical current in underdoped BaFe2(As1 -xPx)2 .

  19. Dielectric Properties of BaTiO3-Based Ceramics under High Electric Field

    NASA Astrophysics Data System (ADS)

    Tsurumi, Takaaki; Adachi, Hiroshige; Kakemoto, Hirofumi; Wada, Satoshi; Mizuno, Youichi; Chazono, Hirokazu; Kishi, Hiroshi

    2002-11-01

    The dielectric properties under a high electric field (ac-field) of BaTiO3-based ceramics with core grains, shell grains and core-shell grains were compared with those of multilayer ceramic capacitors (MLCCs) with these three kinds of grains. The MLCCs with the X7R specification had a core-shell structure, and the relative dielectric permittivity (\\varepsilonr) of the dielectric layers in the MLCCs increased with increasing ac-field. Similar behavior was observed in the MLCCs consisting of only cores, indicating that the core predominantly determined the dielectric properties of MLCCs under high ac-fields. The dielectric properties of MLCCs and ceramic plates consisting of only shell grains showed that the shell was the relaxor ferroelectrics. A slight change in the shell composition yielded a large shift of the peak temperature of \\varepsilonr. The shell improved the temperature stability of \\varepsilonr at low temperatures under low ac-fields. In a ceramic plate with relatively large BaTiO3 grains (approximately 3 μm), the maximum \\varepsilonr was observed at a moderate ac-field, which was explained from the electric displacement vs electric field hysteresis curves of ferroelectric BaTiO3. The MLCCs and ceramics plates with fine BaTiO3 grains (0.4 to 0.5 μm) showed similar dielectric behavior to the MLCC with the core-shell structure. The size effect of BaTiO3 played an important role in determining the temperature stability of \\varepsilonr. For future MLCCs with very thin dielectric layers, a microstructure with fine BaTiO3 grains and grain boundary layers of the shell was proposed.

  20. Frustration of Negative Capacitance in Al2O3/BaTiO3 Bilayer Structure

    NASA Astrophysics Data System (ADS)

    Kim, Yu Jin; Park, Min Hyuk; Lee, Young Hwan; Kim, Han Joon; Jeon, Woojin; Moon, Taehwan; Do Kim, Keum; Jeong, Doo Seok; Yamada, Hiroyuki; Hwang, Cheol Seong

    2016-01-01

    Enhancement of capacitance by negative capacitance (NC) effect in a dielectric/ferroelectric (DE/FE) stacked film is gaining a greater interest. While the previous theory on NC effect was based on the Landau-Ginzburg-Devonshire theory, this work adopted a modified formalism to incorporate the depolarization effect to describe the energy of the general DE/FE system. The model predicted that the SrTiO3/BaTiO3 system will show a capacitance boost effect. It was also predicted that the 5 nm-thick Al2O3/150 nm-thick BaTiO3 system shows the capacitance boost effect with no FE-like hysteresis behavior, which was inconsistent with the experimental results; the amorphous-Al2O3/epitaxial-BaTiO3 system showed a typical FE-like hysteresis loop in the polarization – voltage test. This was due to the involvement of the trapped charges at the DE/FE interface, originating from the very high field across the thin Al2O3 layer when the BaTiO3 layer played a role as the NC layer. Therefore, the NC effect in the Al2O3/BaTiO3 system was frustrated by the involvement of reversible interface charge; the highly stored charge by the NC effect of the BaTiO3 during the charging period could not be retrieved during the discharging process because integral part of the polarization charge was retained within the system as a remanent polarization.

  1. Frustration of Negative Capacitance in Al2O3/BaTiO3 Bilayer Structure.

    PubMed

    Kim, Yu Jin; Park, Min Hyuk; Lee, Young Hwan; Kim, Han Joon; Jeon, Woojin; Moon, Taehwan; Kim, Keum Do; Jeong, Doo Seok; Yamada, Hiroyuki; Hwang, Cheol Seong

    2016-01-08

    Enhancement of capacitance by negative capacitance (NC) effect in a dielectric/ferroelectric (DE/FE) stacked film is gaining a greater interest. While the previous theory on NC effect was based on the Landau-Ginzburg-Devonshire theory, this work adopted a modified formalism to incorporate the depolarization effect to describe the energy of the general DE/FE system. The model predicted that the SrTiO3/BaTiO3 system will show a capacitance boost effect. It was also predicted that the 5 nm-thick Al2O3/150 nm-thick BaTiO3 system shows the capacitance boost effect with no FE-like hysteresis behavior, which was inconsistent with the experimental results; the amorphous-Al2O3/epitaxial-BaTiO3 system showed a typical FE-like hysteresis loop in the polarization - voltage test. This was due to the involvement of the trapped charges at the DE/FE interface, originating from the very high field across the thin Al2O3 layer when the BaTiO3 layer played a role as the NC layer. Therefore, the NC effect in the Al2O3/BaTiO3 system was frustrated by the involvement of reversible interface charge; the highly stored charge by the NC effect of the BaTiO3 during the charging period could not be retrieved during the discharging process because integral part of the polarization charge was retained within the system as a remanent polarization.

  2. Ternary fluorides BaMF4 (M = Zn, Mg and Mn) at low temperatures.

    PubMed

    Posse, Jose Maria; Grzechnik, Andrzej; Friese, Karen

    2009-10-01

    Ternary fluorides BaMF4 (M = Zn, Mg, Mn) have been studied in the temperature range from 300 to 10 K using synchrotron and laboratory powder and single-crystal diffraction. The first two compounds are stable down to 10 K, while the third one undergoes a phase transition to an incommensurately modulated structure at approximately 250 K. The modulated phase is stable down to 10 K. The magnetic anomalies at 45 and 27 K observed previously in BaMnF4 are exclusively reflected in the behavior of the gamma component of the q vector, which assumes an irrational value of approximately 0.395 A(-1) at the temperature corresponding to the onset of the magnetic ordering and then stays constant down to 10 K. Mn-Mn distances do not indicate any structural response to the magnetic ordering. The formation of the modulated phase can be explained on the basis of simple geometrical criteria. The incorporation of the large Mn cation in the octahedral sheets implies an increase of the cavity in which the Ba ion is incorporated. This leads to the formation of the modulated structure to adapt the coordination sphere around Ba in such a way that the bond-valence sums can be kept close to the ideal value of two. With further lowering of the temperature, the charge balance around the Ba ion requires an increasingly anharmonic character of the modulation function of Ba, until finally at 10 K a crenel-like shape is assumed for the modulation of this atom.

  3. Electric-field control of ferromagnetic resonance in monolithic BaFe12O19-Ba0.5Sr0.5TiO3 heterostructures

    NASA Astrophysics Data System (ADS)

    Das, Jaydip; Song, Young-Yeal; Wu, Mingzhong

    2010-08-01

    This paper demonstrates an electric-field tuning of the ferromagnetic resonance (FMR) responses at millimeter wave frequencies for a monolithic magneto-electric heterostructure. The layered stack is comprised of c-axis oriented and low loss barium hexaferrite (BaM) and (111) oriented ferroelectric barium strontium titanate (BSTO) layers along with embedded platinum electrode layers, all fabricated by pulsed laser deposition technique. A tunability of the FMR frequency as large as 3.5 MHz/V has been observed at 60 GHz due to application of bias voltages in the range of several volts. The realization of such a large tunability relies on the quasi-lattice-to-lattice contact between the BaM and BSTO layers as well as the high quality of those layers.

  4. Conductor-backed coplanar waveguide resonators of Y-Ba-Cu-O and Tl-Ba-Ca-Cu-O on LaAlO3

    NASA Technical Reports Server (NTRS)

    Miranda, F. A.; Bhasin, K. B.; Stan, M. A.; Kong, K. S.; Itoh, T.

    1992-01-01

    Conductor-backed coplanar waveguide (CBCPW) resonators operating at 10.8 GHz have been fabricated from Tl-Ba-Ca-O (TBCCO) and Y-Ba-Cu-O (YBCO) thin films on LaAlO3. The resonators consist of a coplanar waveguide (CPW) patterned on the superconducting film side of the LaAlO3 substrate with a gold ground plane coated on the opposite side. These resonators were tested in the temperature range from 14 to 106 K. At 77 K, the best of our TBCCO and YBCO resonators have an unloaded quality factor (Qo) 7 and 4 times, respectively, larger than that of a similar all-gold resonator. In this study, the Qo's of the TBCCO resonators were larger than those of their YBCO counterparts throughout the aforementioned temperature range.

  5. Magnetotransport of proton-irradiated BaFe2As2 and BaFe1.985Co0.015As2 single crystals

    DOE PAGES

    Moseley, D. A.; Yates, K. A.; Peng, N.; ...

    2015-02-17

    In this paper, we study the magnetotransport properties of the ferropnictide crystals BaFe2As2 and BaFe1.985Co0.015As2. These materials exhibit a high field linear magnetoresistance that has been attributed to the quantum linear magnetoresistance model. In this model, the linear magnetoresistance is dependent on the concentration of scattering centers in the material. By using proton-beam irradiation to change the defect scattering density, we find that the dependence of the magnitude of the linear magnetoresistance on scattering quite clearly contravenes this prediction. Finally, a number of other scaling trends in the magnetoresistance and high field Hall data are observed and discussed.

  6. Large piezoelectric effect in Pb-free Ba(Ti,Sn)O3-x(Ba,Ca)TiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Xue, Dezhen; Zhou, Yumei; Bao, Huixin; Gao, Jinghui; Zhou, Chao; Ren, Xiaobing

    2011-09-01

    We designed a Pb-free pseudo-binary system, Ba(Sn0.12Ti0.88)O3-x(Ba0.7Ca0.3)O3 (BTS-xBCT), characterized by a phase boundary starting from a tricritical triple point of a paraelectric cubic phase, ferroelectric rhombohedral, and tetragonal phases. The optimal composition BTS-30BCT exhibits a high piezoelectric coefficient d33 ˜ 530 pC/N at room temperature. In view of the recent report of high piezoelectricity in another Pb-free system BZT-BCT (Liu and Ren, Phys. Rev. Lett. 103, 257602 (2009)), which possesses a similar tricritical triple point in the phase diagram, it seems that forming a suitable phase boundary starting from a tricritical triple point could be an effective way to develop high-performance Pb-free piezoelectrics.

  7. Crystal structure and polarization hysteresis properties of ferroelectric BaTiO3 thin-film capacitors on (Ba,Sr)TiO3-buffered substrates

    NASA Astrophysics Data System (ADS)

    Maki, Hisashi; Noguchi, Yuji; Kutsuna, Kazutoshi; Matsuo, Hiroki; Kitanaka, Yuuki; Miyayama, Masaru

    2016-10-01

    Ferroelectric BaTiO3 (BT) thin-film capacitors with a buffer layer of (Ba1- x Sr x )TiO3 (BST) have been fabricated on (001) SrTiO3 (STO) single-crystal substrates by a pulsed laser deposition method, and the crystal structure and polarization hysteresis properties have been investigated. X-ray diffraction reciprocal space mapping shows that the BST buffer effectively reduces the misfit strain relaxation of the BT films on SrRuO3 (SRO) electrodes. The BT capacitor with the SRO electrodes on the BST (x = 0.3) buffer exhibits a well-saturated hysteresis loop with a remanent polarization of 29 µC/cm2. The hysteresis loop displays a shift toward a specific field direction, which is suggested to stem from the flexoelectric coupling between the out-of-plane polarization and the strain gradient adjacent to the bottom interface.

  8. The structure of BaCu 3O 4 particles occurring on thin HoBa 2Cu 3O 7 films prepared by MOCVD

    NASA Astrophysics Data System (ADS)

    Zandbergen, H. W.; Jansen, J.; Svetchnikov, V. L.; Graboy, I. E.; Samoylenkov, S.; Gorbenko, O.; Kaul, A. R.

    1999-12-01

    The structure of BaCu 3O 4 phase occurring as particles on the surface of (001) RBa 2Cu 3O 7 epitaxial films prepared by metalorganic chemical vapor deposition (MOCVD) has been investigated with quantitative electron diffraction and HREM. The orthorhombic unit cell is a=1.097(9) nm, b=0.554(3) nm, c=0.394(2) nm with space group Cmmm, the values being in agreement with X-ray diffraction (XRD) study. The structure consists of alternating Cu 3O 4 and Ba layers along the c-axis. The compound is stabilised due to the formation of low-energy coherent boundaries with RBa 2Cu 3O 7 and/or perovskite substrate.

  9. Local anisotropic structure in amorphous Ba-Fe-O films and its role in determining magnetic anisotropy in crystallized Ba-hexaferrite films

    SciTech Connect

    Snyder, J.E.; Harris, V.G.; Koon, N.C.; Sui, X.; Kryder, M.H.

    1995-11-01

    Ba hexaferrite films with the easy direction of magnetization perpendicular or in-plane can be prepared by crystallization of amorphous films deposited under different sputtering conditions. Using polarization-dependent EXAFS (extended x-ray absorption fine structure), the authors have observed anisotropic local structure around the Fe atoms in as-sputtered amorphous Ba-Fe-O films. Such structure has not been detectable by conventional structural characterization techniques (x-ray diffraction, electron diffraction and transmission electron microscopy [TEM]). The results suggest that this local structural anisotropy determines the orientation of the fast-growing basal plane directions during post-deposition annealing and thus the directions of the c-axes and the magnetic anisotropy

  10. Combined backscatter Moessbauer spectrometer/x ray fluorescence analyzer (BaMS/XRF) for extraterrestrial surfaces

    NASA Technical Reports Server (NTRS)

    Shelfer, T. D.; Wills, E. L.; Agresti, D. G.; Pimperl, M. M.; Shen, M. H.; Morris, R. V.; Nguyen, T.

    1993-01-01

    We have designed and tested a prototype combined backscatter Moessbauer spectrometer and x-ray fluorescence analyzer (BaMS/XRF). A space qualified instrument based on this design would be suitable for in-situ use on planetary missions to the surfaces of the Moon (Artemis and lunar outpost), Mars (MESUR), asteroids, or other solid solar system objects. The BaMS/XRF instrument is designed to be capable of concurrent sample analyses for the mineralogy of iron-bearing phases and elemental composition without the need for sample preparation.

  11. DFT study of BaTiO3 (001) surface with O and O2 adsorption

    NASA Astrophysics Data System (ADS)

    Rakotovelo, G.; Moussounda, P. S.; Haroun, M. F.; Légaré, P.; Rakotomahevitra, A.; Parlebas, J. C.

    2007-06-01

    Progress of scanning tunneling microscopy (STM) allowed to handle various molecules adsorbed on a given surface. New concepts emerged with molecules on surfaces considered as nano machines by themselves. In this context, a thorough knowledge of surfaces and adsorbed molecules at an atomic scale is thus particularly invaluable. In this work, within the framework of density functional theory (DFT), we present an electronic and structural ab initio study of a BaTiO3 (001) surface (perovskite structure) in its paraelectric phase. As far as we know the atomic and molecular adsorption of oxygen at surface is then analyzed for the first time in the literature. Relaxation is taken into account for several layers. Its analysis for a depth of at least four layers enables us to conclude that a reasonable approximation for a BaTiO3 (001) surface is provided with a slab made up of nine plans. The relative stability of two possible terminations is considered. By using a kinetic energy cut off of 400 eV, we found that a surface with BaO termination is more stable than with TiO2 termination. Consequently, a surface with BaO termination was chosen to adsorb either O atom or O2 molecule and the corresponding calculations were performed with a coverage 1 on a (1×1) cell. A series of cases with O2 molecule adsorbed in various geometrical configurations are also analyzed. For O2, the most favorable adsorption is obtained when the molecule is placed horizontally, with its axis, directed along the Ba-Ba axis and with its centre of gravity located above a Ba atom. The corresponding value of the adsorption energy is -9.70 eV per molecule (-4.85 eV per O atom). The molecule is then rather extended since the O O distance measures 1.829 Å. By comparison, the adsorption energy of an O atom directly located above a Ba atom is only -3.50 eV. Therefore we are allowed to conclude that the O O interaction stabilizes atomic adsorption. Also the local densities of states (LDOS) corresponding to

  12. The luminescence of BaF{sub 2} nanoparticles upon high-energy excitation

    SciTech Connect

    Vistovskyy, V. V. Zhyshkovych, A. V.; Halyatkin, O. O.; Voloshinovskii, A. S.; Mitina, N. E.; Zaichenko, A. S.; Rodnyi, P. A.; Vasil'ev, A. N.; Gektin, A. V.

    2014-08-07

    The dependence of X-ray excited luminescence intensity on BaF{sub 2} nanoparticle size was studied. A sharp decrease of self-trapped exciton luminescence intensity was observed when the nanoparticle size is less than 80 nm. The main mechanism of the luminescence quenching is caused by the escape of electrons from the nanoparticles. Escape of electrons from nanoparticles is confirmed by the considerable increase of luminescence intensity of the polystyrene scintillator with embedded BaF{sub 2} nanoparticles comparing with pure polystyrene scintillator.

  13. First year operational experience with the Cherenkov Detector (DIRC) of BaBar

    SciTech Connect

    Adam, I.; BaBar Collaboration

    2000-04-01

    The DIRC (acronym for Detection of Internally Reflected Cherenkov (light)) is a new type of Cherenkov ring imaging detector based on total internal reflection that is used for the first time in the BaBar detector at PEP-II ring of SLAC. The Cherenkov radiators are long rectangular bars made of synthetic fused silica. The photon detector is a water tank equipped with an array of 10,752 conventional photomultipliers. The first year operational experience in the BaBar detector is presented using cosmic data and collision data in the energy region of the Y(4s) resonance.

  14. Crossings in alternating-parity bands of neutron-rich Ba nuclei

    SciTech Connect

    Urban, W.; Jones, M.A.; Durell, J.L.

    1995-07-22

    {sup 144}Ba and {sup 146}Ba nuclei produced in the spontaneous fission of {sup 248}Cm have been studied using the EUROGRAM II array. Spins and parities of excited levels have been deduced from triple-{gamma} angular correlation and direction-polarization correlation measurements, which is the first use of these techniques in studies of fission product nuclei. Ground-state, alternating-parity bands have been extended significantly and crossing in these bands has been found in both isotopes. For the first time alternating-parity band termination by particle alignment has been observed.

  15. Pr Substitution at Y and Ba sites in YBCO (123) System

    NASA Astrophysics Data System (ADS)

    Sharma, P. K.; Kumar, Sudhish; Dolia, S. N.; Singhal, R. K.

    2011-07-01

    We present structural, transport, and iodometric study of YBa2Cu3O7-δ system with Pr3+ substituting both the Y3+ and the Ba2+sites. The rate of the Tc depression in the case when with Pr3+ substitutes the Ba2+ is much higher than the case when Pr3+ is substituted at the Y3+ site. This is explained due to a composite effect of the depletion of itinerant holes due to the progressive depletion of the oxygen content, and the loss of orthorhombicity. Further studies on electronic structure and itinerant holes and their relation with superconductivity are underway.

  16. Magnetic levitation and stiffness in melt-textured Y-Ba-Cu-O

    NASA Astrophysics Data System (ADS)

    Hull, J. R.; Mulcahy, T. M.; Salama, K.; Selvamanickam, V.; Weinberger, B. R.; Lynds, L.

