Sample records for lagoa real ba

  1. New geological model of the Lagoa Real uraniferous albitites from Bahia (Brazil)

    NASA Astrophysics Data System (ADS)

    de Oliveira Chaves, Alexandre

    2013-09-01

    New evidence supported by petrography (including mineral chemistry), lithogeochemistry, U-Pb geochronology by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), and physicochemical study of fluid and melt inclusions by LA-ICP-MS and microthermometry, point to an orogenic setting of Lagoa Real (Bahia-Brazil) involving uraniferous mineralization. Unlike the previous models in which uraniferous albitites represent Na-metasomatised 1.75 Ga anorogenic granitic rocks, it is understood here that they correspond to metamorphosed sodium-rich and quartz-free 1.9 Ga late-orogenic syenitic rocks (Na-metasyenites). These syenitic rocks are rich not only in albite, but also in U-rich titanite (source of uranium). The interpretation of geochemical data points to a petrogenetic connection between alkali-diorite (local amphibolite protolith) and sodic syenite by fractional crystallization through a transalkaline series. This magmatic differentiation occurred either before or during shear processes, which in turn led to albitite and amphibolite formation. The metamorphic reactions, which include intense recrystallization of magmatic minerals, led uraninite to precipitate at 1.87 Ga under Oxidation/Reduction control. A second population of uraninites was also generated by the reactivation of shear zones during the 0.6 Ga Brasiliano Orogeny. The geotectonic implications include the importance of the Orosirian event in the Paramirim Block during paleoproterozoic Săo Francisco Craton edification and the influence of the Brasiliano event in the Paramirim Block during the West-Gondwana assembly processes. The regional microcline-gneiss, whose protolith is a 2.0 Ga syn-collisional potassic granite, represents the albitite host rock. The microcilne-gneiss has no petrogenetic association to the syenite (albitite protolith) in magmatic evolutionary terms.

  2. Oral health of the Paleoamericans of Lagoa Santa, Central Brazil.

    PubMed

    Da-Gloria, Pedro; Larsen, Clark Spencer

    2014-05-01

    The peopling, origins, and early prehistory of the Americas are topics of intense debate. However, few studies have used human remains to document and interpret patterns of health and lifestyle of Paleoamericans. This study provides the first investigation to characterize oral health in a series of early Holocene skeletal remains from Lagoa Santa, Brazil, a locality containing the remains of some of the earliest inhabitants of South America (10,000-7,000 BP). The sample is composed of 949 teeth and 1925 alveoli from an estimated 113 individuals excavated from 17 archaeological sites located in the State of Minas Gerais. We compare dental caries and abscess prevalence at Lagoa Santa to a large sample of human skeletons from the Western Hemisphere Project (WHP) database using both individual and tooth/alveolus count methods. In addition, antemortem tooth loss and tooth wear were analyzed in Lagoa Santa by sex and age. The results show that Lagoa Santa dental caries and abscess prevalence are significantly higher than observed among other hunter-gatherers included in the WHP database, except when abscess prevalence is considered by individual count. Adult females have less tooth wear coupled with higher prevalence of dental caries and antemortem tooth loss than adult males. These results point to an unexpected record of poor oral health at Lagoa Santa, especially among females. A diet based on a highly cariogenic combination of wild tubers and fruits is suggested as an explanation for the elevated rate, characterizing an early adaptation to a tropical environment in South America. Copyright © 2014 Wiley Periodicals, Inc.

  3. Management of plant species for controlling pests, by peasant farmers at Lagoa Seca, Paraíba state, Brazil: an ethnoecological approach

    PubMed Central

    Guimarães, Andréia de Souza; Mourão, José da Silva

    2006-01-01

    Ethnoecological knowledge may be understood as spontaneous knowledge, culturally referenced of any society's members, learned and transmitted through social interactions and that are targeted at resolution of daily routine situations. The traditional knowledge in small scale economy societies as well as the non-academic knowledge in urban-industrial societies might be included in this concept. An ethnoecological approach study was performed here on people living at the communities of Alvinho, Almeida, Chã do Marinho, Floriano, and Chã de Oiti, all located in the municipality of Lagoa Seca, Paraíba state, Northeast Brazil. The general objective pursued here was to study the knowledge that peasant farmers have on management of plant species utilized for pest control. For this, the methodological instruments employed here to investigate the ethnoecological knowledge were: direct observation, structured and semi-structured interviews, and tours conducted by local peasant farmers. We analyzed the data obtained under an emic/etic view and also by comparing the local knowledge with those obtained from the literature. The results showed that people in those communities utilize management alternatives for controlling pests, which are mainly: (i) fallowing; (ii) crop rotation; (iii) destruction of crop remains and fruits attacked by pests; (iv) alternations of crops with repellent plants; and/or (v) mixed cropping; (vi) insect's larvae covered with soil; (vii) crops irrigated abundantly; and (viii) soil preparation. The recovery and comprehension we get about this knowledge as well as the farmers' savoir faire, are extremely important to the revival of ancient agricultural practices, which have been forgotten due to advances in modern agriculture. The data obtained here showed that a huge body of knowledge the farmers have on many forms or strategies of management are generally compatible with scientific knowledge. PMID:17026748

  4. Real-time Stack Monitoring at the BaTek Medical Isotope Production Facility

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McIntyre, Justin I.; Agusbudiman, A.; Cameron, Ian M.

    2016-04-01

    Radioxenon emissions from radiopharmaceutical production are a major source of background concentrations affecting the radioxenon detection systems of the International Monitoring System (IMS). Collection of real-time emissions data from production facilities makes it possible to screen out some medical isotope signatures from the IMS radioxenon data sets. This paper describes an effort to obtain and analyze real-time stack emissions data with the design, construction and installation of a small stack monitoring system developed by a joint CTBTO-IDC, BATAN, and PNNL team at the BaTek medical isotope production facility near Jakarta, Indonesia.

  5. Hydrology and Salt Balance in a Large, Hypersaline Coastal Lagoon: Lagoa de Araruama, Brazil

    NASA Astrophysics Data System (ADS)

    Kjerfve, Björn; Schettini, C. A. F.; Knoppers, Bastiaan; Lessa, Guilherme; Ferreira, H. O.

    1996-06-01

    Lagoa de Araruama in the state of Rio de Janeiro, Brazil, is a hypersaline coastal lagoon as a result of semi-arid climate conditions, a small drainage basin and a choked entrance channel. The lagoon has been continuously hypersaline for at least 4·5 centuries, but the mean salinity has varied substantially. It has recently decreased from 57 to 52 as indicated by density (salinity) measurements between 1965 and 1990. Analysis of more than 20 years of salinity time series data, in addition to monthly lagoon cruises to measure the spatial salinity distribution, indicate that the lagoon salinity largely fluctuates in response to the difference between evaporation and precipitation. The major factor explaining the long-term trend of decreasing salinity in the lagoon is the constant pumping of 1 m 3s -1of freshwater to the communities surrounding the lagoon from an adjacent watershed, and subsequent discharge of this water into Lagoa de Araruama. The net salt budget is primarily a balance between the advective import of salt from the coastal ocean and eddy diffusive export of salt to the ocean, although the extensive mining of salt from the lagoon during past decades is also a small but significant contribution to the salt budget. The flushing half-life is proposed as a useful time scale of water exchange, is calculated based on a combination of hydrological and tidal processes, and is excellent for comparison of lagoons and assessing water quality changes. The flushing half-life measures 83·5 days for Lagoa de Araruama, considerably longer than for most other coastal lagoons. The proposed dredging of a second ocean channel to Lagoa de Araruama is probably not a good idea. It is likely to accelerate the decrease of lagoon salinity and somewhat improve the lagoon water exchange. At the same time, this will eliminate the apparent buffering capacity provided by the hypersaline environment, and thus may potentially cause water quality problems.

  6. Does the Lagoa do peixe sandbar opening influence the macrophyte richness and composition in Southern Brazil wetlands?

    PubMed

    Rolon, Ana Silvia; Rocha, Odete; Maltchik, Leonardo

    2013-03-01

    The Lagoa do Peixe has its connection with the sea artificially opened every year at the end of winter. However, this management has been carried out without the evaluation of the impact of this opening in the aquatic biodiversity. This information is crucial for the management of the natural resources of the Lagoa do Peixe National Park, the unique Ramsar site in Southern Brazil. The following questions were analyzed: (1) Do richness and composition of aquatic macrophytes from Lagoa do Peixe floodplain varies temporarily according to the sandbar opening and closing? (2) Does the variation pattern of the macrophyte community changed according to the sandbar opening and closing? A set of eight sampling sites of 1ha were selected over the Lagoa do Peixe floodplain: four sites not influenced by the artificial sandbar opening and four sites influenced by this event, being two sites closer to the sandbar opening and the two sites distant to the sandbar opening. The samplings were carried out between November 2007 and October 2009. The results show that although the artificial sandbar breaching does not affect the aquatic macrophyte richness at the floodplain, it affects the dynamics of species composition. The hydrological variation related to this management can be the main factor of the continuous change in the species composition in the floodplain, especially in the Southern portion. In order to avoid impacts in the macrophyte conservation, the artificial sandbar opening should be considered carefully, since the area of study is one of the most important conservation units to wetland systems in Southern Brazil.

  7. Nutrient budgets and trophic state in a hypersaline coastal lagoon: Lagoa de Araruama, Brazil

    NASA Astrophysics Data System (ADS)

    Souza, Marcelo F. L.; Kjerfve, Björn; Knoppers, Bastiaan; Landim de Souza, Weber F.; Damasceno, Raimundo N.

    2003-08-01

    Lagoa de Araruama in the state of Rio de Janeiro, Brazil, is a hypersaline lagoon with salinity varying spatially from 45 to 56. We collected water samples during monthly cruises throughout the lagoon, and along the streams feeding the system, from April 1991 to March 1992. Nutrients and other water quality parameters exhibited great spatial and temporal variations. Mass balance calculations indicate large amounts of anthropogenic nutrient inputs. The data indicate that the lagoon currently is oligotrophic but is in a state of transition to become a mesotrophic system. Molar dissolved inorganic nitrogen:dissolved inorganic phosphorus (DIN/DIP) varied between 2.2:1 and 659:1 with a volume-weighted average of 22:1. The high DIN/DIP ratio contrasts with that found in nearby lagoons, suggesting that phytoplankton primary production is limited by phosphorus in Lagoa de Araruama. The major loss of DIP is apparently driven by biological assimilation and diagenic reactions in the sediments. Calculations indicate that the lagoon is slightly net autotrophic at +0.9 mol C m -2 yr -1. This suggests that the biomass of the primary producers is restricted by phosphorus availability. Phosphorus retention in the sediment and the hypersaline state of the lagoon prevent changes in autotrophic communities and the formation of eutrophic conditions.

  8. Bottom Characterization with High Resolution Sonar Data and Geochemical Analyses of an Uninvestigated Cone in Lagoa das Furnas on São Miguel Island, Azores Archipelago

    NASA Astrophysics Data System (ADS)

    Andersson, T.

    2015-12-01

    Lagoa das Furnas is a crater lake located in an area exposed to geohazards from earthquakes and volcanic activity on the island São Miguel in the Azores Archipelago. The Furnas volcanic center has a long history of earthquakes and volcanic activity. The area is relatively well studied except for the lake floor. Therefore, a high resolution geophysical and geological mapping survey was conducted at Lagoa das Furnas. Sidescan sonar was used to map the surface of the lake floor and single beam sonar was used to acquire sub-bottom profiles. In addition to the geophysical mapping, sediment surface sampling and core drilling were carried out followed by geochemical analyses of the retrieved material. The mapped data permitted a characterization of the floor of Lagoa das Furnas and revealed several volcanic features including fumarolic activity and a previously uninvestigated volcanic cone in the southern part of the lake. In order to unravel the origin of this cone several methods were applied, including analyses of tephra and minerals collected from the cone itself and from nearby deposits of two known eruptions, Furnas I and Furnas 1630. Sedimentological, petrological, geochemical and geochronological studies of pyroclastic deposits from the cone suggest a subaqueous eruption linked to the Furnas 1630 eruption. The chemistry of glass and crystal fragments sampled from the cone suggests that it is composed of more evolved magma than that of the main Furnas 1630, implying that the lake cone is likely a product of the last eruptional phase. According to historical records, two of three lakes were lost due the Furnas 1630 eruption. The results of this study show that the remaining lake is most likely Lagoa das Furnas, which consequently must have existed before the 1630 eruption.

  9. Beta-gamma spectroscopy of the neutron-rich 150Ba

    NASA Astrophysics Data System (ADS)

    Yokoyama, R.; Ideguchi, E.; Simpson, G. S.; Tanaka, Mn; Nishimura, S.; Doornenbal, P.; Lorusso, G.; Söderström, P.-A.; Sumikama, T.; Wu, J.; Xu, Z. Y.; Aoi, N.; Baba, H.; Bello Garrote, F. L.; Benzoni, G.; Browne, F.; Daido, R.; Fang, Y.; Fukuda, N.; Gottardo, A.; Gey, G.; Go, S.; Inabe, N.; Isobe, T.; Kameda, D.; Kobayashi, K.; Kobayashi, M.; Kojouharov, I.; Komatsubara, T.; Kubo, T.; Kurz, N.; Kuti, I.; Li, Z.; Matsushita, M.; Michimasa, S.; Moon, C. B.; Nishibata, H.; Nishizuka, I.; Odahara, A.; Patel, Z.; Rice, S.; Sahin, E.; Sakurai, H.; Schaffner, H.; Sinclair, L.; Suzuki, H.; Takeda, H.; Taprogge, J.; Vajta, Zs; Watanabe, H.; Yagi, A.; Inakura, T.

    2018-04-01

    Excited states in the neutron-rich nucleus ^{150}Ba have been observed via β-γ spectroscopy at the Radioactive Isotope Beam Factory, RIKEN Nishina Center. The ^{150}Ba ions were produced by the in-flight fission of a ^{238}U beam with an energy of 345 MeV/nucleon. The E(2+) energy of ^{150}Ba was identified at 100 keV, which is the lowest known in the neutron-rich Ba isotopes. A γ-ray peak was also observed at 597 keV. A mean-field calculation with a fully 3D real space was performed and a static octupole deformation was obtained for the Ba isotopes. K^{π}=0- and 1- excited states with significant octupole collectivity were newly predicted at around or lower than 1 MeV on the ground state of ^{150}Ba by a random-phase approximation calculation. The 597 keV γ ray can be interpreted as a negative-parity state, showing that ^{150}Ba may possess octupole collectivity.

  10. VizieR Online Data Catalog: AKARI IRC asteroid sample diameters & albedos (Ali-Lagoa+, 2018)

    NASA Astrophysics Data System (ADS)

    Ali-Lagoa, V.; Mueller, T. G.; Usui, F.; Hasegawa, S.

    2017-11-01

    Table 1 contains the best-fitting values of size and beaming parameter and corresponding visible geometric albedos for the full AKARI IRC sample. We fitted the near-Earth asteroid thermal model (NEATM) of Harris (1998Icar..131..291H) to the AKARI IRC thermal infrared data (Murakami et al., 2007PASJ...59S.369M, Onaka et al., 2007PASJ...59S.401O, Ishihara et al., 2010A&A...514A...1I, Cat. II/297, Usui et al., 2011PASJ...63.1117U, Cat. J/PASJ/63/1117, Takita et al., 2012PASJ...64..126T, Hasegawa et al., 2013PASJ...65...34H, Cat. J/PASJ/65/34). The NEATM implementation is described in Ali-Lagoa and Delbo' (2017A&A...603A..55A, cat. J/A+A/603/A55). Minimum relative errors of 10, 15, and 20 percent are given for size, beaming parameter and albedo in those cases where the beaming parameter could be fitted. Otherwise, a default value of the beaming parameter is assumed based on Eq. 1 in the article, and the minimum relative errors in size and albedo increase to 20 and 40 percent (see the discussions in Mainzer et al., 2011ApJ...736..100M, Ali-Lagoa et al., 2016A&A...591A..14A, Cat. J/A+A/591/A14). We also provide the asteroid absolute magnitudes and G12 slope parameters retrieved from Oszkiewicz et al. (2012), the number of observations used in each IRC band (S9W and L18W), plus the heliocentric and geocentric distances and phase angle (r, Delta, alpha) based on the ephemerides taken from the MIRIADE service (http://vo.imcce.fr/webservices/miriade/?ephemph). (1 data file).

  11. Demographic pressure over the Environmental Protected Area of the Lagoa Santa Karst, Minas Gerais State, Brazil

    NASA Astrophysics Data System (ADS)

    Travassos, L. E. P.

    2009-04-01

    The State of Minas Gerais, Brazil, is approximately 586.528 km2. From this total, it is believed that about 29,000 km2(Piló 1997; 1999) are composed by carbonatic rocks. With a total of 853 municipalities and some evident environmental problems, the biggest problem is the proper final waste disposal as noticed by Travassos et al (2008). This work is intended to demonstrate the potential degradation of karst scenarios due to the increasing urbanization in the so called "North Vector". There are two State Parks and six other Conservation Units in this region. Historically the cities near this region have been used as dormitory towns. Further north, various ranches, country houses for the weekend and rural hostels are set on karst terrains. The municipalities of Vespasiano, Pedro Leopoldo, Confins, Lagoa Santa, Matozinhos, Funilândia and Prudente de Morais are within the 360 km2-large Environmental Protected Area of the Lagoa Santa Karst. All these municipalities have been facing demographic growth and consequently generate the anthropogenic pressure over the karst. Up to the date on which this abstract was written, the Decree n˚ 6640/2008, signed by the Brazilian government, is in effect. It substituted the previous one, Decree n˚ 99556/1990, which protected the Brazilian speleological heritage. According to the new Decree, now there are no warranties that caves will be protected against infra-structure constructions and mining companies. Besides, it also establishes relevance criteria that point out which caves which can be destroyed without any compensation at all. Certainly the speleological community is already mobilized against this new Decree. Keywords: karst, endokarst, exokarst, Cordisburgo region, Minas Gerais, Brazil.

  12. 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.

  13. Solvo-thermal synthesis of a unique alkaline earth-transition Ba-Cd micro-porous coordination framework as hetero-metallic luminescent sensor for Cu2+ and real-time detection of benzaldehyde

    NASA Astrophysics Data System (ADS)

    Ding, Bin; Ma, Dian Xue; Zhang, Hui Min; Meng, Xin; Qiu, Rong Rong; Ren, Rong; Wu, Jie; Wu, Xiang Xia; Huo, Jian Zhong; Liu, Yuan Yuan; Shi, Xue Fang

    2018-06-01

    In this work a unique hetero-metallic alkaline earth-transition Ba-Cd luminescent micro-porous metal-organic framework {[BaCd(μ6-tp)1.5(μ2-Cl)(H2O) (DMF)2]·0.75H2O}n (H2tp = terephthalic acid) (1) has been prepared under solvo-thermal conditions. In 1 infinite 1D {Ba-X-Cd} (X = O, Cl) inorganic chains are linked via these full de-pronated tp2- ligands forming a unique 3D I1O2 type micro-porous coordination framework. PXRD patterns of 1 have been determined confirming pure phases of 1. Luminescence investigations suggested that 1 exhibits highly selective and sensitive sensing for trace amounts of benzaldehyde in ethanol, which provides a facile method for real-time detection of benzaldehyde. Meanwhile 1 also exhibits highly selective and sensitive sensing for Cu2+ over other cations with high quenching efficiency Ksv value 1.15 × 104 L·mol-1. As far as we know, 1 represents the first example of alkaline earth-transition hetero-metallic Ba-Cd micro-porous coordination framework as bi-functional luminescent probes for Cu2+ and benzaldehyde.

  14. Transport properties of layered Ba(Pb,Bi)O3 thin films

    NASA Astrophysics Data System (ADS)

    Hassink, G. W. J.; Munakata, K.; Hammond, R. H.; Beasley, M. R.

    2012-02-01

    Doped BaBiO3 is a 3D oxide superconductor with a maximum Tc of 30 K for Ba0.6K0.4BiO3. There has been a lot of discussion on whether this high Tc can be explained purely by electron-phonon coupling with a high coupling constant λ. In addition, the presence of real-space paired 6s^2 electrons in the parent compound raise intriguing questions about whether there is an electron-electron coupling interaction as well. This possible negative-U interaction might be used to implement the suggestion by Berg, Orgad and Kivelson [Phys.Rev.B 78, 094509] that for a two-layer system where one layer provides electron pairing interaction and the other layer is conducting, the whole can be superconducting with a high Tc. Here we discuss the transport properties of BaPbO3/BaBiO3 bilayers, where the BaBiO3 layer is thought to act as the pairing layer, while the BaPbO3 acts as the conducting layer. The transport behavior changes to insulating upon decreasing the metallic BaPbO3 layer thickness at values that single films are expected to still be metallic.

  15. Solvo-thermal synthesis of a unique alkaline earth-transition Ba-Cd micro-porous coordination framework as hetero-metallic luminescent sensor for Cu2+ and real-time detection of benzaldehyde.

    PubMed

    Ding, Bin; Ma, Dian Xue; Zhang, Hui Min; Meng, Xin; Qiu, Rong Rong; Ren, Rong; Wu, Jie; Wu, Xiang Xia; Huo, Jian Zhong; Liu, Yuan Yuan; Shi, Xue Fang

    2018-06-15

    In this work a unique hetero-metallic alkaline earth-transition Ba-Cd luminescent micro-porous metal-organic framework {[BaCd(μ 6 -tp) 1.5 (μ 2 -Cl)(H 2 O) (DMF) 2 ]·0.75H 2 O} n (H 2 tp=terephthalic acid) (1) has been prepared under solvo-thermal conditions. In 1 infinite 1D {Ba-X-Cd} (X=O, Cl) inorganic chains are linked via these full de-pronated tp 2- ligands forming a unique 3D I 1 O 2 type micro-porous coordination framework. PXRD patterns of 1 have been determined confirming pure phases of 1. Luminescence investigations suggested that 1 exhibits highly selective and sensitive sensing for trace amounts of benzaldehyde in ethanol, which provides a facile method for real-time detection of benzaldehyde. Meanwhile 1 also exhibits highly selective and sensitive sensing for Cu 2+ over other cations with high quenching efficiency K sv value 1.15×10 4 L·mol -1 . As far as we know, 1 represents the first example of alkaline earth-transition hetero-metallic Ba-Cd micro-porous coordination framework as bi-functional luminescent probes for Cu 2+ and benzaldehyde. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Syntheses, crystal structure, and electronic properties of the five ABaMQ{sub 4} compounds RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mesbah, Adel; ICSM, UMR 5257 CEA / CNRS / UM / ENSCM, Site de Marcoule-Bâtiment 426, BP 17171, 30207 Bagnols-sur-Cèze Cedex; Prakash, Jai

    Five new compounds belonging to the ABaMQ{sub 4} family were synthesized by solid-state chemistry at 1123 K. The compounds RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4} are isostructural and have the TlEuPS{sub 4} structure type. They crystallize in space group D{sup 16}{sub 2h} – Pnma of the orthorhombic system. Their structure consists isolated MQ{sub 4} tetrahedra separated by A and Ba atoms to form a salt-like structure. Density Functional Theory (DFT) calculations of the electronic structures with the use of the HSE functional suggest that the compounds are semiconductors with calculated band gaps of 3.3 eVmore » (RbBaPS{sub 4}), 3.4 eV (CsBaPS{sub 4}), 2.3 eV (CsBaVS{sub 4}), and 1.6 eV (RbBaVSe{sub 4}). - Graphical abstract: General view of the ABaMQ{sub 4} structure down the a axis. - Highlights: • Five new ABaMQ{sub 4} compounds were synthesized by solid-state chemistry at 1123 K. • RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4} have the TlEuPS{sub 4} structure type. • The compounds are semiconductors with calculated band gaps ranging from 1.6 to 3.4 eV.« less

  17. 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 (CsAlSi 2O 6), CsTiSi 2O 6.5 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, Cs xBa (1-x)/2TiSi 2O 6.5 and Cs xBa 1-xTiSi 2O 7-0.5x, (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 Cs xBa (1-x)/2TiSi 2O 6.5 samplesmore » are phase-pure, Cs xBa 1-xTiSi 2O 7-0.5x samples contain Cs3x/(2+x)Ba (1-x)/(2+x)TiSi 2O 6.5 pollucites (i.e., also two-Cs-to-one-Ba substitution) and a secondary phase, fresnoite (Ba2TiSi2O8). Thus, the Cs xBa 1-xTiSi 2O 7-0.5x series is energetically less favorable than Cs xBa (1-x)/2TiSi 2O 6.5. To study the stability systematics of Cs xBa (1-x)/2TiSi 2O 6.5 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

  18. CR@BaSO4: an acid rain-indicating material.

    PubMed

    Gao, Hong-Wen; Xu, Xin-Hui

    2011-12-28

    The CR@BaSO(4) hybrid was synthesized, characterized and used as an acid rain-indicating (ARI) material. A painted ARI umbrella was discolored after exposure to simulated acid rain of pH 5 or less and returned to the initial color after the rain stopped. Such a functionalized material may make acid rain visual to remind people in real-time. This journal is © The Royal Society of Chemistry 2011

  19. The Ba 4d-4f giant dipole resonance in complex Ba/Si compounds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sahle, Ch. J.; Sternemann, C.; Sternemann, H.

    2014-08-06

    The shape of the Ba 4d–4f giant dipole resonance is studied for Ba atoms embedded inside complex Si networks covering structures consisting of Si nanocages and nanotubes, i.e. the clathrate Ba 8Si 46, the complex compound BaSi 6, and the semiconducting BaSi 2. Here, non-resonant x-ray Raman scattering is used to investigate confinement effects on the shape of the giant resonance in the vicinity of the Ba NIV, V-edge. The distinct momentum transfer dependence of the spectra is analyzed and discussed. The measurements are compared to calculations of the giant resonance within time-dependent local density approximation in the dipole limit.more » No modulation of the giant resonance's shape for Ba atoms confined in different local environments was observed, in contrast to the calculations. The absence of such shape modulation for complex Ba/Si compounds is discussed providing important implications for further studies of giant resonance phenomena utilizing both theory and experiment.« less

  20. The Ba 4d-4f giant dipole resonance in complex Ba/Si compounds

    NASA Astrophysics Data System (ADS)

    Sahle, Ch J.; Sternemann, C.; Sternemann, H.; Tse, J. S.; Gordon, R. A.; Desgreniers, S.; Maekawa, S.; Yamanaka, S.; Lehmkühler, F.; Wieland, D. C. F.; Mende, K.; Huotari, S.; Tolan, M.

    2014-02-01

    The shape of the Ba 4d-4f giant dipole resonance is studied for Ba atoms embedded inside complex Si networks covering structures consisting of Si nanocages and nanotubes, i.e. the clathrate Ba8Si46, the complex compound BaSi6, and the semiconducting BaSi2. Here, non-resonant x-ray Raman scattering is used to investigate confinement effects on the shape of the giant resonance in the vicinity of the Ba NIV, V-edge. The distinct momentum transfer dependence of the spectra is analyzed and discussed. The measurements are compared to calculations of the giant resonance within time-dependent local density approximation in the dipole limit. No modulation of the giant resonance’s shape for Ba atoms confined in different local environments was observed, in contrast to the calculations. The absence of such shape modulation for complex Ba/Si compounds is discussed providing important implications for further studies of giant resonance phenomena utilizing both theory and experiment.

  1. Reconciling elemental Ba and barite as proxies of export production: Multiple Ba reservoirs in biogenic sediment

    NASA Astrophysics Data System (ADS)

    Murray, R. W.; Kryc, K. A.; Murray, D. W.

    2003-12-01

    The use of barite has long been recognized as a promising proxy for export production due to the relationship between its formation and settling biogenic matter. Accordingly, excess Ba (total Ba minus Ba associated with terrigenous material) calculations have been applied as a proxy of barite to assess export production, although this approach may be problematic. For example, because there are additional carrying phases of Ba in sediment other than terrigenous Ba and barite (e.g., oxides, organic matter), excess Ba may not be related in a predictable manner to export production. Indeed, previous workers have also identified the importance of non-barite reservoirs of Ba in sediment traps (e.g., Dymond et al., 1992; Francois et al., 1995) and sediment (e.g., Schroeder et al., 1997; Eagle et al., 2003). Despite these multiple reservoirs, the use of elemental Ba in biogenic sediment as a proxy of export production has a proven and resilient track record. To further understand the partitioning of Ba in biogenic sediment, we sequentially extracted seven, operationally-defined fractions (loosely-bound, exchangeable, carbonate, oxide, organic, opal, and residual) of sediment from surface and downcore samples from a cross-equatorial meridional transect in the equatorial Pacific. We find that Ba is evenly distributed between the sedimentary components with approximately 25-40 percent of the total extracted Ba in each of the exchangeable, carbonate, and oxide fractions for both surface and downcore sediment samples. In the surface sediment transect across the equator, there is no Ba in the residual fraction, and between 10 and 50 percent of the total extracted Ba is in the organic fraction. Also, downcore samples that were extracted from sediments with low relative bulk Ba/Ti tend to have Ba in both the residual and organic fractions as opposed to samples with high relative bulk Ba/Ti where there is a lack of Ba in both the residual and organic fractions. These observations

  2. Using real time traveler demand data to optimize commuter rail feeder systems.

    DOT National Transportation Integrated Search

    2012-08-01

    "This report focuses on real time optimization of the Commuter Rail Circulator Route Network Design Problem (CRCNDP). The route configuration of the circulator system where to stop and the route among the stops is determined on a real-time ba...

  3. Electrical Conduction of Ba(Ti0.99Fe0.01)O3-δ Ceramic at High Temperatures

    NASA Astrophysics Data System (ADS)

    Yu, Zi-De; Chen, Xiao-Ming

    2018-03-01

    BaTiO3 and Ba(Ti0.99Fe0.01)O3-δ ceramics with dense microstructure have been synthesized by a solid-state reaction method, and their electrical conduction investigated by broadband electrical impedance spectroscopy at frequencies from 0.05 Hz to 3 × 106 Hz and temperatures from 200°C to 400°C. Compared with BaTiO3, the real part of the permittivity and the phase-transition temperature of Ba(Ti0.99Fe0.01)O3-δ decreased. Relaxation peaks appeared in the curves of the imaginary part of the permittivity as a function of frequency. With increase in frequency, the peaks gradually shifted towards higher frequency and their height increased. Conductivity was closely related to frequency and temperature. Frequency-dependent conductivity was analyzed using the Jonscher double power law. Compared with BaTO3, Ba(Ti0.99Fe0.01)O3-δ exhibited high impedance at given frequency and temperature. Impedance Cole-Cole plots displayed two semicircles, which could be well fit using two parallel RC equivalent circuit models. The conductivity activation energy was found to be around 1 eV. For Ba(Ti0.99Fe0.01)O3-δ , the electrical modulus curve versus frequency displayed two peaks.

  4. Electrical Conduction of Ba(Ti0.99Fe0.01)O3- δ Ceramic at High Temperatures

    NASA Astrophysics Data System (ADS)

    Yu, Zi-De; Chen, Xiao-Ming

    2018-07-01

    BaTiO3 and Ba(Ti0.99Fe0.01)O3- δ ceramics with dense microstructure have been synthesized by a solid-state reaction method, and their electrical conduction investigated by broadband electrical impedance spectroscopy at frequencies from 0.05 Hz to 3 × 106 Hz and temperatures from 200°C to 400°C. Compared with BaTiO3, the real part of the permittivity and the phase-transition temperature of Ba(Ti0.99Fe0.01)O3- δ decreased. Relaxation peaks appeared in the curves of the imaginary part of the permittivity as a function of frequency. With increase in frequency, the peaks gradually shifted towards higher frequency and their height increased. Conductivity was closely related to frequency and temperature. Frequency-dependent conductivity was analyzed using the Jonscher double power law. Compared with BaTO3, Ba(Ti0.99Fe0.01)O3- δ exhibited high impedance at given frequency and temperature. Impedance Cole-Cole plots displayed two semicircles, which could be well fit using two parallel RC equivalent circuit models. The conductivity activation energy was found to be around 1 eV. For Ba(Ti0.99Fe0.01)O3- δ , the electrical modulus curve versus frequency displayed two peaks.

  5. Laser cooling of BaF

    NASA Astrophysics Data System (ADS)

    Bo, Yan; Bu, Wenhao; Chen, Tao; Lv, Guitao

    2017-04-01

    In this poster, we report our recently experimental progresses in laser cooling of BaF molecule. Our theoretic calculation shows BaF is a good candidate for laser cooling: quasi-cycling transitions, good wavelengths (around 900nm) for the main transitions. We have built a 4K cryogenic machine, laser ablate the target to make BaF molecules. The precise spectroscopy of BaF is measured and the laser cooling related transitions are identified. The collision between BaF and 4K He is carefully characterized. The quasi-cycling transition is demonstrated. And laser cooling experiment is going on.

  6. VizieR Online Data Catalog: Ba V, Ba VI, and Ba VII oscillator strengths (Rauch+, 2014)

    NASA Astrophysics Data System (ADS)

    Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

    2014-04-01

    table1.dat contains calculated HFR oscillator strengths (loggf) and transition probabilities (gA, in 1/s) in Ba V. CF is the cancellation factor as defined by Cowan (1981). In columns 3 and 6, e is written for even and o for odd. table2.dat contains calculated HFR oscillator strengths (loggf) and transition probabilities (gA, in 1/s) in Ba VI. CF is the cancellation factor as defined by Cowan (1981). In columns 3 and 6, e is written for even and o for odd. table3.dat contains calculated HFR oscillator strengths (loggf) and transition probabilities (gA, in 1/s) in Ba VII. CF is the cancellation factor as defined by Cowan (1981). In columns 3 and 6, e is written for even and o for odd. (3 data files).

  7. Synthesis and characterization of BaGa2O4 and Ba3Co2O6(CO3)0.6 compounds in the search of alternative materials for Proton Ceramic Fuel Cell (PCFC)

    NASA Astrophysics Data System (ADS)

    Acuña, Wilder; Tellez, Jhoan F.; Macías, Mario A.; Roussel, Pascal; Ricote, Sandrine; Gauthier, Gilles H.

    2017-09-01

    BaGa2O4 and Ba3Co2O6(CO3)0.6 compounds were studied as electrolyte and cathode materials for Proton Ceramic Fuel Cells (PCFC), respectively. Not only BaGa2O4 rapidly reacts with atmospheric H2O and CO2 and leads to a progressive material decomposition, but it does not present real hydration properties in normal conditions of pressure. On the other hand, the basic cobalt oxocarbonate Ba3Co2O6(CO3)0.6 exhibits an interesting tendency for weight uptake and formation of hydrogencarbonate groups in moist heating/cooling conditions. This material was therefore considered for complementary studies in order to confirm its potential use as mixed proton-electron conductor, taking into account the ordered intergrowth of carbonates and face sharing Co-octahedra columns forming a pseudo-one-dimensional structure. Some preliminary results concerning electrochemical properties of the barium cobalt oxocarbonate as a PCFC cathode are also described and show at the moment modest performance, possibly related to a hydrated/carbonated surface layer contribution and/or the lack of electron percolation within the electrode layer.

  8. Enhanced and broadband microwave absorption of flake-shaped Fe and FeNi composite with Ba ferrites

    NASA Astrophysics Data System (ADS)

    Li, Wangchang; Lv, Junjun; Zhou, Xiang; Zheng, Jingwu; Ying, Yao; Qiao, Liang; Yu, Jing; Che, Shenglei

    2017-03-01

    In order to achieve a broad bandwidth absorber at high frequency, the composites of M-type ferrite BaCo1.0Ti1.0Fe10O19 (BaM) with flaked carbonyl iron powders (CIP) and flaked Fe50Ni50 were prepared to optimize the surface impedance in broadband frequency, respectively. The diameter of the flaked carbonyl iron powders (CIP) and Fe50Ni50 is in the range of 5-10 μm and 10-20 μm and the thickness of the CIP and Fe50Ni50 is close to 200 nm and 400 nm, respectively. The complex permeability and permittivity show that the addition of BaM obviously reduces the values of real part of permittivity and imaginary part of the permeability which can enhance the matched-wave-impedance. The absorption bands less than -10 dB of CIP-BaM and FeNi-BaM absorber approach to 5.5 GHz (5.7-11.2 GHz) and 7 GHz (11-18 GHz) at 1.5 mm. However, the bands of CIP and FeNi are only 1.9 GHz (4.7-6.6 GHz) and 2.1 GHz (4.0-6.1 GHz). Hence, the electromagnetic match property is greatly improved by BaM ferrites, and this composite shows a broaden absorption band.

  9. 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).

  10. Reactions of NO2 with BaO/Pt(111) Model Catalysts: The Effects of BaO Film Thickness and NO2 Pressure on the Formation of Ba(NOx)2 Species

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mudiyanselage, Kumudu; Yi, Cheol-Woo; Szanyi, Janos

    2011-05-31

    The adsorption and reaction of NO2 on BaO (<1, ~3, and >20 monolayer equivalent (MLE))/Pt(111) model systems were studied with temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and infrared reflection absorption spectroscopy (IRAS) under ultra-high vacuum (UHV) as well as elevated pressure conditions. NO2 reacts with sub-monolayer BaO (<1 MLE) to form nitrites only, whereas the reaction of NO2 with BaO (~3 MLE)/Pt(111) produces mainly nitrites and a small amount of nitrates under UHV conditions (PNO2 ~ 1.0 × 10-9 Torr) at 300 K. In contrast, a thick BaO(>20 MLE) layer on Pt(111) reacts with NO2 to form nitrite-nitratemore » ion pairs under the same conditions. At elevated NO2 pressures (≥ 1.0 × 10-5 Torr), however, BaO layers at all these three coverages convert to amorphous barium nitrates at 300 K. Upon annealing to 500 K, these amorphous barium nitrate layers transform into crystalline phases. The thermal decomposition of the thus-formed Ba(NOx)2 species is also influenced by the coverage of BaO on the Pt(111) substrate: at low BaO coverages, these species decompose at significantly lower temperatures in comparison with those formed on thick BaO films due to the presence of Ba(NOx)2/Pt interface where the decomposition can proceed at lower temperatures. However, the thermal decomposition of the thick Ba(NO3)2 films follows that of bulk nitrates. Results obtained from these BaO/Pt(111) model systems under UHV and elevated pressure conditions clearly demonstrate that both the BaO film thickness and the applied NO2 pressure are critical in the Ba(NOx)2 formation and subsequent thermal decomposition processes.« less

  11. Anisotropic Dirac Fermions in BaMnBi2 and BaZnBi2

    NASA Astrophysics Data System (ADS)

    Ryu, Hyejin; Park, Se Young; Li, Lijun; Ren, Weijun; Petrovic, Cedomir; Hwang, Choonkyu; Mo, Sung-Kwan

    We report electronic structures of BaMnBi2 and BaZnBi2 sharing similar structural properties but having different valence configuration of the Mn/Zn-Bi complex. Our angle-resolved photoemission measurements found a strong anisotropic Dirac dispersion in BaMnBi2 and a complete departure from the Dirac dispersion in BaZnBi2. Our findings, substantiated by the first principle calculations, allow us to understand role of Mn/Zn-Bi tetrahedra in the changes of the electronic structures as well as the effect of varying band filling of Bi-square net. Work at BNL was supported by the U.S. Dept of Energy-BES, Division of Materials Science and Engineering, under Contract No. DE-SC0012704 and Chinese Academy of Sciences under Grant No. KJZD-EW-M05.

  12. Improvement of the field-trapping capabilities of bulk Nd Ba Cu O superconductors using Ba Cu O substrates

    NASA Astrophysics Data System (ADS)

    Matsui, Motohide; Nariki, Shinya; Sakai, Naomichi; Iwafuchi, Kengo; Murakami, Masato

    2006-07-01

    We used Ba-Cu-O substrates to fabricate bulk Nd-Ba-Cu-O superconductors using a top-seeded melt-growth method. There were several advantages for the use of Ba-Cu-O substrate compared to conventional substrate materials such as MgO, ZrO2, Al2O3, RE123 and RE211 (RE = rare earth). The Ba-Cu-O did not react with the precursor and minimized liquid loss. Accordingly, the introduction of large-sized cracks was suppressed. We also found that Tc values were high at the bottom regions, which was ascribed to the beneficial effect of Ba-Cu-O in suppressing Nd/Ba substitution. As a result, we obtained bulk Nd-Ba-Cu-O superconductors that exhibited fairly good field-trapping capabilities, even at the bottom surfaces.

  13. 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.

  14. Ba3CuOs2O9 and Ba3ZnOs2O9, a comparative study

    NASA Astrophysics Data System (ADS)

    Feng, Hai L.; Jansen, Martin

    2018-02-01

    Polycrystalline samples of Ba3CuOs2O9 and Ba3ZnOs2O9 were synthesized by solid-state reactions. Ba3CuOs2O9 crystallizes in Cmcm, while Ba3ZnOs2O9 adopts the hexagonal space group P63/mmc. Both the crystal structures consist of face-sharing Os-centered octahedra forming dimer-like Os2O9 units, which are interconnected by corner-sharing CuO6, or ZnO6 octahedra, respectively. In Ba3CuOs2O9, the CuO6 octahedra show a characteristic Jahn-Teller distortion. Both, Ba3CuOs2O9 and Ba3ZnOs2O9, are electrically insulating. Magnetic and specific heat measurements confirm that Ba3CuOs2O9 is antiferromagnetically ordered below 47 K. Analysis of the magnetic data indicated that its magnetic properties are dominated by Cu2+ ions. The magnetic susceptibility of Ba3ZnOs2O9 is weakly temperature-dependent with a broad maximum ≈ 280 K, indicating the presence of strong exchange interactions within the Os2O9 dimer. The residual magnetic susceptibility at low temperatures also suggests the presence of appreciable exchange coupling between the dimers.

  15. Barium bioaccumulation by bacterial biofilms and implications for Ba cycling and use of Ba proxies.

    PubMed

    Martinez-Ruiz, Francisca; Jroundi, Fadwa; Paytan, Adina; Guerra-Tschuschke, Isabel; Abad, María Del Mar; González-Muñoz, María Teresa

    2018-04-24

    Ba proxies have been broadly used to reconstruct past oceanic export production. However, the precise mechanisms underlying barite precipitation in undersaturated seawater are not known. The link between bacterial production and particulate Ba in the ocean suggests that bacteria may play a role. Here we show that under experimental conditions marine bacterial biofilms, particularly extracellular polymeric substances (EPS), are capable of bioaccumulating Ba, providing adequate conditions for barite precipitation. An amorphous P-rich phase is formed at the initial stages of Ba bioaccumulation, which evolves into barite crystals. This supports that in high productivity regions where large amounts of organic matter are subjected to bacterial degradation, the abundant EPS would serve to bind the necessary Ba and form nucleation sites leading to barite precipitation. This also provides new insights into barite precipitation and opens an exciting field to explore the role of EPS in mineral precipitation in the ocean.

  16. Uniform-large Area BaSrTiO3 Growth and Novel Material Designs to Enable Fabrication of High Quality, Affordable, and Performance Consistent Phase Shifters for OTM Phased Array Antennas

    DTIC Science & Technology

    2012-07-11

    molar flux of each precursor entering the reactor. The molar fluxes for Ba , Sr , and Ti are measured and computed in real-time, and these measured values...allows control of the relative amounts of Ba , Sr , and Ti, and the overall total mass flow in umole/min reaching the substrate. In all, there are three...is the Ba:Sr ratio with depth (from the top of the film). The ratio of Ba to Sr was controlled from 0.87 to 0.43. The total film thickness is 130 nm

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ahmed, M.A., E-mail: moala@47hotmail.com; 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{submore » 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.« less

  18. BaTiO3-core Au-shell nanoparticles for photothermal therapy and bimodal imaging.

    PubMed

    Wang, Yanfei; Barhoumi, Aoune; Tong, Rong; Wang, Weiping; Ji, Tianjiao; Deng, Xiaoran; Li, Lele; Lyon, Sophie A; Reznor, Gally; Zurakowski, David; Kohane, Daniel S

    2018-05-01

    We report sub-100 nm metal-shell (Au) dielectric-core (BaTiO 3 ) nanoparticles with bimodal imaging abilities and enhanced photothermal effects. The nanoparticles efficiently absorb light in the near infrared range of the spectrum and convert it to heat to ablate tumors. Their BaTiO 3 core, a highly ordered non-centrosymmetric material, can be imaged by second harmonic generation, and their Au shell generates two-photon luminescence. The intrinsic dual imaging capability allows investigating the distribution of the nanoparticles in relation to the tumor vasculature morphology during photothermal ablation. Our design enabled in vivo real-time tracking of the BT-Au-NPs and observation of their thermally-induced effect on tumor vessels. Photothermal therapy induced by plasmonic nanoparticles has emerged as a promising approach to treating cancer. However, the study of the role of intratumoral nanoparticle distribution in mediating tumoricidal activity has been hampered by the lack of suitable imaging techniques. This work describes metal-shell (Au) dielectric-core (BaTiO 3 ) nanoparticles (abbreviated as BT-Au-NP) for photothermal therapy and bimodal imaging. We demonstrated that sub-100 nm BT-Au-NP can efficiently absorb near infrared light and convert it to heat to ablate tumors. The intrinsic dual imaging capability allowed us to investigate the distribution of the nanoparticles in relation to the tumor vasculature morphology during photothermal ablation, enabling in vivo real-time tracking of the BT-Au-NPs and observation of their thermally-induced effect on tumor vessels. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  19. Influence diagnostics for count data under AB-BA crossover trials.

    PubMed

    Hao, Chengcheng; von Rosen, Dietrich; von Rosen, Tatjana

    2017-12-01

    This paper aims to develop diagnostic measures to assess the influence of data perturbations on estimates in AB-BA crossover studies with a Poisson distributed response. Generalised mixed linear models with normally distributed random effects are utilised. We show that in this special case, the model can be decomposed into two independent sub-models which allow to derive closed-form expressions to evaluate the changes in the maximum likelihood estimates under several perturbation schemes. The performance of the new influence measures is illustrated by simulation studies and the analysis of a real dataset.

  20. 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.

  1. BaBar Experiment Public Web Site

    Science.gov Websites

    spotlights BaBar time-reversal measurement. December 14, 2012 PhysicsWorld.com has selected the BaBar time . BaBar Makes First Direct Observation of Time-Reversal Violation August 30, 2012 Fundamental interactions among particles are oblivious to the direction of time (a movie of a rock thrown up and falling back

  2. Stellar laboratories. III. New Ba v, Ba vi, and Ba vii oscillator strengths and the barium abundance in the hot white dwarfs G191-B2B and RE 0503-289

    NASA Astrophysics Data System (ADS)

    Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

    2014-06-01

    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 v-vii 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 × 10-4 (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 × 10-6 (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. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for

  3. Electronic and optical properties of double perovskite Ba2VMoO6: FP-LAPW study

    NASA Astrophysics Data System (ADS)

    Hnamte, Lalhriatpuia; Sandeep, Joshi, Himanshu; Thapa, R. K.

    2018-05-01

    The calculation is carried out using the FPLAPW method in the DFT framework within mBJ and LDA using the WIEN2k code. The investigation of electronic properties showed Ba2VMoO6 to be semi-metal in spin-up and insulation in spin down. In both spin up and spin down channel, direct band gap along with indirect band gap in ΓX direction was observed. For investigation of the optical transitions in this compound, the real and imaginary parts of the dielectric function, reflectivity, refractive index and optical conductivity of real and imaginary parts are calculated and analysed.

  4. Near real-time estimation of burned area using VIIRS 375 m active fire product

    NASA Astrophysics Data System (ADS)

    Oliva, P.; Schroeder, W.

    2016-12-01

    Every year, more than 300 million hectares of land burn globally, causing significant ecological and economic consequences, and associated climatological effects as a result of fire emissions. In recent decades, burned area estimates generated from satellite data have provided systematic global information for ecological analysis of fire impacts, climate and carbon cycle models, and fire regimes studies, among many others. However, there is still need of near real-time burned area estimations in order to assess the impacts of fire and estimate smoke and emissions. The enhanced characteristics of the Visible Infrared Imaging Radiometer Suite (VIIRS) 375 m channels on board the Suomi National Polar-orbiting Partnesship (S-NPP) make possible the use of near real-time active fire detection data for burned area estimation. In this study, consecutive VIIRS 375 m active fire detections were aggregated to produce the VIIRS 375 m burned area (BA) estimation over ten ecologically diverse study areas. The accuracy of the BA estimations was assessed by comparison with Landsat-8 supervised burned area classification. The performance of the VIIRS 375 m BA estimates was dependent on the ecosystem characteristics and fire behavior. Higher accuracy was observed in forested areas characterized by large long-duration fires, while grasslands, savannas and agricultural areas showed the highest omission and commission errors. Complementing those analyses, we performed the burned area estimation of the largest fires in Oregon and Washington states during 2015 and the Fort McMurray fire in Canada 2016. The results showed good agreement with NIROPs airborne fire perimeters proving that the VIIRS 375 m BA estimations can be used for near real-time assessments of fire effects.

  5. REPRODUCTION IN VITRO OF ENTAMŒBA TETRAGENA AND ENTAMŒBA COLI FROM THEIR CYSTS

    PubMed Central

    Yoshida, Kazuyoshi

    1920-01-01

    1. The vegetative forms of amebæ may be developed in vitro from the cysts. 2. The cysts of Entamœba tetragena and Entamœba coli each produce only a single vegetative individual. It has not been observed in vitro that a number of daughter amebæ, corresponding to the number of nuclei present in the cyst, emerge from the mother cyst, as claimed by Casagrandi and Barbagallo, Schaudinn, and a number of other investigators. 3. The daughter nuclei in the cystic stage correspond to the gamete nuclei of other protozoa. The syngamic nuclear union in the case of these two amebæ does not take place in the tetranuclear stage of the cyst, as claimed by Schaudinn and Wenyon, but during reproduction. 4. The process of autogamy of both amebæ is not restricted to two nuclei; it may involve more than two, which unite to form a syncaryon. In the case of all other protozoa, autogamy is restricted to two nuclei. 5. In order to distinguish the two types of autogamy, one has been termed simple autogamy and the other polynuclear autogamy. The latter may again be classified according to the number of nuclei involved, as trinuclear and tetranuclear autogamy. 6. The majority of cysts treated for 5 minutes in a 2 per cent solution of hydrochloric acid survives. 7. It was possible to demonstrate in vitro the developmental cycle of Entamœba tetragena. 8. No evidence of heterogamy has been observed in vitro in Entamœba tetragena or Entamœba coli. 9. The vegetative form of Entamœba tetragena, at a certain stage of its life cycle in vitro, shortly after its formation, has not only one or two, but may have as many as three or four nuclei. PMID:19868451

  6. Dielectric properties of PVDF/0.5(Ba0.7Ca0.3)TiO3-0.5Ba(Zr0.2Ti0.8)O3 composites

    NASA Astrophysics Data System (ADS)

    Pandey, Bablu K.; Chandra, K. P.; Kolte, Jayant; Kulkarni, A. R.; Jayaswal, S. K.; Prasad, K.

    2018-05-01

    Ceramic powder of 0.50(Ba0.7Ca0.3)TiO3-0.50Ba(Zr0.2Ti0.8)O3(BCZT50) at morphotropic phase boundary composition was prepared usingsolid-statesynthesis technique followed by extensive high energy ball milling. The crystal symmetry, space group and unit cell dimensions were determined from the X-raydiffraction data of BCZT50 using FullProf software andthe average crystallite size was estimated using Williamson-Hall approach. FTIR spectra confirmed the formation of perovskite type solid solutions. The prepared ceramic powder was utilized to prepare lead-free (1- x)PVDF/xBCZT50 ceramic-polymer composites with x = 0.025, 0.05, 0.10, 0.15, 0.20, 0.25 were prepared using melt- mixing technique. The distribution of BCZT50 particles in the PVDF matrix were examined using anoptical microscope. Filler concentration dependent real and imaginary parts of dielectric constant data followed exponential growth types of variation. The low value of tanδ(˜10-2) can be advantageous forsensing/detectionapplications.

  7. 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}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    He, Hua; Stoyko, Stanislav; Bobev, Svilen, E-mail: bobev@udel.edu

    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)more » 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

  8. 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.

  9. Dielectric properties of (CuO, CaO2, and BaO)y/CuTl-1223 composites

    NASA Astrophysics Data System (ADS)

    Mumtaz, M.; Kamran, M.; Nadeem, K.; Jabbar, Abdul; Khan, Nawazish A.; Saleem, Abida; Tajammul Hussain, S.; Kamran, M.

    2013-07-01

    We synthesized (CuO, CaO2, and BaO)y/Cu0.5Tl0.5Ba2Ca2Cu3O10-δ (y = 0, 5%, 10%, 15%) composites by solid-state reaction and characterized them by x-ray diffraction, scanning electron microscopy, dc-resistivity, and Fourier transform infrared spectroscopy. Frequency and temperature dependent dielectric properties, such as real and imaginary parts of the dielectric constant, dielectric loss, and ac-conductivity of these composites were studied by capacitance and conductance measurements as a function of frequency (10 kHz to 10 MHz) and temperature (78 to 300 K). X-ray diffraction analysis reveals that the characteristic behavior of the superconductor phase and the structure of Cu0.5Tl0.5Ba2Ca2Cu3O10-δ are nearly undisturbed by doping with nanoparticles. Scanning electron microscopy images show the improvement in the intergranular linking between the superconducting grains occurring with increasing nanoparticle concentration. Microcracks are healed up with these nanoparticles, and superconducting volume fraction is also increased. Dielectric properties of these composites strongly depend on the frequency and temperature. Zero resistivity critical temperature and dielectric properties show opposite trends with the addition of nanoparticles to the Cu0.5Tl0.5Ba2Ca2Cu3O10-δ superconductor matrix.

  10. 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. 133 Ba+: a new ion qubit

    NASA Astrophysics Data System (ADS)

    Christensen, Justin; Hucul, David; Campbell, Wesley; Hudson, Eric

    2017-04-01

    133 Ba+ combines many of the advantages of commonly used trapped ion qubits. 133Ba+ has a nuclear spin 1/2, allowing for a robust hyperfine qubit with simple state preparation and readout. The existence of long-lived metastable D-states and a lack of low-lying F-states simplifies shelving, which will allow high fidelity state detection. The visible wavelength optical transitions enable the use of high-power lasers, low-loss fibers, high quantum efficiency detectors, and other optical technologies developed for visible wavelength light. Furthermore, background-free qubit readout, where the readout is insensitive to laser scatter, is possible in 133Ba+, and simplifies its use in small ion traps and the study of ions near surfaces. We report progress on realizing this qubit. We load barium ions into an ion trap using thermal ionization from a platinum ribbon. We experimentally demonstrate the isotopic purification of large numbers of barium ions using laser heating and cooling along with mass filtering to produce isotopically pure chains of any naturally-occurring barium isotope. This purification process has allowed us to laser cool rare, naturally-occurring barium isotopes 132Ba+and130Ba+, and we report the isotope shifts from 138Ba+ of the P1/2 to D3/2 transitions near 650 nm for the first time. In addition, we have developed an ion gun to produce high luminosity ion beams with adjustable mean kinetic energy by combining a surface ionization source and ion optics.

  12. The effect of canopy closure on chimpanzee nest abundance in Lagoas de Cufada National Park, Guinea-Bissau.

    PubMed

    Sousa, Joana; Casanova, Catarina; Barata, André V; Sousa, Cláudia

    2014-04-01

    The present study aimed to gather baseline information about chimpanzee nesting and density in Lagoas de Cufada Natural Park (LCNP), in Guinea-Bissau. Old and narrow trails were followed to estimate chimpanzee density through marked-nest counts and to test the effect of canopy closure (woodland savannah, forest with a sparse canopy, and forest with a dense canopy) on nest distribution. Chimpanzee abundance was estimated at 0.79 nest builders/km(2), the lowest among the areas of Guinea-Bissau with currently studied chimpanzee populations. Our data suggest that sub-humid forest with a dense canopy accounts for significantly higher chimpanzee nest abundance (1.50 nests/km of trail) than sub-humid forest with a sparse canopy (0.49 nests/km of trail) or woodland savannah (0.30 nests/km of trail). Dense-canopy forests play an important role in chimpanzee nesting in the patchy and highly humanized landscape of LCNP. The tree species most frequently used for nesting are Dialium guineense (46%) and Elaeis guineensis (28%). E. guineensis contain nests built higher in the canopy, while D. guineense contain nests built at lower heights. Nests observed during baseline sampling and replications suggest seasonal variations in the tree species used for nest building.

  13. Dielectric relaxation in 0-3 PVDF-Ba(Fe{sub 1/2}Nb{sub 1/2})O{sub 3} composites

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chandra, K. P., E-mail: kpchandra23@gmail.com; Singh, Rajan; Kulkarni, A. R., E-mail: ajit2957@gmail.com

    2016-05-06

    (1-x)PVDF-xBa(Fe{sub 1/2}Nb{sub 1/2})O{sub 3} ceramic-polymer composites with x = 0.025, 0.05, 0.10, 0.15 were prepared using melt-mixing technique. The crystal symmetry, space group and unit cell dimensions were determined from the XRD data of Ba(Fe{sub 1/2}Nb{sub 1/2})O{sub 3} using FullProf software, whereas crystallite size and lattice strain were estimated using Williamson-Hall approach. The distribution of Ba(Fe{sub 1/2}Nb{sub 1/2})O{sub 3} particles in the PVDF matrix were examined on the cryo-fractured surfaces using a scanning electron microscope. Cole-Cole and pseudo Cole-Cole analysis suggested the dielectric relaxation in this system to be of non-Debye type. Filler concentration dependent real and imaginary parts ofmore » dielectric constant as well as ac conductivity data followed definite trends of exponential growth types of variation.« less

  14. 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.

  15. 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.

  16. Structural properties of ultrafine Ba-hexaferrite nanoparticles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Makovec, Darko, E-mail: Darko.Makovec@ijs.si; Primc, Darinka; Sturm, Saso

    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.more » 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.« less

  17. (Ba+Sr)/Ti ratio dependence of the dielectric properties for (Ba0.5Sr0.5)TiO3 thin films prepared by ion beam sputtering

    NASA Astrophysics Data System (ADS)

    Yamamichi, Shintaro; Yabuta, Hisato; Sakuma, Toshiyuki; Miyasaka, Yoichi

    1994-03-01

    (Ba0.5Sr0.5)TiO3 thin films were prepared by ion beam sputtering from powder targets with (Ba+Sr)/Ti ratios ranging from 0.80 to 1.50. All of the perovskite (Ba,Sr)TiO3 films were single phase except for the film with a (Ba+Sr)/Ti ratio of 1.41. The dielectric constant values notably depended on the (Ba+Sr)/Ti ratio for films thicker than 70 nm. The highest dielectric constant of 580 was achieved for the 5% (Ba+Sr) rich film. This (Ba+Sr)/Ti ratio dependence was diminished by the thickness dependence for thinner films. The grain sizes for the 9% (Ba+Sr) rich film and for the 6% (Ba+Sr) poor film ranged from 70 to 100 nm and from 30 to 60 nm, respectively. This grain size difference could explain why slightly A-site rich (Ba,Sr)TiO3 films have a larger dielectric constant than A-site poor films.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bodeux, Romain; Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac; Michau, Dominique, E-mail: dominique.michau@icmcb.cnrs.fr

    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 similarmore » 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.« less

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pan, Ming-Yan; Xia, Sheng-Qing, E-mail: shqxia@sdu.edu.cn; Liu, Xiao-Cun

    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 measuredmore » 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.« less

  20. Growth of BaSi2 continuous films on Ge(111) by molecular beam epitaxy and fabrication of p-BaSi2/n-Ge heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Takabe, Ryota; Yachi, Suguru; Tsukahara, Daichi; Toko, Kaoru; Suemasu, Takashi

    2017-05-01

    We grew BaSi2 films on Ge(111) substrates by various growth methods based on molecular beam epitaxy (MBE). First, we attempted to form BaSi2 films directly on Ge(111) by MBE without templates. We next formed BaSi2 films using BaGe2 templates as commonly used for MBE growth of BaSi2 on Si substrates. Contrary to our prediction, the lateral growth of BaSi2 was not promoted by these two methods; BaSi2 formed not into a continuous film but into islands. Although streaky patterns of reflection high-energy electron diffraction were observed inside the growth chamber, no X-ray diffraction lines of BaSi2 were observed in samples taken out from the growth chamber. Such BaSi2 islands were easily to get oxidized. We finally attempted to form a continuous BaSi2 template layer on Ge(111) by solid phase epitaxy, that is, the deposition of amorphous Ba-Si layers onto MBE-grown BaSi2 epitaxial islands, followed by post annealing. We achieved the formation of an approximately 5-nm-thick BaSi2 continuous layer by this method. Using this BaSi2 layer as a template, we succeeded in forming a-axis-oriented 520-nm-thick BaSi2 epitaxial films on Ge substrates, although (111)-oriented Si grains were included in the grown layer. We next formed a B-doped p-BaSi2(20 nm)/n-Ge(111) heterojunction solar cell. A wide-spectrum response from 400 to 2000 nm was achieved. At an external bias voltage of 1 V, the external quantum efficiency reached as high as 60%, demonstrating the great potential of BaSi2/Ge combination. However, the efficiency of a solar cell under AM1.5 illumination was quite low (0.1%). The origin of such a low efficiency was examined.

  1. Pharmacokinetics of [ 14C]-Benzo[a]pyrene (BaP) in humans: Impact of Co-Administration of smoked salmon and BaP dietary restriction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hummel, Jessica M.; Madeen, Erin P.; Siddens, Lisbeth K.

    Benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon (PAH), is a known human carcinogen. In non-smoking adults greater than 95% of BaP exposure is through diet. The carcinogenicity of BaP is utilized by the U.S. EPA to assess relative potency of complex PAH mixtures. PAH relative potency factors (RPFs, BaP=1) are determined from high dose animal data. Here we employed accelerator mass spectrometry (AMS) to determine pharmacokinetics of [ 14C]-BaP in humans following dosing with 46 ng (an order of magnitude lower than human dietary daily exposure and million-fold lower than animal cancer models). To assess the impact of co-administration of foodmore » with a complex PAH mixture, humans were dosed with 46 ng of [ 14C]-BaP with or without smoked salmon. Subjects were asked to avoid high BaP-containing diets and a 3-day dietary questionnaire given to assess dietary exposure prior to dosing and three days post-dosing with [ 14C]-BaP. Co-administration of smoked salmon, containing a complex mixture of PAHs with an RPF of 460 ng BaP eq, reduced and delayed absorption. Administration of canned commercial salmon, containing very low amounts of PAHs, showed the impacts on pharmacokinetics were not due to high amounts of PAHs but rather a food matrix effect.« less

  2. Pharmacokinetics of [ 14C]-Benzo[a]pyrene (BaP) in humans: Impact of Co-Administration of smoked salmon and BaP dietary restriction

    DOE PAGES

    Hummel, Jessica M.; Madeen, Erin P.; Siddens, Lisbeth K.; ...

    2018-03-01

    Benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon (PAH), is a known human carcinogen. In non-smoking adults greater than 95% of BaP exposure is through diet. The carcinogenicity of BaP is utilized by the U.S. EPA to assess relative potency of complex PAH mixtures. PAH relative potency factors (RPFs, BaP=1) are determined from high dose animal data. Here we employed accelerator mass spectrometry (AMS) to determine pharmacokinetics of [ 14C]-BaP in humans following dosing with 46 ng (an order of magnitude lower than human dietary daily exposure and million-fold lower than animal cancer models). To assess the impact of co-administration of foodmore » with a complex PAH mixture, humans were dosed with 46 ng of [ 14C]-BaP with or without smoked salmon. Subjects were asked to avoid high BaP-containing diets and a 3-day dietary questionnaire given to assess dietary exposure prior to dosing and three days post-dosing with [ 14C]-BaP. Co-administration of smoked salmon, containing a complex mixture of PAHs with an RPF of 460 ng BaP eq, reduced and delayed absorption. Administration of canned commercial salmon, containing very low amounts of PAHs, showed the impacts on pharmacokinetics were not due to high amounts of PAHs but rather a food matrix effect.« less

  3. When one becomes two: Ba12In4Se20, not quite isostructural to Ba12In4S19

    NASA Astrophysics Data System (ADS)

    Yin, Wenlong; Iyer, Abishek K.; Li, Chao; Yao, Jiyong; Mar, Arthur

    2017-09-01

    The ternary selenide Ba12In4Se20 was synthesized by reaction of BaSe, In2Se3, and Se at 1023 K. Single-crystal X-ray diffraction revealed a trigonal structure (space group R 3 bar, Z = 6, a = 10.0360(6) Å, c = 78.286(4) Å at room temperature) consisting of one-dimensional stacks of InSe4 tetrahedra, In2Se7 double tetrahedra, selenide Se2- anions, and diselenide Se22- anions, with Ba2+ cations in the intervening spaces. The selenide Ba12In4Se20 can be derived from the corresponding sulfide Ba12In4S19 by replacing one monoatomic Ch2- anion with a diatomic Ch22- anion. An optical band gap of 1.70(2) eV, consistent with the dark red colour of the crystals, was deduced from the UV-vis-NIR diffuse reflectance spectrum.

  4. Real-time water quality monitoring and providing water quality information to the Baltimore Community

    EPA Science Inventory

    EPA and the U.S. Geological Survey (USGS) have initiated the “Village Blue” research project to provide real-time water quality monitoring data to the Baltimore community and increase public awareness about local water quality in Baltimore Harbor and the Chesapeake Ba...

  5. 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.

  6. Unusual very positive enrichment of 13C in carbonate sediments deposited in modern hypersaline environment, Lagoa Salgada, Brazil: Indicator of salinity controlled metabolic processes

    NASA Astrophysics Data System (ADS)

    McKenzie, J. A.; Bovier, C.; Bahniuk, A.; Andersen, M. B.; Vasconcelos, C.

    2016-12-01

    In the geologic record, prolonged intervals of intense δ13C enrichment (>10‰) in carbonate deposits occurred, in particular during the mid-Palaeoproterozoic (2.3-1.9 Ga) and mid-Neoproterozoic (0.8-0.6 Ga) [1]. These anomalously high δ13C values have been interpreted as a global effect due to enhanced burial of organic matter with depleted δ13C values [2]. An alternate interpretation has been proposed whereby the metabolic activity of specific microbial communities, such as methanogens, may have been the source of the strong carbon isotope fractionation [3]. Although such restricted shallow-water environments where methanogens dominate are not widespread today, a unique hypersaline coastal lagoon system, Lagoa Salgada, Brazil provides ideal conditions to study the modern microbial community and its impact on observed extreme δ13C enrichment (up to 20‰) recorded in both in situ stromatolites and carbonate sediments. Here we present our findings and correlations of geochemical data with changing environmental conditions during the last 2600 cal yr BP. This lagoonal system contains highly evaporated water with highest salinities occurring during the dry season. The positive δ13C anomaly shows high and stable values (>14‰) from about 2100 to 1400 cal yr BP. Similar high δ13C values were recorded for the same time period in stromatolite structures growing around the margin of Lagoa Salgada. We propose that the high salinities inhibit photosynthesis, respiration and nitrogen fixation by osmotic stress and, thus, result in increased methanogenesis. We conclude that the combination of methanogenic metabolisms and extreme evaporative conditions is the key factor promoting the production of very high δ13C values observed throughout the lagoonal system, as recorded in both marginal stromatolites and carbonate sediments deposited in the more distal regions of the lagoon. Such unusual environments may have been more widely distributed during the Proterozoic

  7. Coupled dielectric permittivity and magnetic susceptibility in the insulating antiferromagnet Ba2FeSbSe5

    NASA Astrophysics Data System (ADS)

    Maier, S.; Moussa, C.; Berthebaud, D.; Gascoin, F.; Maignan, A.

    2018-05-01

    We report on coupled changes in the dielectric permittivity and the magnetic susceptibility in the insulating antiferromagnet Ba2FeSbSe5. The real part of the dielectric permittivity (ɛ') and the thermal conductivity (κ) shows pronounced anomalies at the Néel temperature (TN). Our findings show that there is a weak coupling between electric dipoles and magnetic spins, which is mediated by spin-lattice coupling possibly through exchange striction effects.

  8. Growth and characterization of BaZnGa

    DOE PAGES

    Jo, Na Hyun; Lin, Qisheng; Nguyen, Manh Cuong; ...

    2017-10-20

    In this paper, we report the growth, structure and characterization of BaZnGa, identifying it as the sole known ternary compound in the Ba–Zn–Ga system. Single crystals of BaZnGa can be grown out of excess Ba–Zn and adopt a tI36 structure type. There are three unique Ba sites and three M = Zn/Ga sites. Using DFT calculations we can argue that whereas one of these three M sites is probably solely occupied by Ga, the other two M sites, most likely, have mixed Zn/Ga occupancy. Finally, temperature-dependent resistivity and magnetization measurements suggest that BaZnGa is a poor metal with no electronicmore » or magnetic phase transitions between 1.8 and 300 K.« less

  9. Surface spins enhanced magnetoelectric coefficient and impedance spectroscopy of BaFe{sub 0.01}Ti{sub 0.99}O{sub 3} and BaFe{sub 0.015}Ti{sub 0.985}O{sub 3} nanorods

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Verma, Kuldeep Chand, E-mail: kuldeep0309@yahoo.co.in; Akal School of Physics, Eternal University, Baru Sahib, Himachal Pradesh 173101; Tripathi, S.K.

    2015-08-15

    Highlights: • Multiferroic Fe-doped BaTiO{sub 3} nanorods. • Sol–gel. • Magnetoelectric coefficient. • Transmission electron microscopy. • Cole–Cole plots. - Abstract: Multiferroic BaFe{sub 0.01}Ti{sub 0.99}O{sub 3} (BFT1) and BaFe{sub 0.015}Ti{sub 0.985}O{sub 3} (BFT15) nanorods were prepared by a sol–gel synthesis and annealed at 700 °C/2 h. The tetragonal phase and nano dimensions of BFT samples are identified by X-ray diffraction and transmission electron microscopy. The enhancement in ferroelectricity depends upon low porosity, tetragonal phase, space charge field, larger surface area and oriented growth. The ferromagnetism depends upon partially filled inner shells, surface spins and oxygen vacancies. The magnetoelectric coefficient ismore » explained on the basis of surface spins, short-range interactions near surface boundary, compressive stress and twin structure contributed by nano grains which can reside stress near grain boundaries. The frequency dependent real (Z′) and imaginary (Z″) parts of impedance spectra are confirmed by the variations that observed in dielectric properties. The values of resistance of grain boundaries, R{sub gb} is higher than grains, R{sub g} indicating that the effect of grain boundaries is dominant in BFT nanorods.« less

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    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 ofmore » 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.« less

  11. A validation of the Danish microbiology database (MiBa) and incidence rate of Actinotignum schaalii (Actinobaculum schaalii) bacteraemia in Denmark.

    PubMed

    Bank, S; Søby, K M; Kristensen, L H; Voldstedlund, M; Prag, J

    2015-12-01

    Actinotignum schaalii (former named Actinobaculum schaalii) can cause urinary tract infections (UTIs) and bacteraemia, mainly in the elderly. A. schaalii is difficult to identify with conventional biochemical tests, and it is often overlooked if the urine is only cultured in ambient air. The aim of this study was to validate data from the nationwide Danish microbiology database (MiBa) with data from the laboratory information system (LIS) at the local department of microbiology in Viborg-Herning, and to evaluate the incidence rate of bacteraemia caused by A. schaalii in Denmark by using data from the MiBa. All departments of microbiology in Denmark report data to the MiBa. All microbiological samples with A. schaalii in Denmark were extracted for a period of 5 years from the MiBa and from the local LISs. All data obtained from our local LIS were also found in the MiBa, except for data on real-time PCR, which were not registered, owing to missing ID codes in the MiBa. From 2010 to 2014, there was a significant increase in the incidence rate of blood cultures with A. schaalii, from 1.8 to 6.8 cases per million, which was probably due to coincident implementation of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) in routine diagnostics. We found that A. schaalii caused bacteraemia and UTIs mainly in the elderly. In conclusion, the MiBa can be a useful source of nationwide microbiological data in Denmark. Our results suggest that the incidence rate of A. schaalii as a cause of bacteraemia has been underestimated, and that culture of urine in CO2 can improve the detection of A. schaalii. Copyright © 2015 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  12. Tuning the giant magnetoelastic transition in Ba3BiIr2O9 and Ba3BiRu2O9

    NASA Astrophysics Data System (ADS)

    Huang, Zixin; Avdeev, Maxim; Kennedy, Brendan J.; Knight, Kevin S.; Zhou, Qingdi; Ling, Chris D.

    2014-07-01

    We have experimentally investigated the effects of pressure on the magnetoelastic transitions associated with the opening of spin-gaps in Ba3BiIr2O9 and Ba3BiRu2O9. For both compounds, reducing the unit cell volume by either external physical and internal chemical pressure was found to reduce the temperature T* of the transition and, to a lesser extent, the magnitude of the associated negative thermal volume expansion. The results yield the latent heat associated with the transitions, -3.34(3) × 102 J mol-1 for Ba3BiIr2O9 and -7.1(5) × 102 J mol-1 for Ba3BiRu2O9. The transition in Ba3BiRu2O9 is significantly more robust than in Ba3BiIr2O9, requiring an order of magnitude higher pressures to achieve the same reduction in T*. The differing responses of the two compounds points to differences between the 4d and 5d metals and hence to the importance of spin-orbit coupling, which is expected to be much stronger in the Ir compound.

  13. Reproducibility of Ba/Ca variations recorded by northeast Pacific bamboo corals

    NASA Astrophysics Data System (ADS)

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

    2017-09-01

    Trace elemental ratios preserved in the calcitic skeleton of bamboo corals have been shown to serve as archives of past ocean conditions. The concentration of dissolved barium (BaSW), a bioactive nutrientlike element, is linked to biogeochemical processes such as the cycling and export of nutrients. Recent work has calibrated bamboo coral Ba/Ca, a new BaSW proxy, using corals spanning the oxygen minimum zone beneath the California Current System. However, it was previously unclear whether Ba/Cacoral records were internally reproducible. Here we investigate the accuracy of using laser ablation inductively coupled plasma mass spectrometry for Ba/Cacoral analyses and test the internal reproducibility of Ba/Ca among replicate radial transects in the calcite of nine bamboo corals collected from the Gulf of Alaska (643-720 m) and the California margin (870-2054 m). Data from replicate Ba/Ca transects were aligned using visible growth bands to account for nonconcentric growth; smoothed data were reproducible within 4% for eight corals (n = 3 radii/coral). This intracoral reproducibility further validates using bamboo coral Ba/Ca for BaSW reconstructions. Sections of the Ba/Ca records that were potentially influenced by noncarbonate bound Ba phases occurred in regions where elevated Mg/Ca or Pb/Ca and coincided with anomalous regions on photomicrographs. After removing these regions of the records, increased Ba/Cacoral variability was evident in corals between 800 and 1500 m. These findings support additional proxy validation to understand BaSW variability on interannual timescales, which could lead to new insights into deep sea biogeochemistry over the past several centuries.

  14. Is BaCr 2 As 2 symmetrical to BaFe 2 As 2 with respect to half 3 d shell filling?

    DOE PAGES

    Richard, P.; van Roekeghem, A.; Lv, B. Q.; ...

    2017-05-25

    We have performed an angle-resolved photoemission spectroscopy study of BaCr 2As 2, which has the same crystal structure as BaFe2As2, a parent compound BaFe 2As 2 of Fe-based superconductors. We determine the Fermi surface of this material and its band dispersion down to 5 eV below the Fermi level. Very moderate band renormalization (1.35) is observed for only two bands. We attribute this small renormalization to enhanced direct exchange as compared to Fe in BaFe 2As 2, and to a larger contribution of the eg orbitals in the composition of the bands forming the Fermi surface.

  15. Biodistribution and Radiation Dosimetry of the Integrin Marker 64Cu-BaBaSar-RGD2 Determined from Whole-Body PET/CT in a Non-Human Primate

    NASA Astrophysics Data System (ADS)

    Liu, Shuanglong; Vorobyova, Ivetta; Park, Ryan; Conti, Peter S.

    2017-10-01

    Introduction: 64Cu-BaBaSar-RGD2 is a positron emission radiotracer taken up by integrin αvβ3, which is overexpressed in many malignancies. The aim of this study was to evaluate the biodistribution of 64Cu-BaBaSar-RGD2 in a non-human primate with positron emission tomography and to estimate the absorbed doses in major organs for human. Materials and methods: Whole-body PET imaging was done in a Siemens Biograph scanner in a male macaque monkey. After an i.v. injection of 13.1–19.7 MBq/kg of 64Cu-BaBaSar-RGD2, whole body scan was collected for a total duration of 180 min. Attenuation and scatter corrections were applied to reconstruction of the whole-body emission scan. After image reconstruction, three-dimensional volumes of interest (VOI) were hand-drawn on the PET transaxial or coronal slices of the frame where the organ was most conspicuous. Time-activity curves for each VOI were obtained, and residence time of each organ was calculated by integration of the time-activity curves. Human absorbed doses were estimated using the standard human model in OLINDA/EXM software. Results: Injection of 64Cu-BaBaSar-RGD2 was well tolerated in the macaque monkey, with no serious tracer-related adverse events observed. 64Cu-BaBaSar-RGD2 was cleared rapidly from the blood pool, with a 12.1-min biological half-time. Increased 64Cu-BaBaSar-RGD2 uptake was observed in the kidneys, and bladder, with mean percentage injected dose (ID%) values at 1 h after injection approximately 35.50 ± 6.47 and 36.89 ± 5.48, respectively. The calculated effective dose was 15.30 ± 2.21 µSv/MBq, and the kidneys had the highest absorbed dose at 108.43 ± 16.41 µGy/MBq using the non-voiding model. For an injected activity of 925 MBq 64Cu for human, the effective dose would be 14.2 ± 2.1 mSv. Discussion: Due to the limitation of the monkey number, we evaluated 64Cu-BaBaSar-RGD2 in the same monkey of three imaging sessions. Measured absorbed doses and effective doses of 64Cu-BaBaSar-RGD2 are

  16. Understanding Ferromagnetic Phase Stability, Electronic and Transport Properties of BaPaO3 and BaNpO3 from Ab-Initio Calculations

    NASA Astrophysics Data System (ADS)

    Khandy, Shakeel Ahmad; Gupta, Dinesh C.

    2017-10-01

    An extensive study of rare-earth perovskite BaPaO3 and BaNpO3 has been performed by first-principles tactics based on density functional theory (DFT), because the delocalized f-electrons play an important role in the band structure formation, to reveal their impact on the overall physical and chemical properties; it has turned out to be an interesting theme. Along with critical radii and thermoelectric properties, two different theories are employed to calculate the structural properties. The DFT and empirically calculated lattice constants are in rational accord with the experimental results. The critical radius calculations show that the BaPaO3 lattice has a smaller oxygen migration activation energy than the BaNpO3. In addition, we discuss the band profile and magnetic moments for these materials, which demonstrate the half-metallic ferromagnetism with a direct energy gap of 3.91 eV for BaPaO3 and an indirect gap of 3.79 eV for BaNpO3. More interestingly, the integral magnetic moments are in accordance with the Slater-Pauling rule.

  17. Études RMN haute résolution et RPE des composés Ba 3C 60 et Ba 6C 60

    NASA Astrophysics Data System (ADS)

    Rezzouk, Abdellah; Dafir, Driss; Errammach, Youssef; Rachdi, Férid

    2003-07-01

    We report the results of 13C MAS NMR and EPR measurements on Ba 3C 60 and Ba 6C 60 fullerides. Using high resolution NMR, we were able to identify an isotropic line around 156 ppm for Ba 3C 60 and a broad isotropic one with three components at 132, 134.6, 139.9 ppm for Ba 6C 60 compound. The latter line is consistent with orientationally ordered C 60 molecules leading to three unequivalent carbon sites in agreement with X-ray studies. A strong diamagnetic shift was observed for the NMR line of Ba 6C 60 that is interpreted in terms of transition moment in an indirect gap system. EPR results confirm the insulating nature of both studied compounds. To cite this article: A. Rezzouk et al., C. R. Physique 4 (2003).

  18. Tuning the giant magnetoelastic transition in Ba3BiIr2O9 and Ba3BiRu2O9.

    PubMed

    Huang, Zixin; Avdeev, Maxim; Kennedy, Brendan J; Knight, Kevin S; Zhou, Qingdi; Ling, Chris D

    2014-07-09

    We have experimentally investigated the effects of pressure on the magnetoelastic transitions associated with the opening of spin-gaps in Ba3BiIr2O9 and Ba3BiRu2O9. For both compounds, reducing the unit cell volume by either external physical and internal chemical pressure was found to reduce the temperature T(*) of the transition and, to a lesser extent, the magnitude of the associated negative thermal volume expansion. The results yield the latent heat associated with the transitions, -3.34(3) × 10(2) J mol(-1) for Ba3BiIr2O9 and -7.1(5) × 10(2) J mol(-1) for Ba3BiRu2O9. The transition in Ba3BiRu2O9 is significantly more robust than in Ba3BiIr2O9, requiring an order of magnitude higher pressures to achieve the same reduction in T(*). The differing responses of the two compounds points to differences between the 4d and 5d metals and hence to the importance of spin-orbit coupling, which is expected to be much stronger in the Ir compound.

  19. First-principles study of (Ba ,Ca ) TiO3 and Ba (Ti ,Zr ) O3 solid solutions

    NASA Astrophysics Data System (ADS)

    Amoroso, Danila; Cano, Andrés; Ghosez, Philippe

    2018-05-01

    (Ba ,Ca ) TiO3 and Ba (Ti ,Zr ) O3 solid solutions are the building blocks of lead-free piezoelectric materials that attract a renewed interest. We investigate the properties of these systems by means of first-principles calculations, with a focus on the lattice dynamics and the competition between different ferroelectric phases. We first analyze the four parent compounds in order to compare their properties and their different tendency towards ferroelectricity. The core of our study is systematic characterization of the binary systems (Ba ,Ca ) TiO3 and Ba (Ti ,Zr ) O3 within both the virtual crystal approximation and direct supercell calculations. In the case of Ca doping, we find a gradual transformation from B -site to A -site ferroelectricity due to steric effects that largely determines the behavior of the system. In the case of Zr doping, in contrast, the behavior is eventually dominated by cooperative Zr-Ti motions and the local electrostatics. In addition, our comparative study reveals that the specific microscopic physics of these solids sets severe limits to the applicability of the virtual crystal approximation for these systems.

  20. High-pressure synthesis of the cubic perovskite BaRuO3 and evolution of ferromagnetism in ARuO3 (A = Ca, Sr, Ba) ruthenates.

    PubMed

    Jin, C-Q; Zhou, J-S; Goodenough, J B; Liu, Q Q; Zhao, J G; Yang, L X; Yu, Y; Yu, R C; Katsura, T; Shatskiy, A; Ito, E

    2008-05-20

    The cubic perovskite BaRuO(3) has been synthesized under 18 GPa at 1,000 degrees C. Rietveld refinement indicates that the new compound has a stretched Ru-O bond. The cubic perovskite BaRuO(3) remains metallic to 4 K and exhibits a ferromagnetic transition at T(c) = 60 K, which is significantly lower than the T(c) approximately = 160 K for SrRuO(3). The availability of cubic perovskite BaRuO(3) not only makes it possible to map out the evolution of magnetism in the whole series of ARuO(3) (A = Ca, Sr, Ba) as a function of the ionic size of the A-site r(A,) but also completes the polytypes of BaRuO(3). Extension of the plot of T(c) versus r(A) in perovskites ARuO(3) (A = Ca, Sr, Ba) shows that T(c) does not increase as the cubic structure is approached, but has a maximum for orthorhombic SrRuO(3). Suppressing T(c) by Ca and Ba doping in SrRuO(3) is distinguished by sharply different magnetic susceptibilities chi(T) of the paramagnetic phase. This distinction has been interpreted in the context of a Griffiths' phase on the (Ca Sr)RuO(3) side and bandwidth broadening on the (Sr,Ba)RuO(3) side.

  1. High-pressure synthesis of the cubic perovskite BaRuO3 and evolution of ferromagnetism in ARuO3 (A = Ca, Sr, Ba) ruthenates

    PubMed Central

    Jin, C.-Q.; Zhou, J.-S.; Goodenough, J. B.; Liu, Q. Q.; Zhao, J. G.; Yang, L. X.; Yu, Y.; Yu, R. C.; Katsura, T.; Shatskiy, A.; Ito, E.

    2008-01-01

    The cubic perovskite BaRuO3 has been synthesized under 18 GPa at 1,000°C. Rietveld refinement indicates that the new compound has a stretched Ru–O bond. The cubic perovskite BaRuO3 remains metallic to 4 K and exhibits a ferromagnetic transition at Tc = 60 K, which is significantly lower than the Tc ≈ 160 K for SrRuO3. The availability of cubic perovskite BaRuO3 not only makes it possible to map out the evolution of magnetism in the whole series of ARuO3 (A = Ca, Sr, Ba) as a function of the ionic size of the A-site rA, but also completes the polytypes of BaRuO3. Extension of the plot of Tc versus rA in perovskites ARuO3 (A = Ca, Sr, Ba) shows that Tc does not increase as the cubic structure is approached, but has a maximum for orthorhombic SrRuO3. Suppressing Tc by Ca and Ba doping in SrRuO3 is distinguished by sharply different magnetic susceptibilities χ(T) of the paramagnetic phase. This distinction has been interpreted in the context of a Griffiths' phase on the (Ca Sr)RuO3 side and bandwidth broadening on the (Sr,Ba)RuO3 side. PMID:18480262

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Kai-tuo; He, Yan; Liang, Zhong-yuan

    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 whenmore » 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.« less

  3. Antiferromagnetic structure and electronic properties of BaCr2As2 and BaCrFeAs2

    NASA Astrophysics Data System (ADS)

    Filsinger, Kai A.; Schnelle, Walter; Adler, Peter; Fecher, Gerhard H.; Reehuis, Manfred; Hoser, Andreas; Hoffmann, Jens-Uwe; Werner, Peter; Greenblatt, Martha; Felser, Claudia

    2017-05-01

    Recent theoretical studies suggest that superconductivity may be found in doped chromium pnictides with crystal structures similar to their iron counterparts. Here, we report a comprehensive study on the magnetic arsenides BaCr2As2 and BaCrFeAs2 (space group I 4 /m m m ), which are possible mother compounds with d4 and d5 electron configurations, respectively. DFT-based calculations of the electronic structure evidence metallic antiferromagnetic ground states for both compounds. By powder neutron diffraction, we confirm for BaCr2As2 a robust ordering in the antiferromagnetic G -type structure at TN=580 K with μCr=1.9 μB . Anomalies in the lattice parameters point to magnetostructural coupling effects. In BaCrFeAs2, the Cr and Fe atoms randomly occupy the transition-metal site and G -type order is found below 265 K with μCr /Fe=1.1 μB . 57Fe Mössbauer spectroscopy demonstrates that only a small ordered moment is associated with the Fe atoms, in agreement with electronic structure calculations leading to μFe˜0 . The temperature dependence of the hyperfine field does not follow that of the total moments. Both compounds are metallic but show large enhancements of the linear specific heat. Electrical transport in BaCrFeAs2 is dominated by the atomic disorder and the partial magnetic disorder of Fe. Our results indicate that Néel-type order is unfavorable for Fe moments and thus it is destabilized with increasing Fe content.

  4. Strain induced optical properties of BaReO3

    NASA Astrophysics Data System (ADS)

    Kumavat, Sandip R.; Kansara, Shivam; Gupta, Sanjeev K.; Sonvane, Yogesh

    2018-05-01

    Here, we have performed strain induce optical properties of BaReO3 by using density functional theory (DFT). We noticed that after applying intrinsic and extrinsic strain to the BaReO3, it shows the metallic behavior. We also studied optical properties, which show good activity in the ultraviolet region. The results show that after applying intrinsic and extrinsic strain to BaReO3 the absorption peaks are shifted towards the high UV region of the spectrum. Thus, we concluded that, BaReO3 material with extrinsic strain can be useful for high frequency UV device and optoelectronic devices.

  5. 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.

  6. Investigation of structural, ferroelectric, piezoelectric and dielectric properties of Ba0.92Ca0.08TiO3-BaTi0.96Zr0.04O3 lead-free electroceramics

    NASA Astrophysics Data System (ADS)

    Keswani, Bhavna C.; Patil, S. I.; Kolekar, Y. D.

    2018-04-01

    Lead free ferroelectric with composition 0.55Ba0.92Ca0.08TiO3-0.45BaTi0.96Zr0.04O3 (BCT8-BZT4) was synthesized by solid state reaction method and investigated their structural, ferroelectric, piezoelectric and dielectric properties. X-ray diffraction analysis shows that BCT8-BZT4 ceramic possess both tetragonal (space group P4mm) and orthorhombic (space group Amm2) crystal structure which was further confirmed from Raman spectra spectroscopy. The micronized grains were observed from scanning electron micrographs while the presence of polarization-electric field hysteresis loop confirms ferroelectric nature of BCT8-BZT4 ceramic. Higher values of maximum polarization (Pmax = 22.27 μC/cm2), remnant polarization (Pr = 11.61 μC/cm2), coercive electric field (Ec = 4.77 kV/cm) and direct piezoelectric coefficient (d33) approximately 185 pC/N were observed. The real part of dielectric constant with frequency shows the usual dielectric dispersion behaviour at RT. The observed properties show that the lead free BCT8-BZT4 ceramic is suitable for ferroelectric memory device, piezoelectric sensor, capacitor, etc. applications.

  7. ESR and nonresonant microwave absorption of ErBa2Cu3O(7-delta) and HoBa2Cu3O(7-delta) single crystals

    NASA Astrophysics Data System (ADS)

    Tagaya, Kimihito; Fukuoka, Nobuo; Nakanishi, Shigemitsu

    1990-12-01

    ESR measurements were performed for ErBa2Cu3O(7-delta) and HoBa2Cu3O(7-delta) single crystals from 77 K to room temperature. The ESR signals of Er2BaCuO5 and Ho2BaCuO5 were observed, and their temperature variations were investigated. Nonresonant microwave absorption was also observed below the superconducting critical temperature of 93 K. The principal values of lower critical field were determined.

  8. Synthesis and Thermodynamic Stability of Ba2B‧B″O6 and Ba3B*B″2O9 Perovskites Using the Molten Salt Method

    NASA Astrophysics Data System (ADS)

    Meng, Wei; Virkar, Anil V.

    1999-12-01

    A number of mixed perovskites of the types Ba2B‧B″O6 (BaB‧1/2B″1/2O3) and Ba3B*B″2O9 (BaB*1/3B″2/3O3) where B‧=Gd, La, Nd, Sm, or Y; B″=Nb and B*=Ca were synthesized by a conventional calcination process, as well as by the molten salt method. The former consists of calcining appropriate mixtures of oxide or carbonate precursors in air at elevated temperatures (∼1250°C). The latter method consists of adding appropriate mixtures of oxide or carbonate precursors to a molten salt bath at relatively low temperatures (on the order of 300 to 500°C) so that the requisite compound is formed by dissolution-reprecipitation. X-ray diffraction confirmed the formation of a single-phase perovskite in each case with calcination at 1250°C. In a molten salt bath, however, all except Ba2LaNbO6 and Ba2NdNbO6 formed the perovskite structure. On the contrary, powders of Ba2LaNbO6 and Ba2NdNbO6 formed by a high-temperature calcination process readily decomposed when introduced into the molten salt bath. The formation of the requisite perovskite at a temperature as low as 350°C in a molten salt suggests that: (a) The perovskite is stable at 350°C. (b) The molten salt exhibits sufficient precursor solubility for the dissolution-reprecipitation process to occur in a reasonable time. Similarly, the decomposition of Ba2LaNbO6 and Ba2NdNbO6 in a molten salt bath shows that these materials are thermodynamically unstable at the temperature of the molten salt bath.

  9. Changing Morphology of BaO/AI₂O₃ during NO₂ Uptake and Release

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Szanyi, Janos; Kwak, Ja Hun; Hanson, Jonathan

    2005-04-21

    The changes in the morphology of Ba-oxide-based NOx storage/reduction catalysts were investigated using time resolved x-ray diffraction, transmission electron microscopy and energy dispersed spectroscopy. Large Ba(NO₃)₂ crystallites form on the alumina support when the catalyst is prepared by the incipient wetness method using an aqueous Ba(NO₃)₂ solution. Heating the sample to 873K in a He flow results in the decomposition of the Ba(NO₃)₂ phase and the formation of both a monolayer BaO film strongly interacting with the alumina support, and nano crystalline BaO particles. Upon NO₂ exposure of these BaO phases at room temperature, small (nano-sized) Ba(NO₃)₂ crystals and amore » monolayer of surface nitrate form. Heating this sample in NO₂ results in the coalescence of the nano crystalline Ba(NO₃)₂ particles into large crystals. The average crystal size in the re-formed Ba(NO₃)₂ layer is significantly smaller than that measured after the catalyst preparation. Evidence is also presented for the existence of a monolayer Ba(NO₃)₂ phase after thermal treatment in NO₂, in addition to these large crystals. These results clearly demonstrate the dynamic nature of the Ba-containing phases that are active in the NOx storage/reduction process. The proposed morphology cycle may contribute to the understanding of the changes observed in the performances of these catalysts during actual operating conditions.« less

  10. Understanding Practical Catalysts Using a Surface Science Approach. The Importance of Strong Interaction between BaO and Al 2O 3 in NO x Storage Materials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yi, Cheol-Woo W.; Kwak, Ja Hun; Peden, Charles H.F.

    2007-09-21

    Modern surface science techniques have been commonly applied to understand issues arising from practical catalytic systems.[1-4] However, the applicability of most of the results obtained from model systems has been limited, due, primarily, to the vastly different conditions studies on model and practical systems are carried out (catalyst composition, reaction conditions etc.).[5, 6] Therefore, the need to conduct experiments on compositionally similar systems (model and practical) is necessary to obtain valuable information on the workings of real catalysts. In this communication we demonstrate the utility of surface science studies on model catalysts in understanding the properties of high surface area,more » BaO-based NO x storage-reduction (NSR) catalysts.[7] We present evidence for the facile formation of surface barium aluminate-like species even at very low coverages of BaO. This Ba-aluminate layer, however, can react with NO 2 resulting in the formation of a bulk-like Ba(NO 3) 2 phase. In order to construct model catalysts that are representative of the practical NO x storage systems, we first needed to estimate the BaO covareges on the high surface area catalysts. Since the publication of the work by Fanson et al.[8], BaO loadings of 8 – 10 wt.% on a γ-alumina support (200 m 2/g) have been regarded as corresponding to one monolayer (ML) coverage, based on the unit cell size of bulk BaO. The coverage equivalent of one ML, however, was significantly underestimated. Assuming complete spreading of the BaO layer and using a Ba–O distance of ~ 2.77 Å (one unit of BaO occupies 1.53 × 10 -19 m 2), 10 wt.% loading of BaO would cover only about 1/3 of the alumina surface. Table 1 shows our calculated estimates of two-dimensional BaO coverages as a function of loading on a -Al 2O 3 surface (200 m 2/g) based on the lattice parameters of bulk BaO[9] (5.54 Å). Based on these values, for our model system studies we prepared BaO/Al 2O 3/NiAl(110) materials in

  11. Thermoelectric properties of doped BaHfO{sub 3}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dixit, Chandra Kr., E-mail: ckparadise@gmail.com, E-mail: sharmarameshfgiet@gmail.com; Bhamu, K. C.; Sharma, Ramesh, E-mail: ckparadise@gmail.com, E-mail: sharmarameshfgiet@gmail.com

    2016-05-06

    We have studied the structural stability, electronic structure, optical properties and thermoelectric properties of doped BaHfO{sub 3} by full potential linearized augmented plane wave (FP-LAPW) method. The electronic structure of BaHfO{sub 3} doped with Sr shows enhances the indirect band gaps of 3.53 eV, 3.58 eV. The charge density plots show strong ionic bonding in Ba-Hf, and ionic and covalent bonding between Hf and O. Calculations of the optical spectra, viz., the dielectric function, refractive index and extinction coefficient are performed for the energy range are calculated and analyzed. Thermoelectric properties of semi conducting are also reported first time. Themore » doped BaHfO{sub 3} is approximately wide band gap semiconductor with the large p-type Seebeck coefficient. The power factor of BaHfO{sub 3} is increased with Sr doping, decreases because of low electrical resistivity and thermal conductivity.« less

  12. Real-Time Fourier Transformed Holographic Associative Memory With Photorefractive Material

    NASA Astrophysics Data System (ADS)

    Changsuk, Oh; Hankyu, Park

    1989-02-01

    We describe a volume holographic associative memory using photorefractive material and conventional planar mirror. Multiple hologram is generated with two angular multiplexed writing beams and Fourier transformed object beam in BaTiO3 crystal at 0.6328 μm. Complete image can be recalled successfully by partial input of original stored image. It is proved that our system is useful for optical implementation of real-time associative memory and location addressable memory.

  13. Genome Sequence of African Swine Fever Virus BA71, the Virulent Parental Strain of the Nonpathogenic and Tissue-Culture Adapted BA71V.

    PubMed

    Rodríguez, Javier M; Moreno, Leticia Tais; Alejo, Alí; Lacasta, Anna; Rodríguez, Fernando; Salas, María L

    2015-01-01

    The strain BA71V has played a key role in African swine fever virus (ASFV) research. It was the first genome sequenced, and remains the only genome completely determined. A large part of the studies on the function of ASFV genes, viral transcription, replication, DNA repair and morphogenesis, has been performed using this model. This avirulent strain was obtained by adaptation to grow in Vero cells of the highly virulent BA71 strain. We report here the analysis of the genome sequence of BA71 in comparison with that of BA71V. They possess the smallest genomes for a virulent or an attenuated ASFV, and are essentially identical except for a relatively small number of changes. We discuss the possible contribution of these changes to virulence. Analysis of the BA71 sequence allowed us to identify new similarities among ASFV proteins, and with database proteins including two ASFV proteins that could function as a two-component signaling network.

  14. Genome Sequence of African Swine Fever Virus BA71, the Virulent Parental Strain of the Nonpathogenic and Tissue-Culture Adapted BA71V

    PubMed Central

    Rodríguez, Javier M.; Moreno, Leticia Tais; Alejo, Alí; Lacasta, Anna; Rodríguez, Fernando; Salas, María L.

    2015-01-01

    The strain BA71V has played a key role in African swine fever virus (ASFV) research. It was the first genome sequenced, and remains the only genome completely determined. A large part of the studies on the function of ASFV genes, viral transcription, replication, DNA repair and morphogenesis, has been performed using this model. This avirulent strain was obtained by adaptation to grow in Vero cells of the highly virulent BA71 strain. We report here the analysis of the genome sequence of BA71 in comparison with that of BA71V. They possess the smallest genomes for a virulent or an attenuated ASFV, and are essentially identical except for a relatively small number of changes. We discuss the possible contribution of these changes to virulence. Analysis of the BA71 sequence allowed us to identify new similarities among ASFV proteins, and with database proteins including two ASFV proteins that could function as a two-component signaling network. PMID:26618713

  15. 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.

  16. 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.

  17. Ba 2TeO: A new layered oxytelluride

    DOE PAGES

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

    2015-02-01

    For single crystals of the new semiconducting oxytelluride phase, Ba 2TeO, we synthesized from barium oxide powder and elemental tellurium in a molten barium metal flux. Ba 2TeO 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 Ba 2TeO is highly insulating.

  18. Alizarin Complexone Functionalized Mesoporous Silica Nanoparticles: A Smart System Integrating Glucose-Responsive Double-Drugs Release and Real-Time Monitoring Capabilities.

    PubMed

    Zou, Zhen; He, Dinggeng; Cai, Linli; He, Xiaoxiao; Wang, Kemin; Yang, Xue; Li, Liling; Li, Siqi; Su, Xiaoya

    2016-04-06

    The outstanding progress of nanoparticles-based delivery systems capable of releasing hypoglycemic drugs in response to glucose has dramatically changed the outlook of diabetes management. However, the developed glucose-responsive systems have not offered real-time monitoring capabilities for accurate quantifying hypoglycemic drugs released. In this study, we present a multifunctional delivery system that integrates both delivery and monitoring issues using glucose-triggered competitive binding scheme on alizarin complexone (ALC) functionalized mesoporous silica nanoparticles (MSN). In this system, ALC is modified on the surface of MSN as the signal reporter. Gluconated insulin (G-Ins) is then introduced onto MSN-ALC via benzene-1,4-diboronic acid (BA) mediated esterification reaction, where G-Ins not only blocks drugs inside the mesopores but also works as a hypoglycemic drug. In the absence of glucose, the sandwich-type boronate ester structure formed by BA binding to the diols of ALC and G-Ins remains intact, resulting in an fluorescence emission peak at 570 nm and blockage of pores. Following a competitive binding, the presence of glucose cause the dissociation of boronate ester between ALC and BA, which lead to the pores opening and disappearance of fluorescence. As proof of concept, rosiglitazone maleate (RSM), an insulin-sensitizing agent, was doped into the MSN to form a multifunctional MSN (RSM@MSN-ALC-BA-Ins), integrating with double-drugs loading, glucose-responsive performance, and real-time monitoring capability. It has been demonstrated that the glucose-responsive release behaviors of insulin and RSM in buffer or in human serum can be quantified in real-time through evaluating the changes of fluorescence signal. We believe that this developed multifunctional system can shed light on the invention of a new generation of smart nanoformulations for optical diagnosis, individualized treatment, and noninvasive monitoring of diabetes management.

  19. Analysis of oxygen binding-energy variations for BaO on W

    NASA Astrophysics Data System (ADS)

    Haas, G. A.; Shih, A.; Mueller, D.; Thomas, R. E.

    Interatomic Auger analyses have been made of different forms of BaO layers on W substrates. Variations in Auger spectroscopy energies of the Ba4dBa5pO2p interatomic Auger transition were found to be largely governed by the O2p binding energy of the BaO adsorbate. This was illustrated by comparing results of the Auger data values with values derived from O2p binding energies using ultraviolet photoelectron spectroscopy. Very good agreement was observed not only for the W<100> substrate but also for the W<110> substrate which showed two oxygen-induced electronics state. Variations in binding energy were noted for different states of BaO lattice formation and for different amounts of oxidation, ranging from the transition of Ba to BaO and continuing to the BaO 2 stoichiometry and beyond. Effects were also reported for adsorbate alignment and thermal activation (i.e., reduction) of the oxidized state. An empirical relationship was found suggesting that the more tightly bound the O2p states of the BaO adsorbate were, the lower its work function would be. This link between binding energy and work function was observed to be valid not only for cases of poisoning by oxidation, but held as well during reactivation by the subsequent reduction of the oxide. In addition, this relationship also appeared to predict the low work function obtained through the introduction of substances such as Sc to the BaO-W system. Possible qualitative reasons which might contribute to this are discussed in terms of enhanced dipole effects and shifts in band structure.