    1992-09-01

    Magnetic levitation and stiffness have been measured in several systems composed of a permanent magnet elastically suspended above a stationary melt-textured sample of Y-Ba-Cu-O. The levitation force and vertical stiffness have been calculated on the basis of magnetization measurements of the same system, and the calculated results showed excellent agreement with the experimental measurements. Based on the force and magnetization measurements, it is predicted that the same Y-Ba-Cu-O material configured in a geometry suitable for magnetic bearings could produce a levitation pressure of 100-400 kPa at 20 K.

  17. Energy Calibration of the BaBar EMC Using the Pi0 Invariant Mass Method

    SciTech Connect

    Tanner, David J.; /Manchester U.

    2007-04-06

    The BaBar electromagnetic calorimeter energy calibration method was compared with the local and global peak iteration procedures, of Crystal Barrel and CLEO-II. An investigation was made of the possibility of {Upsilon}(4S) background reduction which could lead to increased statistics over a shorter time interval, for efficient calibration runs. The BaBar software package was used with unreconstructed data to study the energy response of the calorimeter, by utilizing the {pi}{sup 0} mass constraint on pairs of photon clusters.

  18. Theoretical investigation of optical and structural properties of Ba-doped ZnO material

    NASA Astrophysics Data System (ADS)

    Lacerda, L. H. S.; de Lazaro, S. R.; Ribeiro, R. A. P.

    2015-11-01

    The doping process is a technique widely used for improving the properties of semiconductors. Through insertion of doping controlled amount is possible change drastically the electronic, optical and structural properties of a material. This work focuses on effects of Ba atoms insertion on wurtzite-ZnO structure at 12.5% amount. The results showed that the presence of Ba in low quantity cause increase in the lattice parameters and decrease in band- gap in relation to the ZnO material. In the percentage of 12.5%, the doping is noted as a potential alternative for application in opt-electronic devices, electronic devices, solar cells and photocatalytic process.

  19. Inhomogeneity Induced Coupling in YBCO/BaTiO{sub 3} Composites

    SciTech Connect

    Mohanta, A.; Behera, D.

    2008-10-23

    Ferroelectric and high temperature superconducting materials are two promising materials for future electronic devices. The superconducting properties and the related microstructures of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} with BaTiO{sub 3} addition, prepared by partial melt processing, were investigated with temperature-resistivity, X-ray diffraction and SEM-EDX analysis. For lower concentration of BaTiO{sub 3} it shows a fractal behaviour approaching the exponent of three-dimensional percolation model. The transport properties studied by four-probe arrangement show a different behaviour depending on the wt.% of ferroelectric to superconductor.

  20. Measurement of the magnetic moment of the 10{sup +} isomer in {sup 132}Ba

    SciTech Connect

    Harissopulos, S.; Gelberg, A.; Dewald, A.; Hass, M.; Weissman, L.; Broude, C.

    1995-10-01

    The magnetic moment of the 10{sup +} isomeric state of {sup 132}Ba at 3115 keV was measured as {ital g}={minus}0.156(11). A 60 MeV {sup 12}C beam from the Koffler Pelletron accelerator at the Weizmann Institute was used in the reaction {sup 124}Sn({sup 12}C,4{ital n}){sup 132}Ba. The measured {ital g} factor confirms the ({nu}{ital h}{sub 11/2}){sup {minus}2} configuration of the level. The result is compared with other {ital g} factors in neighboring {ital N}=76 isotones.

  1. The ICNP BaT - from translation tool to translation web service.

    PubMed

    Schrader, Ulrich

    2009-01-01

    The ICNP BaT has been developed as a web application to support the collaborative translation of different versions of the ICNP into different languages. A prototype of a web service is described that could reuse the translations in the database of the ICNP BaT to provide automatic translations of nursing content based on the ICNP terminology globally. The translation web service is based on a service-oriented architecture making it easy to interoperate with different applications. Such a global translation server would free individual institutions from the maintenance costs of realizing their own translation services.

  2. First Year Operational Experience with the Cherenkov Detector (DIRC) of BaBar

    SciTech Connect

    Spanier, Stefane

    2000-04-21

    The DIRC (acronym for Detection of Internally Reflected Cherenkov (light)) is a new type of Cherenkov ring imaging detector based on total internal reflection that is used for the first time in the BaBar detector at PEP-II ring of SLAC. The Cherenkov radiators are long rectangular bars made of synthetic fused silica. The photon detector is a water tank equipped with an array of 10,752 conventional photomultipliers. The first year operational experience in the BaBar detector is presented using cosmic data and collision data in the energy region of the Upsilon(4S) resonance.

  3. Ab initio study of double perovskites Ba2DySbO6

    NASA Astrophysics Data System (ADS)

    Jha, Dhiraj Kumar; Mandal, Golak; Ray, Chandan; Himanshu, A. K.; Singh, B. K.; Kumar, Uday; Choudhary, B. K.

    2016-05-01

    First principle study of the electronic band structure of Ba2DySbO6 synthesied by the solid state reaction technique have been performed within the framework of density function theory using WIEN2K. It has been shown in the absence of electron-electron interaction (U=0), BaDySO6 behaves like a half-metal. Even in the presence of DFT+U, electron-electron interaction via the Hubbard term (from U = 0, 2.72e -7.02eV), it still shows half metals.

  4. Magnetic levitation and stiffness in melt-textured Y-Ba-Cu-O

    SciTech Connect

    Hull, J.R.; Mulcahy, T.M. ); Salama, K.; Selvamanickam, V. ); Weinberger, B.R.; Lynds, L. )

    1992-09-01

    Magnetic levitation and stiffness have been measured in several systems composed of a permanent magnet elastically suspended above a stationary melt-textured sample of Y-Ba-Cu-O. The levitation force and vertical stiffness have been calculated on the basis of magnetization measurements of the same system, and the calculated results showed excellent agreement with the experimental measurements. Based on the force and magnetization measurements, it is predicted that the same Y-Ba-Cu-O material configured in a geometry suitable for magnetic bearings could produce a levitation pressure of 100--400 kPa at 20 K.

  5. Acoustical facies analysis at the Ba Lat delta front (Red River Delta, North Vietnam)

    NASA Astrophysics Data System (ADS)

    van den Bergh, G. D.; van Weering, Tj. C. E.; Boels, J. F.; Duc, D. M.; Nhuan, M. T.

    2007-02-01

    A shallow penetrating, high-resolution acoustic study was performed in the Ba Lat delta, the major distributary of the Red River System in Northern Vietnam. An acoustic facies map was constructed and the various facies types were validated through analysis of bottom sediments, by a study of gravity cores collected at 22 stations. Analysis of the acoustic profiles and gravity cores revealed the presence of an asymmetrical, S to SW prograding prodelta lobe, in accordance with the prevailing longshore currents to the S. The southern part of this prodelta is detached from the protruding Ba Lat delta front. The prodelta is dominated by muddy sediments with minor thin (<5 cm) sandy and silty layers. The coarser-grained layers decrease in abundance away from the Ba Lat river mouth. Offshore, the modern delta deposits are characterized by an off-lapping contact over a semi-prolonged bottom reflector lacking any sub-bottom reflectors. This semi-prolonged bottom reflector is correlated with sandy deposits of presumably Early Holocene age. Bottom and coastal erosion is restricted to two areas N and SW of the Ba Lat. Erosion in the North is inferred to be due to reduced sediment supply as a result of shifting in 1971 of the main outlet to its present, more southern location. The erosional area along the Hai Hau coast SW of the Ba Lat also has experienced a reduction in sediment supply in the course of the 20th century, when the local Song Vop distributary channel became less active and was completely dammed in the 1970s. Most sediment supplied by the Ba Lat at present bypasses the Hai Hau erosional coastal zone, as the active part of the Ba Lat prodelta is detached from the coast SW of the Ba Lat. An active, NNE-SSW trending fault system with surface expression is located along the offshore edge of the prodelta, and is linked to deeper fault structures in this active neotectonic region. Subsurface reflectors are folded in the vicinity of the fault.

  6. Electron-hole asymmetry, Dirac fermions, and quantum magnetoresistance in BaMnBi2

    DOE PAGES

    Li, Lijun; Wang, Kefeng; Graf, D.; ...

    2016-03-28

    Here, we report two-dimensional quantum transport and Dirac fermions in BaMnBi2 single crystals. BaMnBi2 is a layered bad metal with highly anisotropic conductivity and magnetic order below 290 K. Magnetotransport properties, nonzero Berry phase, small cyclotron mass, and the first-principles band structure calculations indicate the presence of Dirac fermions in Bi square nets. Quantum oscillations in the Hall channel suggest the presence of both electron and hole pockets, whereas Dirac and parabolic states coexist at the Fermi level.

  7. Three-phase percolative silver-BaTiO3-epoxy nanocomposites with high dielectric constants

    SciTech Connect

    Qi, Lai; Lee, Burtrand I.; Samuels, William D.; Exarhos, Gregory J.; Parker, Sam G.

    2006-08-01

    A three-phase epoxy-based composite with randomly distributed Ag nanoparticles and BaTiO3 particles was synthesized in this work. By integrating Ag nanoparticles into the epoxy resin, the dielectric properties of the resin is significantly enhanced, which provides an ideal host for further mixing with BaTiO3 to prepare high-dielectric-constant polymer-based dielectrics. The devices that adopt these composites demonstrate high relative dielectric constants (?r ? 450) at room temperature, which is 110 times higher than that of the epoxy matrix. These nanocomposites were found with potential to be applied in the embedded capacitor applications.

  8. Effect of surface moisture on dielectric behavior of ultrafine BaTiO3 particulates.

    NASA Technical Reports Server (NTRS)

    Mountvala, A. J.

    1971-01-01

    The effects of adsorbed H2O on the dielectric properties of ultrafine BaTiO3 particulates of varying particle size and environmental history were determined. The dielectric behavior depends strongly on surface hydration. No particle size dependence of dielectric constant was found for dehydroxylated surfaces in ultrafine particulate (unsintered) BaTiO3 materials. For equivalent particle sizes, the ac conductivity is sensitive to surface morphology. Reactions with H2O vapor appear to account for the variations in dielectric properties. Surface dehydration was effectively accomplished by washing as-received powders in isopropanol.

  9. Synthesis and characterization of hollow mesoporous BaFe12O19 spheres

    SciTech Connect

    Xu, X; Park, J; Hong, YK; Lane, AM

    2015-02-01

    A facile method is reported to synthesize hollow mesoporous BaFe12O19 spheres using a template-free chemical etching process. Hollow BaFe12O19 spheres were synthesized by conventional spray pyrolysis. The mesoporous structure is achieved by alkaline ethylene glycol etching at 185 degrees C, with the porosity controlled by the heating time. The hollow porous structure is confirmed by SEM, TEM, and FIB-FESEM characterization. The crystal structure and magnetic properties are not significantly affected after the chemical etching process. The formation mechanism of the porous structure is explained by grain boundary etching. (C) 2014 Elsevier Inc. All rights reserved.

  10. Metallic properties of Ba{sub 2}Cu{sub 3}P{sub 4} and BaCu{sub 2}Pn{sub 2} (Pn=As, Sb)

    SciTech Connect

    Saparov, Bayrammurad; Sefat, Athena S.

    2012-07-15

    We report the synthesis of ternary barium copper pnictides, Ba{sub 2}Cu{sub 3}P{sub 4} and BaCu{sub 2}Pn{sub 2} (Pn=As, Sb), and their structural, magnetic, and transport properties. They all crystallize in different structures shown by X-ray diffraction, although their structures reveal close relations. The body-centered tetragonal BaCu{sub 2}As{sub 2} adopts ThCr{sub 2}Si{sub 2}-type (I4/mmm) structure, whereas Ba{sub 2}Cu{sub 3}P{sub 4} is a copper-deficient derivative of this phase, crystallizing in the body-centered orthorhombic space group, Ibam. There are two polymorphs of BaCu{sub 2}Sb{sub 2}: {alpha}-BaCu{sub 2}Sb{sub 2} that adopts CaBe{sub 2}Ge{sub 2}-type structure; {beta}-BaCu{sub 2}Sb{sub 2} that is a 2:1 combination of CaBe{sub 2}Ge{sub 2}- and ThCr{sub 2}Si{sub 2}-type structural segments. All phases are metallic and non-magnetic. The room temperature thermal conductivity for polycrystalline BaCu{sub 2}As{sub 2} is Almost-Equal-To 2 W/(m K) and the Seebeck coefficient is Almost-Equal-To 15 {mu}V/K, which result in a small ( Almost-Equal-To 0.03) thermoelectric figure of merit. - Graphical abstract: Ternary copper pnictides of barium Ba{sub 2}Cu{sub 3}P{sub 4} and BaCu{sub 2}Pn{sub 2} (Pn=As, Sb) show metallic and non-magnetic behavior. Highlights: Black-Right-Pointing-Pointer Synthesis of Ba{sub 2}Cu{sub 3}P{sub 4} and BaCu{sub 2}Pn{sub 2} (Pn=As, Sb). Black-Right-Pointing-Pointer A new form of BaCu{sub 2}Sb{sub 2} (CaBe{sub 2}Ge{sub 2}-type) obtained and characterized. Black-Right-Pointing-Pointer The phases are metallic and non-magnetic in agreement with theory. Black-Right-Pointing-Pointer The thermal conductivity and Seebeck coefficient of BaCu{sub 2}As{sub 2} are quite low.

  11. Superconductivity and fluctuations in Ba1–pKpFe2As2 and Ba(Fe1–nCon)2As2

    DOE PAGES

    Böhm, T.; Hosseinian Ahangharnejhad, R.; Jost, D.; ...

    2016-08-11

    In this paper, we study the interplay of fluctuations and superconductivity in BaFe2As2 (Ba-122) compounds with Ba and Fe substituted by K (p doping) and Co (n doping), respectively. To this end, we measured electronic Raman spectra as a function of polarization and temperature. We observe gap excitations and fluctuations for all doping levels studied. The response from fluctuations is much stronger for Co substitution and, according to the selection rules and the temperature dependence, originates from the exchange of two critical spin fluctuations with characteristic wave vectors (±π,0) and (0,±π). At 22% K doping (p = 0.22), we findmore » the same selection rules and spectral shape for the fluctuations but the intensity is smaller by a factor of 5. Since there exists no nematic region above the orthorhombic spin-density-wave (SDW) phase, the identification of the fluctuations via the temperature dependence is not possible. The gap excitations in the superconducting state indicate strongly anisotropic near-nodal gaps for Co substitution which make the observation of collective modes difficult. The variation with doping of the spectral weights of the A1g and B1g gap features does not support the influence of fluctuations on Cooper pairing. Thus, the observation of Bardasis–Schrieffer modes inside the nearly clean gaps on the K-doped side remains the only experimental evidence for the relevance of fluctuations for pairing.« less

  12. Ionic, electronic and ion-diffusion controlled relaxation processes in CaF2, BaF2 and LiBaF3 crystals

    NASA Astrophysics Data System (ADS)

    Ziraps, V.; Kulis, P.; Tale, I.; Veispals, A.

    The ionic, electronic and anion-diffusion controlled thermally stimulated relaxation (TSR) processes at 80-700 K in CaF2 BaF2 and LiBaF3 crystals (X-ray irradiated or non-irradiated) have been investigated by means of ionic conductivity, ionic thermally stimulated (TS) depolarization current (TSDC); as well as current (TSC), luminescence (TSL) and bleaching (TSB) techniques. Above 250-290 K broad and overlapping anion TSDC peaks and correlated TSB stages are detected. The TSB kinetics is initiated and controlled by anion detrapping and interaction with the localized charges, i.e., the anion-diffusion controlled TSR processes take place in fluorides. The TSL and TSC data for LiBaF3 indicate that the lifetime and drift of electrons at 80-250 K is very small because of deep retrapping. The main TSL peaks at 132K, 170K and 220 K are caused by Vk center detrapping and hole-diffusion controlled tunnel recombination within pairs like .

  13. High-pressure densified solid solutions of alkaline earth hexaborides (Ca/Sr, Ca/Ba, Sr/Ba) and their high-temperature thermoelectric properties

    SciTech Connect

    Gürsoy, M.; Takeda, M.; Albert, B.

    2015-01-15

    Solid solutions of alkaline earth hexaborides were synthesized and densified by spark plasma sintering at 100 MPa. The high-temperature thermoelectric properties (Seebeck coefficients, electrical and thermal diffusivities, heat capacities) were measured between room temperature and 1073 K. CaB{sub 6}, SrB{sub 6}, BaB{sub 6} and the ternary hexaborides Ca{sub x}Sr{sub 1−x}B{sub 6}, Ca{sub x}Ba{sub 1−x}B{sub 6}, Sr{sub x}Ba{sub 1−x}B{sub 6} (x = 0.25, 0.5, 0.75) are n-type conducting compounds over the whole compositional and thermal ranges. The values of the figure of merit ZT for CaB{sub 6} (ca. 0.3 at 1073 K) were found to be significantly increased compared to earlier investigations which is attributed to the densification process. - Highlights: • Solid solutions of alkaline earth hexaborides were synthesized. • High-temperature thermoelectric properties of mixed calcium borides are excellent. • Spark plasma source densification results in high ZT values. • Borides are rare-earth free and refractory materials.

  14. Preparation and Characterization of DyBa2Cu3Oy Thick Films with Dy2BaO4 Precursor

    NASA Astrophysics Data System (ADS)

    Kawata, S.; Muralidhar, M.; Inoue, K.; Murakami, M.

    DyBa2Cu3Oy (Dy-123) thick films were fabricated from Dy2BaO4, BaCuO2, and CuO powders. We have added 0, 1, 2, and 4 wt% of Ag2O. Mixture of alpha-terpineol and 2-ethyl acetate was used as a solvent, to which 100nm-sized stoichiometric powdered mixture was added and grinded for several hours to form a highly dense paste. Thick film precursors were prepared by spreading the paste on MgO substrates with a screen printing technique. The films were sintered with a double-step annealing process. The Dy-123 thick films obtained were of good quality. XRD analyses confirmed the formation of a high-quality c-axis oriented Dy-123 for films annealed at 1070oC for 10 min and at 880oC for 2 h. Scanning electron microscopy showed the formation of large flat grains. Onset Tc was 91 K according to magnetization measurements. The present results suggest that this process might be useful for the preparation of large-area superconducting thick films on MgO substrates in a short processing time.

  15. Photoinduced charge transfer properties and photocatalytic activity in Bi2O3/BaTiO3 composite photocatalyst.

    PubMed

    Fan, Haimei; Li, Haiyan; Liu, Bingkun; Lu, Yongchun; Xie, Tengfeng; Wang, Dejun

    2012-09-26

    A series of Bi(2)O(3)/BaTiO(3) composite photocatalysts with different mass ratios of Bi(2)O(3) vs BaTiO(3) were prepared by an impregnating-annealing method. X-ray diffraction (XRD), high-resolution transmission electron microscopic (HRTEM), and UV-vis diffuse reflection spectroscopy (DRS) confirmed that Bi(2)O(3) and BaTiO(3) coexisted in the composites. The results of surface photovoltage (SPV) experiments showed enhancements of photovoltaic response in composites, which indicated a higher separation efficiency of photoinduced charges due to the establishment of an efficient interfacial electric field between Bi(2)O(3) and BaTiO(3) in the composites. The consistency of phtocatalytic activity and photovoltaic response intensity of photocatalysts showed that the efficiency interfacial electric field between Bi(2)O(3) and BaTiO(3) played an important role in improving the degradation efficiency of Rhodamine B (RhB). The 60%-Bi(2)O(3)/BaTiO(3) sample with the best activity was found by optimizing the mass ratios of Bi(2)O(3) vs. BaTiO(3). On the basis of the work function (WF) measurements, a reasonable energy band diagram was proposed for BaTiO(3)/Bi(2)O(3) composite. It would be helpful in designing and constructing high efficiency heterogeneous semiconductor photocatalyst.

  16. The Role of Area 10 (BA10) in Human Multitasking and in Social Cognition: A Lesion Study

    ERIC Educational Resources Information Center

    Roca, Maria; Torralva, Teresa; Gleichgerrcht, Ezequiel; Woolgar, Alexandra; Thompson, Russell; Duncan, John; Manes, Facundo

    2011-01-01

    A role for rostral prefrontal cortex (BA10) has been proposed in multitasking, in particular, the selection and maintenance of higher order internal goals while other sub-goals are being performed. BA10 has also been implicated in the ability to infer someone else's feelings and thoughts, often referred to as theory of mind. While most of the data…

  17. 17 CFR 240.15Ba1-5 - Amendments to Form MA and Form MA-I.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Amendments to Form MA and Form MA-I. 240.15Ba1-5 Section 240.15Ba1-5 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules and...

  18. Baumot BA-B Diesel Particulate Filter with Pre-Catalyst (ETV Mobile Source Emissions Control Devices) Verification Report

    EPA Science Inventory

    The Baumot BA-B Diesel Particulate Filter with Pre-Catalyst is a diesel engine retrofit device for light, medium, and heavy heavy-duty diesel on-highway engines for use with commercial ultra-low-sulfur diesel (ULSD) fuel. The BA-B particulate filter is composed of a pre-catalyst ...

  19. Crystal structure and physical properties of the new chalcogenides Ba3Cu(17-x)(S,Te)11 and Ba3Cu(17-x)(S,Te)11.5 with two different Cu clusters.

    PubMed

    Kuropatwa, Bryan A; Assoud, Abdeljalil; Kleinke, Holger

    2011-08-15

    The sulfide-tellurides Ba(3)Cu(17-x)(S,Te)(11) and Ba(3)Cu(17-x)(S,Te)(11.5) were synthesized from the elements in stoichiometric ratios heated to 1073 K, followed by slow cooling to 873 K over 100 h. Ba(3)Cu(17-x)(S,Te)(11) is isostructural to Ba(3)Cu(17-x)(Se,Te)(11) when [S] > [Te], space group R ̅3m, with lattice dimensions of a = 12.009(1) Å, c = 27.764(2) Å, V = 3467.6(5) Å(3), for Ba(3)Cu(15.7(4))S(7.051(5))Te(3.949) (Z = 6). The structure is composed of Cu atoms forming paired hexagonal antiprisms, capped on the two outer hexagonal faces, where each Cu atom is tetrahedrally coordinated by four Q (= S, Te) atoms. The new variant is formed when [Te] > [S]; then Ba(3)Cu(17-x)(S,Te)(11.5) adopts space group Fm3̅m with a = 17.2095(8) Å, V = 5096.9(4) Å(3), for Ba(3)Cu(15.6(2))S(5.33(4))Te(6.17) (Z = 8). This structure consists of eight Te-centered Cu(16) icosioctahedra per cell interconnected by cubic Cu(8) units centered by Q atoms. Electronic structure calculations and property measurements illustrate that these compounds behave as extrinsic p-type semiconductors-toward metallic behavior for the latter compound. With standard oxidation states Ba(2+), Cu(+), and Q(2-), the electron precise formulas are Ba(3)Cu(16)Q(11) and Ba(3)Cu(17)Q(11.5).

  20. Characterization of the insulator barrier and the superconducting transition temperature in GdBa{sub 2}Cu{sub 3}O{sub 7−δ}/BaTiO{sub 3} bilayers for application in tunnel junctions

    SciTech Connect

    Navarro, H. Sirena, M.; Haberkorn, N.; Yang, Ilkyu; Kim, Jeehoon

    2015-07-28

    The optimization of the superconducting properties in a bottom electrode and the quality of an insulator barrier are the first steps in the development of superconductor/insulator/superconductor tunnel junctions. Here, we study the quality of a BaTiO{sub 3} tunnel barrier deposited on a 16 nm thick GdBa{sub 2}Cu{sub 3}O{sub 7−δ} thin film by using conductive atomic force microscopy. We find that the tunnel current is systematically reduced (for equal applied voltage) by increasing the BaTiO{sub 3} barrier thickness between 1.6 and 4 nm. The BaTiO{sub 3} layers present an energy barrier of ≈1.2 eV and an attenuation length of 0.35–0.5 nm (depending on the applied voltage). The GdBa{sub 2}Cu{sub 3}O{sub 7−δ} electrode is totally covered by a BaTiO{sub 3} thickness above 3 nm. The presence of ferroelectricity was verified by piezoresponse force microscopy for a 4 nm thick BaTiO{sub 3} top layer. The superconducting transition temperature of the bilayers is systematically suppressed by increasing the BaTiO{sub 3} thickness. This fact can be associated with stress at the interface and a reduction of the orthorhombicity of the GdBa{sub 2}Cu{sub 3}O{sub 7−δ}. The reduction in the orthorhombicity is expected by considering the interface mismatch and it can also be affected by reduced oxygen stoichiometry (poor oxygen diffusion across the BaTiO{sub 3} barrier)

  1. Ca, Sr and Ba stable isotopes reveal the fate of soil nutrients along a tropical climosequence

    USGS Publications Warehouse

    Bullen, Thomas D.; Chadwick, Oliver A.

    2016-01-01

    Nutrient biolifting is an important pedogenic process in which plant roots obtain inorganic nutrients such as phosphorus (P) and calcium (Ca) from minerals at depth and concentrate those nutrients at the surface. Here we use soil chemistry and stable isotopes of the alkaline earth elements Ca, strontium (Sr) and barium (Ba) to test the hypothesis that biolifting of P has been an important pedogenic process across a soil climosequence developed on volcanic deposits at Kohala Mountain, Hawaii. The geochemical linkage between these elements is revealed as generally positive site-specific relationships in soil mass gains and losses, particularly for P, Ba and Ca, using the ratio of immobile elements titanium and niobium (Ti/Nb) to link individual soil samples to a restricted compositional range of the chemically and isotopically diverse volcanic parent materials. At sites where P is enriched in surface soils relative to abundances in deeper soils, the isotope compositions of exchangeable Ca, Sr and Ba in the shallowest soil horizons (< 10 cm depth) are lighter than those of the volcanic parent materials and trend toward those of plants growing on fresh volcanic deposits. In contrast the isotope composition of exchangeable Ba in deeper soil horizons (> 10 cm depth) at those sites is consistently heavier than the volcanic parent materials. The isotope compositions of exchangeable Ca and Sr trend toward heavier compositions with depth more gradually, reflecting increasing leakiness from these soils in the order Ba < Sr < Ca and downward transfer of light biocycled Ca and Sr to deeper exchange sites. Given the long-term stability of ecosystem properties at the sites where P is enriched in surface soils, a simple box model demonstrates that persistence of isotopically light exchangeable Ca, Sr and Ba in the shallowest soil horizons requires that the uptake flux to plants from those near-surface layers is less than the recycling flux returned to the surface as

  2. Novel reddish-orange-emitting BaLa2Si2S8:Eu(2+) thiosilicate phosphor for LED lighting.

    PubMed

    Lee, Szu-Ping; Chan, Ting-Shan; Chen, Teng-Ming

    2015-01-14

    A novel reddish-orange-emitting BaLa2Si2S8:Eu(2+) thiosilicate was prepared in a sealed fused silica ampule and its crystal structure was refined using Rietveld methods. The BaLa2Si2S8:Eu(2+) phosphor is excitable over a broad range from UV to blue (350-450 nm) and generated a reddish-orange broadband emission peaking at 645 nm with a quantum efficiency of ∼24%. The thermal luminescence quenching of BaLa2Si2S8:Eu(2+) was investigated over the range 25 to 150 °C. This phosphor was utilized to incorporate with two commercially available phosphors, blue BaMgAl10O17:Eu(2+) and green (Ba,Sr)2SiO4:Eu(2+), and a near-UV LED chip (405 nm), a white light with Ra of ∼94 was obtained.

  3. Long-term monitoring of Jupiter's South Temperate domain: Oval BA and the cyclic development of structured sectors

    NASA Astrophysics Data System (ADS)

    Rogers, J.; Adamoli, G.; Hahn, G.; Jacquesson, M.; Vedovato, M.; Mettig, H.-J.

    2013-09-01

    The pattern of atmospheric phenomena in Jupiter's South Temperate domain, covering the years 2001-2012, is here deduced from amateur images. We summarise the long-term history of the major features, viz. a succession of structured cyclonic sectors of the South Temperate Belt (STB), one of which is coupled to the single large anticyclonic oval (oval BA). The other structured segments begin as small dark spots or streaks remote from oval BA, then expand, and eventually catch up and merge with the dark segment at BA, inducing intense disturbance in and around it. This cycle has been completed three times in 15 years, maintaining at least 2 structured sectors at all times. The major changes in drift rate of oval BA appear to be due to the impacts and subsequent shrinkage of the structured segments. From 2008 onwards, oval BA has been shrinking and shifting southwards.

  4. Interface control of ferroelectricity in LaNiO{sub 3}-BaTiO{sub 3} superlattices

    SciTech Connect

    Wu, Yin-Zhong; Lu, Hai-Shuang; Cai, Tian-Yi; Ju, Sheng

    2014-08-15

    LaNiO{sub 3}-BaTiO{sub 3} superlattices with different types of interfaces are studied from first-principles density-functional theory. It is revealed that the ferroelectricity in the superlattice with (NiO{sub 2}){sup −}/(BaO){sup 0} interfaces is enhanced from that of the superlattice with (LaO){sup +}/(TiO{sub 2}){sup 0} interfaces. The origin lies at the polar discontinuity at the interface, which makes the holes localized within the (NiO{sub 2}){sup −}/(BaO){sup 0} interface, but drives a penetration of electrons into BaTiO{sub 3} component near (LaO){sup +}/(TiO{sub 2}){sup 0} interface. Our calculations demonstrate an effective avenue to the robust ferroelectricity in BaTiO{sub 3} ultrathin films.

  5. Sr/Ca and Ba/Ca variations in environmental and biological sources: A survey of marine and terrestrial systems

    NASA Astrophysics Data System (ADS)

    Peek, Stephanie; Clementz, Mark T.

    2012-10-01

    The relative concentrations of strontium to calcium (Sr/Ca) and barium to calcium (Ba/Ca) in mammalian bioapatite are common biogeochemical indicators for trophic level and/or dietary preferences in terrestrial foodwebs; however, similar research in marine foodwebs is lacking. This study combined environmental and biological Sr/Ca and Ba/Ca data from both terrestrial and marine settings from 62 published books, reports, and studies along with original data collected from 149 marine mammals (30 species) and 83 prey items (18 species) and found that variations in Sr/Ca and Ba/Ca ratios of biological and environmental samples are appreciably different in terrestrial and marine systems. In terrestrial systems, environmental sources account for most of the variations in Sr/Ca and Ba/Ca ratios. In contrast, environmental sources in marine systems (i.e., seawater) are comparatively invariant, meaning most of the variations in Sr/Ca and Ba/Ca ratios originate from biological processes. Marine consumers, particularly non-mammalian and mammalian vertebrates, show evidence of biopurification of Ca relative to Sr and Ba, similar to what is observed in terrestrial systems; however, unlike terrestrial systems, variations in Sr/Ca and Ba/Ca ratios of environmental sources are overprinted by bioaccumulation of Sr and Ba at the base of marine foodwebs. This demonstrates that in marine systems, spatial or temporal differences may have little to no effect on Sr/Ca and Ba/Ca ratios of marine vertebrates, making Sr/Ca, and to a lesser extent Ba/Ca, potentially useful global proxies for trophic level and dietary preferences of marine vertebrates.

  6. Heterogeneous Nucleation and Growth of Barium Sulfate at Organic-Water Interfaces: Interplay between Surface Hydrophobicity and Ba2+ Adsorption

    DOE PAGES

    Dai, Chong; Stack, Andrew G.; Koishi, Ayumi; ...

    2016-05-10

    Barium sulfate (BaSO4) is a common scale-forming mineral in natural and engineered systems, yet the rates and mechanisms of heterogeneous BaSO4 nucleation are not understood. To address these, we created idealized interfaces on which to study heterogeneous nucleation rates and mechanisms, which also are good models for organic–water interfaces: self-assembled thin films terminated with different functional groups (i.e., -COOH, -SH, or mixed -SH & COOH) coated on glass slides. BaSO4 precipitation on coatings from Barite-supersaturated solutions (saturation index, SI, = 1.1) was investigated using grazing-incidence small-angle X-ray scattering. After reaction for 1 h, a little amount of BaSO4 formed onmore » hydrophilic bare and -COOH coated glasses. Meanwhile, BaSO4 nucleation was significantly promoted on hydrophobic -SH and mixed -SH & COOH coatings. This is because substrate hydrophobicity likely affected the interfacial energy and hence thermodynamic favorability of heterogeneous nucleation. The heterogeneous BaSO4 nucleation and growth kinetics were found to be affected by the amount of Ba2+ adsorption onto the substrate and incipient BaSO4 nuclei. The importance of Ba2+ adsorption was further corroborated by the finding that precipitation rate increased under [Ba2+]/[SO42–] concentration ratios >1. These observations suggest that thermodynamic favorability for nucleation is governed by substrate–water interfacial energy, while given favorable thermodynamics, the rate is governed by ion attachment to substrates and incipient nuclei.« less

  7. Studies of local structural distortions in strained ultrathin BaTiO3 films using scanning transmission electron microscopy.

    PubMed

    Park, Daesung; Herpers, Anja; Menke, Tobias; Heidelmann, Markus; Houben, Lothar; Dittmann, Regina; Mayer, Joachim

    2014-06-01

    Ultrathin ferroelectric heterostructures (SrTiO3/BaTiO3/BaRuO3/SrRuO3) were studied by scanning transmission electron microscopy (STEM) in terms of structural distortions and atomic displacements. The TiO2-termination at the top interface of the BaTiO3 layer was changed into a BaO-termination by adding an additional BaRuO3 layer. High-angle annular dark-field (HAADF) imaging by aberration-corrected STEM revealed that an artificially introduced BaO-termination can be achieved by this interface engineering. By using fast sequential imaging and frame-by-frame drift correction, the effect of the specimen drift was significantly reduced and the signal-to-noise ratio of the HAADF images was improved. Thus, a quantitative analysis of the HAADF images was feasible, and an in-plane and out-of-plane lattice spacing of the BaTiO3 layer of 3.90 and 4.22 Å were determined. A 25 pm shift of the Ti columns from the center of the unit cell of BaTiO3 along the c-axis was observed. By spatially resolved electron energy-loss spectroscopy studies, a reduction of the crystal field splitting (CFS, ΔL3=1.93 eV) and an asymmetric broadening of the eg peak were observed in the BaTiO3 film. These results verify the presence of a ferroelectric polarization in the ultrathin BaTiO3 film.

  8. Noncentrosymmetric selenide Ba4Ga4GeSe12: Synthesis, structure, and optical properties

    NASA Astrophysics Data System (ADS)

    Yin, Wenlong; Iyer, Abishek K.; Li, Chao; Lin, Xinsong; Yao, Jiyong; Mar, Arthur

    2016-09-01

    The selenide Ba4Ga4GeSe12, synthesized by reaction of BaSe, Ga2Se3, and GeSe2 at 1173 K, adopts a noncentrosymmetric tetragonal structure (space group P 4 bar21 c , Z=2, a=13.5468(4) Å, c=6.4915(2) Å) consisting of a three-dimensional network built from two types of corner-sharing MSe4 tetrahedra, with Ba cations occupying the intervening voids. It is isostructural to Pb4Ga4GeS12, Pb4Ga4GeSe12, and Ba4Ga4SnSe12, but differs subtly in site ordering. Structural refinements and bond valence sum analysis suggest partial disorder manifested by mixing of 0.75 Ga and 0.25 Ge within one tetrahedral site, and occupation of exclusively Ga within the other tetrahedral site. The optical band gap of 2.18(2) eV, measured from the UV/VIS/NIR diffuse reflectance spectrum, agrees with a calculated gap of 2.35 eV between valence and conduction bands and is consistent with the orange-yellow color of the crystals. Nonlinear optical measurements on powder samples revealed a weak second harmonic generation signal using 2.09 μm as the fundamental laser wavelength.

  9. Giant thermal vibrations in the framework compounds Ba1 -xSrxAl2O4

    NASA Astrophysics Data System (ADS)

    Kawaguchi, S.; Ishii, Y.; Tanaka, E.; Tsukasaki, H.; Kubota, Y.; Mori, S.

    2016-08-01

    Synchrotron x-ray diffraction experiments were performed on the network compounds Ba1 -xSrxAl2O4 at temperatures between 15 and 800 K. The ferroelectric phase of the parent BaAl2O4 is largely suppressed by substituting a small amount of Sr for Ba and disappears for x ≥0.1 . Structural refinements reveal that the isotropic atomic displacement parameter Biso in the bridging oxygen atom is largely independent of temperature and retains an anomalously large value in the adjacent paraelectric phase even at the lowest temperature. The Biso systematically increases as x increases, exhibiting an especially large value for x =0.5 . According to previous electron diffraction experiments for Ba1 -xSrxAl2O4 with x ≥0.1 , strong thermal diffuse scattering occurs at two reciprocal points relating to two distinct soft modes at the M and K points over a wide range of temperatures below 800 K [Y. Ishii et al., Sci. Rep. 6, 19154 (2016), 10.1038/srep19154]. Although the latter mode disappears at approximately 200 K, the former does not condense, at least down to 100 K. The anomalously large Biso observed in this study is ascribed to these soft modes existing in a wide temperature range.

  10. The use of 133 Ba+ as a new candidate for trapped atomic ion qubits

    NASA Astrophysics Data System (ADS)

    Hucul, David; Christiansen, Justin; Campbell, Wesley; Hudson, Eric

    2016-05-01

    Trapped atomic ions are qubit standards in quantum information science because of their long coherence times and high fidelity entangling gates. Many different atomic ions have been used as qubits, each with strengths and weaknesses dictated by its atomic structure. We propose to use 133 Ba+ as an atomic qubit. 133 Ba+ is a nearly ideal, all-purpose candidate by combining many of the strengths of different workhorse atomic ions. 133 Ba+, like 171 Yb+, has a nuclear spin 1/2, allowing for a robust hyperfine qubit with simple state preparation and readout via differential fluorescence. The lack of a low-lying F-state, like in Ca+, simplifies high-fidelity qubit state detection that relies on shelving a qubit level to a meta-stable excited state. In addition, 133 Ba+ can be used for background-free qubit state detection where the wavelength of the qubit detection light differs from all excitation light by at least 50 THz. Unlike all other ions in use, the optical transitions of barium are in the visible spectrum, enabling the use of high power lasers, low-loss fibers, high quantum efficiency detectors, and other technologies developed for visible wavelengths of light to ease some requirements toward scaling a quantum system.