  20. Rietveld refined structural and room temperature vibrational properties of BaTiO3 doped La0.67Ba0.33MnO3 composites

    NASA Astrophysics Data System (ADS)

    Dar, M. A.; Sheikh, M. W.; Malla, M. S.; Varshney, Dinesh

    2016-05-01

    The composites of (1-x) La0.67Ba0.33MnO3 (LBMO) + xBaTiO3 (BTO) (x = 0, 0.25 and 1.0) were synthesized by conventional solid-state reaction method. Rietveld refinement was employed to characterize the structural information of the prepared ceramics. The result of the Rietveld refinement of X-ray powder diffraction of La0.67Ba0.33MnO3 and BaTiO3 shows that these compounds crystallize in rhombohedral (R3c) and tetragonal (P4mm), respectively. The structural parameters and the reliability factors for the LBMO-BTO composite ceramics were successfully determined by the Rietveld refinement. At room temperature, Raman active phonon modes predicted by the group theory were observed only in BaTiO3 and composite sample. Pure LBMO does not show any Raman active Phonon mode at room temperature.

  1. The Crystal Structure of Ba 17Sm 10Cl 64

    NASA Astrophysics Data System (ADS)

    Liu, Guo; Eick, Harry A.

    1999-08-01

    The structure of Ba17Sm10Cl64, prepared by solvolytic extraction of a program-cooled 1:1 BaCl2:SmCl3 molar mixture sealed in a quartz tube and heated to 750°C, was determined from single-crystal X-ray diffraction data. The compound exhibits cubic symmetry, space group Pa3 (No. 205) with a=21.366(2) Å and Z=4. Refinement effected with I>2σ(I) yielded R1= 0.0926 and wR2=0.216. One Ba atom is 12-coordinated by Cl atoms in a distorted icosahedral arrangement; the three other Ba atoms are 10-coordinated in a distorted bicapped cubic arrangement. There are two Sm atom sites. The coordination around one Sm atom is best described as square antiprismatic, but one Sm-Cl distance is too long for effective bonding. The other Sm atom site, occupied statistically by {1}/{3}Ba and {2}/{3}Sm atoms, is 9-coordinated by Cl atoms in a monocapped square antiprismatic arrangement. The two types of Sm sites combine to form an M6Cl37 cuboctahedral cluster of the composition BaSm5Cl37. It is shown that the cβ phase identified previously in the Yb-F and related fluoride systems is probably isostructural with Ba17Sm10Cl64.

  2. Spectroscopic evidence of photogenerated carrier separation by built-in electric field in Sb-doped n-BaSi2/B-doped p-BaSi2 homojunction diodes

    NASA Astrophysics Data System (ADS)

    Kodama, Komomo; Takabe, Ryota; Deng, Tianguo; Toko, Kaoru; Suemasu, Takashi

    2018-05-01

    The operation of a BaSi2 homojunction solar cell is first demonstrated. In n+-BaSi2 (20 nm)/p-BaSi2 (500 nm)/p+-BaSi2 (50 nm) homojunction diodes on p+-Si(111) (resistivity ρ < 0.01 Ω cm), the internal quantum efficiency (IQE) under AM1.5 illumination becomes pronounced at wavelengths λ < 800 nm and exceeded 30% at λ = 500 nm. In contrast, the IQE values are small at λ < 600 nm in n+-BaSi2 (300 nm)/p-Si (ρ > 0.1 Ω cm) heterojunction diodes, but are high in the range between 600 and 1200 nm. The difference in spectral response demonstrates the photogenerated carrier separation by the built-in electric field in the homojunction diode.

  3. Thermoelectric transport properties of BaBiTe{sub 3}-based materials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhou, Yiming; Zhao, Li-Dong, E-mail: zhaolidong@buaa.edu.cn

    BaBiTe{sub 3}, a material with low thermal conductivity, is an inferior thermoelectric material due to the poor electrical properties originated from its narrow band gap. We choose two types of dopants, K and La, trying to optimize its electrical transport properties. The minority carriers, which harm the Seebeck coefficient in this system, are suppressed by La doping. With the increase of both electrical conductivity and Seebeck coefficient, the power factor of 3% La doped BaBiTe{sub 3} reaches 3.7 μW cm{sup −1} K{sup −2} which increased by 40% from undoped BaBiTe{sub 3}. Besides high power factor, the thermal conductivity is alsomore » reduced in it. Eventually, a high ZT value, 0.25 at 473 K, for n-type BaBiTe{sub 3} is achieved in 3% La doped BaBiTe{sub 3}. - Graphical abstract: BaBiTe{sub 3} possesses a low thermal conductivity. However, it is an inferior thermoelectric material due to the poor electrical properties originated from its narrow band gap. A high ZT value of 0.25 at 473 K for n-type BaBiTe{sub 3} can be achieved through optimizing electrical transport properties via La doping. - Highlights: • BaBiTe{sub 3} is an analogue of these promising thermoelectric materials: such as CsBi{sub 4}Te{sub 6} and K{sub 2}Bi{sub 8}Se{sub 13}, etc. • BaBiTe{sub 3} possesses a low thermal conductivity. • La is an effective dopant to enhance electrical transport properties. • A high ZT value of 0.25 at 473 K can be achieved in n-type La-doped BaBiTe{sub 3}.« less

  4. 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.

  5. Nuclear spectroscopy of doubly-even130,132Ba

    NASA Astrophysics Data System (ADS)

    Gupta, Anuradha; Gupta, Surbhi; Singh, Suram; Bharti, Arun

    2018-05-01

    A comparative study of some high-spin characteristic nuclear structure properties of doubly-even 130,132Ba nuclei has been made using two microscopic frameworks - CHFB and PSM. The yrast spectra, intrinsic quadrupole moment and deformation systematics of these nuclei have been successfully calculated. Further, the calculated data from both the frameworks is also compared with the available experimental data and a good agreement has been obtained. The present CHFB calculations describes very well the low spin structure of even-even 130,132Ba nuclei whereas PSM calculations provide a qualitative description of the high-spin band structure of doubly-even 130,132Ba nuclei.

  6. Effects of La-doped BaSnO3epitaxial electrode on the ferroelectric properties of BaTiO3

    NASA Astrophysics Data System (ADS)

    Lee, Hahoon; Kim, Young Mo; Kim, Youjung; Shin, Juyeon; Char, Kookrin

    In order to integrate the newly discovered high-mobility perovskite semiconductor BaSnO3 with a ferroelectric perovskite, we have grown epitaxial ferroelectric BaTiO3 (BTO) on top of the 4 % La-doped BaSnO3 (BLSO). X-ray diffraction measurement suggests that the BTO film on top of BLSO electrode is tensilely strained due to the larger lattice constant of BLSO. An all epitaxial sandwich structure of BLSO/BTO/BLSO was fabricated in order to measure the ferroelectric properties of the BTO under tensile strain. The polarization-electric field (P-E) hysteresis curve will be discussed from the viewpoint of the tensile strain. In addition, the breakdown field will be measured to evaluate the potential of BTO for a gate oxide on top of BLSO. Samsung science and technology foundation.

  7. Semiconducting Ba 3Sn 3Sb 4 and Metallic Ba 7–xSn 11Sb 15–y ( x = 0.4, y = 0.6) Zintl Phases

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Haijie; Narayan, Awadhesh; Stoumpos, Constantinos C.

    In this paper, we report the discovery of two ternary Zintl phases Ba 3Sn 3Sb 4 and Ba 7-xSn 11Sb 15-y, (x = 0.4, y = 0.6). Ba 3Sn 3Sb 4 adopts the monoclinic space group P2 1/c with a = 14.669(3) Å, b = 6.9649(14) Å, c = 13.629(3) Å, and β = 104.98(3)°. It features a unique corrugated two-dimensional (2D) structure consisting of [Sn 3Sb 4] 6- layers extending along the ab plane with Ba 2+ atoms sandwiched between them. The non-stoichiometric Ba 6.6Sn 11Sb 14.4 has a complex one-dimensional (1D) structure adopting the orthorhombic space group Pnma,more » with unit cell parameters a = 37.964(8) Å, b = 4.4090(9) Å and c = 24.682(5) Å. It consists of large double Sn-Sb ribbons separated by Ba 2+ atoms. Ba3Sn3Sb4 is an n-type semiconductor which has a narrow energy gap of ~0.18 eV and a room temperature carrier concentration of ~4.2 × 10 18 cm -3. Lastly, Ba 6.6Sn 11Sb 14.4 is determined to be a metal with electrons being the dominant carriers.« less

  8. Semiconducting Ba 3Sn 3Sb 4 and Metallic Ba 7–xSn 11Sb 15–y ( x = 0.4, y = 0.6) Zintl Phases

    DOE PAGES

    Chen, Haijie; Narayan, Awadhesh; Stoumpos, Constantinos C.; ...

    2017-11-08

    In this paper, we report the discovery of two ternary Zintl phases Ba 3Sn 3Sb 4 and Ba 7-xSn 11Sb 15-y, (x = 0.4, y = 0.6). Ba 3Sn 3Sb 4 adopts the monoclinic space group P2 1/c with a = 14.669(3) Å, b = 6.9649(14) Å, c = 13.629(3) Å, and β = 104.98(3)°. It features a unique corrugated two-dimensional (2D) structure consisting of [Sn 3Sb 4] 6- layers extending along the ab plane with Ba 2+ atoms sandwiched between them. The non-stoichiometric Ba 6.6Sn 11Sb 14.4 has a complex one-dimensional (1D) structure adopting the orthorhombic space group Pnma,more » with unit cell parameters a = 37.964(8) Å, b = 4.4090(9) Å and c = 24.682(5) Å. It consists of large double Sn-Sb ribbons separated by Ba 2+ atoms. Ba3Sn3Sb4 is an n-type semiconductor which has a narrow energy gap of ~0.18 eV and a room temperature carrier concentration of ~4.2 × 10 18 cm -3. Lastly, Ba 6.6Sn 11Sb 14.4 is determined to be a metal with electrons being the dominant carriers.« less

  9. Structural, microstructural and electrical characterization of BaSnO3 and Ba0.90Y0.10SnO3 synthesized by solution combustion method

    NASA Astrophysics Data System (ADS)

    Kumar, Upendra; Yadav, Dharmendra; Upadhyay, Shail; Thakur, Anukul K.

    2018-04-01

    Powder of perovskite oxides BaSnO3 and Ba0.90Y0.10SnO3 have been synthesized by solution combustion method. Rietveld profile analysis shows that the phases crystallize with cubic unit cell in the space group pm3m. Further purity of the synthesized powders was checked by Fourier transform of infrared (FTIR) spectroscopy. The average grain size of the sintered samples was obtained using Scanning electron microscopy (SEM) and found to be 4.9 and 2.8 1m for BaSnO3 and Ba0.90Y0.10SnO3, respectively. The AC conductivity (σac) of synthesized samples was measured in the frequency range from 24Hz-1MHz and temperature range 100 - 600°C. Conductivity spectra of both the samples followed universal Johnscher's power law at different temperatures. The value of bulk or dc conductivity (σdc) at different temperatures has been extracted by fitting the Johnscher's power law to AC conductivity spectra. The activation energy for σc has been obtained from the least square linear fit of data points and found to be 0.53 eV and 0.43 eV, respectively for BaSnO3 and Ba0.90Y0.10SnO3. Based on the value of activation energy it is proposed that conduction in these samples is govern via hopping of (OH)•. The value of conductivity at temperature 550°C of Ba0.90Y0.10SnO3 is 0.00406 S-cm-1 higher than BaSnO3 (0.00173 S-cm-1) at the same temperature.

  10. Synthesis of the complex fluoride LiBaF 3 and optical spectroscopy properties of LiBaF 3: M( M=Eu,Ce) through a solvothermal process

    NASA Astrophysics Data System (ADS)

    Hua, Ruinian; Lei, Bingfu; Xie, Demin; Shi, Chunshan

    2003-11-01

    The complex fluoride LiBaF 3 and LiBaF 3: M( M=Eu, Ce) is solvothermally synthesized at 180°C and characterized by means of X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis and infrared spectroscopy. In the solvothermal process, the solvents, molar ratios of initial mixtures and reaction temperature play important roles in the formation of products. The excitation and emission spectra of the LiBaF 3: M( M=Eu,Ce) have been measured by fluorescence spectrophotometer. In the LiBaF 3:Eu emission spectra, there is one sharp line emission located at 360 nm arising from f→ f transition of Eu 2+ in the host lattice, and typical doublet 5 d-4 f emission of Ce 3+ in LiBaF 3 powder is shown.

  11. Manganese Vanadate Chemistry in Hydrothermal BaF 2 Brines: Ba 3 Mn 2 (V 2 O 7 ) 2 F 2 and Ba 7 Mn 8 O 2 (VO 4 ) 2 F 23

    DOE PAGES

    Sanjeewa, Liurukara D.; McMillen, Colin D.; McGuire, Michael A.; ...

    2016-12-05

    We synthesized manganese vanadate fluorides using high-temperature hydrothermal techniques with BaF 2 as a mineralizer. Ba 3Mn 2(V 2O 7) 2F 2 crystallizes in space group C2/c and consists of dimers built from edge-sharing MnO 4F 2 trigonal prisms with linking V 2O 7 groups. Ba 7Mn 8O 2(VO 4) 2F 23 crystallizes in space group Cmmm, with a manganese oxyfluoride network built from edge- and corner-sharing Mn 2+/3+(O,F) 6 octahedra. The resulting octahedra form alternating Mn 2+ and Mn 2+/3+ layers separated by VO 4 tetrahedra. This latter compound exhibits a canted antiferromagnetic order below TN = 25 K.

  12. Improvement of electron mobility in La:BaSnO{sub 3} thin films by insertion of an atomically flat insulating (Sr,Ba)SnO{sub 3} buffer layer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shiogai, Junichi, E-mail: junichi.shiogai@imr.tohoku.ac.jp; Nishihara, Kazuki; Sato, Kazuhisa

    One perovskite oxide, ASnO{sub 3} (A = Sr, Ba), is a candidate for use as a transparent conductive oxide with high electron mobility in single crystalline form. However, the electron mobility of films grown on SrTiO{sub 3} substrates does not reach the bulk value, probably because of dislocation scattering that originates from the large lattice mismatch. This study investigates the effect of insertion of bilayer BaSnO{sub 3} / (Sr,Ba)SnO{sub 3} for buffering this large lattice mismatch between La:BaSnO{sub 3} and SrTiO{sub 3} substrate. The insertion of 200-nm-thick BaSnO{sub 3} on (Sr,Ba)SnO{sub 3} bilayer buffer structures reduces the number of dislocationsmore » and improves surface smoothness of the films after annealing as proved respectively by scanning transmission electron microscopy and atomic force microscopy. A systematic investigation of BaSnO{sub 3} buffer layer thickness dependence on Hall mobility of the electron transport in La:BaSnO{sub 3} shows that the highest obtained value of mobility is 78 cm{sup 2}V{sup −1}s{sup −1} because of its fewer dislocations. High electron mobility films based on perovskite BaSnO{sub 3} can provide a good platform for transparent-conducting-oxide electronic devices and for creation of fascinating perovskite heterostructures.« less

  13. Effects of oxygen vacancy on the photoconductivity in BaSnO3

    NASA Astrophysics Data System (ADS)

    Park, Jisung; Char, Kookrin; Institute of Applied Physics, Department of Physics; Astronomy, Seoul National University Team

    We have found the photoconductive behavior of BaSnO3, especially their magnitude and time dependence, is very sensitive to the oxygen vacancy concentration. We made epitaxial BaSnO3 film with BaHfO3 buffer layer by pulsed laser deposition. As we had reported before, MgO substrate with its large band gap size about 7.8 eV was used to exclude any photoconductance from the substrate. BaHfO3 layer was used to reduce the threading dislocation density in BaSnO3 film. To control the oxygen vacancy concentration in the BaSnO3 film, we annealed the sample in Ar or O2 atmosphere with varying annealing conditions. After each annealing process, photoconductivity of BaSnO3 was measured during illumination of UV light. The result showed that the magnitude of photoconductivity of BaSnO3 increased after annealing at higher temperature in Ar atmosphere, while the changes in the dark current remains minimal. The result can be explained by a hole trap mechanism. Higher Fermi level due to the increased oxygen vacancy concentration can cause occupation of deep acceptor levels in dislocations of the BaSnO3 film. These occupied deep acceptor levels in turn trap photo-generated holes so that the recombination of electron-hole pair is deterred. Samsung Science and Technology Foundation.

  14. 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).

  15. Electronic structure of BaNi2As2

    NASA Astrophysics Data System (ADS)

    Zhou, Bo; Xu, Min; Zhang, Yan; Xu, Gang; He, Cheng; Yang, L. X.; Chen, Fei; Xie, B. P.; Cui, Xiao-Yu; Arita, Masashi; Shimada, Kenya; Namatame, Hirofumi; Taniguchi, Masaki; Dai, X.; Feng, D. L.

    2011-01-01

    BaNi2As2, with a first-order phase transition around 131 K, is studied by the angle-resolved photoemission spectroscopy. The measured electronic structure is compared to the local-density approximation calculations, revealing similar large electronlike bands around M¯ and differences along Γ¯-X¯. We further show that the electronic structure of BaNi2As2 is distinct from that of the sibling iron pnictides. Particularly, there is no signature of band folding, indicating no collinear spin-density-wave-related magnetic ordering. Moreover, across the strong first-order phase transition, the band shift exhibits a hysteresis, which is directly related to the significant lattice distortion in BaNi2As2.

  16. Snynthesis and magnetization of BaLn2O4 (Ln = lanthanide)

    NASA Astrophysics Data System (ADS)

    Lundberg, Matthew

    The BaLn2O4 family has been synthesized successfully as single crystals by the flux-growth method. The phases crystallize in the CaV2O4 structure prototype in space group Pnma (# 62). The structure has been studied using single-crystal x-ray diffraction, and stoichiometry confirmed with EDS, and the unit cell parameters and atomic positions have been determined for the whole lanthanide series (with the exception of the Lu compound). The effects of the lanthanide ionic radius on the atomic positions in the unit cell has been studied in terms of fractional atomic coordinates, bond lengths and angles, and bond valence sums. Magnetic measurements have been performed on the series with the exception of the La, Eu, and Lu members in the form of susceptibility versus temperature. The crystals all show signs of geometric antiferromagnetic frustration with the Neel temperatures significantly below the temperature predicted by the Weiss constant. Additionally some members of the family, namely BaCe2O4, BaNd2O4, BaPr 2O4, BaSm2O4, BaTb2O 4, and BaYb2O4 show significant crystal field splitting, that causes deviation from Currie-Weiss behavior.

  17. The 226Ra-Ba relationship in the North Atlantic during GEOTRACES-GA01

    NASA Astrophysics Data System (ADS)

    Le Roy, Emilie; Sanial, Virginie; Charette, Matthew A.; van Beek, Pieter; Lacan, François; Jacquet, Stéphanie H. M.; Henderson, Paul B.; Souhaut, Marc; García-Ibáñez, Maribel I.; Jeandel, Catherine; Pérez, Fiz F.; Sarthou, Géraldine

    2018-05-01

    We report detailed sections of radium-226 (226Ra, T1/2 = 1602 years) activities and barium (Ba) concentrations determined in the North Atlantic (Portugal-Greenland-Canada) in the framework of the international GEOTRACES program (GA01 section - GEOVIDE project, May-July 2014). Dissolved 226Ra and Ba are strongly correlated along the section, a pattern that may reflect their similar chemical behavior. Because 226Ra and Ba have been widely used as tracers of water masses and ocean mixing, we investigated their behavior more thoroughly in this crucial region for thermohaline circulation, taking advantage of the contrasting biogeochemical patterns existing along the GA01 section. We used an optimum multiparameter (OMP) analysis to distinguish the relative importance of physical transport (water mass mixing) from nonconservative processes (sedimentary, river or hydrothermal inputs, uptake by particles and dissolved-particulate dynamics) on the 226Ra and Ba distributions in the North Atlantic. Results show that the measured 226Ra and Ba concentrations can be explained by conservative mixing for 58 and 65 % of the samples, respectively, notably at intermediate depth, away from the ocean interfaces. 226Ra and Ba can thus be considered conservative tracers of water mass transport in the ocean interior on the space scales considered here, namely, on the order of a few thousand kilometers. However, regions in which 226Ra and Ba displayed nonconservative behavior and in some cases decoupled behaviors were also identified, mostly at the ocean boundaries (seafloor, continental margins and surface waters). Elevated 226Ra and Ba concentrations found in deepwater in the West European Basin suggest that lower Northeast Atlantic Deep Water (NEADWl) accumulates 226Ra and Ba from sediment diffusion and/or particle dissolution during transport. In the upper 1500 m of the West European Basin, deficiencies in 226Ra and Ba are likely explained by their incorporation in planktonic calcareous

  18. A binary link tracker for the BaBar level 1 trigger system

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berenyi, A.; Chen, H.K.; Dao, K.

    1999-08-01

    The BaBar detector at PEP-II will operate in a high-luminosity e{sup +}e{sup {minus}} collider environment near the {Upsilon}(4S) resonance with the primary goal of studying CP violation in the B meson system. In this environment, typical physics events of interest involve multiple charged particles. These events are identified by counting these tracks in a fast first level (Level 1) trigger system, by reconstructing the tracks in real time. For this purpose, a Binary Link Tracker Module (BLTM) was designed and fabricated for the BaBar Level 1 Drift Chamber trigger system. The BLTM is responsible for linking track segments, constructed bymore » the Track Segment Finder Modules (TSFM), into complete tracks. A single BLTM module processes a 360 MBytes/s stream of segment hit data, corresponding to information from the entire Drift Chamber, and implements a fast and robust algorithm that tolerates high hit occupancies as well as local inefficiencies of the Drift Chamber. The algorithms and the necessary control logic of the BLTM were implemented in Field Programmable Gate Arrays (FPGAs), using the VHDL hardware description language. The finished 9U x 400 mm Euro-format board contains roughly 75,000 gates of programmable logic or about 10,000 lines of VHDL code synthesized into five FPGAs.« less

  19. Raman study of the thermal stability of HgBa 2CaCu 2O 6+δ and HgBa 2Ca 2Cu 3O 8+δ

    NASA Astrophysics Data System (ADS)

    Chang, H.; He, Z. H.; Meng, R. L.; Xue, Y. Y.; Chu, C. W.

    1995-02-01

    We studied the thermal stability of HgBa 2CaCu 2O 6+δ and HgBa 2Ca 2Cu 3O 8+δ at varying laser irradiation power. Each compound has two Raman bands around 570 and 590 cm -1 which are assigned to the vibrations of the interstitial oxygen in HgO δ layers and the apical oxygen in BaO layers, respectively. The 590 cm -1 band shifts position slightly with irradiation, and both the intensity and position of the 570 cm -1 band vary significantly with the laser power. The occupation factor of the interstitial oxygen is sensitive to the annealing temperature. At higher temperatures (550-600°C), both compounds decompose into various (Ba,Cu)-oxides such as Ba 1- xCa xCuO 2.

  20. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 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 P-00... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Barium manganese oxide (BaMnO3). 721...

  1. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 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 P-00... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium manganese oxide (BaMnO3). 721...

  2. 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 P-00...

  3. 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 P-00...

  4. 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 P-00...

  5. Uranium deposits of Brazil

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    NONE

    Brazil is a country of vast natural resources, including numerous uranium deposits. In support of the country`s nuclear power program, Brazil has developed the most active uranium industry in South America. Brazil has one operating reactor (Angra 1, a 626-MWe PWR), and two under construction. The country`s economic challenges have slowed the progress of its nuclear program. At present, the Pocos de Caldas district is the only active uranium production. In 1990, the Cercado open-pit mine produced approximately 45 metric tons (MT) U{sub 3}O{sub 8} (100 thousand pounds). Brazil`s state-owned uranium production and processing company, Uranio do Brasil, announced itmore » has decided to begin shifting its production from the high-cost and nearly depleted deposits at Pocos de Caldas, to lower-cost reserves at Lagoa Real. Production at Lagoa Real is schedules to begin by 1993. In addition to these two districts, Brazil has many other known uranium deposits, and as a whole, it is estimated that Brazil has over 275,000 MT U{sub 3}O{sub 8} (600 million pounds U{sub 3}O{sub 8}) in reserves.« less

  6. K and Ba distribution in the structures of the clathrate compounds K(x)Ba(16-x)(Ga,Sn)136 (x = 0.8, 4.4, and 12.9) and K(x)Ba(8-x)(Ga,Sn)46 (x = 0.3).

    PubMed

    Schäfer, Marion C; Bobev, Svilen

    2013-04-01

    Studies of the K-Ba-Ga-Sn system produced the clathrate compounds K(0.8(2))Ba(15.2(2))Ga(31.0(5))Sn(105.0(5)) [a = 17.0178 (4) Å], K(4.3(3))Ba(11.7(3))Ga(27.4(4))Sn(108.6(4)) [a = 17.0709 (6) Å] and K(12.9(2))Ba(3.1(2))Ga(19.5(4))Sn(116.5(4)) [a = 17.1946 (8) Å], with the type-II structure (cubic, space group Fd3m), and K(7.7(1))Ba(0.3(1))Ga(8.3(4))Sn(37.7(4)) [a = 11.9447 (4) Å], with the type-I structure (cubic, space group Pm3n). For the type-II structures, only the smaller (Ga,Sn)24 pentagonal dodecahedral cages are filled, while the (Ga,Sn)28 hexakaidecahedral cages remain empty. The unit-cell volume is directly correlated with the K:Ba ratio, since an increasing amount of monovalent K occupying the cages causes a decreasing substitution of the smaller Ga in the framework. All three formulae have an electron count that is in good agreement with the Zintl-Klemm rules. For the type-I compound, all framework sites are occupied by a mixture of Ga and Sn atoms, with Ga showing a preference for Wyckoff site 6c. The (Ga,Sn)20 pentagonal dodecahedral cages are occupied by statistically disordered K and Ba atoms, while the (Ga,Sn)24 tetrakaidecahedral cages encapsulate only K atoms. Large anisotropic displacement parameters for K in the latter cages suggest an off-centering of the guest atoms.

  7. Crystal structure and physical properties of quaternary clathrates Ba{sub 8}Zn{sub x}Ge{sub 46-x-y}Si{sub y}, Ba{sub 8}(Zn,Cu){sub x}Ge{sub 46-x} and Ba{sub 8}(Zn,Pd){sub x}Ge{sub 46-x}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nasir, Navida; Grytsiv, Andriy; Melnychenko-Koblyuk, Nataliya

    2010-10-15

    Three series of vacancy-free quaternary clathrates of type I, Ba{sub 8}Zn{sub x}Ge{sub 46-x-y}Si{sub y}, Ba{sub 8}(Zn,Cu){sub x}Ge{sub 46-x}, and Ba{sub 8}(Zn,Pd){sub x}Ge{sub 46-x}, have been prepared by reactions of elemental ingots in vacuum sealed quartz at 800 {sup o}C. In all cases cubic primitive symmetry (space group Pm3n, a{approx}1.1 nm) was confirmed for the clathrate phase by X-ray powder diffraction and X-ray single crystal analyses. The lattice parameters show a linear increase with increase in Ge for Ba{sub 8}Zn{sub x}Ge{sub 46-x-y}Si{sub y}. M atoms (Zn, Pd, Cu) preferably occupy the 6d site in random mixtures. No defects were observed formore » the 6d site. Site preference of Ge and Si in Ba{sub 8}Zn{sub x}Ge{sub 46-x-y}Si{sub y} has been elucidated from X-ray refinement: Ge atoms linearly substitute Si in the 24k site whilst a significant deviation from linearity is observed for occupation of the 16i site. A connectivity scheme for the phase equilibria in the 'Ba{sub 8}Ge{sub 46}' corner at 800 {sup o}C has been derived and a three-dimensional isothermal section at 800 {sup o}C is presented for the Ba-Pd-Zn-Ge system. Studies of transport properties carried out for Ba{sub 8{l_brace}}Cu,Pd,Zn{r_brace}{sub x}Ge{sub 46-x} and Ba{sub 8}Zn{sub x}Si{sub y}Ge{sub 46-x-y} evidenced predominantly electrons as charge carriers and the closeness of the systems to a metal-to-insulator transition, fine-tuned by substitution and mechanical processing of starting material Ba{sub 8}Ge{sub 43}. A promising figure of merit, ZT {approx}0.45 at 750 K, has been derived for Ba{sub 8}Zn{sub 7.4}Ge{sub 19.8}Si{sub 18.8}, where pricey germanium is exchanged by reasonably cheap silicon. - Graphical abstract: Quaternary phase diagram of Ba-Pd-Zn-Ge system at 800 {sup o}C.« less

  8. 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

  9. Left cytoarchitectonic BA 44 processes syntactic gender violations in determiner phrases.

    PubMed

    Heim, Stefan; van Ermingen, Muna; Huber, Walter; Amunts, Katrin

    2010-10-01

    Recent neuroimaging studies make contradictory predictions about the involvement of left Brodmann's area (BA) 44 in processing local syntactic violations in determiner phrases (DPs). Some studies suggest a role for BA 44 in detecting local syntactic violations, whereas others attribute this function to the left premotor cortex. Therefore, the present event-related functional magnetic resonance imaging (fMRI) study investigated whether left-cytoarchitectonic BA 44 was activated when German DPs involving syntactic gender violations were compared with correct DPs (correct: 'der Baum'-the[masculine] tree[masculine]; violated: 'das Baum'--the[neuter] tree[masculine]). Grammaticality judgements were made for both visual and auditory DPs to be able to generalize the results across modalities. Grammaticality judgements involved, among others, left BA 44 and left BA 6 in the premotor cortex for visual and auditory stimuli. Most importantly, activation in left BA 44 was consistently higher for violated than for correct DPs. This finding was behaviourally corroborated by longer reaction times for violated versus correct DPs. Additional brain regions, showing the same effect, included left premotor cortex, supplementary motor area, right middle and superior frontal cortex, and left cerebellum. Based on earlier findings from the literature, the results indicate the involvement of left BA 44 in processing local syntactic violations when these include morphological features, whereas left premotor cortex seems crucial for the detection of local word category violations. © 2010 Wiley-Liss, Inc.

  10. Synthesis, structures, and phase transitions of barium bismuth iridium oxide perovskites Ba{sub 2}BiIrO{sub 6} and Ba{sub 3}BiIr{sub 2}O{sub 9}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ling, Chris D., E-mail: c.ling@chem.usyd.edu.a; Bragg Institute, ANSTO, PMB 1, Menai 2234; Kennedy, Brendan J.

    The Ba-Bi-Ir-O system is found to contain two distinct perovskite-type phases: a rock-salt ordered double perovskite Ba{sub 2}BiIrO{sub 6}; and a 6H-type hexagonal perovskite Ba{sub 3}BiIr{sub 2}O{sub 9}. Ba{sub 2}BiIrO{sub 6} undergoes a series of symmetry-lowering phase transitions on cooling Fm3-barm->R3-barc->12/m(C2/m)->I1-bar(P1-bar), all of which are second order except the rhombohedral->monoclinic one, which is first order. The monoclinic phase is only observed in a 2-phase rhombohedral+monoclinic regime. The transition and 2-phase region lie very close to 300 K, making the room-temperature X-ray diffraction patterns extremely complex and potentially explaining why Ba{sub 2}BiIrO{sub 6} had not previously been identified and reported. Amore » solid solution Ba{sub 2}Bi{sub 1+x}Ir{sub 1-x}O{sub 6}, analogous to Ba{sub 2}Bi{sub 1+x}Ru{sub 1-x}O{sub 6}, 0<=x<=2/3, was not observed. The 6H-type phase Ba{sub 3}BiIr{sub 2}O{sub 9} undergoes a clean second-order phase transition P6{sub 3}/mmc->C2/c at 750 K, unlike 6H-type Ba{sub 3}LaIr{sub 2}O{sub 9}, the P6{sub 3}/mmc structure of which is highly strained below {approx}750 K but fails to distort coherently to the monoclinic phase. - Graphical abstract: Structure of Ba{sub 3}BiIr{sub 2}O{sub 9} at 300 K. BiO{sub 6} octahedra are purple, IrO{sub 6} octahedra are gold, and Ba atoms are green. Thermal ellipsoids at 90% probability.« less

  11. Interaction of ultra-depleted MORBs with plagioclase: implications for CO2/Ba ratios

    NASA Astrophysics Data System (ADS)

    Shimizu, K.; Hauri, E.; Saal, A. E.; Perfit, M. R.; Hekinian, R.

    2017-12-01

    Carbon in Earth's upper mantle can significantly reduce its solidus temperature, which in turn can affect other physical properties through generation of partial melt. Carbon content in the depleted upper mantle can be estimated using ultra-depleted mid-ocean ridge basalt (UD-MORB) glasses and melt inclusions that are undersaturated in CO2. CO2 has been shown to behave as a highly incompatible element during mantle melting both through natural samples and experiments. Given its highly incompatible behavior, CO2/Ba and CO2/Nb ratios in CO2 undersaturated UD-MORBs have been used to estimate the CO2/Ba and CO2/Nb ratios and carbon content in Earth's upper mantle. A potential issue with part of this approach is the effect of melt-plagioclase chemical interaction on the CO2/Ba ratios in UD-MORBs. Plagioclase is ubiquitous in the oceanic crust and is enriched in Ba relative to other phases. Chemical interactions (assimilation and/or diffusion) between MORB melts and plagioclase bearing rocks have been shown to affect the Ba (and Sr and Eu) concentrations in MORBs, implying that such processes may also affect their CO2/Ba ratio. Hence, understanding the effect of chemical interaction between plagioclase and UD-MORBs is important for having better constraints on CO2/Ba ratio and carbon content in Earth's upper mantle. In this study, we report on the compositions of olivine-hosted melt inclusions and glasses from the Siqueiros and Garrett transform faults. A subset of melt inclusions in lavas from both transform faults show potential signatures of chemical interaction with plagioclase such as low CO2/Ba, Nb/Ba, and Nd/Sr. CO2 degassing cannot explain the low CO2/Ba ratio in the samples as they are undersaturated in CO2. To better understand the effect of chemical interaction with plagioclase on the composition of UD-MORBs, we model end-member scenarios, which are (1) assimilation of plagioclase and (2) diffusion of elements from plagioclase into the UD-MORBs. In general

  12. First principle study of heterostructure of BaBi3-stanene for topological superconductor applications

    NASA Astrophysics Data System (ADS)

    Kore, Ashish; Singh, Poorva

    2018-05-01

    We have studied the heterostructure of BaBi3 (superconductor) and stanene (topological insulator) with the aim of inducing topological superconductivity in stanene, due to proximity with superconductor BaBi3. The density functional theory calculations have been done for 2D structure of BaBi3 as well as for monolayer of stanene, separately. We find that compared to bulk BaBi3, the 2D bandstructure has contributions coming from both Ba and Bi atoms, unlike bulk where only Bi-p states are contributing to the bandstructure. Surface reconstruction of surface and sub-surface layer of 2D BaBi3 is also evident. The bandstructure of heterostructure of BaBi3-stanene is expected to bring out explicit features of topological superconductivity and indicating the presence of Majorana fermions.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    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 tomore » 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

  14. 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.

  15. Performance simulation of BaBar DIRC bar boxes in TORCH

    NASA Astrophysics Data System (ADS)

    Föhl, K.; Brook, N.; Castillo García, L.; Cussans, D.; Forty, R.; Frei, C.; Gao, R.; Gys, T.; Harnew, N.; Piedigrossi, D.; Rademacker, J.; Ros García, A.; van Dijk, M.

    2017-12-01

    TORCH is a large-area precision time-of-flight detector based on the DIRC principle. The DIRC bar boxes of the BaBar experiment at SLAC could possibly be reused to form a part of the TORCH detector time-of-flight wall area, proposed to provide positive particle identification of low momentum kaons in the LHCb experiment at CERN. For a potential integration of BaBar bar boxes into TORCH, new imaging readout optics are required. From the several designs of readout optics that have been considered, two are used in this paper to study the effect of BaBar bar optical imperfections on the detector reconstruction performance. The kaon-pion separation powers obtained from analysing simulated photon hit patterns show the performance reduction for a BaBar bar of non-square geometry compared to a perfectly rectangular cross section.

  16. Design, synthesis and luminescence properties of Ba2 YB2 O6 Cl- and Ba2 YB2 O6 F-based phosphors.

    PubMed

    Chen, Wanping; Yang, Xin; Liu, Yan; Dai, Xiaoyan

    2015-05-01

    Using a high-temperature solid-state reaction, the chlorine in Ba2 YB2 O6 Cl is gradually replaced by F, and a new compound with the nominal chemical formula Ba2 YB2 O6 F and two phosphors doped with Ce(3+) and Eu(3+) , respectively, are obtained. X-Ray diffraction and photoluminescence spectroscopy are used to characterize the as-synthesized samples. The as-synthesized Ba2 YB2 O6 Cl exhibits bright blue emission in the spectral range ~ 330-410 nm with a maximum around 363 nm under X-ray or UV excitation. Ba2 YB2 O6 F:0.01Ce(3+) exhibits blue emission in the range ~ 340-570 nm with a maximum around 383 nm. Ba2 YB2 O6 F:0.01Eu(3+) exhibits a predominantly (5) D0 -(7)  F2 emission (~610 nm) and the relative intensities of the (5) D0 -(7)  F0,1,2 emissions are tunable under different wavelength UV excitation. The luminescence behaviors of the two phosphors are explained simply in terms of the host composition and site occupancy probability of Ce(3+) and Eu(3+) , respectively. The results indicate that these phosphors have potential application as a blue phosphor or as a red phosphor. Copyright © 2014 John Wiley & Sons, Ltd.

  17. Synthesis of Ba 0.6K 0.4BiO 3 and BaPb 0.75Bi 0.25O 3 superconductors by sol-gel process

    NASA Astrophysics Data System (ADS)

    Rao, G. V. Rama; Varadaraju, U. V.; Mannan, S. L.

    1994-12-01

    We have synthesised Ba 0.6K 0.4BiO 3 (BKB) and BaPb 1-xBi xO 3-y compounds by sol-gel process. IR spectra of gels indicated the bridging type of bonding between metal carboxylates leading to the formation of homogeneous gels. BKB and BaPb 0.75Bi 0.25O 3 compounds exhibited sharp superconducting transitions from R-T and χ-T measurements indicating excellent homogeneity of the samples

  18. Synthesis and Characterization of BaFeO3, (Ba,Bi)FeO3, and Related Epitaxial Thin Films and Nanostructures

    DTIC Science & Technology

    2009-01-01

    measured magnetizations of Ba-doped bulk BiFeO3 samples65, 68 The coercivity, or resistance of the sample to 72 demagnetization , is about 6000 Oe on...methods for sample analysis are briefly discussed. Investigation of BaFeO3 and its structural and magnetic properties, which differ from that of the bulk ...at the atomic level. The interfaces comprised of a magnetic and ferroelectric material layered on one another has great advantage over bulk

  19. Effect of lithium doping in BaTiO3 ceramics for vibration sensor application

    NASA Astrophysics Data System (ADS)

    Praveen, E.; Murugan, S.; Jayakumar, K.

    2018-04-01

    Phase pure undoped and Lithium doped BaTiO3 particles have been synthesized by high temperature solid-state reaction method. Substitution of Lithium at the Ba2+ site in BaTiO3 lattice has been investigated. The structural, vibrational, electrical and mechanical characterization have been carried out. The poled samples were used as a sensing element for the detection of mechanical oscillations and the presence of 80 Hz pulse in the output spectrum manifest the response of the sensor element to the applied mechanical stress. In comparison with pure BaTiO3 the sensitivity of Li doped BaTiO3 is 14 times greater than the pure BaTiO3. This confirms that Li doped BaTiO3 could be an efficient candidate for the functionalization of vibration sensors in space application.

  20. [Raman studies of nanocrystalline BaTiO3 ceramics].

    PubMed

    Xiao, Chang-jiang; Jin, Chang-qing; Wang, Xiao-hui

    2008-12-01

    High pressure can significantly increase the densification. Further, during the high pressure assisted sintering, the nucleation rate is increased due to reduced energy barrier and the growth rate is suppressed due to the decreased diffusivity. Thus high pressure enables the specimen to be fabricated with relatively lower temperature and shorter sintering period that assures to obtain dense nanocrystalline ceramics. Dense nanocrystalline BaTiO3 ceramics with uniform grain sizes of 60 and 30 nm, respectively, were obtained by pressure assisted sintering. The crystal structure and phase transitions were investigated by Raman scattering at temperatures ranging from -190 to 200 degrees C. The Raman results indicated that the evolution of Raman spectrum with grain size is characterized by an intensity decrease, a broadening of the line width, a frequency shift, and the disappearance of the Raman mode. With increasing temperature, similar to 3 mm BaTiO3 normal ceramics, the successive phase transitions from rhombohedral to orthorhombic, orthorhombic to tetragonal, and tetragonal to cubic were also observed in nanocrystalline BaTiO3 ceramics. In addition, when particle size is reduced to the nanoscale, one will find some unusual physical properties in nanocrystalline ceramics, compared with those of coarse-grained BaTiO3 ceramics. The different coexistences of multiphase were found at different temperature. Especially, the ferroelectric tetragonal and orthorhombic phase can coexist at room temperature in nanocrystalline BaTiO3 ceramics. The phenomenon can be explained by the internal stress. The coexistences of different ferroelectric phases at room temperature indicate that the critical grain size for the disappearance of ferroelectricity in nanocrystalline BaTiO3 ceramics fabricated by pressure assisted sintering is below 30 nm.

  1. New Spectroscopy at BaBar

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    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 takenmore » 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.« less

  2. Superconductivity of Ba8Si46-xGax clathrates

    NASA Astrophysics Data System (ADS)

    Li, Yang; Zhang, Ruihong; Chen, Ning; Ma, Xingqiao; Cao, Guohui; Luo, Z. P.; Hu, C. R.; Ross, Joseph H., Jr.

    2007-03-01

    We have presented a combined experimental and theoretical study of the effect of Gallium substitution on the superconductivity of the type I clathrate Ba8Si46-xGax. In Ga-doped clathrates, the Ga state is found to be strongly hybridized with the cage conduction-band state. Ga substitution results in a shift toward to a lower energy, a decrease of density of states at Fermi level, a lowering of the carrier concentration and a breakage of integrity of the sp3 hybridized networks. These play key roles in the suppression of superconductivity. For Ba8Si40Ga6, the onset of the superconducting transition occurs at Tc=3.3 K. The investigation of the magnetic superconducting state shows that Ba8Si40Ga6 is a type II superconductor. The critical magnetic fields were measured to be Hc1=35 Oe and Hc2=8.5 kOe. Our estimate of the lectron-phonon coupling reveals that Ba8Si40Ga6 is a moderate phonon-mediated BCS superconductor.

  3. 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.

  4. Improvement of β-phase crystal formation in a BaTiO3-modified PVDF membrane

    NASA Astrophysics Data System (ADS)

    Lin, SHEN; Lei, GONG; Shuhua, CHEN; Shiping, ZHAN; Cheng, ZHANG; Tao, SHAO

    2018-04-01

    In this paper, low temperature plasma is used to modify the surface of barium titanate (BaTiO3) nanoparticles in order to enhance the interfacial compatibility between ferroelectric poly(vinylidene fluoride) (PVDF) and BaTiO3 nanoparticles. The results demonstrate that oxygenic groups are successfully attached to the BaTiO3 surface, and the quantity of the functional groups increases with the treatment voltage. Furthermore, the effect of modified BaTiO3 nanoparticles on the morphology and crystal structure of the PVDF/BaTiO3 membrane is investigated. The results reveal that the dispersion of BaTiO3 nanoparticles in the PVDF matrix was greatly improved due to the modification of the BaTiO3 nanoparticles by air plasma. It is worth noting that the formation of a β-phase in a PVDF/modified BaTiO3 membrane is observably promoted, which results from the strong interaction between PVDF chains and oxygenic groups fixed on the BaTiO3 surface and the better dispersion of BaTiO3 nanoparticles in the PVDF matrix. Besides, the PVDF/modified BaTiO3 membrane at the treatment voltage of 24 kV exhibits a lower water contact angle (≈68.4°) compared with the unmodified one (≈86.7°). Meanwhile, the dielectric constant of PVDF/BaTiO3 nanocomposites increases with the increase of working voltage.

  5. BA3b and BA1 activate in a serial fashion after median nerve stimulation: direct evidence from combining source analysis of evoked fields and cytoarchitectonic probabilistic maps.

    PubMed

    Papadelis, Christos; Eickhoff, Simon B; Zilles, Karl; Ioannides, Andreas A

    2011-01-01

    This study combines source analysis imaging data for early somatosensory processing and the probabilistic cytoarchitectonic maps (PCMs). Human somatosensory evoked fields (SEFs) were recorded by stimulating left and right median nerves. Filtering the recorded responses in different frequency ranges identified the most responsive frequency band. The short-latency averaged SEFs were analyzed using a single equivalent current dipole (ECD) model and magnetic field tomography (MFT). The identified foci of activity were superimposed with PCMs. Two major components of opposite polarity were prominent around 21 and 31 ms. A weak component around 25 ms was also identified. For the most responsive frequency band (50-150 Hz) ECD and MFT revealed one focal source at the contralateral Brodmann area 3b (BA3b) at the peak of N20. The component ~25 ms was localised in Brodmann area 1 (BA1) in 50-150 Hz. By using ECD, focal generators around 28-30 ms located initially in BA3b and 2 ms later to BA1. MFT also revealed two focal sources - one in BA3b and one in BA1 for these latencies. Our results provide direct evidence that the earliest cortical response after median nerve stimulation is generated within the contralateral BA3b. BA1 activation few milliseconds later indicates a serial mode of somatosensory processing within cytoarchitectonic SI subdivisions. Analysis of non-invasive magnetoencephalography (MEG) data and the use of PCMs allow unambiguous and quantitative (probabilistic) interpretation of cytoarchitectonic identity of activated areas following median nerve stimulation, even with the simple ECD model, but only when the model fits the data extremely well. Copyright © 2010 Elsevier Inc. All rights reserved.

  6. Effects of disordered Ru substitution in BaFe2As2: possible realization of superdiffusion in real materials.

    PubMed

    Wang, Limin; Berlijn, Tom; Wang, Yan; Lin, Chia-Hui; Hirschfeld, P J; Ku, Wei

    2013-01-18

    An unexpected insensitivity of the Fermi surface to impurity scattering is found in Ru substituted BaFe(2)As(2) from first-principles theory, offering a natural explanation of the unusual resilience of transport and superconductivity to a high level of disordered substitution in this material. This robustness is shown to originate from a coherent interference of correlated on-site and intersite impurity scattering, similar in spirit to the microscopic mechanism of superdiffusion in one dimension. Our result also demonstrates a strong substitution dependence of the Fermi surface and carrier concentration and provides a resolution to current discrepancies in recent photoelectron spectroscopy. These effects offer a natural explanation of the diminishing long-range magnetic, orbital, and superconducting orders with high substitution.

  7. Uniaxial strain control of spin-polarization in multicomponent nematic order of BaFe 2As 2

    DOE PAGES

    Kissikov, T.; Sarkar, R.; Lawson, M.; ...

    2018-03-13

    The iron-based high temperature superconductors exhibit a rich phase diagram reflecting a complex interplay between spin, lattice, and orbital degrees of freedom. The nematic state observed in these compounds epitomizes this complexity, by entangling a real-space anisotropy in the spin fluctuation spectrum with ferro-orbital order and an orthorhombic lattice distortion. A subtle and less-explored facet of the interplay between these degrees of freedom arises from the sizable spin-orbit coupling present in these systems, which translates anisotropies in real space into anisotropies in spin space. We present nuclear magnetic resonance studies, which reveal that the magnetic fluctuation spectrum in the paramagneticmore » phase of BaFe 2As 2 acquires an anisotropic response in spin-space upon application of a tetragonal symmetry-breaking strain field. Lastly, our results unveil an internal spin structure of the nematic order parameter, indicating that electronic nematic materials may offer a route to magneto-mechanical control.« less

  8. A novel BA complex network model on color template matching.

    PubMed

    Han, Risheng; Shen, Shigen; Yue, Guangxue; Ding, Hui

    2014-01-01

    A novel BA complex network model of color space is proposed based on two fundamental rules of BA scale-free network model: growth and preferential attachment. The scale-free characteristic of color space is discovered by analyzing evolving process of template's color distribution. And then the template's BA complex network model can be used to select important color pixels which have much larger effects than other color pixels in matching process. The proposed BA complex network model of color space can be easily integrated into many traditional template matching algorithms, such as SSD based matching and SAD based matching. Experiments show the performance of color template matching results can be improved based on the proposed algorithm. To the best of our knowledge, this is the first study about how to model the color space of images using a proper complex network model and apply the complex network model to template matching.

  9. SimBA: simulation algorithm to fit extant-population distributions.

    PubMed

    Parida, Laxmi; Haiminen, Niina

    2015-03-14

    Simulation of populations with specified characteristics such as allele frequencies, linkage disequilibrium etc., is an integral component of many studies, including in-silico breeding optimization. Since the accuracy and sensitivity of population simulation is critical to the quality of the output of the applications that use them, accurate algorithms are required to provide a strong foundation to the methods in these studies. In this paper we present SimBA (Simulation using Best-fit Algorithm) a non-generative approach, based on a combination of stochastic techniques and discrete methods. We optimize a hill climbing algorithm and extend the framework to include multiple subpopulation structures. Additionally, we show that SimBA is very sensitive to the input specifications, i.e., very similar but distinct input characteristics result in distinct outputs with high fidelity to the specified distributions. This property of the simulation is not explicitly modeled or studied by previous methods. We show that SimBA outperforms the existing population simulation methods, both in terms of accuracy as well as time-efficiency. Not only does it construct populations that meet the input specifications more stringently than other published methods, SimBA is also easy to use. It does not require explicit parameter adaptations or calibrations. Also, it can work with input specified as distributions, without an exemplar matrix or population as required by some methods. SimBA is available at http://researcher.ibm.com/project/5669 .