  11. The Three-Year B.A. Who Will Choose It? Who Will Benefit?

    ERIC Educational Resources Information Center

    Stark, Joan S.

    The present study explored the characteristics of students who take advantage of the option to complete the B.A. degree in 3 years at Goucher College. At Goucher, the optional 3-year degree plan has been selected by students of exceedingly diverse academic potential and background, and different ideas of what for them constitutes a successful…

  12. SuperMemo; XIA LI BA REN (Macintosh Version 1.0).

    ERIC Educational Resources Information Center

    Wharton, Charlotte; Bourgerie, Dana S.

    1994-01-01

    Describes "SuperMemo," a memorization tool that uses an automated flashcard scheme that can include sound and graphics in the database of study items. Based on the learner's performance, "SuperMemo" schedules items to appear for review. Xia Li Ba Ren ("common person" in Chinese) is the name of a Chinese word processor that runs with a standard…

  13. A Learning Module for BA Students to Develop ICT Skills for Their Learning Activities

    ERIC Educational Resources Information Center

    Platteaux, Hervé; Hoein, Sergio

    2015-01-01

    This case illustrates the process of developing a learning module to support BA students in their use of ICT (Information and Communication Technology) tools in their learning. At the university where this case occurred, the skill level of ICT use among students in a learning context was very heterogeneous. The E-learning Competency Centre, or…

  14. Residual stress dependant anisotropic band gap of various (hkl) oriented BaI2 films

    NASA Astrophysics Data System (ADS)

    Kumar, Pradeep; Gulia, Vikash; Vedeshwar, Agnikumar G.

    2013-11-01

    The thermally evaporated layer structured BaI2 grows in various completely preferred (hkl) film orientations with different growth parameters like film thickness, deposition rate, substrate temperature, etc. which were characterized by structural, morphological, and optical absorption measurements. Structural analysis reveals the strain in the films and the optical absorption shows a direct type band gap. The varying band gaps of these films were found to scale linearly with their strain. The elastic moduli and other constants were also calculated using Density Functional Theory (DFT) formalism implemented in WIEN2K code for converting the strain into residual stress. Films of different six (hkl) orientations show stress free anisotropic band gaps (2.48-3.43 eV) and both positive and negative pressure coefficients. The negative and positive pressure coefficients of band gap are attributed to the strain in I-I (or Ba-Ba or both) and Ba-I distances along [hkl], respectively. The calculated band gaps are also compared with those experimentally determined. The average pressure coefficient of band gap of all six orientations (-0.071 eV/GPa) found to be significantly higher than that calculated (-0.047 eV/GPa) by volumetric pressure dependence. Various these issues have been discussed with consistent arguments. The electron effective mass me*=0.66m0 and the hole effective mass mh*=0.53m0 have been determined from the calculated band structure.

  15. Single mutations that redirect internal proton transfer in the ba3 oxidase from Thermus thermophilus.

    PubMed

    Smirnova, Irina; Chang, Hsin-Yang; von Ballmoos, Christoph; Ädelroth, Pia; Gennis, Robert B; Brzezinski, Peter

    2013-10-08

    The ba3-type cytochrome c oxidase from Thermus thermophilus is a membrane-bound proton pump. Results from earlier studies have shown that with the aa3-type oxidases proton uptake to the catalytic site and "pump site" occurs simultaneously. However, with ba3 oxidase the pump site is loaded before proton transfer to the catalytic site because the proton transfer to the latter is slower than that with the aa3 oxidases. In addition, the timing of formation and decay of catalytic intermediates is different in the two types of oxidases. In the present study, we have investigated two mutant ba3 CytcOs in which residues of the proton pathway leading to the catalytic site as well as the pump site were exchanged, Thr312Val and Tyr244Phe. Even though ba3 CytcO uses only a single proton pathway for transfer of the substrate and "pumped" protons, the amino-acid residue substitutions had distinctly different effects on the kinetics of proton transfer to the catalytic site and the pump site. The results indicate that the rates of these reactions can be modified independently by replacement of single residues within the proton pathway. Furthermore, the data suggest that the Thr312Val and Tyr244Phe mutations interfere with a structural rearrangement in the proton pathway that is rate limiting for proton transfer to the catalytic site.

  16. Phases of Ba adsorption on Si(100)-(2×1) studied by LEED and AES

    NASA Astrophysics Data System (ADS)

    Hu, Xiaoming; Peterson, C. A.; Sarid, D.; Yu, Z.; Wang, J.; Marshall, D. S.; Droopad, R.; Hallmark, J. A.; Ooms, W. J.

    1999-05-01

    Phase transitions of Ba adsorption on a clean Si(001)-(2×1) studied by low energy electron diffraction (LEED) and Auger electron spectroscopy (AES) are reported. The depositions of the Ba were performed with (a) the substrate held at room temperature followed by annealing at elevated temperatures, and (b) the substrate held at 900°C. While confirming earlier established phases, the existence of 4× streaks in the (3×2)+c(6×2) and (2×1) phases has been identified. Also found was a real-time phase transition from a (3×2) phase to a mixture of (3×2) and c(6×2) phases during sample cooling. Finally, it was found that AES of Ba/Si peak ratios exhibit plateaus in the phase vs. temperature diagram for the (3×2), (3×2)+c(6×2), and (2×1)+4× streak phases, indicating a temperature-dependent mechanism limiting the Ba coverage.

  17. Polygyny without wealth: popularity in gift games predicts polygyny in BaYaka Pygmies.

    PubMed

    Chaudhary, Nikhil; Salali, Gul Deniz; Thompson, James; Dyble, Mark; Page, Abigail; Smith, Daniel; Mace, Ruth; Migliano, Andrea Bamberg

    2015-05-01

    The occurrence of polygynous marriage in hunter-gatherer societies, which do not accumulate wealth, remains largely unexplored since resource availability is dependent on male hunting capacity and limited by the lack of storage. Hunter-gatherer societies offer the greatest insight in to human evolution since they represent the majority of our species' evolutionary history. In order to elucidate the evolution of hunter-gatherer polygyny, we study marriage patterns of BaYaka Pygmies. We investigate (i) rates of polygyny among BaYaka hunter-gatherers; (ii) whether polygyny confers a fitness benefit to BaYaka men; (iii) in the absence of wealth inequalities, what are the alternative explanations for polygyny among the BaYaka. To understand the latter, we explore differences in phenotypic quality (height and strength), and social capital (popularity in gift games). We find polygynous men have increased reproductive fitness; and that social capital and popularity but not phenotypic quality might have been important mechanisms by which some male hunter-gatherers sustained polygynous marriages before the onset of agriculture and wealth accumulation.

  18. Mechanisms for O2 dissociation over the BaO (100) surface

    NASA Astrophysics Data System (ADS)

    Lu, Nai-Xia; Fu, Gang; Xu, Xin; Wan, Hui-Lin

    2008-01-01

    We have investigated the atomic and molecular oxygen adsorptions on the various sites of the BaO (100) surface with both cluster models and the periodic slab models. We found that the atomic oxygen prefers to adsorb on the surface O2- to form the closed-shell peroxides with the binding energies of 83-88kcal/mol. Such a high exothermicity provides a large driving force for the dissociation of molecular O2 on the BaO surfaces. As molecular oxygen approaches the BaO surfaces, the triplet ground state O2 molecule first binds electrostatically on top of the surface Ba2+ site. It further quenches to the singlet potential energy surface to form a covalently bonded O32- species. We proposed a plausible pathway in which the O32- species acts as the key precursor for further dissociation, leading eventually to the formation of surface peroxides O22-. This mechanism is helpful for the understanding of a series of related catalytic processes such as the oxidative coupling of methane, the NOx storage reduction, etc.

  19. Optical observation of spin-density-wave fluctuations in Ba122 iron-based superconductors

    NASA Astrophysics Data System (ADS)

    Xu, B.; Dai, Y. M.; Xiao, H.; Shen, B.; Ye, Z. R.; Forget, A.; Colson, D.; Feng, D. L.; Wen, H. H.; Qiu, X. G.; Lobo, R. P. S. M.

    2016-08-01

    In iron-based superconductors, a spin-density-wave (SDW) magnetic order is suppressed with doping, and unconventional superconductivity appears in close proximity to the SDW instability. The optical response of the SDW order shows clear gap features: substantial suppression in the low-frequency optical conductivity, alongside a spectral weight transfer from low to high frequencies. Here, we study the detailed temperature dependence of the optical response in three different series of the Ba122 system [Ba1 -xKxFe2As2 , Ba (Fe1-xCox) 2As2 , and BaFe2(As1-xPx) 2 ]. Intriguingly, we find that the suppression of the low-frequency optical conductivity and spectral weight transfer appear at a temperature T* much higher than the SDW transition temperature TSDW. Since this behavior has the same optical feature and energy scale as the SDW order, we attribute it to SDW fluctuations. Furthermore, T* is suppressed with doping, closely following the doping dependence of the nematic fluctuations detected by other techniques. These results suggest that the magnetic and nematic orders have an intimate relationship, in favor of the magnetic-fluctuation-driven nematicity scenario in iron-based superconductors.

  20. Genome Sequence of the Human Abscess Isolate Streptococcus intermedius BA1.

    PubMed

    Planet, Paul J; Rampersaud, Ryan; Hymes, Saul R; Whittier, Susan; Della-Latta, Phyllis A; Narechania, Apurva; Daugherty, Sean C; Santana-Cruz, Ivette; Desalle, Robert; Ravel, Jacques; Ratner, Adam J

    2013-01-01

    Streptococcus intermedius is a human pathogen with a propensity for abscess formation. We report a high-quality draft genome sequence of S. intermedius strain BA1, an isolate from a human epidural abscess. This sequence provides insight into the biology of S. intermedius and will aid investigations of pathogenicity.

  1. Specification of hepatopancreas progenitors in zebrafish by hnf1ba and wnt2bb

    PubMed Central

    Lancman, Joseph J.; Zvenigorodsky, Natasha; Gates, Keith P.; Zhang, Danhua; Solomon, Keely; Humphrey, Rohan K.; Kuo, Taiyi; Setiawan, Linda; Verkade, Heather; Chi, Young-In; Jhala, Ulupi S.; Wright, Christopher V. E.; Stainier, Didier Y. R.; Dong, P. Duc Si

    2013-01-01

    Although the liver and ventral pancreas are thought to arise from a common multipotent progenitor pool, it is unclear whether these progenitors of the hepatopancreas system are specified by a common genetic mechanism. Efforts to determine the role of Hnf1b and Wnt signaling in this crucial process have been confounded by a combination of factors, including a narrow time frame for hepatopancreas specification, functional redundancy among Wnt ligands, and pleiotropic defects caused by either severe loss of Wnt signaling or Hnf1b function. Using a novel hypomorphic hnf1ba zebrafish mutant that exhibits pancreas hypoplasia, as observed in HNF1B monogenic diabetes, we show that hnf1ba plays essential roles in regulating β-cell number and pancreas specification, distinct from its function in regulating pancreas size and liver specification, respectively. By combining Hnf1ba partial loss of function with conditional loss of Wnt signaling, we uncover a crucial developmental window when these pathways synergize to specify the entire ventrally derived hepatopancreas progenitor population. Furthermore, our in vivo genetic studies demonstrate that hnf1ba generates a permissive domain for Wnt signaling activity in the foregut endoderm. Collectively, our findings provide a new model for HNF1B function, yield insight into pancreas and β-cell development, and suggest a new mechanism for hepatopancreatic specification. PMID:23720049

  2. White HDPE bottles as source of serious contamination of water samples with Ba and Zn.

    PubMed

    Reimann, Clemens; Grimstvedt, Andreas; Frengstad, Bjørn; Finne, Tor Erik

    2007-03-15

    During a recent study of surface water quality factory new white high-density polyethylene (HDPE) bottles were used for collecting the water samples. According to the established field protocol of the Geological Survey of Norway the bottles were twice carefully rinsed with water in the field prior to sampling. Several blank samples using milli-Q (ELGA) water (>18.2 MOmega) were also prepared. On checking the analytical results the blanks returned values of Ag, Ba, Sr, V, Zn and Zr. For Ba and Zn the values (c. 300 microg/l and 95 microg/l) were about 10 times above the concentrations that can be expected in natural waters. A laboratory test of the bottles demonstrated that the bottles contaminate the samples with significant amounts of Ba and Zn and some Sr. Simple acid washing of the bottles prior to use did not solve the contamination problem for Ba and Zn. The results suggest that there may exist "clean" and "dirty" HDPE bottles depending on manufacturer/production process. When collecting water samples it is mandatory to check bottles regularly as a possible source of contamination.

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

    SciTech Connect

    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.

  4. Two-dimensional measurement of the nonlinearity parameter B/A in excised biological samples.

    PubMed

    Saito, Shigemi; Kim, Jung-Ho

    2011-06-01

    The method previously developed for measuring the acoustic nonlinearity parameter B/A in a liquid sample with a volume as small as 0.1 ml [S. Saito, J. Acoust. Soc. Am. 127, 51(2010)] has been automated and applied to two-dimensional measurements of excised biological samples using a LabVIEW program. The focus of the sound beam is laterally shifted on the 3 × 3 mm(2) area of the sample while measuring the B/A successively. By displaying the result of 256 time repeated measurements with an interval of 0.2 mm in two dimensions, a C-mode image was generated for B/A. The images of linear properties such as density, sound speed, and attenuation coefficient are also obtained. The image, whose pattern can be different from those of the density and sound speed, has the capability to reveal the detailed structure of the B/A, which varies from region to region in a single biological sample. The application of the method to small samples is also demonstrated by measuring a thermally coagulated biological sample.

  5. Two-dimensional measurement of the nonlinearity parameter B/A in excised biological samples

    NASA Astrophysics Data System (ADS)

    Saito, Shigemi; Kim, Jung-Ho

    2011-06-01

    The method previously developed for measuring the acoustic nonlinearity parameter B/A in a liquid sample with a volume as small as 0.1 ml [S. Saito, J. Acoust. Soc. Am. 127, 51(2010)] has been automated and applied to two-dimensional measurements of excised biological samples using a LabVIEW program. The focus of the sound beam is laterally shifted on the 3 × 3 mm2 area of the sample while measuring the B/A successively. By displaying the result of 256 time repeated measurements with an interval of 0.2 mm in two dimensions, a C-mode image was generated for B/A. The images of linear properties such as density, sound speed, and attenuation coefficient are also obtained. The image, whose pattern can be different from those of the density and sound speed, has the capability to reveal the detailed structure of the B/A, which varies from region to region in a single biological sample. The application of the method to small samples is also demonstrated by measuring a thermally coagulated biological sample.

  6. Crystal structure of the 4H BaCrO 3 polytype

    NASA Astrophysics Data System (ADS)

    Chamberland, B. L.

    1982-07-01

    The structure of the four-layer hexagonal BaCrO 3 polytype, prepared at high temperature and high pressure, was determined utilizing a Picker FACS-I diffractometer. The hexagonal black crystal was found to crystallize with a four-layer stacking sequence in space group {P6 3}/{mmc} having unit cell parameters a = 5.660(1) and c = 9.357(1) Å. The structure was determined from 668 independent reflections of which 605 were considered observed. Equivalent reflections were averaged and this operation yielded 130 unique, observed reflections. Refinement of the structure by least-squares methods gave a conventional R value of 3.0%. The structure consists of a four-layer stacking sequence of close-packed BaO 3 layers containing tetravalent chromium in all the octahedral oxygen interstices. The compound was found to be isostructural with β-BaMnO 3 and the recently reported BaRhO 3 and SrMnO 3.

  7. KrF laser-induced ablation and patterning of Y--Ba--Cu--O films

    SciTech Connect

    Heitz, J.; Wang, X.Z.; Schwab, P.; Baeuerle, D. ); Schultz, L. )

    1990-09-01

    The ablation and patterning of Y--Ba--Cu--O films on (100) SrTiO{sub 3} and (100) MgO substrates by KrF excimer-laser light projection was investigated. Three different regimes of laser-material interactions were observed. Transition temperatures and critical current densities in laser-fabricated strip lines were investigated.

  8. Rare Hadronic and Radiative Penguin B Decays at BaBar

    SciTech Connect

    Willocq, Stephane

    2002-02-07

    We report recent results in the study of rare hadronic and radiative penguin decays of B mesons. These results are based on a sample of 23 million BB pairs collected by the BaBar Collaboration at the SLAC PEP-II e+e- B Factory.

  9. Magnetism of BaFe2Se3 studied by Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Komędera, K.; Jasek, A. K.; Błachowski, A.; Ruebenbauer, K.; Piskorz, M.; Żukrowski, J.; Krztoń-Maziopa, A.; Pomjakushina, E.; Conder, K.

    2015-04-01

    The compound BaFe2Se3 (Pnma) has been synthesized in the form of single crystals with the average composition Ba0.992Fe1.998Se3. The Mössbauer spectroscopy used for investigation of the valence states of Fe in this compound at temperature ranging from 4.2 K till room temperature revealed the occurrence of mixed-valence state for iron. The spectrum is characterized by sharply defined electric quadrupole doublet above magnetic ordering at about 250 K. For the magnetically ordered state one sees four iron sites at least and each of them is described by separate axially symmetric electric field gradient tensor with the principal component making some angle with the hyperfine magnetic field. They form two groups occurring in equal abundances. It is likely that each group belongs to separate spin ladder with various tilts of the FeSe4 tetrahedral units along the ladder. Two impurity phases are found, i.e., superconducting FeSe and some other unidentified iron-bearing phase being magnetically disordered above 80 K. Powder form of BaFe2Se3 is unstable in contact with the air and decomposes slowly to this unidentified phase exhibiting almost the same quadrupole doublet as BaFe2Se3 above magnetic transition temperature.

  10. Superconductivity in 122-type antimonide BaPt2Sb2

    NASA Astrophysics Data System (ADS)

    Imai, Motoharu; Ibuka, Soshi; Kikugawa, Naoki; Terashima, Taichi; Uji, Shinya; Yajima, Takeshi; Kageyama, Hiroshi; Hase, Izumi

    2015-01-01

    The crystal structure, superconducting properties, and electronic structure of the novel superconducting 122-type antimonide BaPt2Sb2 have been studied by measurements of powder x-ray diffraction patterns, electrical resistivity, ac magnetic susceptibility, specific heat, and by ab initio calculations. The material crystallizes in a new monoclinic variant of the CaBe2Ge2 -type structure, in which Pt2Sb2 layers that consist of PtSb4 tetrahedra, and Sb2Pt2 layers that consist of SbPt4 tetrahedra, are stacked alternatively, with Ba atoms located between them. Measurements of electrical resistivity, ac magnetic susceptibility, and specific heat revealed that BaPt2Sb2 is a superconducting material with a critical temperature of 1.8 K. The electronic heat capacity coefficient and the Debye temperature were 8.6 (2 )mJ /mol K2 and 146(4) K, respectively. The upper critical field and the Ginzburg-Landau coherent length were determined to be 0.27 T and 35 nm, respectively. The calculations showed that the material has two three-dimensional Fermi surfaces (FSs) and two two-dimensional FSs, leading to anisotropic transport properties. The d states of the Pt atoms in the Pt2Sb2 layers are the main contributors to the density of states at the Fermi level. A comparison between experimental and calculated results indicates that BaPt2Sb2 is a superconducting material with moderate coupling.