  10. Stromatolite laminae (Lagoa Vermelha, Brasil) as archives for reservoir age changes

    NASA Astrophysics Data System (ADS)

    Bruggmann, Sylvie; Vasconcelos, Crisogono; Hajdas, Irka

    2016-04-01

    As laminated biogenic or abiogenic sedimentary structures [1], stromatolites record environmental changes along growth profiles, revealing possible changes in reservoir ages due to input of older carbon. A modern stromatolite sample was collected in Lagoa Vermelha (100 km east of Rio de Janeiro, Brasil) an area known for upwelling of South Atlantic Central Water (SACW). 34 samples from a transect cutting the lamination were collected with a hand-driller for standard geochemistry and 14C AMS analyses. Shells collected in 2015 were analysed for estimation of the present-day reservoir age. 14C ages of laminae and the reservoir age were used to apply the age-depth model to the stromatolite transect with the OxCal depositional model (Marine13 calibration curve; [2]). Small-scale changes in the composition of laminae report environmental changes, e.g. upwelling. The well-laminated middle part (laminated boundstone; ca. 4cm) of the stromatolite transect was found to have grown in a short time period of less than 100 years (1163-1210 14C y BP), with four excursions towards older 14C ages (ca. 1200 14C y BP). To detect possible changes of marine 14C, calendar years assuming a stable modern reservoir age were used to simulate atmospheric 14C ages with the southern hemisphere IntCal13 atmospheric calibration curve [3]. The offset between the measured and simulated 14C ages indicates a variability of the reservoir age between -99 and 268 14C y with highest reservoir correction found for the layers with indication of environmental changes (e.g. upwelling). Thus, this simulation confirms the occurrence of older carbon and points out the sensitivity of stromatolites for changing reservoir ages. [1] M.A. Semikhatov, C.D. Gebelein, P. Cloud, S.M. Awramik, W.C. Benmore (1979). Stromatolite morphogenesis - progress and problems. Canadian Journal of Earth Sciences, 19:992-1015. [2] P.J. Reimer, E. Bard, A. Bayliss, J. W. Beck, P. G. Blackwell, C. Bronk Ramsey, C. E. Buck, H. Cheng, R

  11. Investigating the Magneto Electric Coupling of [90 wt%Na0.5Bi0.5TiO3 (NBT)-10 wt% BaFe12O19 (BaM)] novel multiferroiccomposite system by increasing of BaM grain size

    NASA Astrophysics Data System (ADS)

    Pattanayak, Ranjit; Raut, Subhajit; Kuila, Sourav; Chandrasekhar, Mallam; Panigrahi, Simanchala

    2017-02-01

    Polycrystalline three novel [90 wt%Na0.5Bi0.5TiO3 (NBT)-10 wt% BaFe12O19 (BaM)] magnetoelctricmultiferroic composite systems were fabricated by considering the variation (increasing) of BaM grain size. The desired formation of composites was confirmed by X-ray diffraction study. The FESEM and SEM study were verified the variation of grain size and 0-3 type connectivity of composite systems. To predict the room temperature multiferroicbehaviour of theses composite systems we were taken PE and MH loop. For investigating the extrinsic and intrinsic magnetoelctric effect magneto impedance spectroscopy was considered for theses composite systems. The variation of intrinsic magnetoelctric coupling was predicted by proposing a simple mechanical model.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hough, J.L.; Darrow, D.; Eaton, J.

    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 inmore » 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.« less

  13. Strain induced enhancement of magnetization in Ba{sub 2}FeMoO{sub 6} based heterostructure with (Ba{sub x}Sr{sub 1-x})TiO{sub 3}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kim, Kyeong-Won; Norton, David P.; Ghosh, Siddhartha, E-mail: ghoshsid@gmail.com

    2016-05-14

    High quality epitaxial Ba{sub 2}FeMoO{sub 6} thin films and Ba{sub 2}FeMoO{sub 6}–(Ba{sub x}Sr{sub 1−x})TiO{sub 3} bi-layer (BL) and superlattice (SL) structures were grown via pulsed laser deposition under low oxygen pressure, and their structural, magnetic, and magneto-transport properties were examined. Superlattice and bi-layer structures were confirmed by X-ray diffraction patterns. Low temperature magnetic measurement shows that the saturation magnetization (M{sub S}) is significantly higher for SLs and almost similar or lower for BLs, when compared to phase pure Ba{sub 2}FeMoO{sub 6} thin films. The variation of the coercive field (H{sub C}) follows exact opposite trend, where BL samples have highermore » H{sub C} and SL samples have lower H{sub C} than pure Ba{sub 2}FeMoO{sub 6} thin films. Also, a significant decrease of the Curie temperature is found in both BL and SL structures compared to pure Ba{sub 2}FeMoO{sub 6} thin films. Negative magneto-resistance is seen in all the BL and SL structures as well as in pure Ba{sub 2}FeMoO{sub 6} thin films. In contrast to the magnetic properties, the magneto-transport properties do not show much variation with induced strain.« less

  14. Crystal growth, differential gas adsorption, high thermal stability, and reversible coordination of two new barium-organic frameworks, Ba(SBA)(DMF){sub 4} and Ba{sub 2}(BTEC)(H{sub 2}O)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Halake, Shobha; Ok, Kang Min, E-mail: kmok@cau.ac.kr

    2015-11-15

    Single crystals of two barium-organic framework materials, Ba(SBA)(DMF){sub 4} (CAUMOF-15) and Ba{sub 2}(BTEC)(H{sub 2}O) (CAUMOF-16), have been grown through solvothermal reactions (H{sub 2}SBA=4,4′-sulfonyldibenzoic acid and H{sub 4}BTEC=1,2,4,5-benzenetetracarboxylic acid). The crystal structures of the reported frameworks have been determined by single-crystal X-ray diffraction. The materials have been fully characterized by powder X-ray diffraction (PXRD), elemental analyses, Infrared (IR) spectroscopy, and thermogravimetric analyses (TGA). CAUMOF-15 reveals a three-dimensional open-framework that comprises of an inorganic motif with one-dimensional chains and the SBA linkers. CAUMOF-16 shows another three-dimensional backbone consisting of layers of edge-shared BaO{sub 9} and BaO{sub 10} polyhedra, and BTEC pillars. Bothmore » of the 3D frameworks exhibit relatively high thermal stabilities. The PXRD and IR spectral data confirm that CAUMOF-15 and CAUMOF-16 reveal reversible coordinations of the respective solvent molecules, DMF and H{sub 2}O. Gas adsorption properties towards nitrogen, hydrogen, and carbon dioxide have been also investigated. - Graphical abstract: Crystals of two new barium-organic frameworks, Ba(SBA)(DMF){sub 4} and Ba{sub 2}(BTEC)(H{sub 2}O), exhibiting a differential gas adsorption, a high thermal stability, and a reversible coordination of solvent molecules have been grown. - Highlights: • Crystals of two new 3D Ba-MOFs are grown. • The two Ba-MOFs reveal very high thermal stabilities up to ca. 400 °C. • Ba(SBA)(DMF){sub 4} exhibits differential gas adsorption properties. • The two Ba-MOFs show reversible coordination of the solvent molecules.« less

  15. 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, 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.

  16. 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.

  17. Evolution of deformation in neutron-rich Ba isotopes up to A =150

    NASA Astrophysics Data System (ADS)

    Licǎ, R.; Benzoni, G.; Rodríguez, T. R.; Borge, M. J. G.; Fraile, L. M.; Mach, H.; Morales, A. I.; Madurga, M.; Sotty, C. O.; Vedia, V.; De Witte, H.; Benito, J.; Bernard, R. N.; Berry, T.; Bracco, A.; Camera, F.; Ceruti, S.; Charviakova, V.; Cieplicka-Oryńczak, N.; Costache, C.; Crespi, F. C. L.; Creswell, J.; Fernandez-Martínez, G.; Fynbo, H.; Greenlees, P. T.; Homm, I.; Huyse, M.; Jolie, J.; Karayonchev, V.; Köster, U.; Konki, J.; Kröll, T.; Kurcewicz, J.; Kurtukian-Nieto, T.; Lazarus, I.; Lund, M. V.; Mǎrginean, N.; Mǎrginean, R.; Mihai, C.; Mihai, R. E.; Negret, A.; Orduz, A.; Patyk, Z.; Pascu, S.; Pucknell, V.; Rahkila, P.; Rapisarda, E.; Regis, J. M.; Robledo, L. M.; Rotaru, F.; Saed-Samii, N.; Sánchez-Tembleque, V.; Stanoiu, M.; Tengblad, O.; Thuerauf, M.; Turturica, A.; Van Duppen, P.; Warr, N.; IDS Collaboration

    2018-02-01

    The occurrence of octupolar shapes in the Ba isotopic chain was recently established experimentally up to N =90 . To further extend the systematics, the evolution of shapes in the most neutron-rich members of the Z =56 isotopic chain accessible at present, Ba,150148, has been studied via β decay at the ISOLDE Decay Station. This paper reports on the first measurement of the positive- and negative-parity low-spin excited states of 150Ba and presents an extension of the β -decay scheme of 148Cs. Employing the fast timing technique, half-lives for the 21+ level in both nuclei have been determined, resulting in T1 /2=1.51 (1 ) ns for 148Ba and T1 /2=3.4 (2 ) ns for 150Ba. The systematics of low-spin states, together with the experimental determination of the B (E 2 :2+→0+) transition probabilities, indicate an increasing collectivity in Ba-150148, towards prolate deformed shapes. The experimental data are compared to symmetry conserving configuration mixing (SCCM) calculations, confirming an evolution of increasingly quadrupole deformed shapes with a definite octupolar character.

  18. A Novel BA Complex Network Model on Color Template Matching

    PubMed Central

    Han, Risheng; Yue, Guangxue; Ding, Hui

    2014-01-01

    A novel BA complex network model of color space is proposed based on two fundamental rules of BA scale-free network model: growth and preferential attachment. The scale-free characteristic of color space is discovered by analyzing evolving process of template's color distribution. And then the template's BA complex network model can be used to select important color pixels which have much larger effects than other color pixels in matching process. The proposed BA complex network model of color space can be easily integrated into many traditional template matching algorithms, such as SSD based matching and SAD based matching. Experiments show the performance of color template matching results can be improved based on the proposed algorithm. To the best of our knowledge, this is the first study about how to model the color space of images using a proper complex network model and apply the complex network model to template matching. PMID:25243235

  19. The correlation between pedestrian injury severity in real-life crashes and Euro NCAP pedestrian test results.

    PubMed

    Strandroth, Johan; Rizzi, Matteo; Sternlund, Simon; Lie, Anders; Tingvall, Claes

    2011-12-01

    The aim of the present study was to estimate the correlation between Euro NCAP pedestrian rating scores and injury outcome in real-life car-to-pedestrian crashes, with special focus on long-term disability. Another aim was to determine whether brake assist (BA) systems affect the injury outcome in real-life car-to-pedestrian crashes and to estimate the combined effects in injury reduction of a high Euro NCAP ranking score and BA. In the current study, the Euro NCAP pedestrian scoring was compared with the real-life outcome in pedestrian crashes that occurred in Sweden during 2003 to 2010. The real-life crash data were obtained from the data acquisition system Swedish Traffic Accident Data Acquisition (STRADA), which combines police records and hospital admission data. The medical data consisted of International Classification of Diseases (ICD) diagnoses and Abbreviated Injury Scale (AIS) scoring. In all, approximately 500 pedestrians submitted to hospital were included in the study. Each car model was coded according to Euro NCAP pedestrian scores. In addition, the presence or absence of BA was coded for each car involved. Cars were grouped according to their scoring. Injury outcomes were analyzed with AIS and, at the victim level, with permanent medical impairment. This was done by translating the injury scores for each individual to the risk of serious consequences (RSC) at 1, 5, and 10 percent risk of disability level. This indicates the total risk of a medical disability for each victim, given the severity and location of injuries. The mean RSC (mRSC) was then calculated for each car group and t-tests were conducted to falsify the null hypothesis at p ≤ .05 that the mRSC within the groups was equal. The results showed a significant reduction of injury severity for cars with better pedestrian scoring, although cars with a high score could not be studied due to lack of cases. The reduction in RSC for medium-performing cars in comparison with low-performing cars

  20. 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…

  1. Beyond survival: fostering growth and innovation in doctoral study--a concept analysis of the Ba space.

    PubMed

    Krahe, J A E; Lalley, Cathy; Solomons, Nan M

    2014-01-25

    This concept analysis examines the Ba space in the context of interdisciplinary doctoral study in nursing and healthcare innovation in a minimal residency program. The authors identified Ba in their small, highly diverse, self-selected doctoral study group and believe Ba is an educational innovation that will prove useful to nursing and healthcare educators. Ba originates from Japanese philosophy and is foundational to the birth and sustainment of environments fostering knowledge creation. Ba manifests in complex environments where participants are emotionally invested and relies on the tacit knowledge of each participant, allowing for synthesis of rationality and intuition. Walker and Avant's concept analysis methodology will explore Ba's centrality to interdisciplinary education. Ba's utility and application in fostering innovation in doctoral study will be illustrated. Ba is a true educational innovation, enriching learning environments promoting interdisciplinary collaboration. Ba permits each member a voice and fosters a safe environment where relationships are created and sustained.

  2. Superconductivity in gallium-substituted Ba8Si46 clathrates

    NASA Astrophysics Data System (ADS)

    Li, Yang; Zhang, Ruihong; Liu, Yang; Chen, Ning; Luo, Z. P.; Ma, Xingqiao; Cao, Guohui; Feng, Z. S.; Hu, Chia-Ren; Ross, Joseph H., Jr.

    2007-02-01

    We report a joint experimental and theoretical investigation of superconductivity in Ga-substituted type-I silicon clathrates. We prepared samples of the general formula Ba8Si46-xGax , with different values of x . We show that Ba8Si40Ga6 is a bulk superconductor, with an onset at TC≈3.3K . For x=10 and higher, no superconductivity was observed down to T=1.8K . This represents a strong suppression of superconductivity with increasing Ga content, compared to Ba8Si46 with TC≈8K . Suppression of superconductivity can be attributed primarily to a decrease in the density of states at the Fermi level, caused by a reduced integrity of the sp3 -hybridized networks as well as the lowering of carrier concentration. These results are corroborated by first-principles calculations, which show that Ga substitution results in a large decrease of the electronic density of states at the Fermi level, which explains the decreased superconducting critical temperature within the BCS framework. To further characterize the superconducting state, we carried out magnetic measurements showing Ba8Si40Ga6 to be a type-II superconductor. The critical magnetic fields were measured to be HC1≈35Oe and HC2≈8.5kOe . We deduce the London penetration depth λ≈3700Å and the coherence length ξc≈200Å . Our estimate of the electron-phonon coupling reveals that Ba8Si40Ga6 is a moderate phonon-mediated BCS superconductor.

  3. Computational study of electronic, optical and thermoelectric properties of X3PbO (X = Ca, Sr, Ba) anti-perovskites

    NASA Astrophysics Data System (ADS)

    Hassan, M.; Arshad, I.; Mahmood, Q.

    2017-11-01

    We report the structural, electronic, optical and thermoelectric (TE) properties of X3PbO (X = Ca, Sr, Ba) anti-perovskites as a function of X cations belonging to the group IIA. The computations are done by using the most recently introduced modified Becke-Johnson potential. It has been observed that the cubic lattice constant increases as the cations change from Ca to Ba, consequently, the bulk modulus reduces. The bottom of conduction band shows strong hybridization between Pb-6p, O-2p and X-s states, in contrast, valence band maxima are mainly manufactured by Pb-6p states. The anti-perovskites exhibit narrow direct band gap that show an inverse relation to the static real dielectric constants that verifies Penn’s model. In addition, the X cations induced tuning of the absorption edge in the visible and the ultraviolet energy suggest optical device applications. The computed TE parameters have been found sensitive to the X cations and have been demonstrated to be best suited for the TE devices operating at high temperatures.

  4. 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.

  5. Lattice dynamics of BaFe 2 X 3 ( 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 T N=255K leaves a fingerprint both in the A 1g and B 3g phonon mode linewidth and energy.« less

  6. High mobility La-doped BaSnO3 on non-perovskite MgO substrate

    NASA Astrophysics Data System (ADS)

    Kim, Youjung; Shin, Juyeon; Kim, Young Mo; Char, Kookrin

    (Ba,La)SnO3 is a transparent perovskite oxide with high electron mobility and excellent oxygen stability. Field effect device with (Ba,La)SnO3 channel was reported to show good output characteristics on STO substrate. Here, we fabricated (Ba,La)SnO3\\ films and field effect devices with (Ba,La)SnO3 channel on non-perovskite MgO substrates, which are available in large size wafers. X-ray diffraction and transmission electron microscope (TEM) images of (Ba,La)SnO3\\ films on MgO substrates show that the films are epitaxial with many threading dislocations. (Ba,La)SnO3 exhibits the high mobility with 97.2 cm2/Vs at 2 % La doping on top of 150 nm thick BaSnO3 buffer layer. Excellent carrier modulation was observed in field effect devices. FET performances on MgO substrates are slightly better than those on SrTiO3 substrates in spite of the higher dislocation density on MgO than on SrTiO3 substrates. These high mobility BaSnO3 thin films and transistors on MgO substrates will accelerate development for applications in high temperature and high power electronics. Samsung Science and Technology Foundation.

  7. Electronic structure of the gold/Bi2Sr2CaCu2O8 and gold/EuBa2Cu3O7 - delta interfaces as studied by photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Dessau, D. S.; Shen, Z.-X.; Wells, B. O.; Spicer, W. E.; List, R. S.; Arko, A. J.; Bartlett, R. J.; Fisk, Z.; Cheong, S.-W.; Mitzi, D. B.; Kapitulnik, A.; Schirber, J. E.

    1990-07-01

    High-resolution photoemission has been used to probe the electronic structure of the gold/Bi2Sr2CaCu2O8 and gold/EuBa2Cu3O7-δ interface formed by a low-temperature (20 K) gold evaporation on cleaved high quality single crystals. We find that the metallicity of the EuBa2Cu3O7-δ substrate in the near surface region (˜5 Å) is essentially destroyed by the gold deposition, while the near surface region of Bi2Sr2CaCu2O8 remains metallic. This has potentially wide ranging consequences for the applicability of the different types of superconductors in real devices.

  8. 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 BaTiO 3 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 Ti 7O 7, 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, andmore » identify the bright protrusions as Ba atoms. The models are consistent with all experimental observations.« less

  9. 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.

  10. Ba 2TeO 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 Ba 2TeO are systematically investigated using density functional theory with a view to understanding its potential as an optoelectronic or transparent conducting material. Ba 2TeO 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 Ba 2TeO is intrinsically p-type conducting under Ba-poor condition. However, the spontaneousmore » formation of the donor defects may constrain the p-type transport properties and would need to be addressed to enable applications.« less

  11. [Descriptive epidemiology of the vascular risk factors in Bañeres. Study group 'Bañeres Project'].

    PubMed

    Mulet, M J; Sánchez-Pérez, R M; Moltó, J M; Adam, A; Blanquer, J; López-Arlandis, J

    Epidemiological studies of the risk factors of cerebrovascular disease are of great interest, particularly the identification of factors which may be modified. Previous studies carried out in the Alcoi region of Alicante province, showed a high prevalence of cerebrovascular disease. The town of Bañeres was therefore chosen for confirmation of this data and identification of the frequency of vascular risk factors. To compare the group of patients with cerebrovascular disease with the remainder of the population interviewed. In a door-to-door study in Bañeres 1,832 people were interviewed as part of the Bañeres Project. The population aged over 45 years was interviewed and filled in a questionnaire for diagnosis of transient ischemic accidents. Arterial hypertension: estimated prevalence 500/1,000 inhabitants, relative risk 3.24; diabetes mellitus: estimated prevalence 195/1,000, relative risk 2.18; coronary artery disease: estimated prevalence 58/1,000, relative risk 1.88; peptic ulcer: estimated prevalence 75/1,000, relative risk 1.23; smoking: estimated prevalence 110/1,000, relative risk 0.46; complete arrhythmia: prevalence 73/1,000, relative risk 5.23. Family histories of cerebrovascular accident, arterial hypertension, diabetes and coronary artery disease were not significant. Arterial hypertension, diabetes mellitus and arrhythmia were significantly more prevalent amongst patients with vascular disease in our setting. We found no association with the other risk factors analyzed.

  12. 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.

  13. BaSi2 formation mechanism in thermally evaporated films and its application to reducing oxygen impurity concentration

    NASA Astrophysics Data System (ADS)

    Hara, Kosuke O.; Yamamoto, Chiaya; Yamanaka, Junji; Arimoto, Keisuke; Nakagawa, Kiyokazu; Usami, Noritaka

    2018-04-01

    Thermal evaporation is a simple and rapid method to fabricate semiconducting BaSi2 films. In this study, to elucidate the BaSi2 formation mechanism, the microstructure of a BaSi2 epitaxial film fabricated by thermal evaporation has been investigated by transmission electron microscopy. The BaSi2 film is found to consist of three layers with different microstructural characteristics, which is well explained by assuming two stages of film deposition. In the first stage, BaSi2 forms through the diffusion of Ba atoms from the deposited Ba-rich film to the Si substrate while in the second stage, the mutual diffusion of Ba and Si atoms in the film leads to BaSi2 formation. On the basis of the BaSi2 formation mechanism, two issues are addressed. One is the as-yet unclarified reason for epitaxial growth. It is found important to quickly form BaSi2 in the first stage for the epitaxial growth of upper layers. The other issue is the high oxygen concentration in BaSi2 films around the BaSi2-Si interface. Two routes of oxygen incorporation, i.e., oxidation of the Si substrate surface and initially deposited Ba-rich layer by the residual gas, are identified. On the basis of this knowledge, oxygen concentration is decreased by reducing the holding time of the substrate at high temperatures and by premelting of the source. In addition, X-ray diffraction results show that the decrease in oxygen concentration can lead to an increased proportion of a-axis-oriented grains.

  14. Direct Observation of Pressure-Driven Valence Electron Transfer in Ba 3 BiRu 2 O 9 , Ba 3 BiIr 2 O 9 , and Ba 4 BiIr 3 O 12

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Blanchard, Peter E. R.; Chapman, Karena W.; Heald, Steve M.

    The hexagonal perovskites Ba3BiIr2O9, Ba3BiRu2O9 and Ba4BiIr3O12 all undergo pressure-induced 1% volume collapses above 5 GPa. These first-order transitions have been ascribed to internal transfer of valence electrons between bismuth and iridium/ruthenium, which is driven by external applied pressure because the reduction in volume achieved by emptying the 6s shell of bismuth upon oxidation to Bi5+ is greater in magnitude than the increase in volume by reducing iridium or ruthenium. Here, we report direct observation of these valence transfers for the first time, using high-pressure X-ray absorption near-edge spectroscopy (XANES) measurements. Our data also support the highly unusual “4+” nominalmore » oxidation state of bismuth in these compounds, although the possibility of local disproportionation into Bi3+/Bi5+ cannot be definitively ruled out. Ab initio calculations reproduce the transition, support its interpretation as a valence electron transfer from Bi to Ir/Ru, and suggest that the high-pressure phase may show metallic behavior (in contrast to the insulating ambient-pressure phase).« less

  15. 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.

  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. Effect of BaSi2 template growth duration on the generation of defects and performance of p-BaSi2/n-Si heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Yachi, Suguru; Takabe, Ryota; Deng, Tianguo; Toko, Kaoru; Suemasu, Takashi

    2018-04-01

    We investigated the effect of BaSi2 template growth duration (t RDE = 0-20 min) on the defect generation and performance of p-BaSi2/n-Si heterojunction solar cells. The p-BaSi2 layer grown by molecular beam epitaxy (MBE) was 15 nm thick with a hole concentration of 2 × 1018 cm-3. The conversion efficiency η increased for films grown at long t RDE, owing to improvements of the open-circuit voltage (V OC) and fill factor (FF), reaching a maximum of η = 8.9% at t RDE = 7.5 min. However, η decreased at longer and shorter t RDE owing to lower V OC and FF. Using deep-level transient spectroscopy, we detected a hole trap level 190 meV above the valence band maximum for the sample grown without the template (t RDE = 0 min). An electron trap level 106 meV below the conduction band minimum was detected for a sample grown with t RDE = 20 min. The trap densities for both films were (1-2) × 1013 cm-3. The former originated from the diffusion of Ba into the n-Si region; the latter originated from defects in the template layer. The crystalline qualities of the template and MBE-grown layers were discussed. The root-mean-square surface roughness of the template reached a minimum of 0.51 nm at t RDE = 7.5 min. The a-axis orientation of p-BaSi2 thin films degraded as t RDE exceeded 10 min. In terms of p-BaSi2 crystalline quality and solar cell performance, the optimum t RDE was determined to be 7.5 min, corresponding to approximately 4 nm in thickness.

  18. Synthesis and electrical properties of BaBiO 3 and high resistivity BaTiO 3 –BaBiO 3 ceramics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    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 tomore » 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.« less

  19. Direct detection of cysteine using functionalized BaTiO3 nanoparticles film based self-powered biosensor.

    PubMed

    Selvarajan, Sophia; Alluri, Nagamalleswara Rao; Chandrasekhar, Arunkumar; Kim, Sang-Jae

    2017-05-15

    Simple, novel, and direct detection of clinically important biomolecules have continuous demand among scientific community as well as in market. Here, we report the first direct detection and facile fabrication of a cysteine-responsive, film-based, self-powered device. NH 2 functionalized BaTiO 3 nanoparticles (BT-NH 2 NPs) suspended in a three-dimensional matrix of an agarose (Ag) film, were used for cysteine detection. BaTiO 3 nanoparticles (BT NPs) semiconducting as well as piezoelectric properties were harnessed in this study. The changes in surface charge properties of the film with respect to cysteine concentrations were determined using a current-voltage (I-V) technique. The current response increased with cysteine concentration (linear concentration range=10µM-1mM). Based on the properties of the composite (BT/Ag), we created a self-powered cysteine sensor in which the output voltage from a piezoelectric nanogenerator was used to drive the sensor. The potential drop across the sensor was measured as a function of cysteine concentrations. Real-time analysis of sensor performance was carried out on urine samples by non-invasive method. This novel sensor demonstrated good selectivity, linear concentration range and detection limit of 10µM; acceptable for routine analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Aspects of forming metal-clad melt-processed Y-Ba-Cu-O tapes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kozlowski, G.; Oberly, C.E.; Ho, J.

    1991-03-01

    This paper reports on melt-processing of Y-Ba-Cu-O superconductor in a usable form for magnet winding which requires the development of a cladding with demanding properties. Numerous recent efforts in cold forming Bi-based superconductor tapes have been successful because a silver tube can be used to constrain the ceramic material, which is sintered at much lower temperature than the Y-Ba-Cu-O. Typical high temperature metals which can be used to encase Y-Ba-Cu-O during sintering do not permit ready diffusion of oxygen as silver does. Recently, the full or partial recovery of superconductivity has been achieved in transition-metal- doped Y-Ba-Cu-O due to themore » partial-melt processing.« less

  1. Recent high-energy marine events in the sediments of Lagoa de Óbidos and Martinhal (Portugal): recognition, age and likely causes

    NASA Astrophysics Data System (ADS)

    Costa, P. J. M.; Leroy, S. A. G.; Dinis, J. L.; Dawson, A. G.; Kortekaas, S.

    2012-05-01

    A key issue in coastal hazards research is the need to distinguish sediments deposited by past extreme storms from those of past tsunamis. This study contributes to this aim by investigating patterns of sedimentation associated with extreme coastal flood events, in particular, within the Lagoa de Óbidos (Portugal). The recent stratigraphy of this coastal lagoon was studied using a wide range of techniques including visual description, grain-size analysis, digital and x-ray photography, magnetic susceptibility and geochemical analysis. The sequence was dated by 14C, 210Pb and Optically Stimulated Luminescence. Results disclose a distinctive coarser sedimentary unit, within the top of the sequence studied, and shown in quartz sand by the enrichment of elements with marine affinity (e.g., Ca and Na) and carbonates. The unit fines upwards and inland, thins inland and presents a sharp erosive basal contact. A noticeable post-event change in the sedimentary pattern was observed. The likely agent of sedimentation is discussed here and the conceivable association with the Great Lisbon tsunami of AD 1755 is debated, while a comparison is attempted with a possibly synchronous deposit from a tsunami in Martinhal (Algarve, Portugal). The possibility of a storm origin is also discussed in the context of the storminess of the western Portuguese coast and the North Atlantic Oscillation. This study highlights certain characteristics of the sedimentology of the deposits that may have a value in the recognition of extreme marine inundation signatures elsewhere in the world.

  2. 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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Navarro, H., E-mail: henrynavarro@cab.cnea.gov.ar; Sirena, M.; Haberkorn, N.

    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 appliedmore » 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)« less

  3. Methodical thermolysis of [Ba2Ti2(thd)4(OnPr)8(nPrOH)2] under autogenous pressure followed by combustion for the synthesis of dielectric tetragonal BaTiO3 nanopowder.

    PubMed

    Pol, Vilas G; Thiyagarajan, P; Moreno, Jose M Calderon; Popa, Monica; Kessler, Vadim G; Gohil, Suresh; Seisenbaeva, Gulaim A

    2009-07-06

    The tetragonal BaTiO(3) nanopowder is synthesized in a solvent-less, efficient process by the thermolysis of a single [Ba(2)Ti(2)(thd)(4)(OnPr)(8)(nPrOH)(2)] precursor in a closed reactor at 700 degrees C under autogenous pressure, followed by combustion. This paper compiles the synthesis of the [Ba(2)Ti(2)(thd)(4)(OnPr)(8)(nPrOH)(2)] precursor, its analysis by mass spectrometry, and implementation for the fabrication of dielectric tetragonal BaTiO(3) nanopowder by controlled efficient thermal decomposition. The as-prepared, intermediate, and final forms of the obtained nanomaterials are systematically analysed by XRD, Raman, and EDS measurements to gain structural and compositional information. Employing HR-SEM, TEM, and HR-TEM techniques, the morphological changes during the structural evolution of all the phases are pursued. The mechanistic elucidation for the fabrication of BaTiO(3) nanopowder is developed on the basis of TGA and DTA data obtained for the initial [Ba(2)Ti(2)(thd)(4)(OnPr)(8)(nPrOH)(2)] reactant as well as the as-prepared BaCO(3) with amorphous Ti phase.

  4. Metrological activity determination of 133Ba by sum-peak absolute method

    NASA Astrophysics Data System (ADS)

    da Silva, R. L.; de Almeida, M. C. M.; Delgado, J. U.; Poledna, R.; Santos, A.; de Veras, E. V.; Rangel, J.; Trindade, O. L.

    2016-07-01

    The National Laboratory for Metrology of Ionizing Radiation provides gamma sources of radionuclide and standardized in activity with reduced uncertainties. Relative methods require standards to determine the sample activity while the absolute methods, as sum-peak, not. The activity is obtained directly with good accuracy and low uncertainties. 133Ba is used in research laboratories and on calibration of detectors for analysis in different work areas. Classical absolute methods don't calibrate 133Ba due to its complex decay scheme. The sum-peak method using gamma spectrometry with germanium detector standardizes 133Ba samples. Uncertainties lower than 1% to activity results were obtained.

  5. 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

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

    PubMed

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

    2014-10-01

    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. 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. 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. 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. The adoption of 85 dBA as the permissible exposure limit has preserved hearing threshold level among participants at 3000 Hz

  7. SN 2015ba: a Type IIP supernova with a long plateau.

    NASA Astrophysics Data System (ADS)

    Dastidar, Raya; Misra, Kuntal; Hosseinzadeh, G.; Pastorello, A.; Pumo, M. L.; Valenti, S.; McCully, C.; Tomasella, L.; Arcavi, I.; Elias-Rosa, N.; Singh, Mridweeka; Gangopadhyay, Anjasha; Howell, D. A.; Morales-Garoffolo, Antonia; Zampieri, L.; Kumar, Brijesh; Turatto, M.; Benetti, S.; Tartaglia, L.; Ochner, P.; Sahu, D. K.; Anupama, G. C.; Pandey, S. B.

    2018-06-01

    We present optical photometry and spectroscopy from about a week after explosion to ˜272 d of an atypical Type IIP supernova, SN 2015ba, which exploded in the edge-on galaxy IC 1029. SN 2015ba is a luminous event with an absolute V-band magnitude of -17.1 ± 0.2 mag at 50 d since explosion and has a long plateau lasting for ˜123 d. The distance to the SN is estimated to be 34.8 ± 0.7 Mpc using the expanding photosphere and standard candle methods. High-velocity H Balmer components constant with time are observed in the late-plateau phase spectra of SN 2015ba, which suggests a possible role of circumstellar interaction at these phases. Both hydrodynamical and analytical modelling suggest a massive progenitor of SN 2015ba with a pre-explosion mass of 24-26 M⊙. However, the nebular spectra of SN 2015ba exhibit insignificant levels of oxygen, which is otherwise expected from a massive progenitor. This might be suggestive of the non-monotonical link between O-core masses and the zero-age main-sequence mass of pre-supernova stars and/or uncertainties in the mixing scenario in the ejecta of supernovae.

  8. Sediment pollution in margins of the Lake Guaíba, Southern Brazil.

    PubMed

    de Andrade, Leonardo Capeleto; Tiecher, Tales; de Oliveira, Jessica Souza; Andreazza, Robson; Inda, Alberto Vasconcellos; de Oliveira Camargo, Flávio Anastácio

    2017-12-02

    Sediments are formed by deposition of organic and inorganic particles on depth of water bodies, being an important role in aquatic ecosystems, including destination and potential source of essential nutrients and heavy metals, which may be toxic for living organisms. The Lake Guaíba supplies water for approximately two million people and it is located in the metropolitan region of Porto Alegre, Rio Grande do Sul State, Brazil. Thus, the aim of this study was to evaluate the sediment pollution in the margins of Lake Guaíba in the vicinity of Porto Alegre city. Surface sediment was sampled in 12 sites to assess the concentration of several elements (C, N, P, Fe, Al, Ca, Mg, Na, K, Mn, Ba, Zn, V, Pb, Cu, Cr, Ni, Cd, Mo, and Se) and the mineralogical composition. Sediment in margins of Lake Guaíba presented predominantly (> 95%) sandy fraction in all samples, but with significant differences between evaluated sites. Sediments in the margins of Lake Guaíba showed indications of punctual water pollution with Pb, Cu, Cr, Ni, TOC, TKN, and P, mainly derived from urban streams that flow into the lake. In order to solve these environmental liabilities, public actions should not focus only on Guaíba, but also in the streams that flow into the lake.

  9. Influence of Ba/Fe mole ratios on magnetic properties, crystallite size and shifting of X-ray diffraction peaks of nanocrystalline BaFe12O19 powder, prepared by sol gel auto combu

    NASA Astrophysics Data System (ADS)

    Suastiyanti, Dwita; Sudarmaji, Arif; Soegijono, Bambang

    2012-06-01

    Barium hexaferrite BaFe12O19 (BFO) is of great importance as permanent magnets, particularly for magnetic recording as well as in microwave devices. Nano-crystalline BFO powders were prepared by sol gel auto combustion method in citric acid - metal nitrates system. Hence the mole ratios of Ba/Fe were variated at 1:12; 1:11.5 and 1:11. Ratio of cation to fuel was fixed at 1:1. An appropriate amount of amonia solution was added dropwise to this solution with constant stirring until the PH reached 7 in all cases. Heating at 850oC for 10 hours for each sample to get final formation of BFO nanocrystalline. The data from XRD showing the lattice parameters a,c and the unit-cell volume V, confirm that BFO with ratio 1:12 has same crystall parameters with ratio 1:11. Ratio of Ba/Fe 1:12 and 1:11 have diffraction pattern similarly at almost each 2 θ for each samples. Ratio of Ba/Fe 1: 11.5 has the finest crystallite size 22 nm. Almost diffraction pattern peaks of Ba/Fe 1:11.5 move to the left from of Ba/Fe 1:12 then return to diffraction pattern of Ba/Fe 1:12 for Ba/Fe 1:11. SEM observations show the particle size less than 100 nm and the same shape for each sample. Ratio of Ba/Fe 1: 12 gives the highest intrinsic coercive Hc = 427.3 kA/m. The highest remanent magnetization is at ratio 1:11 with Mr = 0.170 T. BFO with mole ratio 1:11.5 has the finest grain 22 nm, good magnetic properties and the highest value of best FoM 89%.

  10. Novel phosphate halides BaMn{sup III}[PO{sub 4}]FCl and BaMn{sup III}[PO{sub 4}]F{sub 2}: Effects of mixed halides on crystal structures and magnetic properties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pei, Da-Ting, E-mail: pdtcug@gmail.com; Sun, Wei, E-mail: 421221789@qq.com; Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Canada SK S7N 5E2

    2016-02-15

    Two new phosphate halides BaMn{sup III}[PO{sub 4}]FCl (1) and BaMn{sup III}[PO{sub 4}]F{sub 2} (2), have been synthesized under hydrothermal conditions. Structural characterizations show that both new compounds adopt layered structures but with different polyhedral linkages. Introduction of Cl into Compound (1) results in isolated hemimorphic [MnO{sub 4}FCl] octahedra, different from the chain of [MnO{sub 4}F{sub 2}]/[MnO{sub 2}F{sub 4}] octahedra in Compound (2). These compounds have significantly different molecular vibration modes and thermal stabilities. Magnetic measurements reveal that Compound (2) has larger antiferromagnetic interactions than Compound (1), because the former has strong interactions between Mn{sup 3+}-Mn{sup 3+} ions within corner-shared Mn{supmore » 3+}-octahedral chains whereas the latter only possesses isolated Mn{sup 3+}-octahedra. Both compounds transform to a new orthorhombic compound BaMn{sup II}(PO{sub 4})F (3) after thermal decomposition. - Graphical abstract: The large radius of Cl{sup -} ions makesBaMn{sup III}[PO{sub 4}]FCl to adopt isolated [MnO{sub 4}FCl] rather than corner-sharing octahedra as observed in BaMn{sup III}[PO{sub 4}]F{sub 2}. - Highlights: • Two novel phosphate halides BaMn[PO{sub 4}]FCl and BaMn[PO{sub 4}]F{sub 2} have been prepared. • These new compounds adopt different types of layered structures. • They have different molecular vibration modes and thermal stabilities. • BaMn[PO{sub 4}]FCl has weaker antiferromagnetic interactions than BaMn[PO{sub 4}]F{sub 2}. • The former adopts isolated octahedra whereas the latter adopts octahedral chains.« less

  11. Dielectric properties of Ni-coated BaTiO/sub 3-/PMMA composite.

    PubMed

    Park, Jung Min; Lee, Hee Young; Kim, Jeong-Joo; Park, Eun Tae; Chung, Yul-Kyo

    2008-05-01

    Dielectric properties of Ni-coated BaTiO(3)-PMMA (polymethyl methacrylate) composite were studied from an embedded capacitor application viewpoint. Volume loading of up to 50% was attempted, and the results were compared with uncoated BaTiO(3)-PMMA composite. Ni-coating on BaTiO(3) powder was found to greatly improve the dielectric properties of the composite, especially the dielectric constant value. K values of about 100 with temperature-stable X7E characteristics were realized.

  12. Structural, optical and electronic properties of K2Ba(NO3)4 crystal

    NASA Astrophysics Data System (ADS)

    Isaenko, L. I.; Korzhneva, K. E.; Goryainov, S. V.; Goloshumova, A. A.; Sheludyakova, L. A.; Bekenev, V. L.; Khyzhun, O. Y.

    2018-02-01

    Nitrate crystals reveal nonlinear optical properties and could be considered as converters of laser radiation in the short-wave region. The conditions for obtaining and basic properties of K2Ba(NO3)4 double nitrate crystals were investigated. Crystal growth was implemented by slow cooling in the temperature range of 72-49 °C and low rate evaporation. The structural analysis of K2Ba(NO3)4 formation on the basis of two mixed simple nitrate structures is discussed. The main groups of oscillations in K2Ba(NO3)4 crystal were revealed using Raman and IR spectroscopy, and the table of vibrations for this compound was compiled. The electronic structure of K2Ba(NO3)4 was elucidated in the present work from both experimental and theoretical viewpoints. In particular, X-ray photoelectron spectroscopy (XPS) was employed in the present work to measure binding energies of the atoms constituting the titled compound and its XPS valence-band spectrum for both pristine and Ar+ ion-bombarded surfaces. Further, total and partial densities of states of constituent atoms of K2Ba(NO3)4 have been calculated. The calculations reveal that the O 2p states dominate in the total valence-band region of K2Ba(NO3)4 except of its bottom, where K 3p and Ba 5p states are the principal contributors, while the bottom of the conduction band is composed mainly of the unoccupied O 2p states, with somewhat smaller contributions of the N 2p∗ states as well. With respect to the occupation of the valence band by the O 2p states, the present band-structure calculations are confirmed by comparison on a common energy scale of the XPS valence-band spectrum and the X-ray emission O Kα band for the K2Ba(NO3)4 crystal under study. Furthermore, the present calculations indicate that the K2Ba(NO3)4 compound is a direct-gap material.

  13. Optically stimulated luminescence in an imaging plate using BaFi:Eu.

    PubMed

    Nanto, H; Araki, T; Daimon, M; Kusano, E; Kinbara, A; Kawabata, K; Nakano, Y

    2002-01-01

    BaFI:Eu phosphors are fabricated using a new method of synthesis: liquid phase synthesis, in which the phosphor particles are formed through the association of Ba2+ ions, F-ions and Eu2+ ions in solution. An intense optically stimulated luminescence (OSL) peak at about 410 nm is observed by stimulating X ray irradiated BaFI:Eu phosphor with about 550-750 nm light. It is found that the peak wavelength of the optically stimulation spectrum is about 690 nm. This result suggests that the semiconductor laser can be used as the stimulating light source. It is also found that the OSL intensity is increased with increasing the X ray dose. The BaFI:Eu phosphor as a photostimulable material for the imaging plate of a computed radiography system provides the following advantages; (1) high X ray absorption coefficient, (2) high monodispersion in size which would contribute to sharp images, (3) high OSL and thus low luminescence mottle and (4) high DQE (detective quantum efficiency).

  14. High Pressure Properties of a Ba-Cu-Zn-P Clathrate-I

    DOE PAGES

    Dolyniuk, Juli -Anna; Kovnir, Kirill

    2016-08-12

    Here, the high pressure properties of the novel tetrel-free clathrate, Ba 8Cu 13.1Zn 3.3P 29.6, were investigated using synchrotron powder X-ray diffraction. The pressure was applied using a diamond anvil cell. No structural transitions or decomposition were detected in the studied pressure range of 0.1–7 GPa. The calculated bulk modulus for Ba 8Cu 13.1Zn 3.3P 29.6 using a third-order Birch-Murnaghan equation of state is 65(6) GPa at 300 K. This bulk modulus is comparable to the bulk moduli of Ge- and Sn-based clathrates, like A 8Ga 16Ge 30 (A = Sr, Ba) and Sn 19.3Cu 4.7P 22I 8, but lowermore » than those for the transition metal-containing silicon-based clathrates, Ba 8 T xSi46–x, T = Ni, Cu; 3 ≤ x ≤ 5.« less

  15. Molecular glues for manipulating enzymes: trypsin inhibition by benzamidine-conjugated molecular glues† †Electronic supplementary information (ESI) available: Synthesis of TEG–BA, Gluen–BA, mGluen–BA and Gluen–Ph; 1H NMR, 13C NMR, MALDI-TOF MS, electronic absorption, and CD spectra; zeta potential distributions; SLS plots; DLS histograms; and related experimental procedures. See DOI: 10.1039/c5sc00524h Click here for additional data file.

    PubMed Central

    Mogaki, Rina

    2015-01-01

    Water-soluble bioadhesive polymers bearing multiple guanidinium ion (Gu+) pendants at their side-chain termini (Gluen–BA, n = 10 and 29) that were conjugated with benzamidine (BA) as a trypsin inhibitor were developed. The Gluen–BA molecules are supposed to adhere to oxyanionic regions of the trypsin surface, even in buffer, via a multivalent Gu+/oxyanion salt-bridge interaction, such that their BA group properly blocks the substrate-binding site. In fact, Glue10–BA and Glue29–BA exhibited 35- and 200-fold higher affinities for trypsin, respectively, than a BA derivative without the glue moiety (TEG–BA). Most importantly, Glue10–BA inhibited the protease activity of trypsin 13-fold more than TEG–BA. In sharp contrast, mGlue27–BA, which bears 27 Gu+ units along the main chain and has a 5-fold higher affinity than TEG–BA for trypsin, was inferior even to TEG–BA for trypsin inhibition. PMID:28706668

  16. Chronological, taphonomical, and paleoenvironmental aspects of a Late Pleistocene mammalian fauna from Guanambi, Bahia, Brazil

    NASA Astrophysics Data System (ADS)

    Scherer, Carolina Saldanha; Pales, Letícia Francielle Moreira; Rosa, Mariane; Silva, Samara de Almeida da

    2017-11-01

    Bahia state is widely known for the presence of fossiliferous deposits of Late Pleistocene - early Holocene. Although most studies in the state have been carried out on cave environments, studies concerning natural tank deposits have been expanded in the last few years, particularly in other states of Northeast Brazil. Therefore, the present work aims to study two new natural tanks: "Lagoa das Abelhas" and "Lagoa do Rancho", in Guanambi municipality, south-central Bahia, Brazil. The identified taxa include representatives of Xenarthra (Eremotherium laurillardi, cf. Glossotherium sp., Pachyarmatherium brasiliense, Glyptodontinae, Propraopus sulcatus, Pampatherium humboldti, and Holmesina paulacoutoi), Notoungulata (Toxodontidae), Proboscidea, Perissodactyla (Tapirus terrestris and Equus (Amerhippus) neogaeus), and Cetartiodactyla (Camelidae). The taphonomic analysis allowed the fossiliferous deposit from Lagoa das Abelhas to be classified as an ex situ assemblage, while the Lagoa do Rancho deposit was interpreted as a peripheral assemblage. Based on its paleofaunal composition, the landscape of the Guanambi region would have comprised open areas with pastures and patches with arboreal elements. The 14C radiocarbon dating results point to ages of 22,230 ± 55 years for the Lagoa das Abelhas and 16,020 ± 40 years for the Lagoa do Rancho tanks, indicating that the Guanambi paleofauna lived during the Last Glacial Maximum, in a drier phase of the Late Pleistocene.

  17. X-ray and dielectric characterization of Co doped tetragonal BaTiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Bujakiewicz-Koronska, R.; Vasylechko, L.; Markiewicz, E.; Nalecz, D. M.; Kalvane, A.

    2017-01-01

    The crystal structure modifications of BaTiO3 induced by cobalt doping were studied. The polycrystalline (1 - x)BaTiO3 + xCo2O3 samples, with x ≤ 10 wt.%, were prepared by high temperature sintering conventional method. According to X-ray phase and structural characterization, performed by full-profile Rietveld refinement technique, all synthesized samples showed tetragonal symmetry perovskite structure with minor amount of parasitic phases. Pure single-phase composition has been detected only in the low level of doping BaTiO3. It was indicated that substitution of Co for the Ti sites in the (1 - x)BaTiO3 + xCo2O3 series led to decrease of tetragonality (c/a) of the BaTiO3 perovskite structure. This effect almost vanished in the (1 - x)BaTiO3 + xCo2O3 samples with nominal Co content higher than ∼1 wt.%, in which precipitation of parasitic Co-containing phases CoO and Co2TiO4 has been observed. Based on the results, the solubility limit of Co in Ti sub-lattice in the (1 - x)BaTiO3 + xCo2O3 series is estimated as x = 0.75 wt.%.

  18. Energy transfer between Eu-Mn and photoluminescence properties of Ba0.75Al11O17.25-BaMgAl10O17:Eu2+,Mn2+ solid solution

    NASA Astrophysics Data System (ADS)

    Zhou, Jun; Wang, Yuhua; Liu, Bitao; Li, Feng

    2010-08-01

    In order to evaluate the energy transfer between Eu-Mn in Ba0.75Al11O17.25-BaMgAl10O17 solid solution, Ba0.75Al11O17.25-BaMgAl10O17:Eu2+,Mn2+ phosphors were prepared by flux method. The crystal structure and the morphology of the solid solution were demonstrated by x-ray dirrfactometer and scanning electron microscopy. The photoluminescence mechanisms were explained by the energy transfer of Eu2+ to Mn2+ and the Dexter theory. A redshift of green emission peak and a decrease in decay time with the increase in Mn2+ concentration were observed. These phenomena are attributed to the formation of Mn2+ paired centers after analysis by a method of Pade approximations.

  19. Angle-resolved photoemission observation of Mn-pnictide hybridization and negligible band structure renormalization in BaMn 2 As 2 and BaMn 2 Sb 2

    DOE PAGES

    Zhang, W. -L.; Richard, P.; van Roekeghem, A.; ...

    2016-10-31

    We performed an angle-resolved photoemission spectroscopy study of BaMn 2As 2 and BaMn 2Sb 2, which are isostructural to the parent compound BaFe 2As 2 of the 122 family of ferropnictide superconductors. We show the existence of a strongly k z-dependent band gap with a minimum at the Brillouin zone center, in agreement with their semiconducting properties. Despite the half filling of the electronic 3d shell, we show that the band structure in these materials is almost not renormalized from the Kohn-Sham bands of density functional theory. Finally, our photon-energy-dependent study provides evidence for Mn-pnictide hybridization, which may play amore » role in tuning the electronic correlations in these compounds.« less

  20. From Ba{sub 3}Ta{sub 5}O{sub 14}N to LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2}: Decreasing the optical band gap of a photocatalyst

    DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    Yellow LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} was successfully synthesized as phase-pure material crystallizing isostructurally to previously reported Ba{sub 3}Ta{sub 5}O{sub 14}N and mixed-valence Ba{sub 3}Ta{sup V}{sub 4}Ta{sup IV}O{sub 15}. The electronic structure of LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} 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 Ba{sub 3}Ta{sub 5}O{sub 14}N to 2.63 eV for the new oxide nitride, giving risemore » 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 Ba{sub 3}Ta{sub 5}O{sub 14}N revealing significantly higher activity for LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} under UV-light. - Graphical abstract: X-ray powder diffraction pattern of LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} with the results of the Rietveld refinements. Inset: Unit cell of LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} and polyhedral representation of the crystal structure. - Highlights: • Synthesis of a new oxide nitride LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2}. • Refinement of the crystal structure. • Quantum chemical calculations provided band gap close to the measured value. • New phase shows a higher photocatalytic H{sub 2} evolution rate compared to prior tested Ba{sub 3}Ta{sub 5}O{sub 14}N.« less

  1. Hydrothermal growth of highly textured BaTiO₃ films composed of nanowires.

    PubMed

    Zhou, Zhi; Lin, Yirong; Tang, Haixiong; Sodano, Henry A

    2013-03-08

    Textured barium titanate (BaTiO(3)) films are attracting immense research interest due to their lead-free composition and excellent piezoelectric and dielectric properties. Most synthesis methods for these films require a high temperature, leading to the formation of a secondary phase and an overall decrease in the electrical properties of the ceramic. In order to alleviate these issues, a novel fabrication method is introduced by transferring oriented rutile TiO(2) nanowires to a textured BaTiO(3) film at temperatures below 160 °C. The microstructure and thickness of the fabricated BaTiO(3) films were characterized by scanning electron microscopy, and the crystal structure and degree of orientation were evaluated by x-ray diffraction patterns using the Lotgering method. It is shown that the thickness of the BaTiO(3) film can be controlled by the length of TiO(2) nanowire array template, and the degree of orientation of the textured BaTiO(3) films is highly dependent on the film thickness; the crystallographic orientation has been measured to reach up to 87%. The relative dielectric constant (ε(r) = 1300) and ferroelectric properties (P(r) = 2.7 μC cm(-2), E(c) = 4.0 kV mm(-1)) of the textured BaTiO(3) films were also characterized to demonstrate their potential application in sensors, random access memory, and micro-electromechanical systems.

  2. Preparation of porous (Ba,Sr)TiO3 by adding corn-starch

    NASA Astrophysics Data System (ADS)

    Kim, J.-G.; Sim, J.-H.; Cho, W.-S.

    2002-11-01

    A new method of preparing porous (Ba,Sr)TiO3 ceramics has been introduced, using an ordinary ceramics processing technique. The effect of corn-starch on the positive temperature coefficient of resistivity characteristics and microstructure of the porous (Ba,Sr)TiO3 ceramics has been investigated. When the corn-starch addition was 1-20 wt%, the PTCR jump was over 106 and 1-2 orders higher than that of samples without corn-starch. Also, it was found that the (Ba,Sr)TiO3 ceramics had porous microstructure by the addition of corn-starch. The porosity of the ceramics with 20 wt% corn-starch was 44%. The electrical properties of the (Ba,Sr)TiO3 ceramics have been discussed, based on the microstructure, resistivity of grain boundaries, donor concentration of grains and the electrical potential barrier of grain boundaries.