  11. Ba STARS AND OTHER BINARIES IN FIRST AND SECOND GENERATION STARS IN GLOBULAR CLUSTERS

    SciTech Connect

    D'Orazi, Valentina; Gratton, Raffaele; Lucatello, Sara; Carretta, Eugenio; Bragaglia, Angela; Marino, Anna F.

    2010-08-20

    The determination of the Ba abundance in globular cluster (GC) stars is a very powerful test to address several issues in the framework of multiple population scenarios. We measured the Ba content for a sample of more than 1200 stars in 15 Galactic GCs, using high-resolution FLAMES/Giraffe spectra. We found no variation in [Ba/Fe] ratios for different stellar populations within each cluster; this means that low-mass asymptotic giant branch stars do not significantly contribute to the intracluster pollution. Very interestingly, we found that the fraction of Ba stars in first generation (FG) stars is close to the values derived for field stars ({approx}2%); on the other hand, second generation (SG) stars present a significantly lower fraction. An independent and successful test, based on radial velocity variations among giant stars in NGC 6121, confirms our finding: the binary fraction among FG stars is about {approx}12%, to be compared with {approx}1% of SG stars. This is an evidence that SG stars formed in a denser environment, where infant mortality of binary systems was particularly efficient.

  12. Efficiency of Iranian Translation Syllabus at BA Level; Deficiency: A New Comprehensive Model

    ERIC Educational Resources Information Center

    Sohrabi, Sarah; Rahimi, Ramin; Arjmandi, Masoume

    2015-01-01

    This study aims at investigating the practicality of the current curriculum for translation studies at national level (Iranian curriculum). It is going to have a comprehensive idea of translation students and teachers (university lecturers) over the current translation syllabus at BA level in Iran. A researcher-made CEQ questionnaire (Curriculum…

  13. Characterization of AmiBA2446, a Novel Bacteriolytic Enzyme Active against Bacillus Species

    PubMed Central

    Mehta, Krunal K.; Paskaleva, Elena E.; Azizi-Ghannad, Saba; Ley, Daniel J.; Page, Martin A.

    2013-01-01

    There continues to be a need for developing efficient and environmentally friendly treatments for Bacillus anthracis, the causative agent of anthrax. One emerging approach for inactivation of vegetative B. anthracis is the use of bacteriophage endolysins or lytic enzymes encoded by bacterial genomes (autolysins) with highly evolved specificity toward bacterium-specific peptidoglycan cell walls. In this work, we performed in silico analysis of the genome of Bacillus anthracis strain Ames, using a consensus binding domain amino acid sequence as a probe, and identified a novel lytic enzyme that we termed AmiBA2446. This enzyme exists as a homodimer, as determined by size exclusion studies. It possesses N-acetylmuramoyl-l-alanine amidase activity, as determined from liquid chromatography-mass spectrometry (LC-MS) analysis of muropeptides released due to the enzymatic digestion of peptidoglycan. Phylogenetic analysis suggested that AmiBA2446 was an autolysin of bacterial origin. We characterized the effects of enzyme concentration and phase of bacterial growth on bactericidal activity and observed close to a 5-log reduction in the viability of cells of Bacillus cereus 4342, a surrogate for B. anthracis. We further tested the bactericidal activity of AmiBA2446 against various Bacillus species and demonstrated significant activity against B. anthracis and B. cereus strains. We also demonstrated activity against B. anthracis spores after pretreatment with germinants. AmiBA2446 enzyme was also stable in solution, retaining its activity after 4 months of storage at room temperature. PMID:23872558

  14. Evidence of low dimensional ion transport in mechanosynthesized nanocrystalline BaMgF4.

    PubMed

    Preishuber-Pflügl, F; Wilkening, M

    2014-07-14

    Mechanochemical milling provides a versatile method for the preparation of nano-sized, defect rich, polycrystalline materials. If ionic materials are considered, the transport parameters of the mobile ions may greatly differ from those of the microcrystalline counterparts prepared by conventional synthesis routes. Little is known about ionic conduction in nanocrystalline materials having crystal structures that offer spatially confined transport pathways. Here, we focused on mechanosynthesized BaMgF4 that combines both nanocrystallinity and anisotropic F(-) transport. The preparation of nanocrystalline BaMgF4 is presented as a facile and rapid one-pot procedure. The reaction was followed by X-ray diffraction and high-resolution (19)F nuclear magnetic resonance (NMR) spectroscopy. NMR helped prove the formation of X-ray amorphous compounds as well as the transformation of the starting materials into the final product BaMgF4. Most importantly, besides enhanced conduction properties compared to a single crystal, our broadband impedance spectra reveal characteristics pointing to anisotropic (low dimensional) ion transport processes even in the nanocrystalline form of BaMgF4.

  15. Atomic and electronic structure of the ferroelectric BaTiO{sub 3}/Ge(001) interface

    SciTech Connect

    Fredrickson, Kurt D.; Ponath, Patrick; Posadas, Agham B.; Demkov, Alexander A.; McCartney, Martha R.; Smith, David J.; Aoki, Toshihiro

    2014-06-16

    In this study, we demonstrate the epitaxial growth of BaTiO{sub 3} on Ge(001) by molecular beam epitaxy using a thin Zintl template buffer layer. A combination of density functional theory, atomic-resolution electron microscopy and in situ photoemission spectroscopy is used to investigate the electronic properties and atomic structure of the BaTiO{sub 3}/Ge interface. Aberration-corrected scanning transmission electron micrographs reveal that the Ge(001) 2 × 1 surface reconstruction remains intact during the subsequent BaTiO{sub 3} growth, thereby enabling a choice to be made between several theoretically predicted interface structures. The measured valence band offset of 2.7 eV matches well with the theoretical value of 2.5 eV based on the model structure for an in-plane-polarized interface. The agreement between the calculated and measured band offsets, which are highly sensitive to the detailed atomic arrangement, indicates that the most likely BaTiO{sub 3}/Ge(001) interface structure has been identified.

  16. Lattice dynamics study of scheelite tungstates under high pressure I. BaWO4

    NASA Astrophysics Data System (ADS)

    Manjón, F. J.; Errandonea, D.; Garro, N.; Pellicer-Porres, J.; Rodríguez-Hernández, P.; Radescu, S.; López-Solano, J.; Mujica, A.; Muñoz, A.

    2006-10-01

    Room-temperature Raman scattering has been measured in barium tungstate (BaWO4) up to 16GPa . We report the pressure dependence of all the Raman active first-order phonons of the tetragonal scheelite phase ( BaWO4-I , space group I41/a ), which is stable at normal conditions. As pressure increases the Raman spectrum undergoes significant changes around 6.9GPa due to the onset of the structural phase transition to the monoclinic BaWO4-II phase (space group P21/n ). This transition is only completed above 9.5GPa . A further change in the spectrum is observed at 7.5GPa related to a scheelite-to-fergusonite transition. The scheelite, BaWO4-II , and fergusonite phases coexist up to 9.0GPa due to the sluggishness of the I→II phase transition. Further to the experimental study, we have performed ab initio lattice dynamics calculations that have greatly helped us in assigning and discussing the pressure behavior of the observed Raman modes of the three phases.

  17. Structure and physical properties of the layered iron oxychalcogenide BaFe2Se2O

    NASA Astrophysics Data System (ADS)

    Lei, Hechang; Ryu, Hyejin; Ivanovski, V.; Warren, J. B.; Frenkel, A. I.; Cekic, B.; Yin, Wei-Guo; Petrovic, C.

    2012-11-01

    We have successfully synthesized a layered iron oxychalcogenide BaFe2Se2O single crystal. This compound is built up of Ba and Fe-Se(O) layers alternatively stacked along the c axis. The Fe-Se(O) layers contain double chains of edge-shared Fe-Se(O) tetrahedra that propagate along the b axis and are bridged by oxygen along the a axis. Physical property measurements indicate that BaFe2Se2O is a semiconductor without the Curie-Weiss behavior up to 350 K. There is a possible long-range antiferromagnetic transition at 240 K, corresponding to the peak in specific-heat measurement, and two transitions at 115 K and 43 K where magnetic susceptibility drops abruptly. The magnetic entropy up to 300 K is much smaller than the expected value for Fe2+ in tetrahedral crystal fields and the Mössbauer spectrum indicates that long-range magnetic order is unlikely at 294 K. Our results suggest that BaFe2Se2O is a magnetic insulator at the borderline between a long-range antiferromagnetic spin ordering and possible spin dimerization.

  18. Cultural Conflict in the Novels of Two African Writers, Mariama Ba and Aminata Sow Fall.

    ERIC Educational Resources Information Center

    Stringer, Susan

    1988-01-01

    Literature by African women has a social function. Popular topics are colonialism, feminism, and culture conflict. The works of two Senegalese writers, Ba and Sow Fall, are described and compared. They recognize conflict, but they also write about less obvious social influences and recognize that social change can be beneficial. (VM)

  19. Large miscibility gap in the Ba(MnxFe1-x)2As2 system

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    The compounds BaMn2As2 and BaFe2As2 both crystallize in the body-centered-tetragonal ThCr2Si2-type (122-type) structure at room temperature but exhibit quite different unit cell volumes and very different magnetic and electronic transport properties. Evidently reflecting these disparities, we have discovered a large miscibility gap in the system Ba(MnxFe1-x)2As2. Rietveld refinements of powder x-ray diffraction (XRD) measurements on samples slow-cooled from 1000 °C to room temperature (RT) reveal a two-phase mixture of BaMn2As2 and Ba(Mn0.12Fe0.88)2As2 phases together with impurity phases for x=0.2, 0.4, 0.5, 0.6, and 0.8. We infer that there exists a miscibility gap in this system at 300 K with composition limits 0.12≲x≲1. For samples quenched from 1000 °C to 77 K, the refinements of RT XRD data indicate that the miscibility gap at RT narrows at 1000 °C to 0.2≲x≲0.8. Samples with x=0.4, 0.5, and 0.6 quenched from 1100 to 1400 °C to 77 K contain a single 122-type phase together with significant amounts of Fe1-xMnxAs and FeAs2 impurity phases. These results indicate that the system is not a pseudobinary system over the whole composition range and that the 122-type phase has a significant homogeneity range at these temperatures. Magnetic susceptibility χ, electrical resistivity ρ, and heat capacity measurements versus temperature T of the single-phase quenched polycrystalline samples with x=0.2 and 0.8 are reported. We also report attempts to grow single crystals of the substituted compounds Ba(Mn1-xTx)2As2 (T = Cr, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, and Pt) and BaMn2(As1-xSbx)2 out of Sn flux. Energy-dispersive x-ray analyses show that most of these elements do not substitute into the lattice in amounts greater than 0.5%. However, concentrations of 4.4%, ~10% and 2.6% were achieved for Cr, Fe, and Sb substitutions, respectively, and χ(T) and ρ(T) data for these crystals are presented.

  20. Ba-rich sanidine megacrysts in trachytic rocks of Eslamy volcano, NW Iran

    NASA Astrophysics Data System (ADS)

    Aßbichler, Donjá; Asadpour, Manijeh; Heuss-Aßbichler, Soraya; Kunzmann, Thomas

    2016-04-01

    The Eslamy volcano is located on a peninsula at the eastern coast of Urumieh lake, NW Iran. The complex stratovolcano with gentle slope flanks exposes a collapsed caldera in the central part. Specific features are different sanidine rich rocks that occur in form of ejecta and flows. According to the field observations they are products of one volcanic event. XRF measurements show they all have trachytic compositions. Typical for this locality are the large sanidine phenocrysts. In the trachytic flow the sanidine crystals reach average size of ~4 cm embedded in a greenish-blue matrix consisting mainly of crystallized feldspar and subordinate pyroxen. Occasionally feldspar megacrysts of approx. 10 cm were observed. Na content of the sanidine megacrysts varies between 0.05 - 0.5 pfu with higher concentrations in the cores. Furthermore they show oscillatory zoning patterns caused by variations of Ba content (0-0.04 pfu). The matrix of the trachytic flow consist mainly of interlocking sanidine crystals (0.05-0.45 pfu Na) partly with Ba-rich cores containing up to 0.06 pfu Ba. In contrast to the megacrysts they show slightly higher Fe contents (0.025-0.035 pfu). The volcanic ejecta with bombs of approx. 50 cm in size were found in one distinct layer within a pyroclastic horizon. The average diameter of the feldspar phenocrysts is much smaller (0.5-2 cm). Sanidine is the main phase of these rocks (up to 80 %). As mafic phase up to 30 % pyroxen (mainly diospide) ± biotite can be observed. Accessories are magnetite ± apatite ± titanite ± zircon. In contrast to the flow rocks the main phase of the matrix of the ejecta is always glass with higher Fe2O3 (total) contents (up to 6 wt.-%) indicating a fast cooling of the sample due to ejection. They are completely depleted in Ba. In two samples zoned feldspar relicts enclosed in glass show remolten rims. Similar to flow rocks the feldspar phenocrysts of all ejecta show a complex zoning pattern, e.g. three samples expose high

  1. Clathrate Ba8Au16P30: the "gold standard" for lattice thermal conductivity.

    PubMed

    Fulmer, James; Lebedev, Oleg I; Roddatis, Vladimir V; Kaseman, Derrick C; Sen, Sabyasachi; Dolyniuk, Juli-Anna; Lee, Kathleen; Olenev, Andrei V; Kovnir, Kirill

    2013-08-21

    A novel clathrate phase, Ba8Au16P30, was synthesized from its elements. High-resolution powder X-ray diffraction and transmission electron microscopy were used to establish the crystal structure of the new compound. Ba8Au16P30 crystallizes in an orthorhombic superstructure of clathrate-I featuring a complete separation of gold and phosphorus atoms over different crystallographic positions, similar to the Cu-containing analogue, Ba8Cu16P30. Barium cations are trapped inside the large polyhedral cages of the gold-phosphorus tetrahedral framework. X-ray diffraction indicated that one out of 15 crystallographically independent phosphorus atoms appears to be three-coordinate. Probing the local structure and chemical bonding of phosphorus atoms with (31)P solid-state NMR spectroscopy confirmed the three-coordinate nature of one of the phosphorus atomic positions. High-resolution high-angle annular dark-field scanning transmission electron microscopy indicated that the clathrate Ba8Au16P30 is well-ordered on the atomic scale, although numerous twinning and intergrowth defects as well as antiphase boundaries were detected. The presence of such defects results in the pseudo-body-centered-cubic diffraction patterns observed in single-crystal X-ray diffraction experiments. NMR and resistivity characterization of Ba8Au16P30 indicated paramagnetic metallic properties with a room-temperature resistivity of 1.7 mΩ cm. Ba8Au16P30 exhibits a low total thermal conductivity (0.62 W m(-1) K(-1)) and an unprecedentedly low lattice thermal conductivity (0.18 W m(-1) K(-1)) at room temperature. The values of the thermal conductivity for Ba8Au16P30 are significantly lower than the typical values reported for solid crystalline compounds. We attribute such low thermal conductivity values to the presence of a large number of heavy atoms (Au) in the framework and the formation of multiple twinning interfaces and antiphase defects, which are effective scatterers of heat-carrying phonons.

  2. Glassy and Metastable Crystalline BaTi2O5 by Containerless Processing

    NASA Astrophysics Data System (ADS)

    Yoda, Shinichi; Kentei Yu, Yu; Kumar, Vijaya; Kameko, Masashi

    Many efforts have been devoted to forming bulk glass from the melt of ferroelectric crystalline materials without adding any network-forming oxides such as SiO2 due to the potential for producing transparent glass ceramics with high dielectric constant and enhanced piezoelectric, pyroelectric and electro-optic use. The containerless processing is an attractive synthesis tech-nique as it can prevent melt contamination, minimize heterogeneous nucleation, and allow melt to achieve deep undercooling for forming metastable and glassy materials. We have fabricated a new ferroelectric materiel BaTi2 O5 [1] as bulk glass from melt by us-ing containerless processing and studied the phase relationship between microstructure and ferroelectric properties of BaTi2 O5 [2]. The structures of glassy and metastable crystalline BaTi2 O5 fabricated by the containerless pro-cessing were comprehensively investigated by combined X-ray and neutron diffractions, XANES analyses and computer simulations [3]. The 3-dimensional atomic structure of glassy BaTi2 O5 (g-BaTi2 O5 ), simulated by Reverse Monte Carlo (RMC) modelling on diffraction data, shows that extremely distorted TiO5 polyhedra interconnected with both corner-and edge-shared oxy-gen, formed a higher packing density structure than that of conventional silicate glass linked with only corner-sharing of SiO4 polyhedra. In addition, XANES measurement reveales that five-coordinated TiO5 polyhedra were formable in the crystallized metastable a-and b-BaTi2 O5 phases. The structure of metastable b-BaTi2 O5 was solved by ab initio calculation, and refined by Rietveld refinement as group Pnma with unit lattices a = 10.23784 ˚, b = 3.92715 ˚, c A A = 10.92757 A ˚. Our results show that the glass-forming ability enhanced by containerless pro-cessing, not by `strong glass former', fabricated new bulk oxide glasses with peculiar structures and properties. The intermediate-range structure of g-BaTi2 O5 and the crystalline structure of

  3. Influence of metal ions on the order-disorder transition temperature of the Ba-M-O (M: La, Y, In, or Ga) system

    SciTech Connect

    Mitamura, Takashi; Ogino, Hiroyuki; Kobayashi, Hidehiko . Dept. of Applied Chemistry); Mori, Toshiyuki; Yamamura, Hiroshi . Tsukuba Research Lab.)

    1993-08-01

    Preparation of BaLa[sub 2]O[sub 4], Ba[sub 3]Y[sub 4]O[sub 9], Ba[sub 2]In[sub 2]O[sub 5], and Ba[sub 3]Ga[sub 2]O[sub 6] powders and their sintering were investigated in Ar or air. These sintered bodies with perovskite-related structure were synthesized by reaction sintering, using mixed powders in the atomic ratios of Ba/La = 1, Ba/Y = 0.75, Ba/In = 1, and Ba/Ga = 1.5. The order-disorder transition temperatures of the BaLa[sub 2]O[sub 4], Ba[sub 3]Y[sub 4]O[sub 9], Ba[sub 2]In[sub 2]O[sub 5], and Ba[sub 3]Ga[sub 2]O[sub 6], sintered bodies were 270, 350, 880, and 1,230 C, respectively. It was found that the temperatures were influenced by the ionic radius of cations in B sites, and the transition temperatures decreased with increasing ionic radius.

  4. Syntheses, structures, and optical properties of Ba{sub 4}MInSe{sub 6} (M=Cu, Ag)

    SciTech Connect

    Yin Wenlong; Feng Kai; Hao Wenyu; Yao Jiyong; Wu Yicheng

    2012-08-15

    Two new quaternary chalcogenides, namely Ba{sub 4}MInSe{sub 6} (M=Cu, Ag), were synthesized by solid state reactions. These two isostructural compounds adopt the Ba{sub 2}MnS{sub 3} structure type in the orthorhombic space group Pnma. In the structure, the M and In atoms randomly occupy one crystallographic unique metal position with the molar ratio of 1:1 The (M/In)Se{sub 4} tetrahedra are connected to each other by corner-sharing to form one-dimensional chains along the b direction, which are separated by mono-capped trigonal prismatically coordinated Ba atoms. Based on the diffuse reflectance spectrum, the optical band gaps were determined to be 2.23(2) and 2.41(2) eV for Ba{sub 4}CuInSe{sub 6} and Ba{sub 4}AgInSe{sub 6}, respectively. - Graphical abstract: In the structure of Ba{sub 4}MInSe{sub 6} (M=Cu, Ag), the (M/In)Se{sub 4} tetrahedra are connected by corner-sharing to form chains along the b direction, which are separated by Ba atoms. Highlights: Black-Right-Pointing-Pointer Two new quaternary chalcogenides, Ba{sub 4}MInSe{sub 6} (M=Cu, Ag), were synthesized. Black-Right-Pointing-Pointer Ba{sub 4}MInSe{sub 6} (M=Cu, Ag) are isostructural and crystallize in the Ba{sub 2}MnS{sub 3} structure type Black-Right-Pointing-Pointer The (M/In)Se{sub 4} tetrahedra are connected by corner-sharing to form chains along the b direction. Black-Right-Pointing-Pointer The chains are separated by mono-capped trigonal prismatically coordinated Ba atoms. Black-Right-Pointing-Pointer The optical band gaps are 2.23(2) and 2.41(2) eV for Ba{sub 4}CuInSe{sub 6} and Ba{sub 4}AgInSe{sub 6}, respectively.

  5. Magnetic behaviour of the MTbF{sub 6} fluoroterbates (M=Cd, Ca, Sr, ({alpha}/{beta})-Ba)

    SciTech Connect

    Josse, M.; El-Ghozzi, M.; Avignant, D.; Andre, G.; Bouree, F.; Isnard, O.

    2012-01-15

    Neutron powder diffraction has been performed on the MTbF{sub 6} fluorides (M=Cd, Ca, Sr, ({alpha}/{beta})-Ba). Four of these fluorides (Cd, Ca, Sr, {beta}-Ba) are built of a (pseudo-) tetragonal packing of [TbF{sub 6}]{sup 2-} chains and only differs by the chains relative orientations. Thus this series represents a valuable opportunity to evaluate the Tb{sup 4+}-Tb{sup 4+} magnetic interactions. All the compounds displayed antiferromagnetic order (T{sub N}=2.70 K (Cd), 2.15 K (Ca), 2.60 K (Sr), 2.10 K ({beta}-Ba)), except for the {alpha} form of BaTbF{sub 6}. The crystal structure of this latter fluoroterbate has also been investigated by means of high-resolution neutron powder diffraction. From Neutron Powder Diffraction data, CdTbF{sub 6} and {beta}-BaTbF{sub 6} magnetic structures were determined, together with the metamagnetic behaviour of {beta}-BaTbF{sub 6} as a function of an external magnetic field. A tentative phase diagram is then given for {beta}-BaTbF{sub 6}. Advantage was taken of the polymorphism of the BaTbF{sub 6} fluoroterbate to analyse, on the basis of topological parameters such as bond distances and angles, the magnetic behaviour of its {alpha} and {beta} forms. It was shown that superexchange interactions are present in {beta}-BaTbF{sub 6}, and that these interactions may also rule the magnetic behaviour of the other MTbF{sub 6} (M=Ca, Sr, Cd) tetravalent terbium fluorides. - Graphical abstract: Powder neutron diffraction revealed magnetic order in four of the five investigated fluoroterbates, while crystal chemical analyses of {alpha} and {beta} forms of BaTbF{sub 6} evidenced the existence of superexchange interactions. Highlights: Black-Right-Pointing-Pointer Five fluoroterbates are investigated by Powder Neutron Diffraction (PND). Black-Right-Pointing-Pointer Four of them are antiferromagnetically ordered at 1.4 K. Black-Right-Pointing-Pointer Magnetic structures of {beta}-BaTbF{sub 6} and CdTbF{sub 6} are determined. Black

  6. Melt growth and properties of bulk BaSnO3 single crystals.

    PubMed

    Galazka, Z; Uecker, R; Irmscher, K; Klimm, D; Bertram, R; Kwasniewski, A; Naumann, M; Schewski, R; Pietsch, M; Juda, U; Fiedler, A; Albrecht, M; Ganschow, S; Markurt, T; Guguschev, C; Bickermann, M

    2017-02-22

    We present the first-time growth of bulk BaSnO3 single crystals from the melt by direct solidification, their basic electrical and optical properties as well as their structural quality. Our measurement of the melting point (MP) of BaSnO3 amounts to 1855 °C  ±  25 K. At this temperature an intensive decomposition and non-stoichiometric evaporation takes place as the partial pressure of SnO(g) is about 90 times higher than that of BaO(g). X ray powder diffraction identified only the BaSnO3 perovskite phase, while narrow rocking curves having a full width at half maximum of 26 arcsec and etch pit densities below 10(6) cm(-2) confirm a high degree of structural perfection of the single crystals. In this respect they surpass the structural properties of those single crystals that were reported in the literature. The electrical conductivity of nominally undoped crystals depends on the growth conditions and ranges from insulating to medium n-type conductivity. After post-growth annealing in an oxidizing atmosphere undoped crystals are generally insulating. Doping the crystals with lanthanum during growth results in a high n-type conductivity. For a La doping concentration of 0.123 wt.% we measured an electron concentration of 3.3  ×  10(19) cm(-3) and an electron mobility of 219 cm(2) V(-1) s(-1). Based on optical absorption measurements we determined an energy of 3.17  ±  0.04 eV at 5 K and of 2.99  ±  0.04 eV at 297 K for the indirect band gap of BaSnO3.

  7. Clock distribution for BaF2 readout electronics at CSNS-WNS

    NASA Astrophysics Data System (ADS)

    He, Bing; Cao, Ping; Zhang, De-Liang; Wang, Qi; Zhang, Ya-Xi; Qi, Xin-Cheng; An, Qi

    2017-01-01

    A BaF2 (Barium Fluoride) detector array is designed to precisely measure the (n, γ) cross section at the CSNS-WNS (white neutron source at China Spallation Neutron Source). It is a 4π solid angle-shaped detector array consisting of 92 BaF2 crystal elements. To discriminate signals from the BaF2 detector, a pulse shape discrimination method is used, supported by a waveform digitization technique. There are 92 channels for digitizing. The precision and synchronization of clock distribution restricts the performance of waveform digitizing. In this paper, a clock prototype for the BaF2 readout electronics at CSNS-WNS is introduced. It is based on the PXIe platform and has a twin-stage tree topology. In the first stage, clock is synchronously distributed from the tree root to each PXIe crate through a coaxial cable over a long distance, while in the second stage, the clock is further distributed to each electronic module through a PXIe dedicated differential star bus. With the help of this topology, each tree node can fan out up to 20 clocks with 3U size. Test results show the clock jitter is less than 20 ps, which meets the requirements of the BaF2 readout electronics. Besides, this clock system has the advantages of high density, simplicity, scalability and cost saving, so it can be useful for other clock distribution applications. Supported by National Research and Development plan (2016 YFA0401602) NSAF (U1530111) and National Natural Science Foundation of China (11005107)

  8. Soy molasses as fermentation substrate for production of butanol using Clostridium beijerinckii BA101.

    PubMed

    Qureshi, N; Lolas, A; Blaschek, H P

    2001-05-01

    Spray-dried soy molasses (SDSM) contains the sugars dextrose, sucrose, fructose, pinitol, raffinose, verbascose, melibiose, and stachyose. Of the 746 g kg(-1) total sugars in SDSM, 434 g kg(-1) is fermentable using Clostridium beijerinckii BA101. SDSM was used to produce acetone, butanol, and ethanol (ABE) by C. beijerinckii BA101 in batch cultures. Using 80 g l(-1) SDSM, 10.7 g l(-1) ABE was produced in P2 medium. Higher concentrations of SDSM resulted in poor solvent production due to the presence of excessive salt and inhibitory components. C. beijerinckii BA101 in SDSM at 80 g l(-1) concentration produced 22.8 g l(-1) ABE when supplemented with 25.3 g l(-1) glucose. SDSM contains 57.4 g kg(-1) mineral ash and 2% tri-calcium phosphate. Tri-calcium phosphate up to 43.1 g l(-1) was not inhibitory and at a tri-calcium phosphate concentration of 28.8 g l(-1), the culture produced more solvents (30.1 g l(-1)) than the control experiment (23.8 g l(-1)). In contrast, sodium chloride was a strong inhibitor of C. beijerinckii BA101 cell growth. At a concentration of 10 g l(-1) sodium chloride, a maximum cell concentration of 0.6 g l(-1) was achieved compared to 1.7 g l(-1) in the control experiment. The effects of two salts on specific growth rate constant (mu) and specific rate of ABE production (nu) for C. beijerinckii BA101 were examined.

  9. SIRT1 controls liver regeneration by regulating BA metabolism through FXR and mTOR signaling

    PubMed Central

    García-Rodríguez, Juan L.; Barbier-Torres, Lucía; Fernández-Álvarez, Sara; Juan, Virginia Gutiérrez-de; Monte, María J.; Halilbasic, Emina; Herranz, Daniel; Álvarez, Luis; Aspichueta, Patricia; Marín, Jose J. G.; Trauner, Michael; Mato, Jose M.; Serrano, Manuel; Beraza, Naiara; Martínez-Chantar, María Luz

    2014-01-01

    Sirtuin1 (SIRT1) regulates central metabolic functions such as lipogenesis, protein synthesis, gluconeogenesis and bile acid (BA) homeostasis through deacetylation. Here, we describe that SIRT1 tightly controls the regenerative response of the liver. We performed partial hepatectomy (PH) to transgenic mice that overexpress SIRT1 (SIRT). SIRT mice showed increased mortality, impaired hepatocyte proliferation, BA accumulation and profuse liver injury after surgery. The damaging phenotype in SIRT mice correlated with impaired FXR activity due to persistent deacetylation and lower protein expression that led to decreased FXR-target gene expression; SHP, BSEP and increased Cyp7A1. Next, we convincingly show that 24-norUrsodeoxycholic acid (NorUDCA) attenuates SIRT protein expression, increases the acetylation of FXR and neighboring histones, restores trimethylation of H3K4 and H3K9 and increases miR34a expression, thus re-establishing BA homeostasis. Consequently, NorUDCA restored liver regeneration in SIRT mice, which showed increased survival and hepatocyte proliferation. Furthermore, a Leucine-enriched diet restored mTOR activation, acetylation of FXR and histones, leading to an overall lower BA production through SHP-inhibition of Cyp7A1 and higher transport (BSEP) and detoxification (Sult2a1) leading to an improved liver regeneration. Finally, we found that human HCC samples have increased presence of SIRT1, which correlated with absence of FXR suggesting its oncogenic potential. Conclusions Overall, we define SIRT1 as a key regulator of the regenerative response in the liver through post-transcriptional modifications that regulate the activity of FXR, histones and mTOR. Moreover, our data suggest that SIRT1 contributes to liver tumorigenesis through dysregulation of BA homeostasis by persistent FXR deacetylation. PMID:24338587

  10. Melt growth and properties of bulk BaSnO3 single crystals

    NASA Astrophysics Data System (ADS)

    Galazka, Z.; Uecker, R.; Irmscher, K.; Klimm, D.; Bertram, R.; Kwasniewski, A.; Naumann, M.; Schewski, R.; Pietsch, M.; Juda, U.; Fiedler, A.; Albrecht, M.; Ganschow, S.; Markurt, T.; Guguschev, C.; Bickermann, M.

    2017-02-01

    We present the first-time growth of bulk BaSnO3 single crystals from the melt by direct solidification, their basic electrical and optical properties as well as their structural quality. Our measurement of the melting point (MP) of BaSnO3 amounts to 1855 °C  ±  25 K. At this temperature an intensive decomposition and non-stoichiometric evaporation takes place as the partial pressure of SnO(g) is about 90 times higher than that of BaO(g). X ray powder diffraction identified only the BaSnO3 perovskite phase, while narrow rocking curves having a full width at half maximum of 26 arcsec and etch pit densities below 106 cm-2 confirm a high degree of structural perfection of the single crystals. In this respect they surpass the structural properties of those single crystals that were reported in the literature. The electrical conductivity of nominally undoped crystals depends on the growth conditions and ranges from insulating to medium n-type conductivity. After post-growth annealing in an oxidizing atmosphere undoped crystals are generally insulating. Doping the crystals with lanthanum during growth results in a high n-type conductivity. For a La doping concentration of 0.123 wt.% we measured an electron concentration of 3.3  ×  1019 cm-3 and an electron mobility of 219 cm2 V-1 s-1. Based on optical absorption measurements we determined an energy of 3.17  ±  0.04 eV at 5 K and of 2.99  ±  0.04 eV at 297 K for the indirect band gap of BaSnO3.

  11. Optical and impedance studies of pure and Ba-doped ZnS quantum dots

    NASA Astrophysics Data System (ADS)

    Firdous, Arfat; Baba, M. Aslam; Singh, D.; Bhat, Abdul Hamid

    2015-02-01

    Chemical precipitation method using a high-boiling solvent is used to synthesize ZnS and Ba-doped ZnS quantum dots. The presence of organic ligands in the prepared nanostructures is verified using Fourier transform infra-red spectroscopic studies. The samples have been analysed using X-ray diffraction analysis confirming nanocrystallinity of the as-prepared quantum dots (QD). The mean crystal size obtained by full width half maxima analysis is 3.2 nm for ZnS and 3.9, 4.2 nm for ZnS:Ba (2, 4 mM). TEM micrographs also reveal nanosized particles of ZnS and Ba-doped ZnS. An optical absorption study conducted in UV-Vis range 150-600 nm reveals the transparency of these quantum dots in entire visible range but not in ultraviolet range. The results based on optical analysis yield band gap values as 4.88 eV for ZnS and 4.69, 4.43 eV for ZnS:Ba (2, 4 mM) quantum dots. Impedance analysis of the samples was carried out to reveal the variation of impedance with frequency at room temperature. These results show the capacitive admittance associated with the quantum dots and hence nanostructure ZnS and Ba-doped ZnS can have potential applications in electronics as nano-tuned devices in which resonant frequency can be adjusted by controlling the size and shape of the quantum dots.

  12. Microstructure evolution and electrical characterization of Lanthanum doped Barium Titanate (BaTiO3) ceramics

    NASA Astrophysics Data System (ADS)

    Billah, Masum; Ahmed, A.; Rahman, Md. Miftaur; Mahbub, Rubbayat; Gafur, M. A.; Bashar, M. Shahriar

    2016-07-01

    In the current work, we investigated the structural and dielectric properties of Lanthanum oxide (La2O3) doped Barium Titanate (BaTiO3) ceramics and established a correlation between them. Solid state sintering method was used to dope BaTiO3 with 0.3, 0.5 and 0.7 mole% La2O3 under different sintering parameters. The raw materials used were La2O3 nano powder of ~80nm grain size and 99.995% purity and BaTiO3 nano powder of 100nm grain size and 99.99% purity. Grain size distribution and morphology of fracture surface of sintered pellets were examined by Field Emission Scanning Electron Microscope and X-Ray Diffraction analysis was conducted to confirm the formation of desired crystal structure. The research result reveal that grain size and electrical properties of BaTiO3 ceramic significantly enhanced for small amount of doping (up to 0.5 mole% La2O3) and then decreased with increasing doping concentration. Desired grain growth (0.80-1.3 µm) and high densification (<90% theoretical density) were found by proper combination of temperature, sintering parameters and doping concentration. We found the resultant stable value of dielectric constant was 10000-12000 at 100-300 Hz in the temperature range of 30°-50° C for 0.5 mole% La2O3 with corresponding shift of curie temperature around 30° C. So overall this research showed that proper La3+ concentration can control the grain size, increase density, lower curie temperature and hence significantly improve the electrical properties of BaTiO3 ceramics.

  13. Thermodynamic model for the solubility of BaSeO4(cr) in the aqueous Ba2+-SeO42--Na+-H+-OH--H2O system: Extending to high selenate concentrations

    SciTech Connect

    Rai, Dhanpat; Felmy, Andrew R.; Moore, Dean A.; Kitamura, Akira; Yoshikawa, Hideki; Doi, Reisuke; Yoshida, Yasushi

    2014-09-15

    The solubility of Ba(SeO4, SO4) precipitates was determined as a function of the BaSeO4 mole fractions, ranging from 0.0015 to 0.3830, and time with an equilibration period extending to as long as 302 days. Equilibrium/steady state conditions in this system are reached in ≤ 65 days. Pitzer’s ion interaction model was used to calculate solid and aqueous phase activity coefficients. Thermodynamic analyses showed that the data do not satisfy Gibbs-Duhem equation, thereby demonstrating that a single-solid solution phase does not control both the selenate and sulfate concentrations. Our extensive data with log10 [Ba]) ranging from -3.6 to -5.9 mol.kg-1, log10 [SeO4]) ranging from -3.6 to -5.2 mol.kg-1, and log10 [SO4] ranging from -4.0 to -5.3 mol.kg-1 can be explained with the formation of an ideal BaSeO4 solid solution phase that controls the selenium concentrations and a slightly disordered/less-crystalline BaSO4(s) (log10 K0sp = -9.5 instead of -10.05 for barite) that controls the sulfate concentrations. In these experiments the BaSO4 component of the solid solution phase never reaches thermodynamic equilibrium with the aqueous phase. Thermodynamic interpretations of the data show that both the ideal BaSeO4 solid solution phase and less-crystalline BaSO4(s) phase are in equilibrium with each other in the entire range of BaSeO4 mole fractions investigated in this study.

  14. Progressive Barite Distillation at the Costa Rica Convergent Margin: Implications for Ba Contribution to the Arc Volcanoes

    NASA Astrophysics Data System (ADS)

    Solomon, E.; Kastner, M.; Robertson, G.