  3. Method of Preparing Monoclinic BaO.Al2O3.2SiO2

    DTIC Science & Technology

    Monoclinic celsian (BaO.Al2O3.2SiO2) is produced by heating a stoichiometric, powder mixture of BaCO3 (or BaC2O4), Al2O3, and SiO2 (preferably SiO2 gel) with monoclinic celsian seeds at from 1250 deg C to 1500 deg C.

  4. 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.

  5. Superconductivity achieved at over liquid nitrogen temperature by (mixed rare earths)-Ba-Cu oxides

    NASA Astrophysics Data System (ADS)

    Kishio, Kohji; Kuwahara, Kazuyuki; Kitazawa, Koichi; Fueki, Kazuo; Nakamura, Osamu

    1987-05-01

    Superconducting oxides were fabricated by reaction of powders of BaCO3, CuO and mixed rare earth (RE) carbonates at compositions expressed as (RE)1Ba2Cu3O(9-y). Two types of incompletely separated raw materials of mixed rare earths, namely, heavy rare earths (HRE) and medium rare earths (MRE), were examined. The zero-resistivity critical temperatures were observed at 92.5 K for the (HRE)-Ba-Cu-O and 85.0 K for the (MRE)-Ba-Cu-O systems, respectively, both of which were well above the boiling point of liquid nitrogen.

  6. Ba, B, and U element partitioning in magnesian calcite skeletons of Octocorallia corals

    NASA Astrophysics Data System (ADS)

    Yoshimura, T.; Suzuki, A.; Iwasaki, N.

    2015-01-01

    Barium, boron and uranium element partitioning and oxygen and carbon isotope fractionation of high-Mg calcite skeletons of Octocorallia corals were investigated. The dissolved Ba concentration in seawater and the coral Ba/Ca ratio showed a clear positive correlation. The empirically derived barium partition coefficient is comparable to previous data for not only calcitic corals but also intermediate- to deep-water-dwelling scleractinian corals whose skeletons are composed of aragonite. Octocorallia corals are geologically important producers of biominerals, and they provide long-term records (up to hundreds of years) of environmental conditions in the deep ocean. Our data suggest that Ba/Ca ratios in Octocorallia corals may be a useful proxy for nutrients in intermediate and deep waters. The Ba/Ca ratio, a possible proxy for pH or carbonate ion concentration in seawater, showed the largest correlation with δ13C among the examined parameters. This result implies that the pH of the extracytoplasmic calcifying fluid (ECF) simultaneously influences δ18O, δ13C, and Ba/Ca by influencing the relative contributions of dissolved carbon sources in the ECF. Positive correlations of Ba/Ca with δ18 and δ13C suggest that δ18 and δ13C are enriched in light isotopes when conditions are less alkaline, suggesting a potential role of biological alkalinity pumping becomes more favorable with decreasing calcifying fluid pH. Substantial inter- and intra-specimen variations in Ba/Ca suggest that physicochemical factors do not exert a dominant systematic control on U incorporation.

  7. Surface structure analysis of BaSi2(100) epitaxial film grown on Si(111) using CAICISS

    NASA Astrophysics Data System (ADS)

    Okasaka, Shouta; Kubo, Osamu; Tamba, Daiki; Ohashi, Tomohiro; Tabata, Hiroshi; Katayama, Mitsuhiro

    2015-05-01

    Geometry and surface structure of a BaSi2(100) film on Si(111) formed by reactive deposition epitaxy (RDE) have been investigated using coaxial impact-collision ion scattering spectroscopy and atomic force microscopy. BaSi2(100) film can be grown only when the Ba deposition rate is sufficiently fast. It is revealed that a BaSi2(100) film grown at 600 °C has better crystallinity than a film grown at 750 °C owing to the mixture of planes other than (100) in the RDE process at higher temperatures. The azimuth angle dependence of the scattering intensity from Ba shows sixfold symmetry, indicating that the minimum height of surface steps on BaSi2(100) is half of the length of unit cell. By comparing the simulated azimuth angle dependences for more than ten surface models with experimental one, it is strongly indicated that the surface of a BaSi2(100) film grown on Si(111) is terminated by Si tetrahedra.

  8. Growth of BaSi2 film on Ge(100) by vacuum evaporation and its photoresponse properties

    NASA Astrophysics Data System (ADS)

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

    2017-05-01

    We have successfully grown a polycrystalline orthorhombic BaSi2 film on a Ge(100) substrate by an evaporation method. Deposition of an amorphous Si (a-Si) film on the Ge substrate prior to BaSi2 evaporation plays a critical role in obtaining a high-quality BaSi2 film. By controlling substrate temperature and the thickness of the a-Si film, a crack-free and single-phase polycrystalline orthorhombic BaSi2 film with a long carrier lifetime of 1.5 µs was obtained on Ge substrates. The photoresponse property of the ITO/BaSi2/Ge/Al structure was clearly observed, and photoresponsivity was found to increase with increasing substrate temperature during deposition of a-Si. Furthermore, the BaSi2 film grown on Ge showed a higher photoresponsivity than that grown on Si, indicating the potential application of evaporated BaSi2 on Ge to thin-film solar cells.

  9. 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.

  10. Optical properties of (50-X)BaO-X(YF2)-50P2O5 glasses

    NASA Astrophysics Data System (ADS)

    Narayanan, Manoj Kumar; Shashikala, H. D.

    2018-05-01

    Glasses with composition (50-X)BaO-X(YF2)-50P2O5 (Y - Ca, Ba, X = 0, 10, 20 mol%) were prepared using conventional melt-quenching technique. Optical parameters of prepared samples such as optical band gap energy increased, while Urbach energy and refractive index decreased with partial substitution of BaO with CaF2 or BaF2 in the glass batch.

  11. Allometric constraints on Sr/Ca and Ba/Ca partitioning in terrestrial mammalian trophic chains.

    PubMed

    Balter, Vincent

    2004-03-01

    In biological systems, strontium (Sr) and barium (Ba) are two non-essential elements, in comparison to calcium (Ca) which is essential. The Sr/Ca and Ba/Ca ratios tend to decrease in biochemical pathways which include Ca as an essential element, and these processes are termed biopurification of Ca. The quantitative pathway of the biopurification of Ca in relation to Sr and Ba between two biological reservoirs ( Rn and R(n -1)) is measured with an observed ratio (OR) expressed by the (Sr/Ca) Rn /(Sr/Ca)( Rn-1) and (Ba/Ca) Rn /(Ba/Ca)( Rn-1) ratios. For a mammalian organism, during the whole biopurification of Ca starting with the diet to the ultimate reservoir of Ca which is the bone, the mean values for ORSr and ORBa are 0.25 and 0.2, respectively. In this study, published Sr/Ca and Ba/Ca ratios are used for three sets of soils, plants, and bones of herbivorous and carnivorous mammals, each comprising a trophic chain, to illustrate the biopurification of Ca at the level of trophic chains. Calculated ORSr and ORBa of herbivore bones in relation to plants and of bones of carnivores in relation to bones of herbivores give ORSr=0.30+/-0.08 and ORBa=0.16+/-0.08, thus suggesting that trophic chains reflect the Sr/Ca and Ba/Ca fluxes that are prevalent at the level of a mammalian organism. The slopes of the three regression equations of log(Sr/Ca) vs. log(Ba/Ca) are similar, indicating that the process of biopurification of Ca with respect to Sr and Ba is due to biological processes and is independent of the geological settings. Modifications of the logarithmic expression of the Sr/Ca and Ba/Ca relationship allow a new formula of the biopurification process to be deduced, leading to the general equation ORBa=ORSr(1.79+/-0.33), where the allometric coefficient is the mean of the slopes of the three regression equations. Some recent examples are used to illustrate this new analysis of predator-prey relations between mammals. This opens up new possibilities for the

  12. Nonstoichiometric Solution-Processed BaTiO₃ Film for Gate Insulator Applications.

    PubMed

    Lau, Joyce; Kim, Sangsub; Kim, Hyunki; Koo, Kwangjun; Lee, Jaeseob; Kim, Sangsoo; Choi, Byoungdeog

    2018-09-01

    Solution processed barium titanate (BTO) was used to fabricate an Al/BaTiO3/p-Si metal-insulator-semiconductor (MIS) structure, which was used as a gate insulator. Changes in the electrical characteristics of the film were investigated as a function of the film thickness and post deposition annealing conditions. Our results showed that a thickness of 5 layers and an annealing temperature of 650 °C produced the highest electrical performance. BaxTi1-xO3 was altered at x = 0.10, 0.30, 0.50, 0.70, 0.90, and 1.0 to investigate changes in the electrical properties as a function of composition. The highest dielectric constant of 87 was obtained for x = 0.10, while the leakage current density was suppressed as Ba content increased. The lowest leakage current density was 1.34×10-10 A/cm2, which was observed at x = 0.90. The leakage current was related to the resistivity of the film, the interface states, and grain densification. Space charge limited current (SCLC) was the dominant leakage mechanism in BTO films based on leakage current analysis. Although a Ba content of x = 0.90 had the highest trap density, the traps were mainly composed of Ti-vacancies, which acted as strong electron traps and affected the film resistivity. A secondary phase, Ba2TiO4, which was observed in cases of excess Ba, acted as a grain refiner and provided faster densification of the film during the thermal process. The absence of a secondary phase in BaO (x = 1.0) led to the formation of many interface states and degradation in the electrical properties. Overall, the insulator properties of BTO were improved when the composition ratio was x = 0.90.

  13. Conduction Mechanisms in Multiferroic Multilayer BaTiO3/NiFe2O4/BaTiO3 Memristors

    NASA Astrophysics Data System (ADS)

    Samardzic, N.; Bajac, B.; Srdic, V. V.; Stojanovic, G. M.

    2017-10-01

    Memristive devices and materials are extensively studied as they offer diverse properties and applications in digital, analog and bio-inspired circuits. In this paper, we present an important class of memristors, multiferroic memristors, which are composed of multiferroic multilayer BaTiO3/NiFe2O4/BaTiO3 thin films, fabricated by a spin-coating deposition technique on platinized Si wafers. This cost-effective device shows symmetric and reproducible current-voltage characteristics for the actuating voltage amplitude of ±10 V. The origin of the conduction mechanism was investigated by measuring the electrical response in different voltage and temperature conditions. The results indicate the existence of two mechanisms: thermionic emission and Fowler-Nordheim tunnelling, which alternate with actuating voltage amplitude and operating temperature.

  14. 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.

  15. Two steps hydrothermal growth and characterisations of BaTiO3 films composed of nanowires

    NASA Astrophysics Data System (ADS)

    Zawawi, Che Zaheerah Najeehah Che Mohd; Salleh, Shahril; Oon Jew, Lee; Tufail Chaudhary, Kashif; Helmi, Mohamad; Safwan Aziz, Muhammad; Haider, Zuhaib; Ali, Jalil

    2018-05-01

    Barium titanate (BaTiO3) films composed of nanowires have gained considerable research interest due to their lead-free composition and strong energy conversion efficiency. BaTiO3 films can be developed with a simple two steps hydrothermal reactions, which are low cost effective. In this research, BaTiO3 films were fabricated on titanium foil through two steps hydrothermal method namely, the growth of TiO2 and followed by BaTiO3 films. The structural evolutions and the dielectric properties of the films were investigated as well. The structural evolutions of titanium dioxide (TiO2) and BaTiO3 nanowires were characterized using X-ray diffraction and scanning electron microscopy. First step of hydrothermal reaction, TiO2 nanowires were prepared in varied temperatures of 160 °C, 200 °C and 250 °C respectively. Second step of hydrothermal reaction was performed to produce a layer of BaTiO3 films.

  16. Dielectric and piezoelectric properties of hydroxyapatite-BaTiO3 composites

    NASA Astrophysics Data System (ADS)

    Bowen, C. R.; Gittings, J.; Turner, I. G.; Baxter, F.; Chaudhuri, J. B.

    2006-09-01

    This letter describes the relationships between the composition and the dielectric and piezoelectric properties of hydroxyapatite-barium titanate composites for polarized bone substitutes. The ac conductivity and permittivity were characterized from 0.1Hzto1MHz, along with measurements of the d33 piezoelectric charge coefficient. The addition of BaTiO3 led to an increase in permittivity and ac conductivity of the material. The increase in both properties was attributed to the presence of the high permittivity ferroelectric phase. The d33 and g33 coefficients decreased rapidly as hydroxyapatite was introduced into BaTiO3 material. Composites below 80% by volume of BaTiO3 exhibited no net piezoelectric effect.

  17. 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. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Mapping the involvement of BA 4a and 4p during Motor Imagery.

    PubMed

    Sharma, Nikhil; Jones, P S; Carpenter, T A; Baron, Jean-Claude

    2008-05-15

    Motor Imagery (MI) is an attractive but intriguing means to access the motor network. There are marked inconsistencies in the functional imaging literature regarding the degree, extent and distribution of the primary motor cortex (BA 4) involvement during MI as compared to Executed Movement (EM), which may in part be related to the diverse role of BA 4 and its two subdivisions (i.e., 4a and 4p) in motor processes as well as to methodological issues. Here we used fMRI with monitoring of compliance to show that in healthy volunteers optimally screened for their ability to perform MI the contralateral BA 4 is involved during MI of a finger opposition sequence (2, 3, 4, 5; paced at 1 Hz), albeit less than during EM of the same sequence, and in a location sparing the hand area. Furthermore, both 4a and 4p subdivisions were found to be involved in MI, but the relative involvement of BA 4p appeared more robust and closer to that seen with EM. We suggest that during MI the role of BA 4 and its subdivisions may be non-executive, perhaps related to spatial encoding, though clearly further studies are needed. Finally, we report a similar hemispheric activation balance within BA 4 with both tasks, which extends the commonalities between EM and MI.

  19. Surfactant-assisted synthesis of mono-dispersed cubic BaTiO{sub 3} nanoparticles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hai, Chunxi; Inukai, Koji; Takahashi, Yosuke

    2014-09-15

    Mono-dispersed BaTiO{sub 3} nanoparticles have been prepared via the assistance of capping agent poly(vinylpyrrolidone) (PVP). - Highlights: • BaTiO{sub 3} nanoparticles with single cubic crystal structure. • Poor dispersibility of nanoparticles has been overcome by in situ modification way. • Growth competition between BaTiO3 core and polymer shell. - Abstract: In this study, poly(vinylpyrrolidone)-assisted synthesis of mono-dispersed BaTiO{sub 3} nanoparticles have been reported. The various processing parameters, namely, refluxing temperature, KOH concentration, and poly(vinylpyrrolidone) concentration, have been varied, and the effects on the growth of BaTiO{sub 3} particles have been analyzed systematically. X-ray diffraction studies indicated that poly(vinylpyrrolidone) did notmore » affect the crystal structure, but rather influenced the crystal lattice structure. In addition, the use of surfactant poly(vinylpyrrolidone) hindered the agglomeration of the nanoparticles, and facilitated the formation of mono-dispersed core–shell organic/inorganic hybrid nanocomposite. Furthermore, the mineralizer KOH promoted the dissolution of reactants and promoted the crystallization of BaTiO{sub 3} particles. Accordingly, the dissolution-precipitation scheme was believed to be the mechanism underlying the formation of BaTiO{sub 3} particles. This was further substantiated by the experimental observations, which indicated that the nucleation and crystallization of the particles was affected by the KOH concentration in the reaction system. Finally, the formation of mono-dispersed core–shell nanocomposites proceeded via reaction limited cluster aggregation. We believe that the method proposed in this study could be extended for the synthesis of mono-dispersed nanoparticles for industrial applications.« less

  20. Sequential structural and antiferromagnetic transitions in BaFe2Se3 under pressure

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Lin, Ling-Fang; Zhang, Jun-Jie; Dagotto, Elbio; Dong, Shuai

    2018-01-01

    The discovery of superconductivity in the two-leg ladder compound BaFe2S3 has established the 123-type iron chalcogenides as a novel and interesting subgroup of the iron-based superconductor family. However, in this 123 series, BaFe2Se3 is an exceptional member, with a magnetic order and crystalline structure different from all others. Recently, an exciting experiment reported the emergence of superconductivity in BaFe2Se3 at high pressure [J. Ying et al., Phys. Rev. B 95, 241109(R) (2017), 10.1103/PhysRevB.95.241109]. In this paper, we report a first-principles study of BaFe2Se3 . Our analysis unveils a variety of qualitative differences between BaFe2S3 and BaFe2Se3 , including in the latter an unexpected chain of transitions with increasing pressure. First, by gradually reducing the tilting angle of iron ladders, the crystalline structure smoothly transforms from P n m a to C m c m at ˜6 GPa. Second, the system becomes metallic at 10.4 GPa. Third, its unique ambient-pressure Block antiferromagnetic ground state is replaced by the more common stripe (so-called CX-type) antiferromagnetic order at ˜12 GPa, the same magnetic state as the 123-S ladder. This transition is found at a pressure very similar to the experimental superconducting transition. Finally, all magnetic moments vanish at 30 GPa. This reported theoretical diagram of the complete phase evolution is important because of the technical challenges to capture many physical properties in high-pressure experiments. The information obtained in our calculations suggests different characteristics for superconductivity in BaFe2Se3 and BaFe2S3 : in 123-S pairing occurs when magnetic moments vanish, while in 123-Se the transition region from Block- to CX-type magnetism appears to catalyze superconductivity. Finally, an additional superconducting dome above ˜30 GPa is expected to occur.

  1. 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. Copyright © 2012 Wiley Periodicals, Inc.

  2. 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.

  3. High-pressure electrical resistivity studies for Ba1-xCsxFe2Se3

    NASA Astrophysics Data System (ADS)

    Kawashima, C.; Soeda, H.; Takahashi, H.; Hawai, T.; Nambu, Y.; Sato, T. J.; Hirata, Y.; Ohgushi, K.

    2017-10-01

    High-pressure electrical resistance measurements were performed for iron-based ladder material Ba1-xCsxFe2Se3 (x = 0.25 and 0.65) using a diamond anvil cell (DAC). Recent high-pressure study revealed that iron-based ladder material BaFe2S3 exhibits an insulator-metal transition and superconductivity, and this discovery would provide important insight for understanding the mechanism of iron-based superconductors. Therefore, it is intriguing to investigate the high-pressure properties for the iron-based ladder material Ba1-xCsxFe2Se3 system. The parent compounds BaFe2Se3 and CsFe2Se3 show insulating and magnetic ordering features. For Ba1-xCsxFe2Se3 system, no magnetic ordering is observed for x = 0.25 and minimum charge gap was estimated for x = 0.65. The insulator-metal transitions are observed in both materials.

  4. High-pressure electrical resistivity studies for Ba1-xCsxFe2Se3

    NASA Astrophysics Data System (ADS)

    Kawashima, C.; Soeda, H.; Takahashi, H.; Hawai, T.; Nambu, Y.; Sato, T. J.; Hirata, Y.; Ohgushi, K.

    2017-10-01

    High-pressure electrical resistance measurements were performed for iron-based ladder material Ba1-xCsxFe2Se3 (x = 0.25 and 0.65) using a diamond anvil cell (DAC). Recent high-pressure study revealed that iron-based ladder material BaFe2S3 exhibits an insulator- metal transition and superconductivity, and this discovery would provide important insight for understanding the mechanism of iron-based superconductors. Therefore, it is intriguing to investigate the high-pressure properties for the iron-based ladder material Ba1-xCsxFe2Se3 system. The parent compounds BaFe2Se3 and CsFe2Se3 show insulating and magnetic ordering features. For Ba1-xCsxFe2Se3 system, no magnetic ordering is observed for x = 0.25 and minimum charge gap was estimated for x = 0.65. The insulator-metal transitions are observed in both materials.

  5. Quantitative real-time monitoring of multi-elements in airborne particulates by direct introduction into an inductively coupled plasma mass spectrometer

    NASA Astrophysics Data System (ADS)

    Suzuki, Yoshinari; Sato, Hikaru; Hiyoshi, Katsuhiro; Furuta, Naoki

    2012-10-01

    A new calibration system for real-time determination of trace elements in airborne particulates was developed. Airborne particulates were directly introduced into an inductively coupled plasma mass spectrometer, and the concentrations of 15 trace elements were determined by means of an external calibration method. External standard solutions were nebulized by an ultrasonic nebulizer (USN) coupled with a desolvation system, and the resulting aerosol was introduced into the plasma. The efficiency of sample introduction via the USN was calculated by two methods: (1) the introduction of a Cr standard solution via the USN was compared with introduction of a Cr(CO)6 standard gas via a standard gas generator and (2) the aerosol generated by the USN was trapped on filters and then analyzed. The Cr introduction efficiencies obtained by the two methods were the same, and the introduction efficiencies of the other elements were equal to the introduction efficiency of Cr. Our results indicated that our calibration method for introduction efficiency worked well for the 15 elements (Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Mo, Sn, Sb, Ba, Tl and Pb). The real-time data and the filter-collection data agreed well for elements with low-melting oxides (V, Co, As, Mo, Sb, Tl, and Pb). In contrast, the real-time data were smaller than the filter-collection data for elements with high-melting oxides (Ti, Cr, Mn, Ni, Cu, Zn, Sn, and Ba). This result implies that the oxides of these 8 elements were not completely fused, vaporized, atomized, and ionized in the initial radiation zone of the inductively coupled plasma. However, quantitative real-time monitoring can be realized after correction for the element recoveries which can be calculated from the ratio of real-time data/filter-collection data.

  6. Insecticidal peptides from the theraposid spider Brachypelma albiceps: an NMR-based model of Ba2.

    PubMed

    Corzo, Gerardo; Bernard, Cedric; Clement, Herlinda; Villegas, Elba; Bosmans, Frank; Tytgat, Jan; Possani, Lourival D; Darbon, Herve; Alagón, Alejandro

    2009-08-01

    Soluble venom and purified fractions of the theraposid spider Brachypelma albiceps were screened for insecticidal peptides based on toxicity to crickets. Two insecticidal peptides, named Ba1 and Ba2, were obtained after the soluble venom was separated by high performance liquid chromatography and cation exchange chromatography. The two insecticidal peptides contain 39 amino acid residues and three disulfide bonds, and based on their amino acid sequence, they are highly identical to the insecticidal peptides from the theraposid spiders Aphonopelma sp. from the USA and Haplopelma huwenum from China indicating a relationship among these genera. Although Ba1 and Ba2 were not able to modify currents in insect and vertebrate cloned voltage-gated sodium ion channels, they have noteworthy insecticidal activities compared to classical arachnid insecticidal toxins indicating that they might target unknown receptors in insect species. The most abundant insecticidal peptide Ba2 was submitted to NMR spectroscopy to determine its 3-D structure; a remarkable characteristic of Ba2 is a cluster of basic residues, which might be important for receptor recognition.

  7. Electrical and magnetic properties of 0-3 Ba(Fe1/2Nb1/2)O3/PVDF composites

    NASA Astrophysics Data System (ADS)

    Ranjan, Hars; Mahto, Uttam K.; Chandra, K. P.; Kulkarni, A. R.; Prasad, A.; Prasad, K.

    Lead-free Ba(Fe1/2Nb1/2)O3/PVDF 0-3 composites were fabricated using melt-mixing technique. X-ray diffraction, scanning electron microscopy, dielectric, impedance, ac conductivity, magnetic force microscopy (MFM) and vibrating sample magnetometer studies were undertaken to characterize the samples. Average crystallite size of the Ba(Fe1/2Nb1/2)O3 powder, estimated using Williamson-Hall approach, was found to be ˜42nm. The filler particles of ˜0.5-1μm were found to disperse in the polymer matrix of all the composites. Filler concentration-dependent values of real and imaginary parts of complex permittivity showed increasing trend and were seen to follow Bruggeman and Furukawa equations. The data for ac conductivity exhibited negative temperature coefficient of resistance character of the test materials and were found to obey Jonscher’s power law. The correlated barrier hopping model was found to explain satisfactorily the mechanism of charge transport occurring in the system. MFM confirmed the presence of magnetic phases in the composites. Typical magnetization versus applied field curves indicated the possibility of magnetoelectric coupling in the system. Hence, the present composites have shown themselves as potential multi-functional candidate materials for use in high density data storage applications.

  8. BaSn 2 : A wide-gap strong topological insulator

    DOE PAGES

    Young, Steve M.; Manni, S.; Shao, Junping; ...

    2017-02-15

    BaSn 2 has been shown to form as layers of buckled stanene intercalated by barium ions. However, despite an apparently straightforward synthesis and significant interest in stanene as a topological material, BaSn 2 has been left largely unexplored, and has only recently been recognized as a potential topological insulator. Belonging to neither the lead nor bismuth chalcogenide families, it would represent a unique manifestation of the topological insulating phase. Here in this paper, we present a detailed investigation of BaSn 2, using both ab initio and experimental methods. First-principles calculations demonstrate that this overlooked material is indeed a strong, wide-gapmore » topological insulator with a bulk band gap of 200 meV. We characterize the surface state dependence on termination chemistry, providing guidance for experimental efforts to measure and manipulate its topological properties. Additionally, through ab initio modeling and synthesis experiments, we explore the stability and accessibility of this phase, revealing a complicated phase diagram that indicates a challenging path to obtaining single crystals.« less

  9. Structure, thermal and luminescence properties of Eu/Tb(BA)3phen/PAN fibers fabricated by electrospinning

    NASA Astrophysics Data System (ADS)

    Wang, Shiwei; Xie, Guangbo; Zhang, Jingjing; Zhang, Sen; Li, Tingju

    2018-04-01

    Novel high luminescence fibers often exhibit potential applications in the fields of color displays and sensor systems. In this study, Eu(BA)3phen and Tb(BA)3phen powders was successfully synthesized by solvothermal reactions, firstly. Then, three kinds of novel flexible Eu(BA)3phen/PAN, Tb(BA)3phen/PAN and Eu/Tb(BA)3phen/PAN (BA = benzoic acid, phen = phenanthroline, PAN = Polyacrylonitrile) fibers had been successfully prepared by electrospinning technology. The characterizations of the final products have been investigated in detail. It was found that the diameter of the as-prepared fibers were almost uniform with the fabricated complexes doping into PAN successfully. Thermogravimetric analysis indicates that the thermal stability of the pure PAN fiber could be improved by the incorporation of the complex, although only 1 wt % was added. Furthermore, in Eu/Tb(BA)3phen complex, the fluorescence intensity of Eu3+ ions was remarkably increased by adding Tb3+ ions. This is primarily due to an energy transfer from the 5D4 level of Tb (III) to the 5D0 level of Eu (III) ions, where Tb3+ acted as sensitizer. The corresponding luminescent fibers displayed the same regularity as the complexes. Moreover, with the increasing of the incorporation of complexes into PAN, the fluorescence intensities were significantly enhanced and reached its maximum value at 2.5 wt % for Eu(BA)3phen/PAN fibers and 2.0 wt% for Tb(BA)3phen/PAN fibers. The further intensity decreased with the increasing content of the complexes because of typical emission concentration quenching.

  10. 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.

  11. 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.

  12. Effect of the Cu/Ba ratio for the YBCO deposition onto IBAD template by the MOCVD method

    NASA Astrophysics Data System (ADS)

    Choi, J. K.; Kim, H. J.; Jun, B. H.; Kim, C. J.

    2005-10-01

    YBa2Cu3O7-x (YBCO) thin films were fabricated by the metal organic chemical vapor deposition (MOCVD) using a single liquid source. The copper/barium (Cu/Ba) ratio was varied from 1.26 to 1.38 to optimize the deposition condition. The IBAD template (CeO2/YSZ/stainless steel) was used as a substrate. The growth features of the YBCO films were not significantly influenced by the Cu/Ba ratio, while the superconducting transition temperature (Tc) and critical current (Ic) depended on the Cu/Ba ratio. When Cu/Ba ratio was between 1.26 and 1.29, Tc was as low as 80 K, while as Cu/Ba ratio increased to 1.38, it increased to above 85 K. The highest Tc (89.0 K) and Ic (46.3 A/cm-width) were achieved at the Cu/Ba ratio of 1.38 (Y:Ba:Cu = 1:2.1:2.9). It indicates that the optimum Cu/Ba ratio which differs from stoichiometric balance exists for the formation of the superconducting phase with a high Tc and Ic in MOCVD method.

  13. Significant increase of Curie temperature in nano-scale BaTiO{sub 3}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Yueliang; Liao, Zhenyu; Fang, Fang

    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 resultsmore » 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.« less

  14. PTCR characteristics and microstructure of porous (Ba,Sr)TiO3 ceramics prepared by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Lee, Ki-Ju; Tang, Dongxu; Park, K.; Cho, Won-Seung

    2010-02-01

    Porous Y-doped (Ba,Sr)TiO3 ceramics were prepared by the spark plasma sintering of (Ba,Sr)TiO3 powders with different amounts of carbon black, and by subsequently burning out the carbon black acting as a pore precursor. The microstructure, PTCR and gas-sensing characteristics for porous Y-doped (Ba,Sr)TiO3 ceramics were investigated. Spark plasma sintered (Ba,Sr)TiO3 ceramics revealed a very fine microstructure containing submicron-sized grains with a cubic phase and revealed an increased porosity after the carbon black was burned out. As a result of reoxidation treatment, the grain size of the (Ba,Sr)TiO3 ceramics increased to a few μm and the cubic phase transformed into a tetragonal phase. The phase transformation of (Ba,Sr)TiO3 ceramics was affected by grain size. The PTCR jump in the (Ba,Sr)TiO3 ceramics prepared by adding 40 vol.% carbon black showed an excellent value of 4.72 × 106, which was ten times higher than the PTCR jump in (Ba,Sr)TiO3 ceramics. The electrical resistivity of the porous (Ba,Sr)TiO3 ceramics was recovered as the atmosphere changed from a reducing gas (N2) to an oxidizing gas (O2) under consecutive heating and cooling cycles.

  15. 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)

  16. 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).

  17. Observation of extreme ultraviolet transitions in highly charged Ba{sup 16+} to Ba{sup 23+} ions with electron beam ion trap

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ali, S.; Shimizu, E.; Nakamura, N.

    2016-03-15

    We have investigated extreme ultraviolet emission from highly charged barium using a compact electron beam ion trap at the Tokyo EBIT laboratory. The spectra were recorded for several beam energies ranging from 440 to 740 eV, while keeping the electron beam current constant at 10 mA. Radiation from charge states Zr-like Ba{sup 16+} to As-like Ba{sup 23+} were recorded and identified by varying the electron beam energy across the ionization thresholds and comparing with calculated results. The calculations were performed with a detailed relativistic configuration interaction approach using the Flexible Atomic Code. Several new lines belonging to electric dipole transitions were observedmore » and identified.« less

  18. Magnetotransport of proton-irradiated BaFe 2As 2 and BaFe 1.985Co 0.015As 2 single crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moseley, D. A.; Yates, K. A.; Peng, N.

    2015-02-17

    In this paper, we study the magnetotransport properties of the ferropnictide crystals BaFe 2As 2 and BaFe 1.985Co 0.015As 2. 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 aremore » observed and discussed.« less

  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. Perovskite LaBaCo2O5+δ (LBCO) single-crystal thin films for pressure sensing applications

    NASA Astrophysics Data System (ADS)

    Ma, Y. J.; Xiao, J. Y.; Zhang, Q. Y.; Ma, C. Y.; Jiang, X. N.; Wu, B. Y.; Zeng, X. Y.

    2018-04-01

    Perovskite LaBaCo2O5+δ (LBCO) single-crystal films were deposited on (001) MgO substrates by a magnetron sputtering method and processed into Pirani sensors for investigation of pressure measurements. In comparison to the poly-crystal film deposited under the same condition, the single-crystal LBCO films exhibited rather a large temperature coefficient of resistance and a high sensitivity in response to pressure. The LBCO sensors with dimensions of 30 to 200 μm, which are different from resistor-on-dielectric membrane or micro-beam structures, demonstrated to be capable of making response to the pressures ranging from 5 × 10-2 to 105 Pa with a real dynamic range of 3 to 2 × 103 Pa.

  1. Magmatic evolution of lunar highland rocks estimated from trace elements in plagioclase: A new bulk silicate Moon model with sub-chondritic Ti/Ba, Sr/Ba, and Sr/Al ratios

    NASA Astrophysics Data System (ADS)

    Togashi, Shigeko; Kita, Noriko T.; Tomiya, Akihiko; Morishita, Yuichi

    2017-08-01

    The compositions of host magmas of ferroan anorthosites (FAN-host magmas) were estimated from secondary ion mass spectrometry analyses of plagioclase in lunar highland rocks. The evolution of the magmas was investigated by considering phase relations based on the MELTS algorithm and by re-examining partition coefficients for trace elements between plagioclase and melts. Data little affected by post-magmatic processes were selected by using plagioclase with relatively primitive Sc and Co contents. The FAN-host magma contained 90-174 ppm Sr, 40-119 ppm Ba and 0.5-1.3% TiO2, and had sub-chondritic Sr/Ba and Ti/Ba ratios. It is difficult to account for the formation of FAN-host magma on the basis of magma evolution processes of previously proposed bulk silicate Moon models with chondritic ratios for refractory elements at global scale. Therefore, the source of the FAN-host magma must have had primordial sub-chondritic Sr/Ba and Ti/Ba ratios. The FAN-host magmas were consistent in refractory elements with the estimated host mafic magma for feldspathic crust based on lunar meteorites, and some very-low-Ti mare rocks from lunar meteorites. Here, we propose an alternative bulk silicate Moon model (the cBSM model), which is enriched in crustal components of proto-bodies relative to the present whole Earth-Moon system.

  2. Study of the Mo-Ba partition in 252Cf spontaneous fission

    NASA Astrophysics Data System (ADS)

    Biswas, D. C.; Choudhury, R. K.; Cinausero, M.; Fornal, B.; Shetty, D. V.; Viesti, G.; Fabris, D.; Fioretto, E.; Lunardon, M.; Nebbia, G.; Prete, G.; Bazzacco, D.; DePoli, M.; Napoli, D. R.; Ur, C. A.; Vedovato, G.

    Measurements of fission fragment yields and neutron multiplicities have been carried out for the Mo-Ba fragment pairs in the spontaneous fission of 252Cf, using the γ-ray spectroscopy technique to analyze γ-γ-γ coincidence data. Prompt γ -ray multiplicities were also measured as a function of the number of neutrons emitted in the fission process leading to the Mo-Ba partition. We do not observe the enhancement in the yields of events with high neutron emission multiplicity (νn > 7) that has been associated to a second fission mode leading to the production of hyperdeformed Ba fragments, as reported in some earlier studies. The average γ-ray multiplicity is found to be rather weakly dependent on the number of neutrons emitted in the fission process.

  3. 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.

  4. Structural and magnetic properties and superconductivity in Ba(Fe 1-xTM x) 2As 2

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Thaler, Alexander

    2012-01-01

    We studied the effects on structural and magnetic phase transitions and the emergence of superconductivity in transition metal substituted BaFe 2As 2. We grew four series of Ba(Fe 1-xTM 2) 2As 2 (TM=Ru, Mn, Co+Cr and Co+Mn) and characterized them by crystallographic, magnetic and transport measurements. We also subjected Ba(Fe 1-xCr x) 2As 2 and Ba(Fe 1-xCo x) 2As 2 to heat treatment to explore what changes might be induced.

  5. 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

  6. Structure and Luminescence Properties of New Green-Emitting Phosphor BaAl12O19:Tb

    NASA Astrophysics Data System (ADS)

    Xiao, Linjiu; He, Mingrui; Tian, Yanwen; Chen, Yongjie; Karaki, Tomoaki; Zhang, Liqing; Wang, Ning

    2007-09-01

    New green-emitting BaAl12O19:Tb phosphors were prepared by using the sol-gel method, and their structure and luminescence property were characterized by X-ray diffraction (XRD) analysis and fluorescence spectrometry. The results of XRD analysis revealed that a Ba1-xAl12O19:Tbx crystal structure was obtained at 1300 °C and Tb3+ ions substituted Ba2+ ions into the BaAl12O19 phase in the ion range x=0.005--0.05. The excitation peak of BaAl12O19:Tb was a wide band at approximately 240 nm, originating from the 4 f8-4 f75d1 transition of Tb3+. The emission spectrum consisted of eight emission peaks, originating from the 5D3-7Fi (i=6,5,4,3) and 5D4-7Fj ( j=6,5,4,3) transitions of Tb3+. The emission intensity of BaAl12O19:Tb phosphors at 543 nm was strongest when the phosphors were crystallized at 1300 °C for 2 h, and the content of Tb3+ was 2 mol %.

  7. Synthesis, structural, characterization and dielectric spectroscopy of PVDF - BaTiO3 polymer composite

    NASA Astrophysics Data System (ADS)

    Kulkarni, S. S.; Belavi, P. B.; Khadke, U. V.

    2018-05-01

    In this paper we report the method of synthesis of ferroelectric polymer Polyvinyldene fluoride (PVDF) and Barium Titanate (BaTiO3) composite self supporting thin films and its dielectric response. BaTiO3 was synthesized by solid state reaction method. The PVDF - BaTiO3 polymer composites with various concentrations were synthesized by solution mixing method using Dimethylformadide (DMF) as a solvent. The phase transformation and surface methodology of the prepared composites were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) respectively. The XRD pattern confirms the formation of tetragonal pervoskite structure of ferroelectric phase. The XRD pattern shows the proper mixing of BaTiO3 particles intestinally and found to be improving its crystallinity with increase of BaTiO3 composition in the PVDF matrix. The dielectric properties of the composites as a function of frequency were computed using impedance analyzer. The dielectric constant decreases with increase of frequency shows the Maxwell - Wagner type of interfacial polarization in accordance with Koop's phenomenological theory.

  8. Molten Salt Synthesis and Structural Characterization of BaTiO3 Nanocrystal Ceramics

    NASA Astrophysics Data System (ADS)

    Ahda, S.; Misfadhila, S.; Parikin, P.; Putra, T. Y. S. P.

    2017-02-01

    A new synthesis route to obtain high-purity barium titanate powder, BaTiO3, using the molten salt method by reacting the raw materials (BaCO3 and TiO2) in an atmosphere of molten NaCl and KCl, has been developed. The synthesized BaTiO3 ceramic particles have been successfully carried out at the sintering temperature 950°C for 4 hours. The Rietveld refinement of the XRD diffraction patterns was employed to characterize the structural information of the nanocrystalline BaTiO3 ceramics. The lattice parameters (a=4.0043 Å, b=4.0308Å with space group P4mm) of tetragonal perovskite structure, as an indication of piezoelectric characteristics, have been successfully determined by the Rietveld refinement. While the crystallitte particle size and strains have been obtained for the values of 110.6 nm and 0.74 % respectively

  9. Crystal structure and chemical bonding in the mixed anion compound BaSF.

    PubMed

    Driss, D; Cadars, S; Deniard, P; Mevellec, J-Y; Corraze, B; Janod, E; Cario, L

    2017-11-28

    BaSF was synthesised by a solid state reaction at high temperature and its crystal structure was determined thanks to X-ray diffraction on a single crystal. This transparent yellow fluorochalcogenide has an intergrowth structure built from the stacking of fluorite type layers and sulfur layers. In BaSF sulfur atoms form dimers with interatomic distances as short as 2.1074(10) Å. DFT calculations confirm that this compound is a band insulator with the Fermi level lying in between the antibonding π* and σ* molecular orbitals of the sulfur dimers. Reflectance measurements show that the optical band gap of BaSF is about 2.7 eV in good agreement with the value found from DFT calculations.

  10. 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.

  11. Performances of RPCs in the BaBar experiment

    NASA Astrophysics Data System (ADS)

    Anulli, F.; Baldini, R.; Band, H.; Bionta, R.; Brau, J.; Brigljevic, V.; Buzzo, A.; Calcaterra, A.; Carpinelli, M.; Cartaro, T.; Cavallo, N.; Crosetti, G.; De Nardo, G.; De Sangro, R.; Eichenbaum, A.; Falciai, D.; Fabozzi, F.; Ferroni, F.; Finocchiaro, G.; Forti, F.; Frey, R.; Johnson, J.; Gatto, C.; Grauges-Pous, E.; Iwasaki, M.; Lange, D.; Lista, L.; Lo Vetere, M.; Lu, C.; Neal, H.; Neri, N.; Macri, M.; Messener, B.; Monge, M. R.; Moore, T.; Morganti, S.; Palano, A.; Paoloni, E.; Paolucci, P.; Passaggio, S.; Pastore, F.; Patrignani, C.; Patteri, P.; Peruzzi, I.; Piccolo, D.; Piccolo, M.; Piredda, G.; Pompili, A.; Robutti, E.; Roodman, A.; Santroni, A.; Sciacca, C.; Sinev, N.; Soha, A.; Storm, D.; Tosi, S.; Va'vra, J.; Xie, Y.; Wright, D.; Wisniewski, W.

    2003-12-01

    The BaBar experiment uses a big system based on RPC detectors to discriminate muons from pions and to identify neutral hadrons. About 2000 m2 of RPC chambers have been working at SLAC since the end of 1998. We report on the performances of the RPC chambers focusing on new problems discovered in the RPC behaviour. These problems started very soon after the installation of the chambers on the detector when the high-ambient temperature triggered an increase of dark currents inside the chambers and a reduction of the efficiency. Careful analysis of the BaBar data and dedicated R&D efforts in the laboratory have helped to identify the main source of the trouble in the linseed oil varnish on the bakelite electrodes.

  12. Structural, morphological and Raman studies on hybridized PVDF/BaTiO3 nanocomposites

    NASA Astrophysics Data System (ADS)

    Rajamanickam, N.; Jayakumar, K.; Ramachandran, K.

    2017-05-01

    Hybridized nanocomposites of polyvinylidene fluoride (PVDF) and nano - barium titanate (BaTiO3) were prepared using the solution casting method for different concentrations of nano-BaTiO3 and were characterized by X-ray diffraction and scanning electron microscopy. The flower like structure for morphology was observed in SEM. Raman analysis showed that the modified BaTiO3 particles, due to higher specific surfaces, induce, predominantly, the crystallization of the electrically active β-phase of PVDF, while the initial micron size particles induce the formation of the most common but non-polar α-crystal form.

  13. Inter-atomic force constants of BaF{sub 2} by diffuse neutron scattering measurement

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sakuma, Takashi, E-mail: sakuma@mx.ibaraki.ac.jp; Makhsun,; Sakai, Ryutaro

    2015-04-16

    Diffuse neutron scattering measurement on BaF{sub 2} crystals was performed at 10 K and 295 K. Oscillatory form in the diffuse scattering intensity of BaF{sub 2} was observed at 295 K. The correlation effects among thermal displacements of F-F atoms were obtained from the analysis of oscillatory diffuse scattering intensity. The force constants among neighboring atoms in BaF{sub 2} were determined and compared to those in ionic crystals and semiconductors.

  14. [Research on the degradation of BaP with potassium ferrate characterized by fluorescence].

    PubMed

    Chen, Yu-Zhe; He, Qiang; Yu, Dan-Ni; Li, Si; Tan, Xue-Mei

    2012-07-01

    The degradation of Benzo(a)pyrene (BaP) by potassium ferrate was researched by means of multiple fluorescence spectroscopic methods such as synchronous, time-scan, excitation emission matrix (EEM) and photometry, under the optimal condition. Within the degradation process, the characteristics of the BaP's concentration at different time-intervals, and the kinetics of the degradation of BaP by potassium ferrate were discussed. From the experimental data, both synchronous and EEM spectra's results showed that the concentration of BaP was reduced 90% by potassium ferrate within 20 s after degradation, and the reaction process was very slow after 60 s. The degradation kinetic equation, ln(F0/Ft) = 0.563 2t + 0.171 2, (R2 = 0.994 2), was obtained through a convenient and fast way combining the time-scan fluorescence data and photometry data, and the photometry included the synchronous photometry and emission photometry. According to the kinetic equation, the degradation of BaP by potassium ferrate was in accord with the order of the first order reaction. So this article could provide a very useful conference for the research on the pollutant degradation by potassium ferrate, especially for the degradation process and the degradation mechanisms.

  15. (Mis)use of (133)Ba as a calibration surrogate for (131)I in clinical activity calibrators.

    PubMed

    Zimmerman, B E; Bergeron, D E

    2016-03-01

    Using NIST-calibrated solutions of (131)Ba and (131)I in the 5mL NIST ampoule geometry, measurements were made in three NIST-maintained Capintec activity calibrators and the NIST Vinten 671 ionization chamber to evaluate the suitability of using (133)Ba as a calibration surrogate for (131)I. For the Capintec calibrators, the (133)Ba response was a factor of about 300% higher than that of the same amount of (131)I. For the Vinten 671, the Ba-133 response was about 7% higher than that of (131)I. These results demonstrate that (133)Ba is a poor surrogate for (131)I. New calibration factors for these radionuclides in the ampoule geometry for the Vinten 671 and Capintec activity calibrators were also determined. Published by Elsevier Ltd.

  16. Physical and magnetic properties of (Ba/Sr) substituted magnesium nano ferrites

    NASA Astrophysics Data System (ADS)

    Ateia, Ebtesam E.; Takla, E.; Mohamed, Amira T.

    2017-10-01

    In the presented paper, strontium (Sr) and barium (Ba) nano ferrites were synthesized by citrate auto combustion method. The investigated samples are characterized by X-ray diffraction technique (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. The structural properties of the obtained samples were examined by XRD analysis showing that the synthesized nanoparticles are in cubic spinel structure. The average crystallite sizes are in the range of 22.66 and 21.95 nm for Mg0.7Ba0.3Fe2O4 and Mg0.7 Sr0.3Fe2O4 respectively. The VSM analysis confirms the existence of ferromagnetic nature of Sr2+/Ba2+ substituted magnesium nano particles. Exchange interaction between hard (Sr/Ba) and soft (Mg) magnetic phases improves the structural and magnetic properties of nano ferrite particles. Rigidity modulus, longitudinal and shear wave velocities are predicted theoretically from Raman spectroscopy and structural data of the investigated spinel ferrite. The magnetic and structural properties of magnesium are enhanced by doping with barium and strontium nano particles. The saturation magnetization, remanent magnetization and coercivity reported on vibrating sample magnetometer curve illustrate the promising industrial and magnetic recording applications of the prepared samples.

  17. Computational study of Ca, Sr and Ba under pressure

    NASA Astrophysics Data System (ADS)

    Jona, F.; Marcus, P. M.

    2006-05-01

    A first-principles procedure for the calculation of equilibrium properties of crystals under hydrostatic pressure is applied to Ca, Sr and Ba. The procedure is based on minimizing the Gibbs free energy G (at zero temperature) with respect to the structure at a given pressure p, and hence does not require the equation of state to fix the pressure. The calculated lattice constants of Ca, Sr and Ba are shown to be generally closer to measured values than previous calculations using other procedures. In particular for Ba, where careful and extensive pressure data are available, the calculated lattice parameters fit measurements to about 1% in three different phases, both cubic and hexagonal. Rigid-lattice transition pressures between phases which come directly from the crossing of G(p) curves are not close to measured transition pressures. One reason is the need to include zero-point energy (ZPE) of vibration in G. The ZPE of cubic phases is calculated with a generalized Debye approximation and applied to Ca and Sr, where it produces significant shifts in transition pressures. An extensive tabulation is given of structural parameters and elastic constants from the literature, including both theoretical and experimental results.

  18. Compton scattering studies and electronic properties of BaTiO3

    NASA Astrophysics Data System (ADS)

    Meena, Seema Kumari; Bapna, Komal; Heda, N. L.; Ahuja, B. L.

    2018-04-01

    We present the experimental momentum density of BaTiO3 measured using 20 Ci 137Cs Compton spectrometer. The experimental Compton profile (CP) has been compared with the linear combination of atomic orbitals (LCAO) based theoretical profiles for various exchange-correlation potentials. It is found that LCAO-B3PW based CP gives a better agreement with experiment than other theoretical profiles. We have also deduced the energy bands and density of states (DOS) for BaTiO3 using LCAO-B3PW scheme. The energy bands and DOS suggest an indirect band gap in the system arising due to O-2p states of valence band and Ti-3d states of conduction band. Peculiar electronic response of this system is found to be mainly due to hybridized states of Ba-5p/5s and O-2p orbitals.

  19. A combined ultra-wideline solid-state NMR and DFT study of 137Ba electric field gradient tensors in barium compounds

    NASA Astrophysics Data System (ADS)

    O'Dell, Luke A.; Moudrakovski, Igor L.

    2013-04-01

    Ultra-wideline 137Ba solid-state (SS) NMR spectra have been obtained from a series of five barium compounds (BaSO4, BaMoO4, Ba(CH3COO)2, Ba(OH)2·8H2O and α-Ba2P2O7), using the broadband WURST-QCPMG pulse sequence and magnetic field of 21.1 T. The signals from the two distinct crystallographic sites in α-Ba2P2O7 are resolved, with one of them demonstrating a CQ of 42.3 ± 0.3 MHz, the largest obtained for 137Ba in a powder. The quadrupolar parameters reported in this work are in excellent agreement with the DFT calculations and correlate well with those previously reported by Hamaed et al. (2010) [24].

  20. Terahertz dielectric response of ferroelectric Ba(x)Sr(1-x)TiO3 thin films.

    PubMed

    Kang, Seung Beom; Kwak, Min Hwan; Choi, Muhan; Kim, Sungil; Kim, Taeyong; Cha, Eun Jong; Kang, Kwang Yong

    2011-11-01

    Terahertz time-domain spectroscopy has been used to investigate the dielectric and optical properties of ferroelectric Ba(x)Sr(1-x)TiO(3) thin films for nominal x-values of 0.4, 0.6, and 0.8 in the frequency range of 0.3 to 2.5 THz. The ferroelectric thin films were deposited at approximately 700 nm thickness on [001] MgO substrate by pulsed laser deposition. The measured complex dielectric and optical constants were compared with the Cole-Cole relaxation model. The results show that the Cole-Cole relaxation model fits well with the data throughout the frequency range and the dielectric relaxation behavior of ferroelectric Ba(x)Sr(1-x)TiO(3) thin films varies with the films compositions. Among the compositions of Ba(x)Sr(1-x)TiO(3) films with different Ba/Sr ratios, Ba(0.6)Sr(0.4)TiO(3) has the highest dielectric constants and the shortest dielectric relaxation time.

  1. Surface reconstruction switching induced by tensile stress of DB steps: From Ba/Si(0 0 1)- 2 × 3 to Ba/Si(0 0 1)-4° off- 3 × 2

    NASA Astrophysics Data System (ADS)

    Kim, Hidong; Lkhagvasuren, Altaibaatar; Zhang, Rui; Seo, Jae M.

    2018-05-01

    The alkaline-earth metal adsorption on Si(0 0 1) has attracted much interest for finding a proper template in the growth of high- κ and crystalline films. Up to now on the flat Si(0 0 1) surface with double domains and single-layer steps, the adsorbed Ba atoms are known to induce the 2 × 3 structure through removing two Si dimers and adding a Ba atom per unit cell in each domain. In the present investigation, the Si(0 0 1)-4° off surface with DB steps and single domains has been employed as a substrate and the reconstruction at the initial stage of Ba adsorption has been investigated by scanning tunneling microscopy and synchrotron photoemission spectroscopy. On this vicinal and single domain terrace, a novel 3 × 2 structure rotated by 90° from the 2 × 3 structure has been found. Such a 3 × 2 structure turns out to be formed by adding a Ba atom and a Si dimer per unit cell. This results from the fact that the adsorbed Ba2+ ions with a larger ionic radius relieve tensile stress on the original Si dimers exerted by the rebonded atoms at the DB step.