    2005-12-01

    Convergent margins are areas of intense tectonic activity and dynamic hydrology, thus they are important regions for geochemical cycling between the major reservoirs seawater, oceanic sediment and igneous basement, continental crust, and the mantle. The distillation and loss of some volatiles and fluid-soluble elements, such as Ba, from the shallow subduction zone changes the composition of the slab (sediments and igneous basement) delivered to the depths of magmatism beneath volcanic arcs and, ultimately, the mantle. In margin sediments, Ba is primarily contained in barite that precipitates in water column microenvironments, and is present in biogenic phases such as refractory organic matter and biogenic carbonate, detrital silicates, and Fe-Mn oxyhydroxides. The Ba in silicates is typically immobile during diagenesis; however, in sediments where pore fluid sulfate becomes depleted, barite (BaSO4) dissolves and Ba concentrations rise by several orders of magnitude. In tectonically active regions, like convergent margins, the dissolved Ba can be transported seaward through fluid flow conduits where it is reprecipitated as barite when it reaches sulfate-rich water. The incoming sediment section offshore Costa Rica contains 152 m of hemipelagic sediments (HS) overlying 226 m of pelagic carbonates (PC). This entire sediment section is being underthrust, providing an ideal setting to examine Ba cycling in the shallow levels of the subduction zone. ODP Legs 170 and 205 drilled a transect of 3 boreholes across the Middle America Trench with a reference site seaward of the trench (Site 1039/1253) and two sites landward of the trench that drilled through the margin wedge, the décollement, and the underthrust sediments (Sites 1040/1254, 1043/1255). At Site 1039/1253, sulfate concentrations reach a minimum of ~13 mM within the upper 20 m of the HS and are near seawater value within the PC. At Site 1040/1254, ~1.6 km landward of the trench, sulfate is totally depleted within

  15. The new Hg-rich barium indium mercurides BaInxHg7-x (x=3.1) and BaInxHg11-x (x=0-2.8). Synthesis, crystal and electronic structure

    NASA Astrophysics Data System (ADS)

    Wendorff, Marco; Schwarz, Michael; Röhr, Caroline

    2013-07-01

    The title compounds BaInxHg7-x (x=3.1(1)) and BaInxHg11-x (x=0-2.8) were synthesized from stoichiometric ratios of the elements in Ta crucibles. Their crystal structures have been determined using single crystal X-ray data. BaInxHg7-x (x=3.1(1)) crystallizes in a new structure type (orthorhombic, oC16, space group Cmmm: a=512.02(1), b=1227.68(3), c=668.61(2) pm, Z=2, R1=0.0311). In the structure, the atoms of the three crystallographically different mixed In/Hg positions form planar nets of four-, six- and eight-membered rings. These nets are shifted against each other such that the four-membered rings form empty distorted cubes. The cubes are connected via common edges, corners and folded ladders, which are also found in BaIn2/BaHg2 (KHg2 structure type) and BaIn (α-NaHg type). The Ba atoms are centered in the eight-membered rings and exhibit an overall coordination number of 20. The [BaM20] polyhedra and twice as many distorted [M8] cubes tesselate the space. BaIn2.8Hg8.2 (cubic, cP36, space group Pm3barm, a=961.83(1) pm, Z=3, R1=0.0243) is the border compound of the phase width BaInxHg11-x of the rare BaHg11 structure type. In the structure, ideal [M8] cubes (at the corners of the unit cell) and BaM20 polyhedra (at the edges of the unit cell) represent the building blocks comparable to the other new In mercuride. In accordance with the increased In/Hg content, additional M-pure regions appear: the center of the unit cell contains a huge [Hg(1)M(2)12M(3,4)32] polyhedron, a Hg-centered cuboctahedron of In/Hg atoms surrounded by a capped cantellated cube of 32 additional M atoms. For both structure types, the bonding situation and the ‘coloring’, i.e. the In/Hg distribution of the polyanionic network, are discussed considering the different sizes of the atoms and the charge distribution (Bader AIM charges), which have been calculated within the framework of FP-LAPW density functional theory.

  16. Synthesis and electrical properties of BaBiO 3 and high resistivity BaTiO 3BaBiO 3 ceramics

    SciTech Connect

    Kumar, Nitish; Golledge, Stephen L.; Cann, David P.

    2016-12-01

    Ceramics of the composition BaBiO3 (BB) were sintered in oxygen to obtain a single phase with monoclinic II2/mm symmetry as suggested by high-resolution X-ray diffraction. X-ray photoelectron spectroscopy confirmed the presence of bismuth in two valence states - 3+ and 5+. Optical spectroscopy showed presence of a direct bandgap at ~ 2.2eV and a possible indirect bandgap at ~ 0.9eV. This combined with determination of the activation energy for conduction of 0.25eV, as obtained from ac impedance spectroscopy, suggested that a polaron-mediated conduction mechanism was prevalent in BB. The BB ceramics were crushed, mixed with BaTiO3 (BT), and sintered to obtain BT–BB solid solutions. All the ceramics had tetragonal symmetry and exhibited a normal ferroelectric-like dielectric response. Using ac impedance and optical spectroscopy, it was shown that resistivity values of BT–BB were orders of magnitude higher than BT or BB alone, indicating a change in the fundamental defect equilibrium conditions. A shift in the site occupancy of Bi to the A-site is proposed to be the mechanism for the increased electrical resistivity.

  17. Coincidence recoil-distance Doppler-shift lifetime measurements in {sup 129,130}Ba with EUROBALL Ge cluster detectors

    SciTech Connect

    Stuch, O.; Jessen, K.; Chakrawarthy, R. S.; Dewald, A.; Kuehn, R.; Kruecken, R.; Petkov, P.; Peusquens, R.; Tiesler, H.; Weil, D.

    2000-04-01

    Picosecond lifetimes in {sup 129,130}Ba were determined using the recoil distance technique with a plunger device coupled to an array of EUROBALL-cluster-detectors for the first time. The differential decay curve method in coincidence mode was employed to derive lifetimes for six states in {sup 129}Ba and twelve states in {sup 130}Ba. The resulting B(E2) values are compared with triaxial rotor plus particle calculations for {sup 129}Ba and, in {sup 130}Ba, to the predictions of the general collective model, the interacting boson model, as well as to the symmetric and asymmetric rotor models. In {sup 130}Ba, the transitional quadrupole moment in the ground state band is remarkably constant before and after the backbend. With this data the two-quasiparticle negative parity band in {sup 130}Ba was confirmed to be based on a {pi}(h{sub 11/2}(multiply-in-circle sign)d{sub 5/2}/g{sub 7/2}) configuration. (c) 2000 The American Physical Society.

  18. Structural and antiferromagnetic properties of Ba(Fe1-x-y Cox Rhy)2 As2 compounds

    NASA Astrophysics Data System (ADS)

    Kim, Min Gyu; Heitmann, T. W.; Mulcahy, S. R.; Bourret-Courchesne, E. D.; Birgeneau, R. J.

    We present a systematic investigation of the electrical, structural, and antiferromagnetic properties for the series of Ba(Fe1-x-y CoxRhy)2 As2 compounds with fixed x = 0.027 and 0 < y <0.035. We compare our results for the Co-Rh doped Ba(Fe1-x-y CoxRhy)2 As2 compounds with Ba(Fe 1-xCox)2 As2 compounds. We demonstrate that the electrical, structural, antiferromagnetic, and superconducting properties of the Co-Rh doped compounds are similar to the properties of the Co doped compounds. We find that the overall behaviors of Ba(Fe1-x-y CoxRhy)2 As2 and Ba(Fe1-x Cox)2 As2 compounds are very similar when the total number of the extra electrons per Fe/TM (TM = transition metal) site is considered, which is consistent with the rigid band model. Despite the similarity, we find that the details of the transitions are different in between Ba(Fe1-x-y CoxRhy)2 As2 and Ba(Fe1-x Cox)2 As2 compounds. The work at the Lawrence Berkeley National Laboratory was supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract No. DE-AC02-05CH11231.

  19. HPHT synthesis, structure and electrical properties of type-I clathrates Ba8AlxSi46-x

    NASA Astrophysics Data System (ADS)

    Liu, Binwu; Jia, Xiaopeng; Sun, Hairui; Sun, Bing; Zhang, Yuewen; Liu, Haiqiang; Kong, Lingjiao; Huo, Dexuan; Ma, Hongan

    2016-01-01

    Clathrate compounds Ba8AlxSi46-x were successfully synthesized using the method of high-pressure and high-temperature (HPHT). In this process, we used BaSi2 as one of the starting materials in place of Ba metals, which reduces the complexity of the program caused by the extremely high chemical reactivity. By using this method, the processing time was reduced from few days to an hour. X-ray diffraction and structural refinement indicated this composition crystallized in type-I clathrate phase. Bond length analysis showed the Ba atoms in small dodecahedron had spherical thermal ellipsoids while those in large tetrakaidecahedron displayed anisotropic thermal ellipsoids. The negative Seebeck coefficient indicated transport processes were dominated by electrons as carriers, and increased with the increasing temperature. The electrical properties, including Seebeck coefficient and Power factor, were greatly enhanced by Al substitution. Middle: X-ray Rietveld refinement profile for Ba8Si46 and element mapping for Ba8Al16Si30. Right: Temperature dependence of Seebeck coefficient for Ba8AlxSi46-x prepared by HPHT.

  20. First-Principles Calculation of Solution Energy of Alkaline-Earth Metal Elements to BaTiO3

    NASA Astrophysics Data System (ADS)

    Moriwake, Hiroki; Hirayama, Tsukasa; Ikuhara, Yuichi; Tanaka, Isao

    2007-10-01

    Quantitative analysis of the solution energy of alkaline-earth metal elements to perovskite-type BaTiO3 was carried out by a first-principles calculation combined with thermodynamics theory. The solution energies of neutral solute and a compensated solute with an oxygen vacancy were systematically calculated. They were obtained for two cation sites and four thermodynamical conditions with different chemical potentials of constituent atoms. Both Ca and Sr preferably occupy the Ba site of BaTiO3. On the other hand, Mg occupies the Ti site. This corresponds well to the widely accepted experimental findings regarding site preference. Moreover, under the condition of coexising BaO, CaO and BaTiO3, energy difference between the Ba-site solution and O-vacancy compensated Ti-site solution of Ca ions has been found to be smaller than that of Sr. Under this condition, the O-vacancy compensated Ti-site solution of Ca should be favorable compared with that of Sr. The same number of oxygen vacancies as Ca ions occupying Ti sites can be introduced. This also explains well experimental feature of the Ca-doped BaTiO3-based nonreducible multilayer ceramics capacitor (MLCC) materials regarding solution site of the Ca ion and abundance of O-vacancy.

  1. Quasi-zero lattice mismatch and band alignment of BaTiO{sub 3} on epitaxial (110)Ge

    SciTech Connect

    Hudait, M. K.; Zhu, Y.; Jain, N.; Maurya, D.; Zhou, Y.; Priya, S

    2013-07-14

    Growth, structural, and band alignment properties of pulsed laser deposited amorphous BaTiO{sub 3} on epitaxial molecular beam epitaxy grown (110)Ge layer, as well as their utilization in low power transistor are reported. High-resolution x-ray diffraction demonstrated quasi-zero lattice mismatch of BaTiO{sub 3} on (110)Ge. Cross-sectional transmission electron microscopy micrograph confirms the amorphous nature of BaTiO{sub 3} layer as well as shows a sharp heterointerface between BaTiO{sub 3} and Ge with no traceable interfacial layer. The valence band offset, {Delta}E{sub v}, of 1.99 {+-} 0.05 eV at the BaTiO{sub 3}/(110)Ge heterointerface is measured using x-ray photoelectron spectroscopy. The conduction band offset, {Delta}E{sub c}, of 1.14 {+-} 0.1 eV is calculated using the bandgap energies of BaTiO{sub 3} of 3.8 eV and Ge of 0.67 eV. These band offset parameters for carrier confinement and the interface chemical properties of the BaTiO{sub 3}/(110)Ge system are significant advancement towards designing Ge-based p-and n-channel metal-oxide semiconductor field-effect transistors for low-power application.

  2. Improvement of the performance of microwave X band absorbers based on pure and doped Ba-hexaferrite

    NASA Astrophysics Data System (ADS)

    Seyyed Afghahi, Seyyed Salman; Jafarian, Mojtaba; Salehi, Mohsen; Atassi, Yomen

    2017-01-01

    Optimum Fe/Ba mole ratio is determined in doped Ba-hexaferrite prepared via mechanical activation. X-ray diffractometer (XRD), scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and vector network analyzer are used to analyze phases, structures, electromagnetic and microwave absorption properties. The mole ratio of Fe/Ba=10 is detected to be optimum for doping and synthesizing the Ba-hexaferrite. In order to achieve high absorption in X band the ions of Zr4+-Sn4+-Ti4+-M2+ (M=Mg2+, Zn2+, Cu2+, Co2+) are used as dopants. The results indicate the formation of single phase Ba-hexaferrite in either pure or doped compounds without any non-magnetic intermediate phases and with spherical and hexagonal morphologies respectively for the pure and doped ferrite. It is found out that BaCo2Zr(SnTi)0.5Fe8O19 compound has the maximum saturation magnetization (49.80 emu/g). Also the composite of BaCo2Zr(SnTi)0.5Fe8O19 50 wt% in epoxy resin exhibits a minimum reflection loss of -29 dB at 12.2 GHz with 2.6 GHz bandwidth.

  3. Synthesis, structural and magnetic characterisation of the fully fluorinated compound 6H-BaFeO{sub 2}F

    SciTech Connect

    Clemens, Oliver; Wright, Adrian J.; Berry, Frank J.; Smith, Ronald I.; Slater, Peter R.

    2013-02-15

    The compound 6H-BaFeO{sub 2}F (P6{sub 3}/mmc) was synthesised by the low temperature fluorination of 6H-BaFeO{sub 3-d} using polyvinylidenedifluoride (PVDF) as a fluorination agent. Structural characterisation by XRD and NPD suggests that the local positions of the oxygen and fluorine atoms vary with no evidence for ordering on the anion sites. This compound shows antiferromagnetic ordering at room temperature with antiparallel alignment of the magnetic moments along the c-axis. The use of PVDF also allows the possibility of tuning the fluorine content in materials of composition 6H-BaFeO{sub 3-d}F{sub y} to any value of 0BaFeO{sub 2}F. Highlights: Black-Right-Pointing-Pointer The crystal structure of the hexagonal perovskite phase 6H-BaFeO{sub 2}F. Black-Right-Pointing-Pointer H-BaFeO{sub 2}F and 6H-BaFeO{sub 3-d}F{sub y} were prepared via low temperature fluorination using PVDF. Black-Right-Pointing-Pointer A structural investigation of the compounds BaFeO{sub 2}F is presented in detail. Black-Right-Pointing-Pointer This analysis suggests differences for the local coordination of O{sup 2-} and F{sup -} anions. Black-Right-Pointing-Pointer H-BaFeO{sub 2}F shows antiferromagnetic ordering at 300 K. Black-Right-Pointing-Pointer The magnetic moments align parallel to the a-axis.

  4. First-principles study of twin grain boundaries in epitaxial BaSi2 on Si(111)

    NASA Astrophysics Data System (ADS)

    Baba, Masakazu; Kohyama, Masanori; Suemasu, Takashi

    2016-08-01

    Epitaxial films of BaSi2 on Si(111) for solar cell applications possess three epitaxial variants and exhibit a minority carrier diffusion length (ca. 9.4 μm) much larger than the domain size (ca. 0.2 μm); thus, the domain boundaries (DBs) between the variants do not act as carrier recombination centers. In this work, transmission electron microscopy (TEM) was used to observe the atomic arrangements around the DBs in BaSi2 epitaxial films on Si(111), and the most stable atomic configuration was determined by first-principles calculations based on density functional theory to provide possible interface models. Bright-field TEM along the a-axis of BaSi2 revealed that each DB was a twin boundary between two different epitaxial variants, and that Ba(II) atoms form hexagons containing central Ba(I) atoms in both the bulk and DB regions. Four possible interface models containing Ba(I)-atom interface layers were constructed, each consistent with TEM observations and distinguished by the relationship between the Si tetrahedron arrays in the two domains adjacent across the interface. This study assessed the structural relaxation of initial interface models constructed from surface slabs terminated by Ba(I) atoms or from zigzag surface slabs terminated by Si tetrahedra and Ba(II) atoms. In these models, the interactions or relative positions between Si tetrahedra appear to dominate the relaxation behavior and DB energies. One of the four interface models whose relationship between first-neighboring Si tetrahedra across the interface was the same as that in the bulk was particularly stable, with a DB energy of 95 mJ/m2. There were no significant differences in the partial densities of states and band gaps between the bulk and DB regions, and it was therefore concluded that such DBs do not affect the minority carrier properties of BaSi2.

  5. Metabolism and pharmacokinetics of 8-hydroxypiperidinylmethyl-baicalein (BA-j) as a novel selective CDK1 inhibitor in monkey.

    PubMed

    Guo, Hong-Min; Sun, Yu-Ming; Zhang, Shi-Xuan; Ju, Xiu-Lan; Xie, Ai-Yun; Li, Jing; Zou, Liang; Sun, Xiao-Dan; Li, Hai-Liang; Zheng, Yang

    2015-12-01

    Cyclin-dependent kinase 1 (CDK1) is the only necessary CDK in the cell proliferation process and a new target in the research and development of anti-cancer drugs. 8-Hydroxypiperidinemethyl-baicalein (BA-j) is a Mannich base derivative of baicalein (BA) isolated from Scutellaria baicalensis, as a novel selective CDK1 inhibitor. 12 metabolites of BA-j in the monkey urine were identified by LC-MS-MS and (1)H NMR. The major metabolic pathways of BA-j, by capturing oxygen free radicals ((.)O2(-)) and releasing peroxides (H2O2), are degraded into active intermediate metabolite dihydroflavonol, then into main metabolite M179 by Shiff reaction, second metabolite M264 by sulfation, trace amount of metabolite M559 by glucuronidation UGT1A9, and without metabolism by CYP3A4. The metabolic process of BA-j by regulating intracellular reactive oxygen species (ROS) was related with BA-j selectively inducing apoptosis in cancer cells. Pharmacokinetics of 10mg/kg oral BA-j in monkey by HPLC-UV was best fitted to a two-compartment open model, with t1/2(β) of 4.2h, Cmax 25.4μM at 2h, and Vd 12.6L, meaning the drug distributing widely in body fluids with no special selectivity to certain tissues, and being able to permeate through the blood-brain barrier. The protein binding rate of BA-j was 91.8%. BA-j has excellent druggability for oral administration or injection, and it may be developed into a novel anti-cancer drug as a selective CDK1 inhibitor.

  6. Thermodynamic Model for the Solubility of Ba(SeO4, SO4) Precipitates

    SciTech Connect

    Rai, D.; Felmy, Andrew R.; Moore, Dean A.; Kitamura, Akira; Yoshikawa, Hideki; Doi, Reisuke; Yoshida, Yasushi

    2014-08-15

    The solubility of Ba(SeO4, SO4) precipitates was determined as a function of the BaSeO4 mole fractions, ranging from 0.0015 to 0.3830, and time with an equilibration period extending to as long as 302 days. Equilibrium/steady state conditions in this system are reached in ≤ 65 days. Pitzer’s ion interaction model was used to calculate solid and aqueous phase activity coefficients. Thermodynamic analyses showed that the data do not satisfy Gibbs-Duhem equation, thereby demonstrating that a single-solid solution phase does not control both the selenate and sulfate concentrations. Our extensive data with log 10 [Ba] ranging from -3.6 to -5.9 mol kg-1, log 10 [SeO4] rangingfrom-3.6 to -5.2 mol kg-1, and log 10 [SO4] ranging from-4.0 to -5.3 mol kg-1 can be explained with the formation of an ideal BaSeO4 solid solution phase that controls the selenium concentrations and a slightly disordered/less-crystalline BaSO4(s) (log 10Κ°sp = -9.5 instead of -10.05 for barite) that controls the sulfate concentrations. In these experiments the BaSO4 component of the solid solution phase never reaches thermodynamic equilibrium with the aqueous phase. Thermodynamic interpretations of the data show that both the ideal BaSeO4 solid solution phase and less-crystalline BaSO4 (s) phase are in equilibrium with each other in the entire range of BaSeO4 mole fractions investigated in this study.