  2. Optical properties of BaO added bioactive Na2O-CaO-P2O5 glasses

    NASA Astrophysics Data System (ADS)

    Edathazhe, Akhila B.; Shashikala, H. D.

    2018-04-01

    This paper deals with the effect of BaO addition on the optical properties of bioactive Na2O-CaO-P2O5 glasses for biomedical optics applications. The phosphate glasses with composition (26-x)Na2O-xBaO-29CaO-45P2O5 (x = 0, 5, 10, 15 mol%) have been prepared by melt-quenching technique at 1100°C. The refractive index of glasses increased with BaO content. The optical band gap and Urbach energy of synthesized glasses were derived from the optical absorption spectra by using UV-Visible spectrometer. The addition of 5 mol% of BaO increased the band gap energy of glasses due to the formation of ionic cross-links in the glass structure. The defect and interstitial bonds formation in theglasses decreased with BaO additions as indicated by reductions in the Urbach energy values. No such variations in the band gap and Urbach energy values of glasses were observed with BaO content from 5 to 15 mol%. The molar and oxide ion polarizability values were calculated from the band gap and molar volume of glasses. The increase in the calculated optical basicity and metallization criteria of glasses supported the rise in band gap energy values with BaO additions. As the melting temperature of glasses decreased from 1200 to 1100°C, the refractive index increased as supported by the measured density values. The band gap energy is not changed with melting temperature. The Urbach energy decreased with decrease in melting temperature in case of BaO-free Na2O-CaO-P2O5 glasses, whereas it increased in case of BaO added glasses due to the role of BaO as modifying oxide.

  3. 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.

  4. Feeding dynamics and ecomorphology of Oligosarcus jenynsii (Gunther, 1864) and Oligosarcus robustus (Menezes, 1969) in the Lagoa Fortaleza, southern Brazil.

    PubMed

    Nunes, D M; Hartz, S M

    2006-02-01

    Oligosarcus jenynsii and Oligosarcus robustus are fishes of Characidae family that occur in Rio Grande do Sul, Uruguay and northern Argentina. This work purported to study the feeding dynamics (repletion and hepatosomatic indexes and condition factor) over time, and to investigate the coexistence of these two species by evaluating the partition of resources using qualitative and quantitative analyses of diet, temporal and spatial segregation throughout the water column and some ecomorphological aspects of the species in the Lagoa Fortaleza. Specimens were sampled monthly, from May 2000 to April 2001 during 24 h/month, using stationary gill nets of different mesh sizes. The records of each individual included total and standard length; total, stomach and liver weight; sex and stomach repletion. The variation of the mean values of repletion index and relative frequencies of stomach repletion stages indicate that O. jenynsii and O. robustus do not present seasonal differences in feeding intensity. The hepatosomatic index shows an allocation of energy to the liver during every period except reproduction, when part of the energy is used for gonad maturation. The estimated condition factor for both species reveals an increase in the reproductive period, evidencing the influence of gonads upon the condition of the fish. The diet analysis revealed that O. robustus is piscivorous, whereas O. jenynsii is a generalist carnivore, tending to piscivory as well. The active period of O. robustus is more concentrated at sunrise and sunset, whereas O. jenynsii is continually active, a characteristic related to hunting for prey. The ecomorphological analysis revealed differences between the two species in the dimensions of the mouth. Evidence suggests that the species coexist, sharing food sources, differing in oral morphology but ingesting similar prey, possibly because food is not a limiting factor in the environment.

  5. The Scale Formation of Barite (BaSO4) from Laminar Flowing Water in The Presence of Tartaric Acid and Ba2+ Concentration Variation of Solution

    NASA Astrophysics Data System (ADS)

    Fatra, F.; Ivanto, G.; Dera, N. S.; Muryanto, S.; Bayuseno, A. P.

    2017-05-01

    The barite (BaSO4) scale is a mineral deposit that can be precipitated during the process of drilling oil and gas in the offshore. Deposite scale in pipes can cause a narrowing of the diameter of pipes, and can reduce water flowing in the pipe. The aim of this study is to investigation the effect of the tartaric acid additive and Ba2+ concentration on the growth o the scale formation of barite in the laminar flow of the piping system. Solution forming barite crystal was prepared by mixing equimolar solutions of barium chloride (BaCl2) and sodium sulfate (Na2SO4) with concentration variations of Ba2+ of 3000, 3500, 4000, 4500, and 5000 ppm. The flow rate of solution is 40 ml/min at temperature of 50 °C. Various concentrations of tartaric acid (C4H6O6) of 0 ppm, 5 ppm and 10 ppm were added to the solutions. The formation of barite from the solution was observed by ion conductivity measurement. The obtained barite crystals before and after adding tartaric acid were dried and characterized by using SEM/EDX for morphology and elemental analysis, and XRD for phase identification. The SEM results show that the morphology of the crystals are star-like particles, while XRD analysis confirmed that the barite crystals were produced during the experiments are high purity. Moreover, the tartaric acid can inhibit the crystal growth of barite.

  6. Optical plasma monitoring of Y-Ba-Cu-O rf sputter target transients

    NASA Astrophysics Data System (ADS)

    Klein, J. D.; Yen, A.

    1989-12-01

    The plasma emission spectra resulting from rf sputtering Y-Ba-Cu-O targets were observed as a function of sputter time. Although most lines of the observed spectra are not attributable to target species, peaks associated with each of the cation elements were resolved. The Ba and Cu peaks can be used as tracking indicators of process conditions. For example, switching from an O2/Ar sputter atmosphere to pure Ar enhanced the Ba peak much more than that associated with Cu. The emission spectra from a newly fabricated target exhibited a slow first-order transient response in seeking equilibrium with the rf plasma. The transient response of a previously sputtered target is also first order but has a much shorter time constant.

  7. Improved synthesis of ceramic superconductors with alkaline earth peroxides - Synthesis and processing of Ba2YCu3O(7-x)

    NASA Technical Reports Server (NTRS)

    Hepp, A. F.; Gaier, J. R.; Philipp, W. H.; Warner, J. D.; Aron, P. R.; Pouch, J. J.

    1988-01-01

    Synthesis processes for the preparation of ceramic conductors Ba2YCu3O(7-x) from BaO2 or BaCO3 in flowing O2 or N2 are described, and the characteristics of the materials produced in these processes are compared. Results of EDAX, XRD, SEM, and dc resistivity analyses demonstrated that superconducting materials made from BaO2 were more homogeneous, denser, and more metallic than materials produced from BaCO3, because of the higher reactivity of BaO2. Potential applications of this processes are discussed.

  8. The magnetic properties of BaCo0.5Ni0.5F4

    NASA Astrophysics Data System (ADS)

    Xu, Qingyu; Dai, Chuanjun; Han, Zhida; Li, Qi

    2018-05-01

    The family of BaMF4 with M of magnetic 3d transition metal ions is the typical multiferroic material. Pure phase solid solution of BaCoF4 and BaNiF4 with molar ratio of 1:1 (BaCo0.5Ni0.5F4) is prepared by solid state reaction, which has been confirmed by X ray diffraction patterns. Field dependent magnetization measurements only show the linear curve with temperature down to 5 K, indicating the antiferromagnetic nature. Compared with BaCoF4 and BaNiF4, no significant enhancement of magnetization is observed, indicating the absence of ferrimagnetism and the random distribution of Co and Ni ions. The low temperature magnetic anomalies are studied by zero field cooled (ZFC) and field cooled (FC) temperature dependent magnetization (M-T) measurements. A bifurcation between FC and ZFC M-T curves happens at 118 K, indicating the onset of 2-dimensional antiferromagnetism. The magnetization maximum at 87 K is attributed to the 2-dimensional antiferromagnetic clusters, followed by the drastic decrease of magnetization, which is due to the onset of 3-dimensional antiferromagnetism. A dip is observed in FC M-T curve at 40 K, which is attributed to the 3-dimensional antiferromagnetic clusters. A drastic increase of magnetization is observed at 9 K, which is due to the uncompensated isolated spins. Exchange bias is clearly observed, with blocking temperature of 90 K. The contribution from surface spin glass has been excluded by the AC magnetization measurements, and the mechanism has been explained by the exchange coupling between the two antiferromagnetic phases.

  9. Radioluminescence as a function of temperature and low temperature thermoluminescence of BaY2F8:Ce and BaY2F8:Nd crystals

    NASA Astrophysics Data System (ADS)

    Kowalski, Z.; Kaczmarek, S. M.; Brylew, K.; Drozdowski, W.

    2016-09-01

    Radioluminescence spectra at temperatures ranging from 10 to 320 K and low temperature thermoluminescence glow curves of BaY2F8:Ce and BaY2F8:Nd scintillator crystals have been investigated. In both materials the intensities of the excitonic and the activator ion's emission at X-ray excitation vary with temperature, anticorrelating with each other, which provides valuable information on the host-to-ion energy transfer. Detailed thermoluminescence studies, in turn, prove the existence of charge traps, which introduce quasi-continuous distributions of energy levels into the bandgap.

  10. Thermodynamic properties of Ba{sub 1-x}La{sub x}CoO{sub 3}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gaur, N. K., E-mail: srl-nkgaur@yahoo.co.in; Thakur, Rasna, E-mail: rasnathakur@yahoo.com; Thakur, Rajesh K., E-mail: thakur.rajesh2009@gmail.com

    2016-05-06

    We have predicted the thermodynamic behavior of Ba{sub 1-x}La{sub x}CoO{sub 3} family at temperature 1K≤T≤300K using the Modified Rigid Ion Model (MRIM). The specific heat of BaCoO{sub 3} with La doping in the perovskite structure at A-site has been reported. Also, the cohesive energy (ϕ), molecular force constant (f), Reststrahlen frequency (υ), Debye temperature (θ{sub D}), specific heat (C) and Gruneisen parameter (γ) of Ba{sub 1-x}La{sub x}CoO{sub 3} compounds are discussed.

  11. BaTiO3-based piezoelectrics: Fundamentals, current status, and perspectives

    NASA Astrophysics Data System (ADS)

    Acosta, M.; Novak, N.; Rojas, V.; Patel, S.; Vaish, R.; Koruza, J.; Rossetti, G. A.; Rödel, J.

    2017-12-01

    We present a critical review that encompasses the fundamentals and state-of-the-art knowledge of barium titanate-based piezoelectrics. First, the essential crystallography, thermodynamic relations, and concepts necessary to understand piezoelectricity and ferroelectricity in barium titanate are discussed. Strategies to optimize piezoelectric properties through microstructure control and chemical modification are also introduced. Thereafter, we systematically review the synthesis, microstructure, and phase diagrams of barium titanate-based piezoelectrics and provide a detailed compilation of their functional and mechanical properties. The most salient materials treated include the (Ba,Ca)(Zr,Ti)O3, (Ba,Ca)(Sn,Ti)O3, and (Ba,Ca)(Hf,Ti)O3 solid solution systems. The technological relevance of barium titanate-based piezoelectrics is also discussed and some potential market indicators are outlined. Finally, perspectives on productive lines of future research and promising areas for the applications of these materials are presented.

  12. Device characteristics of organic light-emitting diodes based on electronic structure of the Ba-doped Alq3 layer.

    PubMed

    Lim, Jong Tae; Kim, Kyung Nam; Yeom, Geun Young

    2009-12-01

    Organic light-emitting diodes (OLEDs) with a Ba-doped tris(8-quinolinolato)aluminum(III) (Alq3) layer were fabricated to reduce the barrier height for electron injection and to improve the electron conductivity. In the OLED consisting of glass/ITO/4,4',4"-tris[2-naphthylphenyl-1-phenylamino]triphenylamine (2-TNATA, 30 nm)/4,4'-bis[N-(1-napthyl)-N-phenyl-amino]-biphenyl (NPB, 18 nm)/Alq3 (42 nm)/Ba-doped Alq3 (20 nm, x%: x = 0, 10, 25, and 50)/Al (100 nm), the device with the Alq3 layer doped with 10% Ba showed the highest light out-coupling characteristic. However, as the Ba dopant concentration was increased from 25% to 50%, this device characteristic was largely reduced. The characteristics of these devices were interpreted on the basis of the chemical reaction between Ba and Alq3 and the electron injection property by analyzing the electronic structure of the Ba-doped Alq3 layer. At a low Ba doping of 10%, mainly the Alq3 radical anion species was formed. In addition, the barrier height for electron injection in this layer was decreased to 0.6 eV, when compared to the pristine Alq3 layer. At a high Ba doping of 50%, the Alq3 molecules were severely decomposed. When the Ba dopant concentration was changed, the light-emitting characteristics of the devices were well coincided with the formation mechanism of Alq3 radical anion and Alq3 decomposition species.

  13. Ba9V3Se15: a novel compound with spin chains

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Liu, Min; Wang, Xiancheng; Zhao, Kan; Duan, Lei; Li, Wenmin; Zhao, Jianfa; Cao, Lipeng; Dai, Guangyang; Deng, Zheng; Feng, Shaomin; Zhang, Sijia; Liu, Qingqing; Yang, Yi-feng; Jin, Changqing

    2018-05-01

    In this work, a novel compound Ba9V3Se15 with one-dimensional (1D) spin chains was synthesized under high-pressure and high-temperature conditions. It was systematically characterized via structural, magnetic, thermodynamic and transport measurements. Ba9V3Se15 crystallizes into a hexagonal structure with a space group of P-6c2 (188) and the lattice constants of a  =  b  =  9.5745(7) Å and c  =  18.7814(4) Å. The crystal structure consists of face-sharing octahedral VSe6 chains along c axis, which are trimeric and arranged in a triangular lattice in ab-plane. Ba9V3Se15 is a semiconductor and undergoes complex magnetic transitions. In the zero-field-cooled (ZFC) process with magnetic field of 10 Oe, Ba9V3Se15 sequentially undergoes ferrimagnetic and spin cluster glass transition at 2.5 K and 3.3 K, respectively. When the magnetic field exceeds 50 Oe, only the ferrimagnetic transition can be observed. Above the transition temperature, the specific heat contains a significant magnetic contribution that is proportional to T 1/2. The calculation suggests that the nearest neighbor (NN) intra-chain antiferromagnetic exchange J 1 is much larger than the next nearest neighbor (NNN) intra-chain ferromagnetic exchange J 2. Therefore, Ba9V3Se15 can be regarded as an effective ferromagnetic chains with effective spin-1/2 by the formation of the V(2)(↓) V(1)(↑) V(2)(↓) cluster.

  14. Structural characterization of a new vacancy ordered perovskite modification found for Ba{sub 3}Fe{sub 3}O{sub 7}F (BaFeO{sub 2.333}F{sub 0.333}): Towards understanding of vacancy ordering for different perovskite-type ferrites

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Clemens, Oliver, E-mail: oliver.clemens@kit.edu; Karlsruher Institut für Technologie, Institut für Nanotechnologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen

    2015-05-15

    The new vacancy ordered perovskite-type compound Ba{sub 3}Fe{sub 3}O{sub 7}F (BaFeO{sub 2.33}F{sub 0.33}) was prepared by topochemical low-temperature fluorination of Ba{sub 2}Fe{sub 2}O{sub 5} (BaFeO{sub 2.5}) using stoichiometric amounts of polyvinylidene difluoride (PVDF). The vacancy order was found to be unique so far for perovskite compounds, and the connectivity pattern can be explained by the formula Ba{sub 3}(FeX{sub 6/2}) (FeX{sub 5/2}) (FeX{sub 3/2}X{sub 1/1}), with X=O/F. Mössbauer measurements were used to confirm the structural analysis and agree with the presence of Fe{sup 3+} in the above mentioned coordination environments. Group–subgroup relationships were used to build a starting model for themore » structure solution and to understand the relationship to the cubic perovskite structure. Furthermore, a comparison of a variety of vacancy-ordered iron-containing perovskite-type structures is given, highlighting the factors which favour one structure type over the other depending on the composition. - Graphical abstract: The crystal structure of Ba{sub 3}Fe{sub 3}O{sub 7}F in comparison to other perovskite type ferrites. - Highlights: • The crystal structure of Ba{sub 3}Fe{sub 3}O{sub 7}F in comparison to other perovskite type ferrites. • Ba{sub 3}Fe{sub 3}O{sub 7}F was synthesized by low temperature fluorination of Ba{sub 2}Fe{sub 2}O{sub 5}. • Ba{sub 3}Fe{sub 3}O{sub 7}F shows a unique vacancy order not found for other perovskite type compounds. • The structure of Ba{sub 3}Fe{sub 3}O{sub 7}F was solved using group–subgroup relationships. • A systematic comparison to other ferrite type compounds reveals structural similarities and differences. • The A-site coordination of the cation is shown to play an important role for the type of vacancy order found.« less

  15. Luminescence and energy transfer properties of Ca2Ba3(PO4)3Cl and Ca2Ba3(PO4)3Cl:A (A = Eu2+/Ce3+/Dy3+/Tb3+) under UV and low-voltage electron beam excitation.

    PubMed

    Shang, Mengmeng; Geng, Dongling; Yang, Dongmei; Kang, Xiaojiao; Zhang, Yang; Lin, Jun

    2013-03-18

    Pure Ca2Ba3(PO4)3Cl and rare earth ion (Eu(2+)/Ce(3+)/Dy(3+)/Tb(3+)) doped Ca2Ba3(PO4)3Cl phosphors with the apatite structure have been prepared via a Pechini-type sol-gel process. X-ray diffraction (XRD) and structure refinement, photoluminescence (PL) spectra, cathodoluminescence (CL) spectra, absolute quantum yield, as well as lifetimes were utilized to characterize samples. Under UV light excitation, the undoped Ca2Ba3(PO4)3Cl sample shows broad band photoluminescence centered near 480 nm after being reduced due to the defect structure. Eu(2+) and Ce(3+) ion doped Ca2Ba3(PO4)3Cl samples also show broad 5d → 4f transitions with cyan and blue colors and higher quantum yields (72% for Ca2Ba3(PO4)3Cl:0.04Eu(2+); 67% for Ca2Ba3(PO4)3Cl:0.016Ce(3+)). For Dy(3+) and Tb(3+) doped Ca2Ba3(PO4)3Cl samples, they give strong line emissions coming from 4f → 4f transitions. Moreover, the Ce(3+) ion can transfer its energy to the Tb(3+) ion in the Ca2Ba3(PO4)3Cl host, and the energy transfer mechanism has been demonstrated to be a resonant type, via a dipole-quadrupole interaction. However, under the low voltage electron beam excitation, Tb(3+) ion doped Ca2Ba3(PO4)3Cl samples present different luminescence properties compared with their PL spectra, which is ascribed to the different excitation mechanism. On the basis of the good PL and CL properties of the Ca2Ba3(PO4)3Cl:A (A = Ce(3+)/Eu(2+)/Tb(3+)/Dy(3+)), Ca2Ba3(PO4)3Cl might be promising for application in solid state lighting and field-emission displays.

  16. Low-energy planar magnetic defects in BaFe2As2: Nanotwins, twins, antiphase, and domain boundaries

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Khan, S. N.; Alam, A.; Johnson, Duane D.

    2013-01-01

    In BaFe2As2, structural and magnetic planar defects begin to proliferate below the structural phase transition, affecting descriptions of magnetism and superconductivity.We study, using density-functional theory, the stability and magnetic properties of competing antiphase and domain boundaries, twins and isolated nanotwins (twin nuclei), and spin excitations proposed and/or observed. These nanoscale defects have a very low surface energy (22 210 m Jm 2), with twins favorable to the mesoscale. Defects exhibit smaller moments confined near their boundaries making a uniform-moment picture inappropriate for long-range magnetic order in real samples. Nanotwins explain features in measured pair distribution functions so should be consideredmore » when analyzing scattering data. All these defects can be weakly mobile and/or can have fluctuations that lower« less

  17. 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.

  18. Heterogeneous Nucleation and Growth of Barium Sulfate at Organic-Water Interfaces: Interplay between Surface Hydrophobicity and Ba 2+ Adsorption

    DOE PAGES

    Dai, Chong; Stack, Andrew G.; Koishi, Ayumi; ...

    2016-05-10

    Barium sulfate (BaSO 4) is a common scale-forming mineral in natural and engineered systems, yet the rates and mechanisms of heterogeneous BaSO 4 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 BaSO4more » formed on 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 BaSO 4 nucleation and growth kinetics were found to be affected by the amount of Ba 2+ adsorption onto the substrate and incipient BaSO 4 nuclei. The importance of Ba 2+ adsorption was further corroborated by the finding that precipitation rate increased under [Ba 2+]/[SO 4 2–] 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

  19. Heterogeneous Nucleation and Growth of Barium Sulfate at Organic–Water Interfaces: Interplay between Surface Hydrophobicity and Ba 2+ Adsorption

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dai, Chong; Stack, Andrew G.; Koishi, Ayumi

    2016-05-31

    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

  20. Tuning the nonlinear optical absorption in Au/BaTiO3 nanocomposites with gold nanoparticle concentration

    NASA Astrophysics Data System (ADS)

    Bijeesh, M. M.; Shakhi, P. K.; Varier, Geetha K.; Nandakumar, P.

    2018-06-01

    We report on the nonlinear optical absorption coefficient of Au/BaTiO3 nanocomposite films and its dependence on gold nanoparticle concentration. Au/BaTiO3 nanocomposite films with different molar ratio of Au/Ba are prepared by sol-gel technique and characterized by X-ray diffraction, UV Visible absorption spectroscopy and high resolution transmission electron microscopy. An open aperture Z-scan technique is employed to study the third order nonlinear optical properties of Au/BaTiO3 thin films. An Nd:YAG laser operating at 532 nm wavelength having a pulse width of 5 ns is used for the measurements. The two-photon absorption coefficient of the films increases linearly with gold nanoparticle concentration and significant enhancement of nonlinear optical absorption is observed. This ability to fine tune the nonlinear optical coefficients of Au/BaTiO3 films would be handy in optical device applications.

  1. Theoretical investigation of structural, electronic and optical properties of MgxBa1-xS, MgxBa1-xSe and MgxBa1-xTe ternary alloys using DFT based FP-LAPW approach

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Rahul; Chattopadhyaya, Surya

    2017-11-01

    Density functional theory (DFT) based full-potential linearized augmented plane wave (FP-LAPW) methodology has been employed to investigate theoretically the structural, electronic and optical properties of MgxBa1-xS, MgxBa1-xSe and MgxBa1-xTe ternary alloys for 0 ≤ x ≤ 1 in their rock-salt (B1) crystallographic phase. The exchange-correlation potentials for the structural properties have been computed using the Wu-Cohen generalized-gradient approximation (WC-GGA) scheme, while those for the electronic and optical properties have been computed using both the WC-GGA and the recently developed Tran-Blaha modified Becke-Johnson (TB-mBJ) schemes. The thermodynamic stability of all the ternary alloys have been investigated by calculating their respective enthalpy of formation. The atomic and orbital origin of different electronic states in the band structure of the compounds have been identified from the respective density of states (DOS). Using the approach of Zunger and co-workers, the microscopic origin of band gap bowing has been discussed in term of volume deformation, charge exchange and structural relaxation. Bonding characteristics among the constituent atoms of each of the specimens have been discussed from their charge density contour plots. Optical properties of the binary compounds and ternary alloys have been investigated theoretically in terms of their respective dielectric function, refractive index, normal incidence reflectivity and optical conductivity. Several calculated results have been compared with available experimental and other theoretical data.

  2. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. 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

  4. Syntheses, crystal structures and Raman spectra of Ba(BF{sub 4})(PF{sub 6}), Ba(BF{sub 4})(AsF{sub 6}) and Ba{sub 2}(BF{sub 4}){sub 2}(AsF{sub 6})(H{sub 3}F{sub 4}); the first examples of metal salts containing simultaneously tetrahedral BF{sub 4}{sup -} and octahedral AF{sub 6}{sup -} anions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lozinsek, Matic; Bunic, Tina; Goreshnik, Evgeny, E-mail: evgeny.goreshnik@ijs.s

    2009-10-15

    In the system BaF{sub 2}/BF{sub 3}/PF{sub 5}/anhydrous hydrogen fluoride (aHF) a compound Ba(BF{sub 4})(PF{sub 6}) was isolated and characterized by Raman spectroscopy and X-ray diffraction on the single crystal. Ba(BF{sub 4})(PF{sub 6}) crystallizes in a hexagonal P6-bar2m space group with a=10.2251(4) A, c=6.1535(4) A, V=557.17(5) A{sup 3} at 200 K, and Z=3. Both crystallographically independent Ba atoms possess coordination polyhedra in the shape of tri-capped trigonal prisms, which include F atoms from BF{sub 4}{sup -} and PF{sub 6}{sup -} anions. In the analogous system with AsF{sub 5} instead of PF{sub 5} the compound Ba(BF{sub 4})(AsF{sub 6}) was isolated and characterized.more » It crystallizes in an orthorhombic Pnma space group with a=10.415(2) A, b=6.325(3) A, c=11.8297(17) A, V=779.3(4) A{sup 3} at 200 K, and Z=4. The coordination around Ba atom is in the shape of slightly distorted tri-capped trigonal prism which includes five F atoms from AsF{sub 6}{sup -} and four F atoms from BF{sub 4}{sup -} anions. When the system BaF{sub 2}/BF{sub 3}/AsF{sub 5}/aHF is made basic with an extra addition of BaF{sub 2}, the compound Ba{sub 2}(BF{sub 4}){sub 2}(AsF{sub 6})(H{sub 3}F{sub 4}) was obtained. It crystallizes in a hexagonal P6{sub 3}/mmc space group with a=6.8709(9) A, c=17.327(8) A, V=708.4(4) A{sup 3} at 200 K, and Z=2. The barium environment in the shape of tetra-capped distorted trigonal prism involves 10 F atoms from four BF{sub 4}{sup -}, three AsF{sub 6}{sup -} and three H{sub 3}F{sub 4}{sup -} anions. All F atoms, except the central atom in H{sub 3}F{sub 4} moiety, act as mu{sub 2}-bridges yielding a complex 3-D structural network. - Graphical abstract: The first three compounds, containing simultaneously tetrahedral BF{sub 4}{sup -} and octahedral AF{sub 6}{sup -} (A=P, As) anions have been synthesized and characterized by Raman spectroscopy and X-ray single crystal diffraction. In the system BaF{sub 2}/BF{sub 3}/PF{sub 5}/anhydrous hydrogen

  5. High-mobility BaSnO 3 grown by oxide molecular beam epitaxy

    DOE PAGES

    Raghavan, Santosh; Schumann, Timo; Kim, Honggyu; ...

    2016-01-28

    High-mobility perovskite BaSnO 3 films are of significant interest as newwide 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 3 films have been challenging to grow. Here, we demonstrate a modified oxide molecular beam epitaxy (MBE) approach, which supplies pre-oxidized SnO x. This technique addresses issues in the MBE of ternary stannates related to volatile SnO formation and enables growth of epitaxial, stoichiometric BaSnO 3. We demonstrate room temperature electron mobilities of 150 cm 2 V -1 s -1 in films grownmore » on PrScO 3. Lastly, the results open up a wide range of opportunities for future electronic devices.« less

  6. [Effect of Eu(Pr) substitution at Ba sites on microstructure and superconductivity in EuBa2Cu3O7-delta ceramics].

    PubMed

    Peng, Zhen-sheng; Wang, Zhi-he

    2004-04-01

    Ceramics of Eu1+xBa2-xCu3O7-delta with x = 0.0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 and EuBa2-xPrxCu3O7-delta with x=0.0, 0.05, 0.1, 0.2, 0.3, 0.4 have been synthesized and investigated by X-ray diffraction, resistivity, and Raman spectroscopy. The results show that the transition of crystal structure from orthorhombic to tetragonal occurs and the criticaltemperature decreases withthe increase in doping concentration x. The Raman spectra show that the frequency of the Cu(1)-O(4) stretching mode andthe Cu(2)-(2, 3) out-of-phase mode shifts to higher wave number with increasing doping concentration x.

  7. First-principles study of twin grain boundaries in epitaxial BaSi{sub 2} on Si(111)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Baba, Masakazu; Suemasu, Takashi, E-mail: suemasu@bk.tsukuba.ac.jp; Kohyama, Masanori

    2016-08-28

    Epitaxial films of BaSi{sub 2} 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 BaSi{sub 2} 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 BaSi{sub 2}more » revealed that each DB was a twin boundary between two different epitaxial variants, and that Ba{sup (II)} atoms form hexagons containing central Ba{sup (I)} atoms in both the bulk and DB regions. Four possible interface models containing Ba{sup (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{sup (I)} atoms or from zigzag surface slabs terminated by Si tetrahedra and Ba{sup (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/m{sup 2}. 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 BaSi{sub 2}.« less

  8. Effect of divalent Ba cation substitution with Sr on coupled ‘multiglass’ state in the magnetoelectric multiferroic compound Ba3NbFe3Si2O14

    PubMed Central

    Rathore, Satyapal Singh; Vitta, Satish

    2015-01-01

    (Ba/Sr)3NbFe3Si2O14 is a magneto-electric multiferroic with an incommensurate antiferromagnetic spiral magnetic structure which induces electric polarization at 26 K. Structural studies show that both the compounds have similar crystal structure down to 6 K. They exhibit a transition, TN at 26 K and 25 K respectively, as indicated by heat capacity and magnetization, into an antiferromagnetic state. Although Ba and Sr are isovalent, they exhibit very different static and dynamic magnetic behaviors. The Ba-compound exhibits a glassy behavior with critical slowing dynamics with a freezing temperature of ~35 K and a critical exponent of 3.9, a value close to the 3-D Ising model above TN, in addition to the invariant transition into an antiferromagnetic state. The Sr-compound however does not exhibit any dispersive behavior except for the invariant transition at TN. The dielectric constant reflects magnetic behavior of the two compounds: the Ba-compound has two distinct dispersive peaks while the Sr-compound has a single dispersive peak. Thus the compounds exhibit coupled ‘multiglass’ behavior. The difference in magnetic properties between the two compounds is found to be due to modifications to super exchange path angle and length as well as anti-site defects which stabilize either ferromagnetic or antiferromagnetic interactions. PMID:25988657

  9. Ultrasonic Investigations on Polonides of Ba, Ca, and Pb

    NASA Astrophysics Data System (ADS)

    Singh, Devraj; Bhalla, Vyoma; Bala, Jyoti; Wadhwa, Shikha

    2017-10-01

    The temperature-dependent mechanical and ultrasonic properties of barium, calcium, and lead polonides (BaPo, CaPo, and PbPo) were investigated in the temperature range 100-300 K. The second- and third-order elastic constants (SOECs and TOECs) were computed using Coulomb and Born-Mayer potential and these in turn have been used to estimate other secondary elastic properties such as strength, anisotropy, microhardness, etc. The theoretical approach followed the prediction that BaPo, CaPo, and PbPo are brittle in nature. PbPo is found to be the hardest amongst the chosen compounds. Further the SOECs and TOECs are applied to determine ultrasonic velocities, Debye temperature, and acoustic coupling constants along <100>, <110>, and <111> orientations at room temperature. Additionally thermal conductivity has been computed using Morelli and Slack's approach along different crystallographic directions at room temperature. Finally ultrasonic attenuation due to phonon-phonon interaction and thermoelastic relaxation mechanisms has been computed for BaPo, CaPo, and PbPo. The behaviour of these compounds is similar to that of semi-metals with thermal relaxation time of the order 10-11 s. The present computation study is reasonably in agreement with the available theoretical data for the similar type of materials.

  10. Superconductivity in BaPtSb with an Ordered Honeycomb Network

    NASA Astrophysics Data System (ADS)

    Kudo, Kazutaka; Saito, Yuki; Takeuchi, Takaaki; Ayukawa, Shin-ya; Kawamata, Takayuki; Nakamura, Shinichiro; Koike, Yoji; Nohara, Minoru

    2018-06-01

    Superconductivity in BaPtSb with the SrPtSb-type structure (space group P\\bar{6}m2, D3h1, No. 187) is reported. The structure consists of a PtSb ordered honeycomb network that stacks along the c-axis so that spatial inversion symmetry is broken globally. Electrical resistivity and specific-heat measurements revealed that the compound exhibited superconductivity at 1.64 K. The noncentrosymmetric structure and the strong spin-orbit coupling of Pt and Sb make BaPtSb an attractive compound for studying the exotic superconductivity predicted for a honeycomb network.

  11. 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.

  12. Structural analysis and ferroelectric properties of Fe doped BaTiO{sub 3}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mishra, Ashutosh, E-mail: a.mansuri14@gmail.com, E-mail: amishra1960@yahoo.co.in; Mansuri, Amantulla, E-mail: a.mansuri14@gmail.com, E-mail: amishra1960@yahoo.co.in; Dwivedi, J. P.

    2016-05-23

    The polycrystalline samples of Fe doped BaTiO{sub 3} (BTO) with compositional formula BaTi{sub 1-x}Fe{sub x}O{sub 3} (x = 0, 0.03, 0.04 and 0.05) were prepared by solid-state reaction route. The influence of the Fe content on the structural, vibrational and electric properties of BaTiO{sub 3} was investigated using X-ray powder diffraction (XRD), Raman spectroscopy and Polarization techniques. XRD analysis indicates the formation of single-phase tetragonal structure for all the prepared samples. Tetragonal cubic structure with space group P4mm of all samples is further approved by Rietveld refinement. Room temperature Raman spectra of pure BaTiO{sub 3} show four active modes ofmore » vibration whose intensity decreases with increasing Fe doping. Small shift in Raman modes and increment in the line width has been observed with the doping ions. The hysteresis loop is very well performed with regular sharp characteristic of ferroelectric materials.« less

  13. Fe doped BaTiO3 sensitized by Fe3O4 nanoparticles for improved photoelectrochemical response

    NASA Astrophysics Data System (ADS)

    Upadhyay, Rishibrind Kumar; Sharma, Dipika

    2018-01-01

    Nanostructured powders of pristine Fe3O4, BaTiO3, and Fe-BaTiO3 were synthesized using hydrothermal method and BaTiO3/Fe3O4 and Fe-BaTiO3/Fe3O4 composite sample were also prepared by mixing the appropriate amount of pristine powders. All samples were characterized using x-ray diffraction, SEM and UV-vis spectrometry. Photoelectrochemical properties were investigated in a three-electrode cell system. Maximum photocurrent density of 2.1 mA cm-2 at 0.95 V/SCE was observed for Fe-BaTiO3/Fe3O4 composite sample. Increased photocurrent density offered by composite may be attributed to improved conductivity and better separation of the photogenerated charge carriers at interface.

  14. Effects of vacancies on atom displacement threshold energy calculations through Molecular Dynamics Methods in BaTiO3

    NASA Astrophysics Data System (ADS)

    Gonzalez Lazo, Eduardo; Cruz Inclán, Carlos M.; Rodríguez Rodríguez, Arturo; Guzmán Martínez, Fernando; Abreu Alfonso, Yamiel; Piñera Hernández, Ibrahin; Leyva Fabelo, Antonio

    2017-09-01

    A primary approach for evaluating the influence of point defects like vacancies on atom displacement threshold energies values Td in BaTiO3 is attempted. For this purpose Molecular Dynamics Methods, MD, were applied based on previous Td calculations on an ideal tetragonal crystalline structure. It is an important issue in achieving more realistic simulations of radiation damage effects in BaTiO3 ceramic materials. It also involves irradiated samples under severe radiation damage effects due to high fluency expositions. In addition to the above mentioned atom displacement events supported by a single primary knock-on atom, PKA, a new mechanism was introduced. It corresponds to the simultaneous excitation of two close primary knock-on atoms in BaTiO3, which might take place under a high flux irradiation. Therefore, two different BaTiO3 Td MD calculation trials were accomplished. Firstly, single PKA excitations in a defective BaTiO3 tetragonal crystalline structure, consisting in a 2×2×2 BaTiO3 perovskite like super cell, were considered. It contains vacancies on Ba and O atomic positions under the requirements of electrical charge balance. Alternatively, double PKA excitations in a perfect BaTiO3 tetragonal unit cell were also simulated. On this basis, the corresponding primary knock-on atom (PKA) defect formation probability functions were calculated at principal crystal directions, and compared with the previous one we calculated and reported at an ideal BaTiO3 tetrahedral crystal structure. As a general result, a diminution of Td values arises in present calculations in comparison with those calculated for single PKA excitation in an ideal BaTiO3 crystal structure.

  15. Ba{sub 3}ZnTa{sub 2-x}Nb{sub x}O{sub 9} and Ba{sub 3}MgTa{sub 2-x}Nb{sub x}O{sub 9} (0{<=}x{<=}1): synthesis, structure and dielectric properties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Thirumal, M.; Jawahar, I.N.; Surendiran, K.P.

    2002-11-20

    Oxides belonging to the families Ba{sub 3}ZnTa{sub 2-x}Nb{sub x}O{sub 9} and Ba{sub 3}MgTa{sub 2-x}Nb{sub x}O{sub 9} were synthesized by the solid state reaction route. Sintering temperatures of 1300 deg. C led to oxides with disordered (cubic) perovskite structure. However, on sintering at 1425 deg. C hexagonally ordered structures were obtained for Ba{sub 3}MgTa{sub 2-x}Nb{sub x}O{sub 9} over the entire range (0{<=}x{<=}1) of composition, while for Ba{sub 3}ZnTa{sub 2-x}Nb{sub x}O{sub 9} the ordered structure exists in a limited range (0{<=}x{<=}0.5). The dielectric constant is close to 30 for the Ba{sub 3}ZnTa{sub 2-x}Nb{sub x}O{sub 9} family of oxides while the Mg analoguesmore » have lower dielectric constant of {approx}18 in the range 50 Hz to 500 kHz. At microwave frequencies (5-7 GHz) dielectric constant increases with increase in niobium concentration (22-26) for Ba{sub 3}ZnTa{sub 2-x}Nb{sub x}O{sub 9}; for Ba{sub 3}MgTa{sub 2-x}Nb{sub x}O{sub 9} it varies between 12 and 14. The 'Zn' compounds have much higher quality factors and lower temperature coefficient of resonant frequency compared to the 'Mg' analogues.« less

  16. Evolution of structure and superconductivity in Ba(Ni 1 -xCox)2As2

    NASA Astrophysics Data System (ADS)

    Eckberg, Chris; Wang, Limin; Hodovanets, Halyna; Kim, Hyunsoo; Campbell, Daniel J.; Zavalij, Peter; Piccoli, Philip; Paglione, Johnpierre

    2018-06-01

    The effects of Co substitution on Ba (Ni1-xCox) 2As2 (0 ≤x ≤0.251 ) single crystals grown out of Pb flux are investigated via transport, magnetic, and thermodynamic measurements. BaNi2As2 exhibits a first-order tetragonal to triclinic structural phase transition at Ts=137 K upon cooling, and enters a superconducting phase below Tc=0.7 K. The structural phase transition is sensitive to cobalt content and is suppressed completely by x ≥0.133 . The superconducting critical temperature, Tc, increases continuously with x , reaching a maximum of Tc=2.3 K at x =0.083 and then decreases monotonically until superconductivity is no longer observable well into the tetragonal phase. In contrast to similar BaNi2As2 substitutional studies, which show an abrupt change in Tc at the triclinic-tetragonal boundary that extends far into the tetragonal phase, Ba (Ni1-xCox) 2As2 exhibits a domelike phase diagram centered around the zero-temperature tetragonal-triclinic boundary. Together with an anomalously large heat capacity jump Δ Ce/γ T ˜2.2 near optimal doping, the smooth evolution of Tc in the Ba (Ni1-xCox) 2As2 system suggests a mechanism for pairing enhancement other than phonon softening.

  17. Investigations on the local structures of Cu2+ at various BaO concentrations in 59B2O3-10K2O-(30-x)ZnO-xBaO-1CuO glasses

    NASA Astrophysics Data System (ADS)

    Jin, Jia-Rui; Wu, Shao-Yi; Hong, Jian; Liu, Shi-Nan; Song, Min-Xian; Teng, Bao-Hua; Wu, Ming-He

    2017-11-01

    The local structures and electron paramagnetic resonance (EPR) parameters for Cu2+ in 59B2O3-10K2O-(30-x)ZnO-xBaO-1CuO (BKZBC) glasses are theoretically investigated with distinct modifier BaO concentrations x (= 0, 6, 12, 18, 24 and 30 mol %). The ? clusters are found to undergo the relative tetragonal elongations of about 13.5 and 5.0% at zero and higher BaO concentrations. The concentration dependences of the measured d-d transition bands, g factors and A// are suitably reproduced from the Fourier type functions or sign functions of the relevant quantities with x by using only six adjustable parameters. The features of the EPR parameters and the local structures of Cu2+ are analysed in a consistent way by considering the differences in the local ligand field strength and electronic cloud admixtures around Cu2+ under addition of Ba2+ with the highest ionicity and polarisability. The present theoretical studies would be helpful to the researches on the structures, optical and EPR properties for the similar potassium barium zinc borate glasses containing copper with variation concentration of modifier BaO.

  18. Properties and Degradation of Polarization Reversal of Soft BaTiO3 Ceramics for Ferroelectric Thin-Film Devices

    NASA Astrophysics Data System (ADS)

    Thongrueng, Jirawat; Tsuchiya, Toshio; Masuda, Yoichiro; Fujita, Shigetaka; Nagata, Kunihiro

    1999-09-01

    Soft BaTiO3 ceramics having a very low coercive field of 65 V/mm were prepared by substituting 9 mol% Hf Zr for the Ti-site of BaTiO3, for applications to ferroelectric thin-film devices. Electrical properties of the soft BaTiO3 ceramics were measured and compared with those of normal BaTiO3 ceramics. By substituting Hf Zr for Ti-site, the phase transition temperatures were controlled, and we could select the preferred crystal structure from the tetragonal, orthorhombic and rhombohedral phases at room temperature. In addition, the preparation and characterization of the soft BaTiO3 thin-films using a sol-gel process were carried out.

  19. Structures, phase transitions and microwave dielectric properties of the 6H perovskites Ba 3BSb 2O 9, B=Mg, Ca, Sr, Ba

    NASA Astrophysics Data System (ADS)

    Ling, Chris D.; Rowda, Budwy; Avdeev, Maxim; Pullar, Robert

    2009-03-01

    We present a complete temperature-composition phase diagram for Ba 3BSb 2O 9, B=Mg, Ca, Sr, Ba, along with their electrical behavior as a function of B. These compounds have long been recognized as 6H-type perovskites, but (with the exception of B=Mg) their exact structures and properties were unknown due to their low symmetries, temperature-dependent phase transitions, and difficulties in synthesizing pure samples. The full range of possible space group symmetries is observed, from ideal hexagonal P6 3/ mmc to monoclinic C2/ c to triclinic P1¯. Direct second-order transitions between these phases are plausible according to group theory, and no evidence was seen for any further intermediate phases. The phase diagram with respect to temperature and the effective ionic radius of B is remarkably symmetrical for B=Mg, Ca, and Sr. For B=Ba, a first-order phase transition to a locally distorted phase allows a metastable hexagonal phase to persist to lower temperatures than expected before decomposing around 600 K. Electrical measurements revealed that dielectric permittivity corrected for porosity does not change significantly as a function of B and is in a good agreement with the values predicted by the Clausius-Mossotti equation.

  20. Using coral Ba/Ca records to investigate seasonal to decadal scale biogeochemical cycling in the surface and intermediate ocean.

    NASA Astrophysics Data System (ADS)

    LaVigne, M.; Cobb, K. M.; DeLong, K. L.; Freiberger, M. M.; Grottoli, A. G.; Hill, T. M.; Miller, H. R.; Nurhati, I. S.; Richey, J. N.; Serrato Marks, G.; Sherrell, R. M.

    2016-12-01

    Dissolved barium (BaSW), a bio-intermediate element, is linked to several biogeochemical processes such as the cycling and export of nutrients, organic carbon (Corg), and barite in surface and intermediate oceans. Dynamic BaSW cycling has been demonstrated in the water column on short timescales (days-weeks) while sedimentary records have documented geologic-scale changes in barite preservation driven by export production. Our understanding of how seasonal-decadal scale climate variability impacts these biogeochemical processes currently lacks robust records. Ba/Ca calibrations in surface and deep sea corals suggest barium is incorporated via cationic substitution in both aragonite and calcite. Here we demonstrate the utility of Ba/Ca for reconstructing biogeochemical variability using examples of surface and deep sea coral records. Century-long deep sea coral records from the California Current System (bamboo corals: 900-1500m) record interannual variations in Ba/Ca, likely reflecting changes in barite formation via bacterial Corg respiration or barite saturation state. A surface Porites coral Ba/Ca record from Christmas Island (central equatorial Pacific: 1978-1995) shows maxima during low productivity El Niño warm periods, suggesting that variations in BaSW are driven by biological removal via direct cellular uptake or indirectly via barite precipitation with the decomposition of large phytoplankton blooms at this location. Similarly, a sixteen-year long Siderastera siderea surface coral record from Dry Tortugas, FL (Gulf of Mexico: 1991-2007) shows seasonal Ba/Ca cycles that align with annual chlorophyll and δ13C. Taken together, these records demonstrate the linkages among Corg, nutrient cycling and BaSW in the surface and intermediate ocean on seasonal to decadal timescales. Multi-proxy paleoceanographic reconstructions including Ba/Ca have the potential to elucidate the mechanisms linking past climate, productivity, nutrients, and BaSW cycling in the past.

  1. Structural insights into the thermal decomposition sequence of barium tetrahydrogenorthotellurate(VI), Ba[H{sub 4}TeO{sub 6}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Weil, Matthias, E-mail: Matthias.Weil@tuwien.ac.at; Stöger, Berthold; Gierl-Mayer, Christian

    2016-09-15

    The compounds Ba[H{sub 4}TeO{sub 6}] (I), Ba[H{sub 2}TeO{sub 5}] (II), Ba[Te{sub 2}O{sub 6}(OH){sub 2}] (III) and Ba[TeO{sub 4}] (IV) were prepared by application of a diffusion method (I), under hydrothermal conditions (II and III) and from solid state reactions (IV), respectively. Structure analysis on the basis of single crystal X-ray diffraction data revealed novel structure types for (I), (II) and (III) and isotypism of (IV) with PrSbO{sub 4} and LaSbO{sub 4}. Common feature of the four oxotellurate(VI) structures are [TeO{sub 6}] octahedra. Whereas in the crystal structure of (I) the octahedral units are isolated, they are condensed into chains viamore » corner-sharing in (II) and via edge-sharing in (III) and (IV). The coordination numbers of the barium cations in the four structures range from seven to ten. Although hydrogen atom positions could not be located for the structures of (I) and (II), short interpolyhedral O···O contacts are evident for strong hydrogen bonding. The temperature behaviour of (I), (II) and (IV) was monitored by simultaneous thermal analysis (STA) measurements and in situ powder X-ray diffraction, revealing the decomposition sequence Ba[H{sub 4}TeO{sub 6}] → Ba[H{sub 2}TeO{sub 5}] → Ba[TeO{sub 4}]→ Ba[TeO{sub 3}] upon heating to temperatures up to 900 °C. - Graphical abstract: The crystal structures of the four oxotellurates(VI) were determined from single crystal data. The thermal decomposition of Ba[H{sub 4}TeO{sub 6}], monitored by temperature-dependent X-ray powder diffraction and simultaneous thermal analysis measurements, involves two condensation reactions according to Ba[H{sub 4}TeO{sub 6}]→Ba[H{sub 2}TeO{sub 5}]+H{sub 2}O(↑)→Ba[TeO{sub 4}]+ H{sub 2}O(↑). Display Omitted.« less

  2. Impedance spectroscopy of V2O5-Bi2O3-BaTiO3 glass-ceramics

    NASA Astrophysics Data System (ADS)

    Al-syadi, Aref M.; Yousef, El Sayed; El-Desoky, M. M.; Al-Assiri, M. S.

    2013-12-01

    The glasses within composition as: (80 - x)V2O5/20Bi2O3/xBaTiO3 with x = 2.5, 5, 7.5 and 10 mol% have been prepared. The glass transition (Tg) increases with increasing BaTiO3 content. Synthesized glasses ceramic containing BaTi4O9, Ba3TiV4O15 nanoparticles of the order of 25-35 nm and 30-46 nm, respectively were estimated using XRD. The dielectric properties over wide ranges of frequencies and temperatures were investigated as a function of BaTiO3 content by impedance spectroscopy measurements. The hopping frequency, ωh, dielectric constant, ɛ', activation energies for the DC conduction, Eσ, the relaxation process, Ec, and stretched exponential parameter β of the glasses samples have been estimated. The, ωh,β, decrease from 51.63 to 0.31 × 106 (s-1), 0.84 to 0.79 with increasing BaTiO3 respectively. Otherwise, the Eσ, increase from 0.279 to 0.306 eV with increasing BaTiO3. The value of dielectric constant equal 9.5·103 for the 2.5BaTiO3/77.5V2O5/20Bi2O3 glasses-ceramic at 330 K for 1 KHz which is ten times larger than that of same glasses composition. Finally the relaxation properties of the investigated glasses are presented in the electric modulus formalism, where the relaxation time and the respective activation energy were determined.

  3. Medium-power diode-pumped Nd:BaY2F8 laser

    NASA Astrophysics Data System (ADS)

    Agnesi, Antonio; Guandalini, Annalisa; Lucca, Andrea; Sani, Elisa; Toncelli, Alessandra; Tonelli, Mauro; dell'Acqua, Stefano

    2003-05-01

    We report what is to our knowledge the first Nd:BaY2F8 (Nd:BaYF) laser pumped with a multiwatt fiber-coupled diode array tuned at approximately 804 nm. As much as 2.4 W were obtained with 6.2 W of absorbed pump power, showing efficient operation (51% slope efficiency), excellent beam quality (M2=1.1), and weak thermal lensing. Small intracavity losses (<1%) were measured, indicating both reduced thermally induced aberrations and good optical quality of the laser crystal.

  4. Metal (Ca, Ba, Sr, Pb) heptafluorotantalates(V): Synthesis, Raman spectra and crystal structures

    NASA Astrophysics Data System (ADS)

    Bunič, Tina; Tramšek, Melita; Goreshnik, Evgeny; Žemva, Boris

    2007-01-01

    MTaF 7 (M = Ca, Sr, Ba, Pb) were prepared by the reaction of MF 2 + Ta + F 2 (Ca, Sr, Ba) or MF 2 + TaF 5 in anhydrous HF. CaTaF 7 crystallizes in a monoclinic P2 1/ a space group, a = 9.793(3) Å, b = 11.608(3) Å, c = 13.359(4) Å, β = 90.539(13)°, V = 1518.5(7) Å 3. All Ta atoms possess distorted pentagonal-bipyramidal environment with Ta-F distances of 1.878(14)-2.044(13) Å. Three crystallographically independent Ca atoms have coordination number 8. Ca-F distances lie in the range of 2.239(16)-2.836(17) Å. Each Ca 2+ and TaF 72- moiety is bonded to 6 counter-ions. BaTaF 7 crystallizes in a cubic system, space group Pa3¯,a = 9.9009(3)Å, V = 970.56(5) Å 3. Coordination sphere around Ta atom is mono-capped trigonal prism with a Ta-F distance of 1.916(5)-2.004(5) Å. Two crystallographically independent barium atoms have different coordination numbers: for Ba1 C.N. is 12 with Ba1-F distances of 6 × 2.761(5) Å and 6 × 2.858(5) Å, for Ba2 C.N. is 14 with Ba2-F bond lengths 6 × 2.718(5), 2 × 2.814(8) and 6 × 3.236(5) Å. Ba 2+ and TaF 72- moieties are bonded to 8 neighbors. Isostructural PbTaF 7 and SrTaF 7 appear to be monoclinic, space group P2 1/ m, a = 4.8657(11) Å, b = 7.2298(16) Å, c = 6.7370(16) Å, β = 93.932(13)°, V = 236.44(9) Å 3 for PbTaF 7, and a = 4.875(3) Å, b = 7.196(4) Å, c = 6.7218(13) Å, β = 94.265(10), V = 235.2(2) Å for SrTaF 7. Tantalum coordination polyhedron may be described as a distorted mono-capped trigonal prism with the capping atom located on one of the rectangular faces with Ta-F distances of 1.868(3)-1.982(3) Å (PbTaF 7) and 1.908(16)-2.019(12) Å (SrTaF 7). Lead (or strontium) atoms are 9-coordinated and may be viewed as strongly distorted tri-capped trigonal prism, Pb-F 2.438(4)-2.669(3) Å, Sr-F 2.501(19)-2.860(19) Å. Each cation is connected to 8 anions.