  7. Effects of Pr3+-deficiency on structure and properties of PrBaCo2O5+δ cathode material-A comparison with Ba2+-deficiency case

    NASA Astrophysics Data System (ADS)

    Jiang, Xuening; Shi, Yuchao; Zhou, Wenlong; Li, Xiangnan; Su, Zhixian; Pang, Shengli; Jiang, Lei

    2014-12-01

    Double-layered perovskite oxides of Pr1-yBaCo2O5+δ (P1-yBCO) with A-site Pr3+-deficiency contents of y = 0.00-0.10 have been studied with respect to phase structures, oxygen content, high-temperature chemical stabilities as well as electrical and electrochemical properties as cathode materials of intermediate-temperature solid oxide fuel cells (IT-SOFCs). The Pr3+-deficiency content in P1-yBCO is limited by ∼8 mol%, and the Pr3+-deficiency hardly changes lattice parameters of P1-yBCO. Content of oxygen vacancies increases while that of Co4+ decreases with the higher Pr3+-deficiency content. P1-yBCO is chemically stable with the Gd0.1Ce0.9O1.95 (GDC) electrolyte at 1100 °C and below in air. Introduction of Pr3+-deficiency decreases electrical conductivities and significantly improves electrochemical performance of P1-yBCO. Among the studied oxides, P0.95BCO with 5 mol% Pr3+-deficiency shows the best electrochemical performance with low ASR values of 0.113 Ω cm2 at 600 °C, 0.054 Ω cm2 at 650 °C and 0.028 Ω cm2 at 700 °C respectively, demonstrating it a promising cathode material of IT-SOFCs. The results of P1-yBCO have also been compared with those of Ba2+-deficient PrBa1-xCo2O5+δ (PB1-xCO, x = 0.00-0.10) oxides and major differences have been found in lattice parameters, oxygen content, chemical defects, electrical conductivities and ASR results. Factors contributing to these differences have been discussed.

  8. Ba-filled Ni-Sb-Sn based skutterudites with anomalously high lattice thermal conductivity.

    PubMed

    Paschinger, W; Rogl, G; Grytsiv, A; Michor, H; Heinrich, P R; Müller, H; Puchegger, S; Klobes, B; Hermann, R P; Reinecker, M; Eisenmenger-Sitter, Ch; Broz, P; Bauer, E; Giester, G; Zehetbauer, M; Rogl, P F

    2016-07-05

    Novel filled skutterudites BayNi4Sb12-xSnx (ymax = 0.93) have been prepared by arc melting followed by annealing at 250, 350 and 450 °C up to 30 days in vacuum-sealed quartz vials. Extension of the homogeneity region, solidus temperatures and structural investigations were performed for the skutterudite phase in the ternary Ni-Sn-Sb and in the quaternary Ba-Ni-Sb-Sn systems. Phase equilibria in the Ni-Sn-Sb system at 450 °C were established by means of Electron Probe Microanalysis (EPMA) and X-ray Powder Diffraction (XPD). With rather small cages Ni4(Sb,Sn)12, the Ba-Ni-Sn-Sb skutterudite system is perfectly suited to study the influence of filler atoms on the phonon thermal conductivity. Single-phase samples with the composition Ni4Sb8.2Sn3.8, Ba0.42Ni4Sb8.2Sn3.8 and Ba0.92Ni4Sb6.7Sn5.3 were used to measure their physical properties, i.e. temperature dependent electrical resistivity, Seebeck coefficient and thermal conductivity. The resistivity data demonstrate a crossover from metallic to semiconducting behaviour. The corresponding gap width was extracted from the maxima in the Seebeck coefficient data as a function of temperature. Single crystal X-ray structure analyses at 100, 200 and 300 K revealed the thermal expansion coefficients as well as Einstein and Debye temperatures for Ba0.73Ni4Sb8.1Sn3.9 and Ba0.95Ni4Sb6.1Sn5.9. These data were in accordance with the Debye temperatures obtained from the specific heat (4.4 K < T < 140 K) and Mössbauer spectroscopy (10 K < T < 290 K). Rather small atom displacement parameters for the Ba filler atoms indicate a severe reduction in the "rattling behaviour" consistent with the high levels of lattice thermal conductivity. The elastic moduli, collected from Resonant Ultrasonic Spectroscopy ranged from 100 GPa for Ni4Sb8.2Sn3.8 to 116 GPa for Ba0.92Ni4Sb6.7Sn5.3. The thermal expansion coefficients were 11.8 × 10(-6) K(-1) for Ni4Sb8.2Sn3.8 and 13.8 × 10(-6) K(-1) for Ba0.92Ni4Sb6.7Sn5.3. The room temperature Vickers

  9. Eu-Doped BaTiO3 Powder and Film from Sol-Gel Process with Polyvinylpyrrolidone Additive

    PubMed Central

    García-Hernández, Margarita; García-Murillo, Antonieta; de J. Carrillo-Romo, Felipe; Jaramillo-Vigueras, David; Chadeyron, Geneviève; De la Rosa, Elder; Boyer, Damien

    2009-01-01

    Transparent BaTiO3:Eu3+ films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP) as modifier viscosity. BaTiO3:Eu3+ films ~500 nm thick, crystallized after thermal treatment at 700 ºC. The powders revealed spherical and rod shape morphology. The optical quality of films showed a predominant band at 615 nm under 250 nm excitation. A preliminary luminescent test provided the properties of the Eu3+ doped BaTiO3. PMID:19865533

  10. Real-time surveillance of laboratory confirmed influenza based on the Danish microbiology database (MiBa).

    PubMed

    Voldstedlund, Marianne; Haahr, Malene; Emborg, Hanne-Dorthe; Bang, Henrik; Krause, Tyra

    2013-01-01

    The Danish microbiology database (MiBa) is a national database that automatically accumulates patient test results from all Danish Departments of Clinical Microbiology. As an example for use of MiBa, we describe the real-time surveillance of laboratory confirmed influenza established in October 2012. It functions without any extra burdens of reporting by laboratories or clinicians. This is an important improvement of the existing surveillance for influenza like illness (ILI) which includes only limited virological testing. The MiBa based surveillance adds complete national virological data which are specific for influenza, in contrast to ILI, and serves as a tool for regional and national preparedness and planning.

  11. Initial stages of Ba adsorption on the Si(100)-(2×1) surface at room temperature

    NASA Astrophysics Data System (ADS)

    Yao, X.; Hu, Xiaoming; Sarid, D.; Yu, Z.; Wang, J.; Marshall, D. S.; Droopad, R.; Abrokwah, J. K.; Hallmark, J. A.; Ooms, W. J.

    1999-02-01

    Scanning tunneling microscopy has been used to study the initial stages of room-temperature adsorption of Ba atoms on a clean Si(100)-(2×1) surface. It is found that most Ba atoms are located at type C defects, which stabilizes the dimer buckling in their vicinity, while the rest are located at single dimer sites on top of the Si dimer rows. Analysis of the images reveals that the Ba-Si(100) interactions are mediated by a partial charge transfer from the adsorbate to the substrate.

  12. Flux Pinning Enhancement in YBa2Cu3O7-x Films with BaSnO3 Nanoparticles

    DTIC Science & Technology

    2008-10-01

    YBCO +BaSnO3 samples of different thickness (240, 317, 359 nm ) were compared with two standard ∼300 nm thick YBCO films on a ( 100 ... YBCO + BaSnO3 nanoparticle film. Films were deposited on ( 100 ) lanthanum aluminate single crystal substrates (LaAlO3) to investigate the flux pinning...LAO (Sample 3) YBCO /STO YBCO /LAO YBCO /LAO YBCO /STO YBCO +BaSnO 3 /LAO 106 105 104 1000 100 10 0 2 4 6 8 10 1 Magnetic Field H(T) J c

  13. Synthesis, structural and magnetic characterisation of the fluorinated compound 15R-BaFeO{sub 2}F

    SciTech Connect

    Clemens, Oliver; Berry, Frank J.; Bauer, Jessica; Wright, Adrian J.; Knight, Kevin S.; Slater, Peter R.

    2013-07-15

    The compounds 15R-BaFeO{sub 2}F and 15R-BaFeO{sub 2.27}F{sub 0.5} have been synthesised by the low temperature fluorination of 15R-BaFeO{sub 3−d}F{sub 0.2} using polyvinylidenedifluoride (PVDF) as a fluorination agent. The materials have been structurally characterised by Rietveld analysis of the X-ray- and HRPD-powder neutron diffraction data. A detailed analysis of bond valence sums suggests that the oxide and fluoride ions order on the different anion sites. A reinvestigation of our recently published structure (Clemens et al., 2013) [34] of 6H-BaFeO{sub 2}F is also reported and incorporation of fluoride in h-type layers is also confirmed in this compound. The magnetic moments for 15R-BaFeO{sub 2}F and 15R-BaFeO{sub 2.25}F{sub 0.5} align in the a/b-plane with antiferromagnetic alignment of the moments between adjacent layers, and are flipped by 90° as compared to the precursor compound. 15R-BaFeO{sub 2}F exhibits very robust antiferromagnetism with a Néel temperature between 300 and 400 °C. - Graphical abstract: The crystal and magnetic structure of the perovskite phase 15R-BaFeO{sub 2}F. - Highlights: • 15R-BaFeO{sub 2}F and 15R-BaFeO{sub 2.27}F{sub 0.5}were prepared via low temperature fluorination using PVDF. • A structural investigation of the compounds BaFeO{sub 2}F is presented in detail. • This analysis suggests ordering of O{sup 2−} and F{sup −} anions between different layers. • 15R-BaFeO{sub 2}F shows antiferromagnetic ordering at 300 K with T{sub N} ∼300–400 °C. • The magnetic moments align in the a/b-plane.

  14. Functional Brain Activity within the Medial and Lateral Portion of BA10 during a Prospective Memory Task

    PubMed Central

    Barban, Francesco; Carlesimo, Giovanni Augusto; Macaluso, Emiliano; Caltagirone, Carlo; Costa, Alberto

    2013-01-01

    In this study we tested the gateway hypothesis of Broadmann area 10 (BA10). With a functional magnetic resonance imaging (fMRI) protocol we manipulated the saliency–stimulus-oriented (SO) attending– and the memory load – stimulus-independent (SI) attending–during a prospective memory (PM) task. We found a significant main effect of the SO manipulation within the medial BA10 and a significant interaction between SI attending and PM task within the left lateral BA10. Our results give experimental support to the gateway hypothesis. PMID:22713428

  15. Liquidus projection of the Ag-Ba-Ge system and melting points of clathrate type-I compounds

    SciTech Connect

    Zeiringer, I.; Grytsiv, A.; Broz, P.

    2012-12-15

    The liquidus and solidus projection has been constructed for the Ag-Ba-Ge system up to 33.3 at% Ba, using electron micro probe analysis (EPMA), X-ray powder diffraction (XRD) and differential thermal analysis (DSC/DTA). Eight different primary crystallization regions were found: (Ge), Ba{sub 8}Ag{sub x}Ge{sub 46-x-y}{open_square}{sub y} ({kappa}{sub I}) ({open_square} is a vacancy), Ba{sub 6}Ag{sub x}Ge{sub 25-x} ({kappa}{sub Ix}), BaGe{sub 2}, Ba(Ag{sub 1-x}Ge{sub x}){sub 2} ({tau}{sub 1}), BaAg{sub 2-x}Ge{sub 2+x} ({tau}{sub 2}) BaAg{sub 5} and (Ag). The ternary invariant reactions have been determined for the region investigated and are the basis for a Schulz-Scheil diagram. The second part of this work provides a comprehensive compilation of melting points of ternary A{sub 8}T{sub x}M{sub 46-x} and quaternary (A=Sr, Ba, Eu; T=Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga; M=Si, Ge, Sn) clathrate type-I compounds and decomposition temperatures of inverse clathrate type-I Ge{sub 38}{l_brace}P,As,Sb{r_brace}{sub 8}{l_brace}Cl,Br,I{r_brace}{sub 8}, Si{sub 46-x}P{sub x}Te{sub y} and tin based compounds. - Graphical Abstract: Partial liquidus projection of the Ag-Ba-Ge system. Highlights: Black-Right-Pointing-Pointer The liquidus and solidus projection has been constructed for the Ag-Ba-Ge system up to 33.33 at% Ba. Black-Right-Pointing-Pointer Eight different primary crystallization fields have been found. Black-Right-Pointing-Pointer All the ternary compounds form congruently from the melt. Black-Right-Pointing-Pointer The ternary invariant reactions have been determined and are the basis for a Schulz-Scheil diagram.

  16. Superconductivity in SrCuO2-BaCuO2 Superlattices: Formation of Artificially Layered Superconducting Materials.

    PubMed

    Norton, D P; Chakoumakos, B C; Budai, J D; Lowndes, D H; Sales, B C; Thompson, J R; Christen, D K

    1994-09-30

    Pulsed-laser deposition was used to synthesize artificially layered high-temperature superconductors. Thin-film compounds were formed when the constraint of epitaxy was used to stabilize SrCuO(2)-BaCuO(2) superlattices in the infinite layer structure. Using this approach, two new structural families, Ba(2)Srn-1,Cun+1 O2n+2+delta and Ba(4)Srn-1 Cun+3O2n+6+delta have been synthesized; these families superconduct at temperatures as high as 70 kelvin.

  17. Enhancement of nonlinear optical properties of BaTiO3 nanoparticles by the addition of silver seeds.

    PubMed

    Yust, Brian G; Razavi, Neema; Pedraza, Francisco; Elliott, Zakary; Tsin, Andrew T; Sardar, Dhiraj K

    2012-11-19

    Barium titanate (BaTiO3) is a technologically important material because of its nonlinear properties, such as its strong second harmonic generation and high third order susceptibility. While many nonlinear effects have been extensively studied on the bulk scale, there are still questions regarding the strength of nonlinear effects in nanoparticles. The nonlinear properties of BaTiO3 nanoparticles and nanorods have been studied using the closed aperture z-scan technique. Silver was then grown photochemically on the surface of the BaTiO3 nanoparticles, and it was found that the third order susceptibility increases dramatically.

  18. Experimental study of the astrophysical γ -process reaction 124Xe(α ,γ )128Ba

    NASA Astrophysics Data System (ADS)

    Halász, Z.; Somorjai, E.; Gyürky, Gy.; Elekes, Z.; Fülöp, Zs.; Szücs, T.; Kiss, G. G.; Szegedi, N. T.; Rauscher, T.; Görres, J.; Wiescher, M.

    2016-10-01

    Background: The synthesis of heavy, proton rich isotopes in the astrophysical γ process proceeds through photodisintegration reactions. For the improved understanding of the process, the rates of the involved nuclear reactions must be known. The reaction 128Ba(γ ,α )124Xe was found to affect the abundance of the p nucleus 124Xe in previous rate variation studies. Purpose: Since the stellar rate for this reaction cannot be determined by a measurement directly, the aim of the present work was to measure the cross section of the inverse 124Xe(α ,γ )128Ba reaction and to compare the results with statistical model predictions used in astrophysical networks. Modified nuclear input can then be used to provide an improved stellar reaction rate. Of great importance is the fact that data below the (α ,n ) threshold was obtained. Studying simultaneously the 124Xe(α ,n )127Ba reaction channel at higher energy allowed to further identify the source of a discrepancy between data and prediction. Method: The 124Xe(α ,γ )128Ba and 124Xe(α ,n )127Ba cross sections were measured with the activation method using a thin window 124Xe gas cell and an α beam from a cyclotron accelerator. The studied energy range was between Eα=11 and 15 MeV close above the astrophysically relevant energy range. Results: The obtained cross sections are compared with Hauser-Feshbach statistical model calculations. The experimental cross sections are smaller than standard predictions previously used in astrophysical calculations. As a dominating source of the difference, the theoretical α width was identified. The experimental data suggest an α width lower by at least a factor of 0.125 in the astrophysically important energy range. Conclusions: An upper limit for the 128Ba(γ ,α )124Xe stellar rate was inferred from our measurement. The impact of this rate and lower rates was studied in two different models for core-collapse supernova explosions of 25 M⊙ stars. A significant contribution to

  19. Sympathetic cooling of the Ba{sup +} ion by collisions with ultracold Rb atoms: Theoretical prospects

    SciTech Connect

    Krych, Michal; Skomorowski, Wojciech; Pawlowski, Filip; Moszynski, Robert; Idziaszek, Zbigniew

    2011-03-15

    State-of-the-art ab initio techniques have been applied to compute the potential energy curves of the (BaRb){sup +} molecular ion in the Born-Oppenheimer approximation for the singlet and triplet states dissociating into the ground-state {sup 1}S Rb{sup +} ion and the Ba atom in the ground {sup 1}S state or the lowest singlet or triplet d excited states, and for the singlet and triplet states dissociating into the ground-state {sup 2}S Rb atom and the ground-state {sup 2}S Ba{sup +} ion. The ground-state potential energy was obtained with the coupled-cluster method restricted to single, double, and nonperturbative triple excitations. The first triplet states in the {Sigma}, {Pi}, and {Delta} symmetries were computed with the restricted open-shell coupled-cluster method restricted to single, double, and nonperturbative triple excitations. All other excited-state potential energy curves were computed using the equation of motion approach within the coupled-cluster singles, doubles, and linear triples framework. The long-range coefficients describing the electrostatic, induction, and dispersion interactions at large interatomic distances are also reported. The electric transition dipole moments governing the x {sup 1{Sigma}{yields}1{Sigma}},{sup 1{Pi}} transitions have been obtained as the first residue of the polarization propagator computed with the linear response coupled-cluster method restricted to single and double excitations. Nonadiabatic radial and angular coupling matrix elements as well as the spin-orbit coupling matrix elements have been evaluated using the multireference configuration-interaction method restricted to single and double excitations with a large active space. With these couplings, the spin-orbit-coupled (relativistic) potential energy curves for the 0{sup +} and 1 states relevant for the running experiments have been obtained. Finally, relativistic transition moments and nonadiabatic coupling matrix elements were obtained from the

  20. Theoretical and experimental studies of formation and migration of oxygen vacancies in BaM x Ti1- x O3 (M = Zr, Ge)

    NASA Astrophysics Data System (ADS)

    Umeda, Yuji; Aman, Sanshiro; Kuwabara, Akihide; Moriwake, Hiroki

    2016-10-01

    The formation and migration energies of oxygen vacancies in pure BaTiO3, and BaM x Ti1- x O3 (M = Zr, Ge) are calculated by first-principles calculations to understand the effect of doping on the reliability of multilayer ceramic capacitors (MLCCs). The formation and migration energies of oxygen vacancies are found to be larger in BaZr x Ti1- x O3 than in BaTiO3. This finding could be one of the possible reasons behind the improved reliability of Zr-doped MLCCs materials. On the other hand, by substituting Ge, the migration energy of BaGe x Ti1- x O3 becomes larger than that of BaTiO3. This is despite the smaller oxygen vacancy formation energy in BaGe x Ti1- x O3 than in BaTiO3. Even though Zr and Ge are tetravalent in BaM x Ti1- x O3, their valence states are different after the formation of oxygen vacancies, providing an explanation for the differences in vacancy formation and migration energies between BaZr x Ti1- x O3 and BaGe x Ti1- x O3. Our theoretical results are further confirmed by experiments on these model systems.