  5. The BaMM web server for de-novo motif discovery and regulatory sequence analysis.

    PubMed

    Kiesel, Anja; Roth, Christian; Ge, Wanwan; Wess, Maximilian; Meier, Markus; Söding, Johannes

    2018-05-28

    The BaMM web server offers four tools: (i) de-novo discovery of enriched motifs in a set of nucleotide sequences, (ii) scanning a set of nucleotide sequences with motifs to find motif occurrences, (iii) searching with an input motif for similar motifs in our BaMM database with motifs for >1000 transcription factors, trained from the GTRD ChIP-seq database and (iv) browsing and keyword searching the motif database. In contrast to most other servers, we represent sequence motifs not by position weight matrices (PWMs) but by Bayesian Markov Models (BaMMs) of order 4, which we showed previously to perform substantially better in ROC analyses than PWMs or first order models. To address the inadequacy of P- and E-values as measures of motif quality, we introduce the AvRec score, the average recall over the TP-to-FP ratio between 1 and 100. The BaMM server is freely accessible without registration at https://bammmotif.mpibpc.mpg.de.

  6. Hydrothermal synthesis and structural analysis of new mixed oxyanion borates: Ba11B26O44(PO4)2(OH)6, Li9BaB15O27(CO3) and Ba3Si2B6O16

    NASA Astrophysics Data System (ADS)

    Heyward, Carla; McMillen, Colin D.; Kolis, Joseph

    2013-07-01

    Several new borate compounds, Ba11B26O44(PO4)2(OH)6 (1), Li9BaB15O27(CO3) (2), and Ba3Si2B6O16 (3) were synthesized containing other hetero-oxyanion building blocks in addition to the borate frameworks. They were all prepared under hydrothermal conditions and characterized by single crystal and powder X-ray diffraction, and IR spectroscopy. Crystal data: For 1; space group P21/c, a=6.8909 (14) Å, b=13.629 (3) Å, c=25.851 (5) Å, β=90.04 (3)°; For 2; space group P-31c, a=8.8599 (13) Å, c=15.148 (3) Å; For 3; space group P-1, a=5.0414 (10) Å, b=7.5602 (15) Å, c=8.5374 (17) Å, α=77.15 (3)°, β=77.84 (3)°, γ=87.41 (3)° for 3. Compounds 1 and 2 contain isolated oxyanions [PO4]3- and [CO3]2- respectively, sitting in channels created by the borate framework, while structure 3 has the [SiO4]4- groups directly bonded to the borate groups creating a B-O-Si framework.

  7. Effect of Cr3+ substitution on AC susceptibility of Ba hexaferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Slimani, Y.; Baykal, A.; Manikandan, A.

    2018-07-01

    In this study, nano-sized particles of BaCrxFe12-xO19 (0.0 ≤ x ≤ 1.0) hexaferrite were fabricated through citrate auto gel combustion process and the impact of Cr-ion substitution on ac magnetic susceptibility properties of Ba-hexaferrite were explored. X-ray powder diffraction (XRD) measurements approved the purity of prepared samples and showed a reduction of the average crystallite size with increasing the content of Cr. Transmission electron microscopy (TEM) observation indicated the hexagonal morphology of all samples. AC susceptibility measurements displayed a frequency dependence of the magnetic responses. These measurements indicated that there are strong magnetic interactions (which is the highest for BaCr0.3Fe11.7O19 NP) between particles which cause a superspin glass-like (SSG) behavior at low temperatures. Estimating the values of loss power density revealed an increase of loss power density with increasing Cr-substitution element. The relative sensitivity of the prepared MNPs to the variation of applied frequency is very influenced by Cr-substitution and is highest in BaCr0.3Fe11.7O19 MNPs, suggesting that this sample can be considered as magnetic nanomaterial for hyperthermia and for many other applications.

  8. Vortex pinning in artificially layered Ba(Fe,Co)2As2 film

    NASA Astrophysics Data System (ADS)

    Oh, M. J.; Lee, Jongmin; Seo, Sehun; Yoon, Sejun; Seo, M. S.; Park, S. Y.; Kim, Ho-Sup; Ha, Dong-Woo; Lee, Sanghan; Jo, Youn Jung

    2018-06-01

    Static high critical current densities (Jc) > 1 MA/cm2 with magnetic field parallel or perpendicular to c-axis were realized in Co-doped/undoped multilayerd BaFe2As2 films. We made a current bridge by FIB to allow precise measurements, and confirmed that the boundary quality using FIB was considerably better than the quality achieved using a laser. The presence of a high in-plane Jc suggested the existence of c-axis correlated vortex pinning centers. To clarify the relationship between the Jc performance and superstructures, we investigated the magnetic flux pinning mechanism using scaling theory of the volume pinning force Fp(H). The Jc(H) curves, Fp/Fp,max vs. h = H/Hirr curves, and parameters p and q depended on the characteristics of the flux pinning mechanism. It was found that the dominant pinning mechanism of Co-doped/undoped multilayerd BaFe2As2 films was Δl-pinning and the inserted undoped BaFe2As2 layers remained non-superconducting. The dominant pin geometry varied when the magnetic field direction changed. It was concluded that the artificially layered BaFe2As2 film is a 3-D superconductor due to its long correlation length compared to the thickness of the non-superconducting layer.

  9. Band gap and mobility of epitaxial perovskite BaSn1 -xHfxO3 thin films

    NASA Astrophysics Data System (ADS)

    Shin, Juyeon; Lim, Jinyoung; Ha, Taewoo; Kim, Young Mo; Park, Chulkwon; Yu, Jaejun; Kim, Jae Hoon; Char, Kookrin

    2018-02-01

    A wide band-gap perovskite oxide BaSn O3 is attracting much attention due to its high electron mobility and oxygen stability. On the other hand, BaHf O3 was recently reported to be an effective high-k gate oxide. Here, we investigate the band gap and mobility of solid solutions of BaS n1 -xH fxO3 (x =0 -1 ) (BSHO) as a basis to build advanced perovskite oxide heterostructures. All the films were epitaxially grown on MgO substrates using pulsed laser deposition. Density functional theory calculations confirmed that Hf substitution does not create midgap states while increasing the band gap. From x-ray diffraction and optical transmittance measurements, the lattice constants and the band-gap values are significantly modified by Hf substitution. We also measured the transport properties of n -type La-doped BSHO films [(Ba ,La ) (Sn ,Hf ) O3 ] , investigating the feasibility of modulation doping in the BaSn O3/BSHO heterostructures. The Hall measurement data revealed that, as the Hf content increases, the activation rate of the La dopant decreases and the scattering rate of the electrons sharply increases. These properties of BSHO films may be useful for applications in various heterostructures based on the BaSn O3 system.

  10. Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials.

    PubMed

    Jang, Seon-Min; Yang, Su Chul

    2018-06-08

    Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO 2 epitaxial growth and BaTiO 3 conversion. Through the TiO 2 epitaxial growth on FTO substrate, (001) oriented TiO 2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO 2 NBA was conducted to enlarge the surface area for effective Ba 2+ ion diffusion during the perovskite conversion process from TiO 2 to BaTiO 3 . The final structure of perovskite BaTiO 3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO 3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

  11. Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials

    NASA Astrophysics Data System (ADS)

    Jang, Seon-Min; Yang, Su Chul

    2018-06-01

    Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO2 epitaxial growth and BaTiO3 conversion. Through the TiO2 epitaxial growth on FTO substrate, (001) oriented TiO2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO2 NBA was conducted to enlarge the surface area for effective Ba2+ ion diffusion during the perovskite conversion process from TiO2 to BaTiO3. The final structure of perovskite BaTiO3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

  12. Morphology control of anisotropic BaTiO 3 and BaTiOF 4 using organic-inorganic interaction

    NASA Astrophysics Data System (ADS)

    Masuda, Yoshitake; Tanaka, Yuki; Gao, Yanfeng; Koumoto, Kunihito

    2009-01-01

    We proposed a novel concept for morphology control of barium titanate precursor to fabricate platy particles. Organic molecules play an essential role in the crystallization of BaTiOF 4 to synthesize multi-needle particles, polyhedron particles or platy particles in an aqueous solution. Precursors were successfully transformed to barium titanate single phase by annealing. Platy barium titanate precursor particles are expected for future multilayer ceramic capacitors.

  13. Properties of epitaxial BaTiO{sub 3} deposited on GaAs

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Contreras-Guerrero, R.; Droopad, R.; Veazey, J. P.

    2013-01-07

    Single crystal BaTiO{sub 3} (BTO) has been grown epitaxially on GaAs using molecular beam epitaxy with a 2 unit cell SrTiO{sub 3} nucleation layer. The oxide film is lattice-matched to GaAs through an in-plane rotation of 45 Degree-Sign relative to the (100) surface leading to c-axis orientation of the BaTiO{sub 3}. X-ray diffraction confirmed the crystallinity and orientation of the oxide film with a full width half maximum of 0.58 Degree-Sign for a 7.5 nm thick layer. Piezoresponse force microscopy was used to characterize the ferroelectric domains in the BaTiO{sub 3} layer, and a coercive voltage of 1-2 V andmore » piezoresponse amplitude {approx}5 pm/V was measured.« less

  14. Sr{sub 7}Ge{sub 6}, Ba{sub 7}Ge{sub 6} and Ba{sub 3}Sn{sub 2} -Three new binary compounds containing dumbbells and four-membered chains of tetrel atoms with considerable Ge-Ge {pi}-bonding character

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Siggelkow, Lisa; Hlukhyy, Viktor; Faessler, Thomas F., E-mail: thomas.faessler@lrz.tum.de

    2012-07-15

    The germanides Sr{sub 7}Ge{sub 6} and Ba{sub 7}Ge{sub 6} as well as the stannide Ba{sub 3}Sn{sub 2} were prepared by arc melting and annealing in welded tantalum ampoules using induction as well as resistance furnaces. The compounds were investigated by powder and single crystal X-ray diffraction. Sr{sub 7}Ge{sub 6} and Ba{sub 7}Ge{sub 6} crystallize in the Ca{sub 7}Sn{sub 6} structure type (space group Pmna, Z=4: a=7.777(2) A, b=23.595(4) A, c=8.563(2) A, wR{sub 2}=0.081 (all data), 2175 independent reflections, 64 variable parameters for Sr{sub 7}Ge{sub 6} and a=8.0853(6) A, b=24.545(2) A, c=8.9782(8) A, wR{sub 2}=0.085 (all data), 2307 independent reflections, 64more » variable parameters for Ba{sub 7}Ge{sub 6}). Ba{sub 3}Sn{sub 2} crystallizes in an own structure type with the space group P4{sub 3}2{sub 1}2, Z=4, a=6.6854(2) A, c=17.842(2) A, wR{sub 2}=0.037 (all data), 1163 independent reflections, 25 variable parameters. In Sr{sub 7}Ge{sub 6} and Ba{sub 7}Ge{sub 6} the Ge atoms are arranged as Ge{sub 2} dumbbells and Ge{sub 4} four-membered atom chains. Their crystal structures cannot be rationalized according to the (8-N) rule. In contrast, Ba{sub 3}Sn{sub 2} presents Sn{sub 2} dumbbells as a main structural motif and thereby can be described as an electron precise Zintl phase. The chemical bonding situation in these structures is discussed on the basis of partial and total Density Of States (DOS) curves, band structures including fatbands, topological analysis of the Electron Localization Function (ELF) as well as Bader analysis of the bond critical points using the programs TB-LMTO-ASA and WIEN2K. While Ba{sub 3}Sn{sub 2} reveals semiconducting behaviour, all germanides Ae{sub 7}Ge{sub 6} (Ae=Ca, Sr, and Ba) show metallic properties and a considerable {pi}-bonding character between the Ge atoms of the four-membered chains and the dumbbells. The {pi}-bonding character of the germanides is best reflected by the resonance hybrid structures {l

  15. Real-time observations of interface formation for barium strontium titanate films on silicon

    NASA Astrophysics Data System (ADS)

    Mueller, A. H.; Suvorova, N. A.; Irene, E. A.; Auciello, O.; Schultz, J. A.

    2002-05-01

    Ba.5Sr.5TiO3 (BST) film growth by ion sputtering on bare and thermally oxidized silicon was observed in real time using in-situ spectroscopic ellipsometry and time of flight ion scattering and recoil spectrometry techniques. At the outset of BST film deposition on silicon, an approximately 30 Å film with intermediate static dielectric constant (K˜12) and refractive index (n˜2.6 at photon energies of 1.5-3.25 eV) interface layer formed on bare silicon. The interface layer growth rate was greatly reduced on an oxidized silicon substrate. The results have profound implications on the static dielectric constant of BST.

  16. Composition-dependent surface chemistry of colloidal Ba xSr 1-xTiO 3 perovskite nanocrystals

    DOE PAGES

    Margossian, Tigran; Culver, Sean P.; Larmier, Kim; ...

    2016-11-01

    Ba xSr 1-xTiO 3 perovskite nanocrystals, prepared by the vapor diffusion sol-gel method and characterized by state of the art surface techniques, display significantly different O-H stretching frequencies and adsorption properties towards CO 2 as a function of the alkaline earth composition (Ba vs. Sr). Lastly, the difference of properties can be associated with the more basic nature of BaO-rich than SrO-rich surfaces.

  17. Dynamic Displacement Disorder of Cubic BaTiO3

    NASA Astrophysics Data System (ADS)

    Paściak, M.; Welberry, T. R.; Kulda, J.; Leoni, S.; Hlinka, J.

    2018-04-01

    The three-dimensional distribution of the x-ray diffuse scattering intensity of BaTiO3 has been recorded in a synchrotron experiment and simultaneously computed using molecular dynamics simulations of a shell model. Together, these have allowed the details of the disorder in paraelectric BaTiO3 to be clarified. The narrow sheets of diffuse scattering, related to the famous anisotropic longitudinal correlations of Ti ions, are shown to be caused by the overdamped anharmonic soft phonon branch. This finding demonstrates that the occurrence of narrow sheets of diffuse scattering agrees with a displacive picture of the cubic phase of this textbook ferroelectric material. The presented methodology allows one to go beyond the harmonic approximation in the analysis of phonons and phonon-related scattering.

  18. Ultrasound-assisted synthesis of poly(MMA-co-BA)/ZnO nanocomposites with enhanced physical properties.

    PubMed

    Poddar, Maneesh Kumar; Sharma, Sachin; Pattipaka, Srinivas; Pamu, D; Moholkar, Vijayanand S

    2017-11-01

    The present study reports synthesis and characterization of poly(MMA-co-BA)/ZnO nanocomposites using ultrasound-assisted in-situ emulsion polymerization. Methyl methacrylate (MMA) was copolymerized with butyl acrylate (BA), for enhanced ductility of copolymer matrix, in presence of nanoscale ZnO particles. Ultrasound generated strong micro-turbulence in reaction mixture, which resulted in higher encapsulation and uniform dispersion of ZnO (in native form - without surface modification) in polymer matrix, as compared to mechanical stirring. The nanocomposites were characterized for physical properties and structural morphology using standard techniques such as XRD, FTIR, particle size analysis, UV-Visible spectroscopy, electrical conductivity, TGA, DSC, FE-SEM and TEM. Copolymerization of MMA and BA (in presence of ZnO) followed second order kinetics. Thermal stability (T 10% =324.9°C) and glass transition temperature (T g =67.8°C) of poly(MMA-co-BA)/ZnO nanocomposites showed significant enhancement (35.1°C for 1wt% ZnO and 15.7°C for 4wt% ZnO, respectively), as compared to pristine poly(MMA-co-BA). poly(MMA-co-BA)/ZnO (5wt%) nanocomposites possessed the highest electrical conductivity of 0.192μS/cm and peak UV absorptivity of 0.55 at 372nm. Solution rheological study of nanocomposites revealed enhancement in viscosity with increasing ZnO loading. Maximum viscosity of 0.01Pa-s was obtained for 5wt% ZnO loading. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Magnetic and magnetocaloric properties of Ba and Ti co-doped SrRuO{sub 3}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sarkar, Babusona; Dalal, Biswajit; Dev Ashok, Vishal

    2014-12-28

    Temperature evolution of magnetic properties in Ba and Ti doped SrRuO{sub 3} has been investigated to observe the effects of larger ionic radius Ba at Sr site and isovalent nonmagnetic impurity Ti at Ru site. Ionic radius mismatch and different electronic configuration in comparison with Ru modify Sr(Ba)-O and Ru(Ti)-O bond lengths and Ru-O-Ru bond angle. The apical and basal Ru-O-Ru bond angles vary significantly with Ti doping. Ferromagnetic Curie temperature decreases from 161 K to 149 K monotonically with Ba (10%) and Ti (10%) substitutions at Sr and Ru sites. The zero field cooled (ZFC) magnetization reveals a prominent peak whichmore » shifts towards lower temperature with application of magnetic field. The substitution of tetravalent Ti with localized 3d{sup 0} orbitals for Ru with more delocalized 4d{sup 4} orbitals leads to a broad peak in ZFC magnetization. A spontaneous ZFC magnetization becomes negative below 160 K for all the compositions. The occurrence of both normal and inverse magnetocaloric effects in Ba and Ti co-doped SrRuO{sub 3} makes the system more interesting.« less

  20. Synthesis and characterization of high-Tc superconductors in the Tl-Ca-Ba-Cu-O system

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Farrell, D. E.

    1989-01-01

    Both Tl2Ca2Ba2Cu3O10 and TlCa3BaCu3O8.5 are investigated for superconductivity as a function of the sintering temperature, time, atmosphere, and quench rate in an effort to synthesize the high-Tc superconducting phase in the thallium system. The samples are characterized by electrical resistivity measurements, X-ray diffraction, and scanning electron microscopy. Samples of starting composition Tl2Ca2Ba2Cu3O10 fired in air at 860-900 C and rapidly quenched show a Tc of 96-107 K. In contrast, specimens of starting composition TlCa3BaCu3O8.5 when baked at 900 C and slowly cooled in oxygen superconduct at 116 K and above and consist of Tl2Ca2Ba2Cu3O(10+x) as the dominant phase. The results also show that, in contrast to the case of YBa2Cu3O(7-x), doping with a small concentration of fluorine sharpens the resistive transition and produces a large Tc increase in thallium-based superconductors.

  1. Eu-doped BaTiO₃powder and film from sol-gel process with polyvinylpyrrolidone additive.

    PubMed

    García-Hernández, Margarita; García-Murillo, Antonieta; de J Carrillo-Romo, Felipe; Jaramillo-Vigueras, David; Chadeyron, Geneviève; De la Rosa, Elder; Boyer, Damien

    2009-09-17

    Transparent BaTiO(3):Eu(3+) films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP) as modifier viscosity. BaTiO(3):Eu(3+) films ~500 nm thick, crystallized after thermal treatment at 700 masculineC. 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 Eu(3+) doped BaTiO(3).

  2. Single-crystalline BaTiO3 films grown by gas-source molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Matsubara, Yuya; Takahashi, Kei S.; Tokura, Yoshinori; Kawasaki, Masashi

    2014-12-01

    Thin BaTiO3 films were grown on GdScO3 (110) substrates by metalorganic gas-source molecular beam epitaxy. Titanium tetra-isopropoxide (TTIP) was used as a volatile precursor that provides a wide growth window of the supplied TTIP/Ba ratio for automatic adjustment of the film composition. Within the growth window, compressively strained films can be grown with excellent crystalline quality, whereas films grown outside of the growth window are relaxed with inferior crystallinity. This growth method will provide a way to study the intrinsic properties of ferroelectric BaTiO3 films and their heterostructures by precise control of the stoichiometry, structure, and purity.

  3. Syntheses of nanocrystalline BaTiO3 and their optical properties

    NASA Astrophysics Data System (ADS)

    Yu, J.; Chu, J.; Zhang, M.

    Stoichiometric and titanium-excess nanocrystalline barium titanates were synthesized using a hydrothermal process at various hydrothermal temperatures and with further heat treatment at 500 °C and 900 °C. Owing to the different process conditions, the excess titanium exists in different states and configurations within the nanocrystalline BaTiO3 matrix; this was demonstrated by X-ray diffraction, Raman scattering, and photoluminescence. In these nanocrystalline BaTiO3, the 590, 571, 543 and 694 nm light emission bands were observed; mechanisms leading to such emissions were also discussed.

  4. Deep data mining in a real space: Separation of intertwined electronic responses in a lightly doped BaFe 2As 2

    DOE PAGES

    Ziatdinov, Maxim; Maksov, Artem; Li, Li; ...

    2016-10-25

    Electronic interactions present in material compositions close to the superconducting dome play a key role in the manifestation of high-T c superconductivity. In many correlated electron systems, however, the parent or underdoped states exhibit strongly inhomogeneous electronic landscape at the nanoscale that may be associated with competing, coexisting, or intertwined chemical disorder, strain, magnetic, and structural order parameters. Here we demonstrate an approach based on a combination of scanning tunneling microscopy/spectroscopy and advanced statistical learning for an automatic separation and extraction of statistically significant electronic behaviors in the spin density wave regime of a lightly (~1%) gold-doped BaFe 2As 2.more » Lastly, we show that the decomposed STS spectral features have a direct relevance to fundamental physical properties of the system, such as SDW-induced gap, pseudogap-like state, and impurity resonance states.« less

  5. Deep data mining in a real space: Separation of intertwined electronic responses in a lightly doped BaFe 2As 2

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ziatdinov, Maxim; Maksov, Artem; Li, Li

    Electronic interactions present in material compositions close to the superconducting dome play a key role in the manifestation of high-T c superconductivity. In many correlated electron systems, however, the parent or underdoped states exhibit strongly inhomogeneous electronic landscape at the nanoscale that may be associated with competing, coexisting, or intertwined chemical disorder, strain, magnetic, and structural order parameters. Here we demonstrate an approach based on a combination of scanning tunneling microscopy/spectroscopy and advanced statistical learning for an automatic separation and extraction of statistically significant electronic behaviors in the spin density wave regime of a lightly (~1%) gold-doped BaFe 2As 2.more » Lastly, we show that the decomposed STS spectral features have a direct relevance to fundamental physical properties of the system, such as SDW-induced gap, pseudogap-like state, and impurity resonance states.« less

  6. Synthesis and novel luminescence properties of one-dimension BaMoO{sub 4}:Ln{sup 3+} nanostructures

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Yuping; Li, Mingxia; Pan, Kai

    2015-12-15

    Highlights: • String BaMoO{sub 4}:Ln{sup 3+} nanobeans were prepared by a hydrothermal method. • The Decay dynamics were performed to study the photoluminescence of the BaMoO{sub 4}:Eu{sup 3+} nanobeans. • For BaMoO{sub 4}:Er{sup 3+}/Eu{sup 3+}, the {sup 2}P{sub 3/2} → {sup 4}I{sub 11/2} and {sup 2}H{sub 11/2}/{sup 4}S{sub 3/2} → {sup 4}I{sub 15/2} transitions were observed. - Abstract: String BaMoO{sub 4}:Ln{sup 3+} (Ln = Eu, Tb, Er, and Gd) nanobeans were prepared by a hydrothermal method. The samples were characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscope, and Raman spectrometer. Under direct excitation in themore » charge transfer absorption band, concentration quenching phenomenon occurs and decay dynamics were performed to study the photoluminescence of the string BaMoO{sub 4}:Eu{sup 3+} nanobeans. In the emission spectra of BaMoO{sub 4}:Er{sup 3+}/Eu{sup 3+} under 274 nm excitation, the {sup 2}P{sub 3/2} → {sup 4}I{sub 11/2}, {sup 2}H{sub 11/2} → {sup 4}I{sub 15/2}, and {sup 4}S{sub 3/2} → {sup 4}I{sub 15/2} transitions from Er{sup 3+} ions were observed for the first time. In addition, the photoluminescence properties of BaMoO{sub 4}:Tb{sup 3+}/Eu{sup 3+} and BaMoO{sub 4}:Gd{sup 3+}/Eu{sup 3+} were also investigated.« less

  7. Pt-Bi Antibonding Interaction: The Key Factor for Superconductivity in Monoclinic BaPt2Bi2.

    PubMed

    Gui, Xin; Xing, Lingyi; Wang, Xiaoxiong; Bian, Guang; Jin, Rongying; Xie, Weiwei

    2018-02-19

    In the search for superconductivity in a BaAu 2 Sb 2 -type monoclinic structure, we have successfully synthesized the new compound BaPt 2 Bi 2 , which crystallizes in the space group P2 1 /m (No. 11; Pearson symbol mP10) according to a combination of powder and single-crystal X-ray diffraction and scanning electron microscopy. A sharp electrical resistivity drop and large diamagnetic magnetization below 2.0 K indicates it owns superconducting ground state. This makes BaPt 2 Bi 2 the first reported superconductor in a monoclinic BaAu 2 Sb 2 -type structure, a previously unappreciated structure for superconductivity. First-principles calculations considering spin-orbit coupling indicate that Pt-Bi antibonding interaction plays a critical role in inducing superconductivity.

  8. Growing barium hexaferrite (BaFe{sub 12}O{sub 19}) thin films using chemical solution deposition

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Budiawanti, Sri, E-mail: awanty77@yahoo.com; Faculty of Teacher Training and Education, Sebelas Maret University; Soegijono, Bambang

    Barium hexaferrite (BaFe{sub 12}O{sub 19}, or simply known as BaM) thin films has been recognized as a potential candidate for microwave-based devices, magnetic recording media and data storage. To grow BaM thin films, chemical solution deposition is conducted using the aqueous solution of metal nitrates, which involves spin coatings on Si substrates. Furthermore, Thermal Gravimeter Analysis (TGA), X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM) are applied to evaluate the decomposition behavior, structure, morphology, and magnetic properties of BaM thin films. Additionally, the effects of number of layers variation are also investigated. Finally, magnetic properties analysismore » indicates the isotropic nature of the films.« less

  9. Preparation, photoluminescent properties and luminescent dynamics of BaAlF{sub 5}:Eu{sup 2+} nanophosphors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Wei; College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600; Hua, Ruinian, E-mail: rnhua@dlnu.edu.cn

    2014-12-15

    Graphical abstract: Rice-shaped BaAlF{sub 5}:Eu{sup 2+} nanophosphors were synthesized via one-pot hydrothermal process. The as-prepared BaAlF{sub 5}:Eu{sup 2+} are composed of many particles with an average diameter of 40 nm. When excited at 260 nm, the sharp line emission located at 361 nm of Eu{sup 2+} was observed. The optimum doping concentration of Eu{sup 2+} was confirmed to be 5 mol%. The strong ultraviolet emission of Eu{sup 2+} ions in BaAlF{sub 5}:Eu{sup 2+} nanoparticles suggests that these nanoparticles may have potential applications for sensing, solid-state lasers and spectrometer calibration. - Highlights: • BaAlF{sub 5}:Eu{sup 2+} nanophosphors were synthesized via amore » mild hydrothermal process. • The Van and Huang models were used to research the mechanism of concentration quenching. • The optimum doping concentration of Eu2+ was confirmed to be 5 mol%. - Abstract: Eu{sup 2+}-doped BaAlF{sub 5} nanophosphors were synthesized via a facile one-pot hydrothermal method. The final products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. XRD results showed that the prepared samples are single-phase. The FE-SEM and TEM images indicated that the prepared BaAlF{sub 5}:Eu{sup 2+} nanophosphors are composed of many rice-shaped particles with an average diameter of 40 nm. When excited at 260 nm, BaAlF{sub 5}:Eu{sup 2+} nanophosphors exhibit the sharp line emissions of Eu{sup 2+} at room temperature. The optimum doping concentration of Eu{sup 2+} was confirmed to be 5 mol%. The Van and Huang models were used to study the mechanism of concentration quenching and the electric dipole–dipole interaction between Eu{sup 2+} can be deduced to be a dominant for quenching fluorescence in BaAlF{sub 5}:Eu{sup 2+} nanophosphors. The strong ultraviolet emission of Eu{sup 2+} in BaAlF{sub 5}:Eu{sup 2+} nanophosphors suggests

  10. Different Topological Quantum States in Ternary Zintl compounds: BaCaX (X = Si, Ge, Sn and Pb)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Lin-Lin; Kaminski, Adam; Canfield, Paul C.

    Topological quantum states require stringent combination of crystal symmetry and spin–orbit coupling (SOC) strength. Here in this paper, we report that the ternary Zintl compound series BaCaX (X = Si, Ge, Sn and Pb, Group IV) in the same crystal structure having eight valence electrons per formula unit can host two different topological quantum phases, controlled by atomic size and SOC strength. BaCaSi is a nodal-line semimetal (NLSM) with band inversion protected by mirror symmetry and hosts a strong topological insulator (TI) state when SOC is turned on, thus, a NLSM-TI phase. Moving to larger atomic sizes and heavier atoms,more » BaCaGe and BaCaSn are normal insulators (NIs); then, with the strongest SOC in BaCaPb, a different band inversion is induced, giving a strong TI phase without the need of NLSM. Thus, we also predict two types of topological transitions in a phase diagram for BaCaX: (1) NLSM-TI to NI, then to TI by tuning atomic size and SOC strength via alloying, and (2) NI or TI to NLSM-TI via pressure.« less

  11. Different Topological Quantum States in Ternary Zintl compounds: BaCaX (X = Si, Ge, Sn and Pb)

    DOE PAGES

    Wang, Lin-Lin; Kaminski, Adam; Canfield, Paul C.; ...

    2017-12-14

    Topological quantum states require stringent combination of crystal symmetry and spin–orbit coupling (SOC) strength. Here in this paper, we report that the ternary Zintl compound series BaCaX (X = Si, Ge, Sn and Pb, Group IV) in the same crystal structure having eight valence electrons per formula unit can host two different topological quantum phases, controlled by atomic size and SOC strength. BaCaSi is a nodal-line semimetal (NLSM) with band inversion protected by mirror symmetry and hosts a strong topological insulator (TI) state when SOC is turned on, thus, a NLSM-TI phase. Moving to larger atomic sizes and heavier atoms,more » BaCaGe and BaCaSn are normal insulators (NIs); then, with the strongest SOC in BaCaPb, a different band inversion is induced, giving a strong TI phase without the need of NLSM. Thus, we also predict two types of topological transitions in a phase diagram for BaCaX: (1) NLSM-TI to NI, then to TI by tuning atomic size and SOC strength via alloying, and (2) NI or TI to NLSM-TI via pressure.« less

  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. Local Structure and Anisotropy in the Amorphous Precursor= to Ba-Hexaferrite Thin Films

    NASA Astrophysics Data System (ADS)

    Snyder, J. E.; Harris, V. G.; Koon, N. C.; Sui, X.; Kryder, M. H.

    1996-03-01

    Ba-hexaferrite thin-films for recording media applications are commonly fabricated by a two-step process: sputter-deposition of an amorphous precursor, followed by annealing to crystallize the BaFe_12O_19 phase. The magnetic anisotropy of the crystalline films can be either in-plane or perpendicular, depending on the sputtering process used in the first step. However, conventional characterization techniques (x-ray diffraction and TEM) have been unable to observe any structure in the amorphous precursor films. In this study, such films are investigated by PD-EXAFS (polarization-dependent extended x-ray absorption fine structure). An anisotropic local ordered structure is observed around both Fe and Ba atoms in the "amorphous" films. This anisotropic local structure appears to determine the orientation of the fast-growing basal plane directions during crystallization, and thus the directions of the c-axes and the magnetic anisotropy. Results suggest that the structure of the amorphous films consists of networks made up of units of Fe atoms surrounded by their O nearest neighbors, that are connected together. Ba atoms appear to fit into in-between spaces as network-modifiers.

  14. Four new chalcohalides, NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl: Syntheses, crystal structures and optical properties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Chao; Feng, Kai; Tu, Heng

    Four new chalcohalides, namely NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br, and CsBa{sub 2}SnS{sub 4}Cl, have been synthesized by the conventional high temperature solid-state reactions. They crystallize in three different space groups: space group I4/mcm for NaBa{sub 2}SnS{sub 4}Cl and KBa{sub 2}SnS{sub 4}Cl, Pnma for KBa{sub 2}SnS{sub 4}Br, and P2{sub 1}/c for CsBa{sub 2}SnS{sub 4}Cl. In all four compounds, the X{sup −} halide anions are only connected to six alkali metal or Ba cations, and the Sn atoms are only tetrahedrally enjoined to four S atoms. However, the M–X–Ba pseudo layers and the SnS{sub 4} tetrahedra are arrangedmore » in different ways in the three structural types, which demonstrates the interesting effect of ionic radii on the crystal structures. UV–vis–NIR spectroscopy measurements indicate that NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br, and CsBa{sub 2}SnS{sub 4}Cl have band gaps of 2.28, 2.30, 1.95, and 2.06 eV, respectively. - Graphical abstract: A new series of chalcohalides, NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl have been obtained. They present three different space groups: NaBa{sub 2}SnS{sub 4}Cl and KBa{sub 2}SnS{sub 4}Cl in space group I4/mcm, KBa{sub 2}SnS{sub 4}Br in Pnma and CsBa{sub 2}SnS{sub 4}Cl in space group P2{sub 1}/c. UV–vis–NIR spectroscopy measurements indicate that NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl have band gaps of 2.28, 2.30 1.95, and 2.06 eV, respectively. - Highlights: • Four new chalcohalides, NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl were obtained. • They adopt three different structures owing to different ionic radii and elemental electronegativity. • NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl have

  15. Monoclinic 122-Type BaIr2Ge2 with a Channel Framework: A Structural Connection between Clathrate and Layered Compounds

    DOE PAGES

    Gui, Xin; Chang, Tay-Rong; Kong, Tai; ...

    2017-07-18

    A new 122-type phase, monoclinic BaIr2Ge2 is successfully synthesized by arc melting; X-ray diffraction and scanning electron microscopy are used to purify the phase and determine its crystal structure. BaIr2Ge2 adopts a clathrate-like channel framework structure of the monoclinic BaRh2Si2-type, with space group P21/c. Structural comparisons of clathrate, ThCr2Si2, CaBe2Ge2, and BaRh2Si2 structure types indicate that BaIr2Ge2 can be considered as an intermediate between clathrate and layered compounds. Magnetic measurements show it to be diamagnetic and non-superconducting down to 1.8 K. Different from many layered or clathrate compounds, monoclinic BaIr2Ge2 displays a metallic resistivity. Electronic structure calculations performed for BaIr2Ge2more » support its observed structural stability and physical properties.« less

  16. Monoclinic 122-Type BaIr2Ge2 with a Channel Framework: A Structural Connection between Clathrate and Layered Compounds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gui, Xin; Chang, Tay-Rong; Kong, Tai

    A new 122-type phase, monoclinic BaIr2Ge2 is successfully synthesized by arc melting; X-ray diffraction and scanning electron microscopy are used to purify the phase and determine its crystal structure. BaIr2Ge2 adopts a clathrate-like channel framework structure of the monoclinic BaRh2Si2-type, with space group P21/c. Structural comparisons of clathrate, ThCr2Si2, CaBe2Ge2, and BaRh2Si2 structure types indicate that BaIr2Ge2 can be considered as an intermediate between clathrate and layered compounds. Magnetic measurements show it to be diamagnetic and non-superconducting down to 1.8 K. Different from many layered or clathrate compounds, monoclinic BaIr2Ge2 displays a metallic resistivity. Electronic structure calculations performed for BaIr2Ge2more » support its observed structural stability and physical properties.« less

  17. Optimization of rotational speed for growing BaFe12O19 thin films using spin coating

    NASA Astrophysics Data System (ADS)

    Budiawanti, S.; Soegijono, B.; Mudzakir, I.; Suharno, Fadillah, L.

    2017-07-01

    Barium ferrite (BaFe12O19, BaM) thin films were fabricated by the spin coating of precursors obtained by using a sol-gel method. The effects of the rotational speed on the spin-coating process for growing a BaM thin film were investigated in this study. Coated films were heat-deposited at different rotational speeds ranging from 2000 to 4000 rpm, while the number of layers was set to nine. Further, the effect of the number of layers on the growth of BaM thin films was discussed. For this purpose, we take the layers number 1 to 12 and take the constant rotational speed of 3000 rpm. All the film were characterized using X-Ray diffraction, Scanning Electron microscope, and Energy-dispersive X-Ray spectroscopy and Vibrating Sample Magnetometer. It was found that by increasing the rotational speed the amount of material deposited on the Si substrate decreased. The measured grain size of the BaM thin film was nearly similar for three three different rotational speeds. However, the grain size was found to increase the number of layers.

  18. Microbial release of 226Ra2+ from (Ba,Ra)SO4 sludges from uranium mine wastes.

    PubMed Central

    Fedorak, P M; Westlake, D W; Anders, C; Kratochvil, B; Motkosky, N; Anderson, W B; Huck, P M

    1986-01-01

    226Ra2+ is removed from uranium mine effluents by coprecipitation with BaSO4. (Ba,Ra)SO4 sludge samples from two Canadian mine sites were found to contain active heterotrophic populations of aerobic, anaerobic, denitrifying, and sulfate-reducing bacteria. Under laboratory conditions, sulfate reduction occurred in batch cultures when carbon sources such as acetate, glucose, glycollate, lactate, or pyruvate were added to samples of (Ba,Ra)SO4 sludge. No external sources of nitrogen or phosphate were required for this activity. Further studies with lactate supplementation showed that once the soluble SO4(2-) in the overlying water was depleted, Ba2+ and 226Ra2+ were dissolved from the (Ba,Ra)SO4 sludge, with the concurrent production of S2-. Levels of dissolved 226Ra2+ reached approximately 400 Bq/liter after 10 weeks of incubation. Results suggest that the ultimate disposal of these sludges must maintain conditions to minimize the activity of the indigenous sulfate-reducing bacteria to ensure that unacceptably high levels of 226Ra2+ are not released to the environment. PMID:3752993

  19. Thermoelectric properties of conducting polyaniline/BaTiO3 nanoparticle composite films

    NASA Astrophysics Data System (ADS)

    Anno, H.; Yamaguchi, K.; Nakabayashi, T.; Kurokawa, H.; Akagi, F.; Hojo, M.; Toshima, N.

    2011-05-01

    Conducting polyaniline (PANI)/BaTiO3 nanoparticle composite films with different molar ratio values R=1, 5, 10, and 100 have been prepared on a quartz substrate by casting the m-cresol solution of PANI, (±)-10-camphorsulfonic acid (CSA) and BaTiO3 nanoparticle with an average diameter of about 20 nm. The CSA-doped PANI/BaTiO3 composite films were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, and UV-Vis transmission spectroscopy. The Seebeck coefficient and the electrical conductivity of the films with different R values, together with CSA-doped PANI films, were measured in the temperature range from room temperature to ~400 K. The relation between the Seebeck coefficient and the electrical conductivity in the composite films are discussed from a comparison of them with those of CSA-doped PANI films and other PANI composite films.

  20. 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.

  1. Synthesis and superconductivity of highly underdoped HgBa2CuO4+δ

    NASA Astrophysics Data System (ADS)

    Edwards, P. P.; Gameson, I.; Fletcher, A.; Peacock, G. B.

    1998-05-01

    The highest transition temperature superconductors are found within the complex homologous series HgBa2Can-1CunO2n+2+δ (n=1-7), with the third member, HgBa2Ca2Cu3O8+δ possessing the record-high transition temperature (Tc) of 135 K at room pressure. The first member of this family, HgBa2CuO4+δ having a Tc of up to 97 K, displays the highest transition temperature for any analogous compounds with a single copper-layer. The chemical reaction for the formation of this material is intrinsically complex due to the natural high volatility of mercury-bearing compounds; chemical synthesis has been postulated to proceed via a solid-vapour reaction. With this in mind, we have developed a mixed solid/vapour phase synthesis for HgBa2CuO4+δ using what one might term a `remote' source of mercury, in this case elemental Hg itself. Interestingly, because of the zero oxidation state of elemental mercury in the reagent mixture, the synthesis reaction proceeds under reducing conditions. By this route, a highly underdoped state (Tc<=35 K) of the superconducting phase HgBa2CuO4+δ is readily obtained. This level of underdoping is extremely difficult to achieve by more conventional synthetic routes. We comment on the unusually high oxygen affinity of the resulting underdoped compound, in relation to other cuprate superconductors, and the implied mobility of oxygen defects within the crystal structure.

  2. 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.

  3. Multiphase nanodomains in a strained BaTiO3 film on a GdScO3 substrate

    NASA Astrophysics Data System (ADS)

    Kobayashi, Shunsuke; Inoue, Kazutoshi; Kato, Takeharu; Ikuhara, Yuichi; Yamamoto, Takahisa

    2018-02-01

    Controlling the crystal structure of ferroelectric materials via epitaxial strain, which is a well-known technique in strain engineering, can lead to the formation of unique domain structures generating non-intrinsic phenomena such as electronic conductivity, photovoltages, and enhanced piezoelectric characteristics. Strained BaTiO3 films are promising ferroelectric materials as theoretical modeling predicts that different domain morphologies can introduce additional properties not observed in conventional BaTiO3 ceramics. To rationally design materials for practical application, a thorough understanding of the formation mechanisms and stabilities of different domain structures in strained BaTiO3 films is required. However, there have been very few experimental reports on this topic, and details about the domain structures in strained BaTiO3 films are currently lacking. In this paper, we report multiphase nanodomains in a strained BaTiO3 film deposited on an orthorhombic GdScO3 substrate. The phase-transition behavior of the strained BaTiO3 film reveals that it contains multiple phases at room temperature; the film first undergoes a phase-transition upon heating at around 550 K, and then a paraelectric phase forms at temperatures above 690 K. A picometer-scale analysis of the Ti ion displacements, using an advanced scanning transmission electron microscopy technique, is used to characterize the complex multiphase nanodomains, providing useful insights into the control of domain structures in BaTiO3 films by applying epitaxial strain.

  4. Effects of Sulfation Level on the Desulfation Behavior of Presulfated Pt-BaO/Al2O3 Lean

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kim, D.; Szanyi, J; Kwak, J

    2009-01-01

    Desulfation by hydrogen of presulfated Pt (2 wt %)-BaO(20 wt %)/Al2O3 with various sulfur loading (S/Ba = 0.12, 0.31, and 0.62) were investigated by combining H2 temperature programmed reaction (TPRX), X-ray photoelectron spectroscopy (XPS), in situ sulfur K-edge X-ray absorption near-edge spectroscopy (XANES), and synchrotron time-resolved X-ray diffraction (TR-XRD) techniques. We find that the amount of H2S desorbed during the desulfation in the H2 TPRX experiments is not proportional to the amount of initial sulfur loading. The results of both in situ sulfur K-edge XANES and TR-XRD show that at low sulfur loadings, sulfates were transformed to a BaS phasemore » and remained in the catalyst rather than being removed as H2S. On the other hand, when the deposited sulfur level exceeded a certain threshold (at least S/Ba = 0.31) sulfates were reduced to form H2S, and the relative amount of the residual sulfide species in the catalyst was much less than at low sulfur loading. Unlike samples with high sulfur loading (e.g., S/Ba = 0.62), H2O did not promote the desulfation for the sample with S/Ba of 0.12, implying that the formed BaS species originating from the reduction of sulfates at low sulfur loading are more stable to hydrolysis. The results of this combined spectroscopy investigation provide clear evidence to show that sulfates at low sulfur loadings are less likely to be removed as H2S and have a greater tendency to be transformed to BaS on the material, leading to the conclusion that desulfation behavior of Pt-BaO/Al2O3 lean NOx trap catalysts is markedly dependent on the sulfation levels.« less

  5. 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

  6. Relationship between fabrication method and chemical stability of Ni-BaZr0.8Y0.2O3-δ membrane

    NASA Astrophysics Data System (ADS)

    Fang, Shumin; Wang, Siwei; Brinkman, Kyle S.; Su, Qing; Wang, Haiyan; Chen, Fanglin

    2015-03-01

    NiO effectively promotes the sintering of highly refractory Y-doped BaZrO3 (BZY) through the formation of BaY2NiO5, providing a simple and cost-effective method for the fabrication of dense BZY electrolyte and Ni-BZY hydrogen separation membrane at ∼1400 °C. Unfortunately, insulating BaCO3 and Y2O3 phases formed on the surface of BZY and Ni-BZY prepared by solid state reaction method with NiO after annealing in wet CO2. Ni-BZY membranes prepared from different methods suffered different degree of performance loss in wet H2 at 900 °C. The chemical instability of Ni-BZY is attributed to the formation of a secondary phase (BaY2O4) generated from the reduction of BaY2NiO5 in H2 during the sintering process. Both BaY2O4 and BaY2NiO5 react with H2O, and CO2 at elevated temperatures, generating insulating Ba(OH)2 and BaCO3 phases, respectively. The less BaY2O4 is formed in the fabrication process, the better chemical stability the Ni-BZY membranes possess. Therefore, a new Ni-BZY membrane is prepared through a judicial combination of BZY powders prepared from combined EDTA-citric and solid state reaction methods, and demonstrates exceptional chemical stability in H2O and CO2, enabling stable and even improved hydrogen flux in wet 50% CO2 at 900 °C.

  7. Interfacial magnetic coupling in hetero-structure of Fe/double-perovskite NdBaMn2O6 single crystal

    NASA Astrophysics Data System (ADS)

    Lin, W. C.; Tsai, C. L.; Ogawa, K.; Yamada, S.; Gandhi, Ashish C.; Lin, J. G.

    2018-04-01

    The interfacial magnetic coupling between metallic Fe and the double-perovskite NdBaMn2O6 single crystal was investigated in the heterostructure of 4-nm Pd/10-nm Fe/NdBaMn2O6. A considerable magnetic coupling effect was observed in the temperature range coincident with the magnetic phase transition of NdBaMn2O6. When the temperature was elevated above 270 K, NdBaMn2O6 transformed from a state of antiferromagnetic fluctuating domains to a superparamagnetism-like (ferromagnetic fluctuation) state with high magnetic susceptibility. Concurrently, the interfacial magnetic coupling between the Fe layer and the NdBaMn2O6 crystal was observed, as indicated by the considerable squareness reduction and coercivity enhancement in the Fe layer. Moreover, the presence of the Fe layer changed the magnetic structure of NdBaMn2O6 from conventional 4-fold symmetry to 2-fold symmetry. These observations offer applicable insights into the mutual magnetic interaction in the heterostructures of metallic ferromagnetism/perovskite materials.

  8. Synthesis and Characterization of BaFe12O19/Poly(aniline, pyrrole, ethylene terephthalate) Composites Coatings as Radar Absorbing Material (RAM)

    NASA Astrophysics Data System (ADS)

    Sasria, Nia; Ardhyananta, H.; Fajarin, R.; Widyastuti

    2017-07-01

    This research shows the processing and design of radar absorbing material (RAM) based on barium hexaferrite (BaM) and poly(aniline, pyrrole, ethylene terephthalate) (PAni,PPy,PET). BaM was prepared by sol gel method with Ni-Zn doping at mole fraction of 0. 4 to obtain soft magnetic material. BaM/(PAni,PPy) composites were synthesized by in-situ polymerization method at ˜0 °C. (BaM/PET) composite was prepared by melt compounding at 220°C. The composites were coated on A-grade AH36 steel using Dallenbach Layer, Salisbury Screen and Jaumann Layer methods with thickness of 2, 4, and 6 mm. The composites were evaluated using XRD, SEM, FTIR, VSM, LCM-meter and VNA. Results showed that doped BaM showed BaNixZnxFe12-2xO19 structure. BaM/(PAni,PPy,PET) composites possessed globular morphology with M-O and C-H bonds. BaNixZnxFe12-2xO19 exhibited the value of Ms and Hc, 56.6 emu/g and 60 Oe respectively. High electrical conductivity of 1.77744 × 10-5 S/cm was achieved of BaM/PAni composite. The maximum reflection loss (RL) was reached at - 48.720 dB and 8.1 GHz for BaM/PAni composite coating with 6 mm thickness at Jaumann Layer. These results indicated that BaM/PAni composite was a soft magnetic material with a high RL value that is suitable for RAM, which used in stealth technology on naval vessels.

  9. Ba-filled Ni–Sb–Sn based skutterudites with anomalously high lattice thermal conductivity

    DOE PAGES

    Paschinger, W.; Rogl, Gerda; Grytsiv, A.; ...

    2016-06-21

    Here, in this study, novel filled skutterudites Ba yNi 4Sb 12-xSn x (y max = 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 Ni 4(Sb,Sn) 12, the Ba–Ni–Sn–Sb skutterudite system is perfectly suitedmore » to study the influence of filler atoms on the phonon thermal conductivity. Single-phase samples with the composition Ni 4Sb 8.2Sn 3.8, Ba 0.42Ni 4Sb 8.2Sn 3.8 and Ba 0.92Ni 4Sb 6.7Sn 5.3 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 Ba 0.73Ni 4Sb 8.1Sn 3.9 and Ba 0.95Ni 4Sb 6.1Sn 5.9. 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 Ni 4Sb 8.2Sn 3.8 to 116 GPa for Ba 0.92Ni 4Sb 6.7Sn 5.3. The thermal expansion coefficients were 11.8 × 10 -6 K -1 for Ni 4Sb 8.2Sn

  10. Magneto-optical properties of BaTiO3/La0.76Sr0.24MnO3/BaTiO3 heterostructures

    NASA Astrophysics Data System (ADS)

    Moog, M.; Singamaneni, S. R.; Prater, J. T.; Biegalski, M. D.; Tsui, F.

    2018-05-01

    The magnetic properties of epitaxial BaTiO3/La0.76Sr0.24MnO3/BaTiO3 (BTO/LSMO/BTO) heterostructures have been studied using magneto-optic Kerr effect (MOKE) technique. Both longitudinal and polar MOKE were probed as a function of magnetic field and temperature (in the range between 80 and 320 K) for epitaxial films of BTO/LSMO/BTO and LSMO grown on TiO2-terminated SrTiO3 (001) substrates by pulsed laser deposition technique. The LSMO film without the BTO layers exhibits nearly square field-dependent MOKE hysteresis loops with low saturation fields below a bulk-like Curie temperature (TC) of ˜ 350K. In contrast, the film with the BTO layers exhibits a significantly suppressed TC of 155 K, accompanied by significantly enhanced coercive fields and perpendicular magnetic anisotropy.

  11. Managing SRS competition in a miniature visible Nd:YVO4/BaWO4 Raman laser.

    PubMed

    Li, Xiaoli; Lee, Andrew J; Huo, Yujing; Zhang, Huaijin; Wang, Jiyang; Piper, James A; Pask, Helen M; Spence, David J

    2012-08-13

    We demonstrate the operation of a compact and efficient continuous wave (CW) self-Raman laser utilizing a Nd:YVO4 gain crystal and BaWO4 Raman crystal, generating yellow emission at 590 nm. We investigate the competition that occurs between Stokes lines in the Nd:YVO4 and BaWO4 crystals, and within the BaWO4 crystal itself. Through careful consideration of crystal length and orientation, we are able to suppress competition between Stokes lines, and generate pure yellow emission at 590 nm with output power of 194 mW for just 3.8 W pump power.

  12. Irradiation effect on luminescence properties of fluoroperovskite single crystal (LiBaF3:Eu2+)

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    Single crystals of pure and Eu2+ doped LiBaF3 have been grown from melt by using a vertical Bridgman-Stockbarger method. Effects induced by irradiation on europium doped LiBaF3 (lithium barium fluoride) single crystals were monitored by optical absorption, photoluminescence and thermoluminescence studies. The absorption bands of Eu2+ ions with peaks at 240, 290 and 320 nm were observed in the LiBaF3:Eu2+ crystal. Drastic increase in absorption was noted below 600 nm after gamma irradiation, which was dependent on the radiation dose. The additional absorption peak at around 570 nm was observed in irradiated crystal due to the ionization process Eu2+(-)e-→Eu3+. Photoluminescence of Eu2+ doped LiBaF3 single crystal shows sharp line peaked at ~359 nm and a broad band extending between 370 and 450 nm which shows a considerable reduction in Eu2+ PL intensity after gamma irradiation. Irradiated LiBaF3:Eu2+ sample has revealed three intense TL glow peaks at 128 °C (peak-1), 281 °C (peak-2) and 407 °C (peak-3). Activation energy (E) and frequency factor (s) of the latter two peaks were determined by various heating rate (VHR) method and graphical method.

  13. Sintering and Microstructure of BaTiO3 Nano Particles Synthesized by Molten Salt Method.

    PubMed

    Lee, Chang-Hyun; Shin, Hyo-Soon; Yeo, Dong-Hun; Ha, Gook-Hyun; Nahm, Sahn

    2016-05-01

    In order to establish thinner dielectric layers in thick film electronic components such as MLCC (Multilayer ceramic capacitor), BaTiO3 nanoparticles have been utilized. However, studies on the synthesis of nanoparticles smaller than 20 nm, the characteristics of the BaTiO3 powder, and the powder's sintering are lacking. Therefore, this paper aims to synthesize BaTiO3 particles smaller than 20 nm by using the molten salt method and evaluate the microstructure and dielectric properties by varying the sintering temperature from 750 degrees C to 1200 degrees C. Through the molten salt method and by using KOH-KCl mixed salt, 20 nm BaTiO3 powder was synthesized at a low temperature of 150 degrees C. Sintering the pellets formed from the synthesized 20 nm BaTiO3 nano powder led to the observation of an unusual phenomenon where the particles grew to approximate sizes below 850 degrees C where densification progressed. At sintering temperatures above 950 degrees C, particles that expanded into rod shapes were observed and these particles were identified to be unreacted TiO2 based on the results of the EDX (Energy Dispersive X-ray Spectroscopy) analysis and phase analysis results.

  14. Structural, optoelectronic, and thermoelectric properties of AZn13 (A=Na, K, Ca, Sr, Ba) compounds

    NASA Astrophysics Data System (ADS)

    Basit, Abdul; Murtaza, G.; Mahmood, Asif; Yar, Abdullah; Muhammad, S.

    2016-08-01

    We report the structural, electronic, optical, and thermoelectric properties of the five cubic alkali-earth transition-metals AZn13 (A-Na, K, Ca, Sr, Ba) using density functional theory. Structural properties, electronic structures and optical behaviors are calculated explicitly via highly accurate contemporary full potential-linearized augmented plane wave (FP-LAPW) method. The investigated ground state data of these materials is quite close to the experimental information. The modified Becke-Johnson (mBJ) predicts the intermetallic nature of AZn13 (A-Na, K, Ca, Sr, Ba) materials. The complex dielectric function of these intermetallic compounds has been calculated and the observed noticeable peaks are examined through mBJ. With the help of complex dielectric function, the other important optical parameters like reflectivities, conductivities and refractive indices of AZn13 (A-Na, K, Ca, Sr, Ba) have been calculated as a function of energy. The optical response suggests that AZn13 (A-Na, K, Ca, Sr, Ba) compounds can be used for the optoelectronic devices. Further, the thermoelectric properties have been calculated through BoltzTraP program, the calculated values for different thermoelectric parameters recommend that these AZn13 (A-Na, K, Ca, Sr, Ba) materials are the suitable candidates for thermoelectric applications.

  15. Study of activation cross sections of deuteron induced reactions on barium. Production of 131Cs, 133Ba

    NASA Astrophysics Data System (ADS)

    Tárkányi, F.; Hermanne, A.; Ditrói, F.; Takács, S.; Szücs, Z.; Brezovcsik, K.

    2018-01-01

    In the frame of a systematic study of deuteron induced activation processes on middle mass elements, excitation functions of the natBa(d,x) 135,133,132La, 135m,133m,133mg,131mgBa, 136mg,134mg,132,129Cs reactions were measured up to 50 MeV for the first time. Cross sections were measured with the activation method using a stacked foil irradiation technique followed by HPGe γ-ray spectrometry. A comparison with the results of the nuclear model TALYS code (reported in the TENDL-2015 library) was done. The potential use of the deuteron induced reactions on Ba for applications (131Cs and 131Ba production) is discussed.

  16. Synthesis, crystal structure, and magnetic properties of quaternary iron selenides: Ba{sub 2}FePnSe{sub 5} (Pn=Sb, Bi)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Jian; Greenfield, Joshua T.; Kovnir, Kirill

    Two new barium iron pnictide–selenides, Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5}, were synthesized by a high-temperature solid-state route and their crystal structures were determined using single crystal X-ray diffraction. Both compounds are isomorphic to the high pressure phase Ba{sub 3}FeS{sub 5} and crystallize in the orthorhombic space group Pnma (No. 62) with cell parameters of a=12.603(2)/12.619(2) Å, b=9.106(1)/9.183(1) Å, c=9.145(1)/9.123(1) Å and Z=4 for Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5}, respectively. According to differential scanning calorimetry, Ba{sub 2}FePnSe{sub 5} compounds exhibit high thermal stability and melt congruently at 1055(5) K (Pn=Sb) and 1105(5) K (Pn=Bi). Magnetic characterizations revealmore » strong antiferromagnetic nearest-neighbor interactions in both compounds resulting in an antiferromagnetic ordering at 58(1) K for Ba{sub 2}FeSbSe{sub 5} and 79(2) K for Ba{sub 2}FeBiSe{sub 5}. The magnetic interactions between Fe{sup 3+} centers, which are at least 6 Å apart from each other, are mediated by superexchange interactions. - Graphical abstract: In Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5} the magnetic interactions between Fe{sup 3+} centers, which are at least 6 Å apart from each other, are mediated by superexchange interactions. - Highlights: • New compounds Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5} have been synthesized. • The crystal structure was determined by single crystal X-ray diffraction. • Both compounds melt congruently at temperatures above 1000 K. • Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5} exhibit AFM ordering at 58 K (Sb) and 70 K (Bi). • Magnetic exchange between Fe{sup 3+} is mediated by either Se–Sb(Bi)–Se or Se–Ba–Se bridges.« less

  17. F-aggregate centers formation in BaLiF3 crystals

    NASA Astrophysics Data System (ADS)

    Prado, L.; Gomes, L.; Baldochi, S. L.; Morato, S. P.; Vieira, N. D.

    The kinetics of F-aggregate centers formation is investigated in the inverted fluoroperovskite of BaLiF3 submitted to electron-irradiation. By studies of the changes in the absorption spectra during storage of samples in the dark, at room temperature, it was possible to verify a surprising and interesting dependence on defect formation with the crystal growth direction. In spite of its cubic structure, crystals grown in the <100> and <111> directions and submitted to the same conditions of irradiation, showed in particular, to enhance the production of a defect absorbing at 630 nm in <100> crystals which we believe to correspond to F+2-centers in BaLiF3

  18. Optical properties of Pr-doped BaY2F8

    NASA Astrophysics Data System (ADS)

    Andrade, Adriano B.; de Mello, Ana C. S.; Rezende, Marcos V. dos S.; Baldochi, Sonia L.; Valerio, Mário E. G.

    2014-08-01

    Crystalline samples of Pr-doped BaY2F8 (BaYF) were prepared by zone melting technique. The pure phase obtained was identified by X-ray diffraction measurement. Optical absorption result was evaluated and it showed that the formation of the absorption bands can be connected to color centers generated by radiation in the matrix. Radioluminescence emission measurements after excitation by X-ray showed that the material exhibited components responsible for long lasting phosphorescence. Short decay times were also evaluated, the measurements showed a fast component around 70 ns associated to the 4f15d1 → 4f2 transition of the Pr3+ ion. The Thermoluminescence (TL) results indicate the presence of two trapping centers.

  19. Thermodynamics of "exotic" Bañados-Teitelboim-Zanelli black holes.

    PubMed

    Townsend, Paul K; Zhang, Baocheng

    2013-06-14

    A number of three-dimensional (3D) gravity models, such as 3D conformal gravity, admit "exotic" black hole solutions: the metric is the same as the Bañados-Teitelboim-Zanelli metric of 3D Einstein gravity but with reversed roles for mass and angular momentum, and an entropy proportional to the length of the inner horizon instead of the event horizon. Here we show that the Bañados-Teitelboim-Zanelli solutions of the exotic 3D Einstein gravity (with parity-odd action but Einstein field equations) are exotic black holes, and we investigate their thermodynamics. The first and second laws of black hole thermodynamics still apply, and the entropy still has a statistical interpretation.

  20. Widely tunable 1.94-μm Tm:BaY2F8 laser

    NASA Astrophysics Data System (ADS)

    Galzerano, Gianluca; Cornacchia, Francesco; Parisi, Daniela; Toncelli, Alessandra; Tonelli, Mauro; Laporta, Paolo

    2005-04-01

    A novel BaY2F8 crystal doped with thulium ions is grown and extensively investigated. Owing to the large number of vibronic levels and to a favorable electron-phonon coupling, extremely wide absorption and emission bands around 1.9 μm are observed. A room-temperature Tm:BaY2F8 laser tunable over a 210-nm interval, from 1849 to 2059 nm, is demonstrated.

  1. 65Zn and 133Ba standardizing by photon-photon coincidence counting

    NASA Astrophysics Data System (ADS)

    Loureiro, Jamir S.; da Cruz, Paulo A. L.; Iwahara, Akira; Delgado, José U.; Lopes, Ricardo T.

    2018-03-01

    The LNMRI/Brazil has deployed a system using X-gamma coincidence technique for the standardizing radionuclide, which present simple and complex decay scheme with X-rays of energy below 100 keV. The work was carried on radionuclide metrology laboratory using a sodium iodide detector, for gamma photons, in combination with a high purity germanium detector for X-rays. Samples of 65Zn and 133Ba were standardized and the results for both radionuclides showed good precision and accuracy when compared with reference values. The standardization differences were 0.72 % for 65Zn and 0.48 % for 133Ba samples.

  2. Crystallographic orientation of epitaxial BaTiO3 films: The role of thermal-expansion mismatch with the substrate

    NASA Astrophysics Data System (ADS)

    Srikant, V.; Tarsa, E. J.; Clarke, D. R.; Speck, J. S.

    1995-02-01

    Expitaxial ferroelectric BaTiO3 thin films have been grown on (001) MgO and MgO-buffered (001) GaAs substrates by pulsed laser deposition to explore the effect of substrate lattice parameter. X-ray-diffraction studies showed that the BaTiO3 films on both MgO single-crystal substrates and MgO-buffered (001) GaAs substrates have a cube-on-cube epitaxy; however, for the BaTiO3 films grown on MgO the spacing of the planes parallel to the substrate was close to the c-axis dimension of the unconstrained tetragonal phase, whereas the BaTiO3 films on MgO/GaAs exhibited a spacing closer to the a-axis dimension of the unconstrained tetragonal phase. The cube-on-cube epitaxy was maintained through the heterostructures even when thin epitaxial intermediate buffer layers of SrTiO3 and La(0.5)Sr(0.5)CoO3 were used. The intermediate layers had no effect on the position of the BaTiO3 peak in theta - 2 theta scans. Together, these observations indicate that, for the materials combinations studied, it is the thermal-expansion mismatch between the film and the underlying substrate that determines the crystallographic orientation of the BaTiO3 film. Preliminary measurements indicate that the BaTiO3 films are 'weakly' ferroelectric.

  3. A study approach on ferroelectric domains in BaTiO{sub 3}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rocha, L.S.R.; Cavalcanti, C.S.

    Atomic Force Acoustic Microscopy (AFAM) and Piezoresponse Force Microscopy (PFM) were used to study local elastic and electromechanical response in BaTiO{sub 3} ceramics. A commercial multi-mode Scanning Probe Microscopy (SPM) and AFAM mode to image contact stiffness were employed to accomplish the aforementioned purposes. Stiffness parameters along with Young's moduli and piezo coefficients were quantitatively determined. PFM studies were based on electrostatic and electromechanical response from localized tip-surface contact. Comparison was made regarding the Young's moduli obtained by AFAM and PFM. In addition, phase and amplitude images were analyzed based on poling behavior, obtained via the application of − 10more » V to + 10 V local voltage. - Highlights: •Nanoscale behavior of piezo domains in BaTiO{sub 3} ferroelectric materials •Use of Atomic Force Acoustic Microscopy (AFAM) and Piezo Force Microscopy (PFM) •Local elastic and electromechanical response in BaTiO{sub 3} ceramics •The young's moduli obtained from AFAM and PFM.« less

  4. Synthesis, characterization and microwave characteristics of ATP/BaFe12O19/PANI ternary composites

    NASA Astrophysics Data System (ADS)

    Bai, Dezhong; Feng, Huixia; Chen, Nali; Tan, Lin; Qiu, Jianhui

    2018-07-01

    In this paper, we introduced attapulgite (ATP) into the system of ferrite composites for the first time. By sol-gel self-propagating combustion method, attapulgite/barium ferrite (ATP/BaFe12O19) was prepared, and then ternary composites of attapulgite/barium ferrite/polyaniline (ATP/BaFe12O19/PANI) were obtained by in-situ oxidative polymerization of aniline on ATP/BaFe12O19 mixture. The phase composition, morphology and electromagnetic properties of the as-prepared composites were characterized by X-ray diffraction (XRD), Transmission election microscope (TEM), Fourier transform infrared (FTIR), vibrating sample magnetometer (VSM) and vector network analyzer (VNA). We found that the ATP/BaFe12O19/PANI composites at a thickness of 2 mm have the minimum reflection loss of -11.89 dB at 11.28 GHz, besides the effective absorption bandwidth (less than -5 dB) reached 6.39 GHz (from 8.42 GHz to 14.81 GHz).

  5. Overexpression of Apg-2 increases cell proliferation and protects from oxidative damage in BaF3-BCR/ABL cells.

    PubMed

    Li, Chunli; Liu, Dingbin; Yuan, Ying; Huang, Shifeng; Shi, Meng; Tao, Kun; Feng, Wenli

    2010-04-01

    Apg-2, a mammalian heat-shock protein belonging to the heat-shock protein 110 (Hsp110) family, was previously found to be overexpressed in BaF3-BCR/ABL cells that were treated with hydrogen peroxide (H2O2) through our comparative proteomics study. The expression of Apg-2 in chronic myelogenous leukemia (CML) cells and its role have not been investigated, forming the basis for this study. BaF3-MIGR1 and BaF3-BCR/ABL cell lines stably overexpressing Apg-2 were established and exposed to 50 microM H2O2 for 10 min. Western blot analysis of Apg-2 expression confirmed that H2O2 treatment significantly up-regulated Apg-2 expression. Apg-2 overexpression elevated BaF3-BCR/ABL cell proportions in S and G2/M phase, increased cell proliferation and colony formation in vitro. Moreover, BaF3-MIGR1 and BaF3-BCR/ABL cells were exposed to 50 microM H2O2 in the absence or presence of Apg-2 overexpression and induction of H2AX phosphorylation, the reporters of DNA damage were assessed by Western blot and immunofluorescence. Results showed that exposure to H2O2 induced H2AX phosphorylation in BaF3-MIGR1 cells, but no increase was observed in BaF3-BCR/ABL cells. Together, the data indicate that Apg-2 is overexpressed and overexpression of Apg-2 in BaF3-BCR/ABL cells increases cell proliferation and protects cells from oxidative damage, which may play an important role in CML carcinogenesis and progression.

  6. 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

  7. Two- and Three-Body Charmless B Decays at BaBar

    DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    2012-04-05

    We report recent measurements of rare charmless B decays performed by BaBar. The results are based on the final BaBar dataset of 424 fb{sup -1} collected at the PEP-II B-factory based at the SLAC National Accelerator Laboratory. The study of rare B decays is a key ingredient to meet two of the main goals of the B-factories: assessing the validity of the Cabibbo-Kobayashi-Maskawa (CKM) picture of CP-violation by precisely measuring the elements of the Unitarity Triangle (UT), and searching for hints of New Physics (NP), or otherwise constraining NP scenarios, in processes which are suppressed in the Standard Model (SM).more » In loop processes, in particular, NP at some higher energy scale may manifest itself in the low energy effective theory as new couplings, such as those introduced by new very massive virtual particles in the loop. In NP searches hadronic uncertainties can play a major role, expecially for branching fraction measurements. Many theoretical uncertainties cancel in ratios of amplitudes, and most NP probes are therefore of this kind. In the following sections we report recent measurements, performed by the BaBar Collaboration, that are relevant to NP searches in charmless hadronic B decays.« less

  8. 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

  9. Investigation of physical and mechanical properties of (BaSnO3)x(Bi,Pb)-2223 composite

    NASA Astrophysics Data System (ADS)

    Habanjar, K.; Barakat, M. M. E.; Awad, R.

    2017-07-01

    The effect of BaSnO3 nanoparticles addition on the structural and mechanical properties of (Bi,Pb)-2223 superconducting phase by means of X-rays diffraction analysis (XRD), scanning electron microscope (SEM), electrical resistance and Vickers microhardness measurement was studied. BaSnO3 nanomaterial and (BaSnO3)x(Bi,Pb)-2223 superconducting samples were prepared using co-precipitation method and standard solid-state reaction techniques, respectively. From XRD data, the addition of BaSnO3 into (Bi,Pb)-2223 phase does not affect the tetragonal structure and the lattice parameters. SEM images indicate that the microstructure of (Bi,Pb)-2223 was enhanced by adding BaSnO3 nanoparticles by filling its pores and voids. The superconducting transition temperature Tc as well as the critical transport current density Jc, estimated from electrical resistivity measurements, are increased up to x = 0.5 wt%, then decreased with further increase in x. Vickers microhardness measurements Hv were carried out at room temperature as a function of applied. The experimental Hv results were analysed in view of Meyer’s law, Hays and Kendall (HK) approach, elastic/plastic deformation (EPD) and proportional specimen resistance (PSR). All samples exhibit normal indentation size effect (ISE), in addition to that, the analysis shows that the Hays and Kendall model is the most suitable one to describe the load independent microhardness for (BaSnO3)x(Bi,Pb)-2223 superconducting samples.

  10. Scintillation properties of Eu 2+-doped KBa 2I 5 and K 2BaI 4

    DOE PAGES

    Stand, L.; Zhuravleva, M.; Chakoumakos, Bryan C.; ...

    2015-09-25

    We report two new ternary metal halide scintillators, KBa 2I 5 and K 2BaI 4, activated with divalent europium. Single crystal X-ray diffraction measurements confirmed that KBa 2I 5 has a monoclinic structure (P2 1/c) and that K 2BaI 4 has a rhombohedral structure (R3c). Differential scanning calorimetry showed singular melting and crystallization points, making these compounds viable candidates for melt growth. We grew 13 mm diameter single crystals of KBa 2I 5:Eu 2+ and K 2BaI 4:Eu2+ in evacuated quartz ampoules via the vertical Bridgman technique. The optimal Eu 2+ concentration was 4% for KBa 2I 5 and 7%more » for K 2BaI 4. The X-ray excited emissions at 444 nm for KBa 2I 5:Eu 4% and 448 nm for K 2BaI 4:Eu 7% arise from the 5d-4f radiative transition in Eu 2+. KBa 2I 5:Eu 4% has a light yield of 90,000 photons/MeV, with an energy resolution of 2.4% and K 2BaI 4:Eu 7% has a light yield of 63,000 ph/MeV, with an energy resolution of 2.9% at 662 keV. Both crystals have an excellent proportional response to a wide range of gamma-ray energies.« less

  11. Barium recovery by crystallization in a fluidized-bed reactor: effects of pH, Ba/P molar ratio and seed.

    PubMed

    Su, Chia-Chi; Reano, Resmond L; Dalida, Maria Lourdes P; Lu, Ming-Chun

    2014-06-01

    The effects of process conditions, including upward velocity inside the column, the amount of added seed and seed size, the pH value of the precipitant or the phosphate stream and the Ba/P molar ratio in a fluidized-bed reactor (FBR) were studied with a view to producing BaHPO₄ crystals of significant size and maximize the removal of barium. XRD were used to identify the products that were collected from the FBR. Experimental results show that an upward velocity of 48 cmmin(-1) produced the largest BaHPO₄ crystals with a size of around 0.84-1.0mm. The addition of seed crystals has no effect on barium removal. The use of a seed of a size in the ranges unseeded<0.149-0.29 mm<0.149 mm<0.29-0.42 mm produced increasing amounts of increasingly large crystals. The largest BaHPO₄ crystals were obtained at pH 8.4-8.8 with a Ba/P molar ratio of 1.0. In the homogeneous and heterogeneous processes, around 98% of barium was removed at pH 8.4-8.6 and [Ba]/[P]=1.0. The XRD results show that a significant amount of barium phosphate (Ba₃(PO₄)₂) was obtained at pH 11. The compounds BaHPO₄ and BaO were present at a pH of below 10. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Synthesis, structure, and bonding of BaTl4. Size effects on encapsulation of cations in electron-poor metal networks.

    PubMed

    Dai, Jing-Cao; Gupta, Shalabh; Corbett, John D

    2011-01-03

    The synthesis, structure, and bonding of BaTl(4) are described [C2/m, Z = 4, a = 12.408(3), b = 5.351(1), c = 10.383(2) Å, β = 116.00(3)°]. Pairs of edge-sharing Tl pentagons are condensed to generate a network of pentagonal biprisms along b that encapsulate Ba atoms. Alternating levels of prisms along c afford six more bifunctional Tl atoms about the waists of the biprisms, giving Ba a coordination number of 16. Each Tl atom is bonded to five to seven other Tl atoms and to three to five Ba atoms. There is also strong evidence that Hg substitutes preferentially in the shared edges of the Tl biprisms in BaHg(0.80)Tl(3.20) to generate more strongly bound Hg(2) dimers. Cations that are too small relative to the dimensions of the surrounding polyanionic network make this BaTl(4) structure (and for SrIn(4) and perhaps EuIn(4) as well) one stable alternative to tetragonal BaAl(4)-type structures in which cations are bound in larger hexagon-faced nets, as for BaIn(4) and SrGa(4). Characteristic condensation and augmentation of cation-centered prismatic units is common among many relatively cation- and electron-poor, polar derivatives of Zintl phases gain stability. At the other extreme, the large family of Frank-Kasper phases in which the elements exhibit larger numbers of bonded neighbors are sometimes referred to as orbitally rich.

  13. Temperature dependence of positron annihilation parameters in Tl-Ba-Ca-Cu-O superconductors

    NASA Astrophysics Data System (ADS)

    Sundar, C. S.; Bharathi, A.; Ching, W. Y.; Jean, Y. C.; Hor, P. H.; Meng, R. L.; Huang, Z. J.; Chu, C. W.

    1990-08-01

    The results of positron lifetime and Doppler broadened line-shape parameter measurements as a function of temperature, across Tc, in the Tl-Ba-Ca-Cu-O superconductors are presented. The bulk lifetime in the normal state is found to decrease with the increase in the number of CuO2 layers. Different temperature dependencies of the annihilation parameters are observed in the various Tl systems containing different numbers of CuO2 layers. In the Tl2Ba2Ca2Cu3O10 system, an increase in lifetime is observed below Tc, whereas in Tl2Ba2CaCu2O8, a decrease in lifetime is seen below Tc. In the Tl2Ba2CuO6 system, the lifetime is observed to be temperature independent. The different temperature variations of positron annihilation parameters are discussed in the light of the positron density distribution, obtained with use of the results of the self-consistent orthogonalized linear combination of atomic orbitals band-structure calculations. It is argued that the different temperature dependencies of the annihilation parameters is related to the positron density distribution within the unit cell and arise due to local charge transfer in the vicinity of the CuO2 layer in the superconducting state.

  14. Domain structures and Prco antisite point defects in double-perovskite PrBaCo2O5+δ and PrBa0.8Ca0.2Co2O5+δ.

    PubMed

    Ding, Yong; Chen, Yu; Pradel, Ken C; Zhang, Weilin; Liu, Meilin; Wang, Zhong Lin

    2018-06-15

    Owing to the excellent mixed-ionic and electronic conductivity and fast oxygen kinetics at reduced temperature (<800 °C), double-perovskite oxides such as PrBaCo 2 O 5+δ exhibit excellent properties as an oxygen electrode for solid oxide fuel cells (SOFCs). Using transmission electron microscopy (TEM), we revealed high-density antiphase domain boundaries (APBs) and 90° domain walls in PrBaCo 2 O 5+δ grains. Besides the regular lamellar 90° domain walls in {021} planes, irregular fine 90° domains are attached to the curved APBs. Electron energy-loss spectroscopy (EELS) reveals the composition variation across some of the 90° domain walls. There are fewer Co and more Ba ions approaching the 90° domain walls, while the changes in Pr and O ions are not detectable. We assume that the extra Ba 2+ cations replace the Pr 3+ cations, while the Pr 3+ cations go to the Co site to form Pr Co antisite point defects and become Pr 4+ . In this case, the Pr 4+ cations will help to balance the local charges and have compatible ionic radius with that of Co 3+ . The local strain field around the 90° domain walls play a crucial role in the stabilization of such Pr Co antisite point defects. The antisite point defects have been observed in our high-resolution TEM images and aberration-corrected high-angle annular dark-field (HAADF) scanning TEM images. After Ca 2+ doped into PrBaCo 2 O 5+δ to improve the structure stability, we observed tweed structures in the PrBa 0.8 Ca 0.2 Co 2 O 5+δ grain. The tweed structure is composed of high-density intersected needle-shaped 90° domain walls, which is linked to a strong local strain field and composition variation. Even when the temperature is increased to 750 °C, the domain structures are still stable as revealed by our in situ TEM investigation. Therefore, the influence of the domain structures and the Pr Co antisite defects on the ionic and electric conductivities must be considered. Copyright © 2018. Published by Elsevier

  15. Reactivity of a Thick BaO Film Supported on Pt(111): Adsorption and Reaction of NO2, H2O and CO2

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mudiyanselage, Kumudu; Yi, Cheol-Woo W.; Szanyi, Janos

    2009-09-15

    Reactions of NO2, H2O, and CO2 with a thick (> 20 MLE) BaO film supported on Pt(111) were studied with temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). NO2 reacts with a thick BaO to form surface nitrite-nitrate ion pairs at 300 K, while only nitrates form at 600 K. In the thermal decomposition process of nitrite–nitrate ion pairs, first nitrites decompose and desorb as NO. Then nitrates decompose in two steps : at lower temperature with the release of NO2 and at higher temperature, nitrates dissociate to NO + O2. The thick BaO layer converts completely to Ba(OH)2more » following the adsorption of H2O at 300 K. Dehydration/dehydroxylation of this hydroxide layer can be fully achieved by annealing to 550 K. CO2 also reacts with BaO to form BaCO3 that completely decomposes to regenerate BaO upon annealing to 825 K. However, the thick BaO film cannot be converted completely to Ba(NOx)2 or BaCO3 under the experimental conditions employed in this study.« less

  16. Biosorption behavior and mechanism of lead (II) from aqueous solution by aerobic granules (AG) and bacterial alginate (BA)

    NASA Astrophysics Data System (ADS)

    Wang, Lin; Li, Yu

    2012-12-01

    Lead (Pb) and its compounds are common pollutants in industrial wastewaters. To develop appropriate Pb2+ treatment technologies, aerobic granules (AG) and bacterial alginates (BA) were studied as alternative biosorbents to remove Pb2+ from aqueous solutions. The biosorption mechanism of AG and BA were further analyzed to determine which functional groups in AG and BA are active in Pb2+ biosorption. In this paper, the Pb2+ biosorption behavior of AG and BA was respectively investigated in batch experiments from the perspectives of the initial pH, contact time, and initial Pb2+ concentration. The results showed that biosorption of Pb2+ by AG and BA occurred within 60min at the initial Pb2+ concentrations (0-150 mg L-1). The actual saturated Pb2+ biosorption capability of AG was 101.97 mg g-1 (dry weight of aerobic granular biomass). When the initial pH was 5, the biosorption capability of AG and BA was highest at the initial Pb2+ concentrations (0-20mg L-1). During the process of Pb2+ biosorption, K+, Ca2+, and Mg2+ were released. The Ion Chromatography (IC) and Fourier Transform Infrared Spectroscopy (FTIR) further highlighted the main role of ion exchange between Ca2+ and Pb2+ and sequestration of Pb2+ with carboxyl (-COO-) of AG and BA. This analogical analysis verifies that BA is responsible for biosorption of Pb2+ by AG. At the same optimal pH, AG cultivated with different carbon source has different Pb2+ biosorption capacity. The Pb2+ biosorption by AG with sodium acetate as the sole carbon source is higher than AG with glucose as carbon source.

  17. Magnetic properties of mixed spinel BaTiO{sub 3}-NiFe{sub 2}O{sub 4} composites

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sarkar, Babusona; Dalal, Biswajit; Dev Ashok, Vishal

    2014-03-28

    Solid solution of nickel ferrite (NiFe{sub 2}O{sub 4}) and barium titanate (BaTiO{sub 3}), (100-x)BaTiO{sub 3}–(x) NiFe{sub 2}O{sub 4} has been prepared by solid state reaction. Compressive strain is developed in NiFe{sub 2}O{sub 4} due to mutual structural interaction across the interface of NiFe{sub 2}O{sub 4} and BaTiO{sub 3} phases. Quantitative analysis of X-ray diffraction and X-ray photo electron spectrum suggest mixed spinel structure of NiFe{sub 2}O{sub 4}. A systematic study of composition dependence of composite indicates BaTiO{sub 3} causes a random distribution of Fe and Ni cations among octahedral and tetrahedral sites during non-equilibrium growth of NiFe{sub 2}O{sub 4}. Themore » degree of inversion decreases monotonically from 0.97 to 0.75 with increase of BaTiO{sub 3} content. Temperature dependence of magnetization has been analyzed by four sublattice model to describe complex magnetic exchange interactions in mixed spinel phase. Curie temperature and saturation magnetization decrease with increase of BaTiO{sub 3} concentration. Enhancement of strain and larger occupancy of Ni{sup 2+} at tetrahedral site increase coercivity up to 200 Oe. Magnetostructual coupling induced by BaTiO{sub 3} improves coercivity in NiFe{sub 2}O{sub 4}. An increase in the demagnetization and homogeneity in magnetization process in NiFe{sub 2}O{sub 4} is observed due to the interaction with diamagnetic BaTiO{sub 3}.« less

  18. Synthesis and Photoluminescence Properties of BaWO4:RE3+ (RE = Eu or Sm) Phosphors

    NASA Astrophysics Data System (ADS)

    Cho, Shinho

    2018-04-01

    BaWO4:RE3+ (RE = Eu or Sm) phosphor powders were prepared with different doping concentrations of the activator ion by using the conventional solid-state reaction method. The dependences in the crystal structure, luminescence intensity, and morphology on the Eu3+ and the Sm3+ concentrations in BaWO4 were investigated using X-ray diffraction (XRD), photoluminescence spectrophotometry, and scanning electron microscopy (SEM), respectively. XRD analysis showed tetragonal BaWO4 structures for all the phosphors synthesized, regardless of the type and the doping concentration of the activator ion. SEM images indicated that as the concentration of activator ions was increased, the crystalline particles showed an increasing tendency to agglomerate irregularly. The room temperature excitation spectra of Eu3+- or Sm3+-doped BaWO4 phosphors consisted of a broad charge transfer band in the ultraviolet region and several sharp 4 f-4 f transitions. When Eu3+-doped BaWO4 phosphors were excited at 274 nm, the emission spectra exhibited sharp bands due to inner shell transitions occurring from the excited energy state 5 D 0 to the lower energy levels 7 F J ( J = 1, 2, 3, and 4). For Sm3+-doped BaWO4 phosphors, three intense emission peaks at 568, 603, and 649 nm and a very weak line at 712 nm were observed. The highest asymmetry ratio-the intensity ratio of the 4 G 5/2 → 6 H 9/2 electric dipole to the 4 G 5/2 → 6 H 5/2 magnetic dipole transitions-was obtained for 1 mol% doping of Sm3+, indicating that the Sm3+ ions occupied the non-inversion symmetry sites.

  19. BaP-metals co-exposure induced tissue-specific antioxidant defense in marine mussels Mytilus coruscus.

    PubMed

    Chen, Siyu; Qu, Mengjie; Ding, Jiawei; Zhang, Yifei; Wang, Yi; Di, Yanan

    2018-04-18

    Both benzo(α)pyrene (BaP) and metals are frequently found in marine ecosystem and can cause detrimental effects in marine organism, especially the filter feeder-marine mussels. Although the biological responses in mussels have been well-studied upon the single metal or BaP exposure, the information about antioxidant defense, especially in different tissues of mussels, are still limited. Considering the variety of contaminants existing in the actual marine environment, single BaP (56 μg/L) and the co-exposure with Cu, Cd and Pb (50 μg/L, 50 μg/L and 3 mg/L respectively) were applied in a 6 days exposure followed by 6 days depuration experiment. The alterations of superoxide dismutase (SOD), catalase (CAT) activities and total antioxidant capacity (TAC) level were assessed in haemolymph, gills and digestive glands of marine mussels, Mytilus coruscus. An unparalleled change in antioxidant biomarkers was observed in all cells/tissues, with the SOD activity showing higher sensitivity to exposure. A tissue-specific response showing unique alteration in gill was investigated, indicating the different function of tissues during stress responses. Depressed antioxidant effects were induced by BaP-metals co-exposure, indicating the interaction may alter the intact properties of BaP. To our knowledge, this is the first research to explore the antioxidant defense induced by combined exposure of BaP-metals regarding to tissue-specific responses in marine mussels. The results and experimental model will provide valuable information and can be utilized in the investigation of stress response mechanisms, especially in relation to tissue functions in marine organism in the future. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. Synthesis and luminescence characterization of a new yellowish-orange phosphor: Ba2 B10 O17 :Sm3.

    PubMed

    Li, Jiangong; Yan, Huifang; Yan, Fengmei

    2017-02-01

    A new yellowish-orange emitting phosphor, Ba 2 B 10 O 17 :Sm 3 + for use as a white light-emitting diode (W-LED) was synthesized by a solid-state reaction method. The X-ray diffraction results indicated that a pure Ba 2 B 10 O 17 material was obtained. As a potential yellowish-orange luminescent material for W-LEDs, the Ba 2 B 10 O 17 :Sm 3 + phosphor could be excited effectively by near-ultraviolet (n-UV) light and exhibited yellowish-orange emission centered at 560 nm corresponding to the 4 G 5/2  →  6 H 5/2 transition of Sm 3 + ions. The optimum concentration of Sm 3 + ions in Ba 2 B 10 O 17 , critical transfer distance (Ra) and concentration quenching mechanism of the presented phosphor were investigated. Moreover, CIE chromaticity coordinates and color purity performance of the Ba 2 B 10 O 17 :Sm 3 + phosphor were also discussed. The present work suggests that the Ba 2 B 10 O 17 :Sm 3 + phosphor has potential as a type of yellowish-orange emitting phosphor. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  1. Spin-Coating and Characterization of Multiferroic MFe2O4 (M=Co, Ni) / BaTiO3 Bilayers

    NASA Astrophysics Data System (ADS)

    Quandt, Norman; Roth, Robert; Syrowatka, Frank; Steimecke, Matthias; Ebbinghaus, Stefan G.

    2016-01-01

    Bilayer films of MFe2O4 (M=Co, Ni) and BaTiO3 were prepared by spin coating of N,N-dimethylformamide/acetic acid solutions on platinum coated silicon wafers. Five coating steps were applied to get the desired thickness of 150 nm for both the ferrite and perovskite layer. XRD, IR and Raman spectroscopy revealed the formation of phase-pure ferrite spinels and BaTiO3. Smooth surfaces with roughnesses in the order of 3 to 5 nm were found in AFM investigations. Saturation magnetization of 347 emu cm-3 for the CoFe2O4/BaTiO3 and 188 emu cm-3 for the NiFe2O4/BaTiO3 bilayer, respectively were found. For the CoFe2O4/BaTiO3 bilayer a strong magnetic anisotropy was observed with coercivity fields of 5.1 kOe and 3.3 kOe (applied magnetic field perpendicular and parallel to film surface), while for the NiFe2O4/BaTiO3 bilayer this effect is less pronounced. Saturated polarization hysteresis loops prove the presence of ferroelectricity in both systems.

  2. 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

  3. Interaction between BaCO{sub 3} and OPC/BFS composite cements at 20 {sup o}C and 60 {sup o}C

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Utton, C.A., E-mail: c.utton@sheffield.ac.u; Gallucci, E.; Hill, J.

    2011-03-15

    A BaCO{sub 3} slurry, containing radioactive {sup 14}C, is produced during the reprocessing of spent nuclear fuel. This slurry is encapsulated in a Portland-blastfurnace slag composite cement. The effect of BaCO{sub 3} on the hydration of OPC and Portland-blastfurnace slag cements has been studied in this work. Samples containing a simulant BaCO{sub 3} slurry were cured for up to 720 days at 20 and 60 {sup o}C and analysed by XRD, SEM(EDX) and ICC. BaCO{sub 3} reacted with OPC to precipitate BaSO{sub 4} from a reaction between soluble sulfate and BaCO{sub 3}. Calcium monocarboaluminate subsequently formed from the carbonate released.more » The monocarboaluminate precipitated as crystals in voids formed during hydration. At 60 {sup o}C in OPC, it was not identified by XRD, suggesting the phase is unstable in this system around this temperature. In the Portland-blastfurnace slag cements containing BaCO{sub 3}, less monocarboaluminate and BaSO{sub 4} were formed, but the hydration of BFS was promoted and monocarboaluminate was stable up to 60 {sup o}C.« less

  4. The effect of X-ray exposure on Ba2SiO4:Eu3+

    NASA Astrophysics Data System (ADS)

    Volhard, Max-Fabian; Jüstel, Thomas

    2018-03-01

    The ortho-silicates Ba2SiO4:Eu3+ and Ba2SiO4:Eu2+ are well-established materials for fluorescent light sources, e.g., phosphor converted LEDs. Samples containing Eu2+or Eu3+were synthesised by the solid-state-method, and the phase purity was determined by X-ray powder diffractometry. The photoluminescence of both phosphors was examined as a function of the pre-treatment. Upon irradiation of Ba2SiO4:Eu3+ with X-rays (tungsten target source), the reduction of Eu3+ towards Eu2+ was observed. This reduction behaviour was thoroughly recorded, and the linearity of the process was determined. Furthermore, the relationship between the acceleration voltage and the reduction process is discussed.

  5. 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.

  6. Investigation on growth and macro-defects of Er3+-doped BaY2F8 laser crystal

    NASA Astrophysics Data System (ADS)

    Wang, Shuai; Ruan, Yongfeng; Tsuboi, Taiju; Zhang, Shouchao; Wang, Youfa; Tong, Hongshuang

    2013-08-01

    Large BaY2F8 and Er3+-doped BaY2F8 single crystals were grown by the temperature gradient method. Three kinds of macro-defects were found in BaY2F8 single crystals. These macro-defects include cracks, growth striations and straight pipes. The morphologies and distribution regularities of these macro-defects were observed and studied using a solid polarization microscope. The formation mechanisms and the methods of eliminating these defects were discussed.

  7. PaPrBaG: A machine learning approach for the detection of novel pathogens from NGS data

    NASA Astrophysics Data System (ADS)

    Deneke, Carlus; Rentzsch, Robert; Renard, Bernhard Y.

    2017-01-01

    The reliable detection of novel bacterial pathogens from next-generation sequencing data is a key challenge for microbial diagnostics. Current computational tools usually rely on sequence similarity and often fail to detect novel species when closely related genomes are unavailable or missing from the reference database. Here we present the machine learning based approach PaPrBaG (Pathogenicity Prediction for Bacterial Genomes). PaPrBaG overcomes genetic divergence by training on a wide range of species with known pathogenicity phenotype. To that end we compiled a comprehensive list of pathogenic and non-pathogenic bacteria with human host, using various genome metadata in conjunction with a rule-based protocol. A detailed comparative study reveals that PaPrBaG has several advantages over sequence similarity approaches. Most importantly, it always provides a prediction whereas other approaches discard a large number of sequencing reads with low similarity to currently known reference genomes. Furthermore, PaPrBaG remains reliable even at very low genomic coverages. CombiningPaPrBaG with existing approaches further improves prediction results.

  8. Microstructure and properties of single crystal BaTiO3 thin films synthesized by ion implantation-induced layer transfer

    NASA Astrophysics Data System (ADS)

    Park, Young-Bae; Ruglovsky, Jennifer L.; Atwater, Harry A.

    2004-07-01

    Single crystal BaTiO3 thin films have been transferred onto Pt-coated and Si3N4-coated substrates by the ion implantation-induced layer transfer method using H + and He+ ion coimplantation and subsequent annealing. The transferred BaTiO3 films are single crystalline with root mean square roughness of 17nm. Polarized optical and piezoresponse force microscopy (PFM) indicate that the BaTiO3 film domain structure closely resembles that of bulk tetragonal BaTiO3 and atomic force microscopy shows a 90° a -c domain structure with a tetragonal angle of 0.5°-0.6°. Micro-Raman spectroscopy indicates that the local mode intensity is degraded in implanted BaTiO3 but recovers during anneals above the Curie temperature. The piezoelectric coefficient, d33, is estimated from PFM to be 80-100pm/V and the coercive electric field (Ec) is 12-20kV/cm, comparable to those in single crystal BaTiO3.

  9. The effects of preparation conditions for a BaNbO2 N photocatalyst on its physical properties.

    PubMed

    Hisatomi, Takashi; Katayama, Chisato; Teramura, Kentaro; Takata, Tsuyoshi; Moriya, Yosuke; Minegishi, Tsutomu; Katayama, Masao; Nishiyama, Hiroshi; Yamada, Taro; Domen, Kazunari

    2014-07-01

    BaNbO2 N is a semiconductor photocatalyst active for water oxidation under visible-light irradiation up to λ=740 nm. It is important to understand the nitridation processes of precursor materials to form BaNbO2 N to tune the physical properties and improve the photocatalytic activity. Comprehensive experiments and analyses of temperatures, durations, ammonia flow rates, and barium/niobium ratios in the precursor during the nitridation process reveals that faster ammonia flow rates and higher barium/niobium ratios in the precursors help to suppress reduction of pentavalent niobium ions in the nitridation products and that the use of a precursor prepared by a soft-chemistry route allows the production of BaNbO2 N at lower temperatures in shorter times than the use of physical mixtures of BaCO3 and Nb2 O5 because the niobium species is dispersed among the barium species. BaNbO2 N prepared by the soft-chemistry route exhibits comparatively higher activity than that prepared from physical mixtures of BaCO3 and Nb2 O5 , probably because of lower nitridation temperatures, which suppress excessive dissociation of ammonia, and thereby reduce pentavalent niobium ions, and intimate interaction of niobium and barium sources, which lowers the densities of mid-gap states associated with defects. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Half-metallic ferromagnetism in Fe, Co and Ni doped BaS: First principles calculations

    NASA Astrophysics Data System (ADS)

    Maurya, Savita; Sharma, Ramesh; Bhamu, K. C.

    2018-04-01

    The first principle investigation of structural, electronic, magnetic and optical properties of Ba1-xTMxS (x = 0.25) have been done using FPLAW method within the density functional theory (DFT) using generalized gradient approximation (GGA) for exchange correlation potential using two different functionals which are the PBE-sol and the modified Becke and Johnson local (spin) density approximation (mBJLDA). It was found that mBJLDA functional offer better account for the electronic structure of the Fe, Co and Ni-doped BaS. It was also observed that Fe/Co/Ni d, S p and Ba d states play a major role in determining the electronic properties of this alloy system. Investigation results shows that Ba0.75(Fe/Co/Ni)0.25S is ferromagnetic with magnetic moment of 3.72 µB, 2.73908 µB and 1.74324 µB at Fe, Co and Ni sites respectively. Complex dielectric constant ɛ(ω) and normal incidence reflectivity R(ω) are also been investigate for broad range of photon energies. These results are compared with the some reported existing experimental values.

  11. Low-energy planar magnetic defects in BaFe 2 As 2 : Nanotwins, twins, antiphase, and domain boundaries

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Khan, S. N.; Alam, Aftab; Johnson, Duane D.

    2013-11-27

    In BaFe 2As 2, structural and magnetic planar defects begin to proliferate below the structural phase transition, affecting descriptions of magnetism and superconductivity. We study, using density-functional theory, the stability and magnetic properties of competing antiphase and domain boundaries, twins and isolated nanotwins (twin nuclei), and spin excitations proposed and/or observed. These nanoscale defects have a very low surface energy (22–210 m Jm -2), with twins favorable to the mesoscale. Defects exhibit smaller moments confined near their boundaries—making a uniform-moment picture inappropriate for long-range magnetic order in real samples. Nanotwins explain features in measured pair distribution functions so should bemore » considered when analyzing scattering data. All these defects can be weakly mobile and/or can have fluctuations that lower assessed “ordered” moments from longer spatial and/or time averaging and should be considered directly.« less

  12. Optical monitoring of ion beam Y-Ba-Cu-O sputtering

    NASA Astrophysics Data System (ADS)

    Klein, J. D.; Yen, A.

    1990-11-01

    The emission spectra resulting from ion beam sputtering a Y-Ba-Cu-O target were observed as a function of beam voltage and beam current. The spectra were relatively clean with several peaks readily attributed to each of Y, Ba, and Ar. Monitoring of copper and oxygen was more difficult with a single CuO peak and one O peak evident. The intensities of the cation peaks were linear with respect to beam voltage above 400 V. Since target current was found not to be directly proportional to beam current, target power was defined as the product of beam voltage and target current. The response of cation peak height to changes in target power was linear and similar for variations of either beam voltage or target current.

  13. First identification of excited states in Ba 117 using the recoil- β -delayed proton tagging technique

    DOE PAGES

    Ding, B.; Liu, Z.; Seweryniak, D.; ...

    2017-02-01

    Excited states have been observed for the first time in the neutron-deficient nucleus 117Ba using the recoil-decay tagging technique following the heavy-ion fusion-evaporation reaction 64Zn( 58Ni, 2p3n) 117Ba. Prompt γ rays have been assigned to 117Ba through correlations with β-delayed protons following the decay of A = 117 recoils. Through the analysis of the γ–γ coincidence relationships, a high-spin level scheme consisting of two bands has been established in 117Ba. Based on the systematics of the level spacings in the neighboring barium isotopes, the two bands are proposed to have νh 11/2[532]5/2 – and νd 5/2[413]5/2 + configurations, respectively. Lastly,more » the observed band-crossing properties are interpreted in the framework of cranked shell model.« less

  14. Influences of annealing temperature on structural characterization and magnetic properties of Mn-doped BaTiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Phan, The-Long; Zhang, P.; Grinting, D.; Yu, S. C.; Nghia, N. X.; Dang, N. V.; Lam, V. D.

    2012-07-01

    Polycrystalline samples of BaTiO3 doped with 2.0 at. % Mn were prepared by solid-state reaction at various temperatures (Tan) ranging from 500 to 1350 °C, used high-pure powders of BaCO3, TiO2, and MnCO3 as precursors. Experimental results obtained from x-ray diffraction patterns and Raman scattering spectra reveal that tetragonal Mn-doped BaTiO3 starts constituting as Tan ≈ 500 °C. The Tan increase leads to the development of this phase. Interestingly, there is the tetragonal-hexagonal transformation in the crystal structure of BaTiO3 as Tan ≈ 1100 °C. Such the variations influence directly magnetic properties of the samples. Besides paramagnetic contributions of Mn2+ centers traced to electron spin resonance, the room-temperature ferromagnetism found in the samples is assigned to exchange interactions taking place between Mn3+ and Mn4+ ions located in tetragonal BaTiO3 crystals.

  15. Spectral and multi-wavelength continuous-wave laser properties of Yb3+:BaLaGa3O7

    NASA Astrophysics Data System (ADS)

    Gao, Shufang; Xu, Shan

    2018-05-01

    Yb3+ doped BaLaGa3O7 crystal has been successfully grown by Czochralski method. The polarized absorption spectra, the fluorescence spectra and the fluorescence decay lifetime of Yb3+:BaLaGa3O7 crystal were measured at room temperature. The spectroscopic parameters of Yb3+:BaLaGa3O7 crystal are calculated. A continuous wave output power of 1.32W was obtained with four-wavelength emission corresponding to an optical-optical slope efficiency of 55%.

  16. Fabrication of (Ba,K)Fe2As2 tapes by ex situ PIT process using Ag-Sn alloy single sheath

    NASA Astrophysics Data System (ADS)

    Togano, K.; Gao, Z.; Matsumoto, A.; Kikuchi, A.; Kumakura, H.

    2017-01-01

    Instead of ordinal pure Ag, Ag-based Sn binary alloys (up to 7.5 at%Sn) with higher mechanical strength are used for the sheath material of ex situ powder-in-tube (PIT)-processed (Ba,K)Fe2As2(Ba-122) tapes. We found that the use of the Ag-Sn alloy enhances the densification and texturing of the Ba-122 core, resulting in higher transport, J c. Moreover, the optimum heat treatment temperature for a high J c can be lowered by around 100 °C due to the higher packing density of the Ba-122 core prior to the final heat treatment. We also found that the smoothness of the interface between the sheath and Ba-122 core is significantly improved by using the Ag-Sn binary alloy sheaths. These results show that the Ag-Sn alloy is promising as a sheath material in PIT-processed Ba-122 superconducting wires.

  17. Determining Solute Sources and Water Flowpaths in a Forested Headwater Catchment: Advances With the Ca-Sr-Ba Multi-tracer

    NASA Astrophysics Data System (ADS)

    Bullen, T. D.; Bailey, S. W.; McGuire, K. J.; Zimmer, M. A.; Ross, D. S.

    2011-12-01

    Determining solute sources and water flowpaths in catchments is of critical importance to development of models that effectively describe catchment function. For solutes in soil water and stream water, simple mass balance models that compare precipitation input to catchment outlet compositions can predict average mineral weathering contributions for the catchment as a whole, but fail to provide information about either variability of contributions from different portions of the catchment and different soil depths or processes such as ion exchange and biological cycling. In order to better understand how forested headwater catchments function, we are interpreting concentration and isotope ratios of the alkaline earth elements Ca, Sr and Ba in streamwater, groundwater, the soil ion exchange pool and plants in a hydropedologic context at the 41 hectare hydrologic reference catchment (Watershed 3) at the Hubbard Brook Experimental Forest, New Hampshire, USA. This forested headwater catchment consists of a beech-birch-maple-spruce forest growing on vertically- and laterally-developed Spodosols and Inceptisols formed on granitoid glacial till that mantles Paleozoic metamorphic bedrock. Across the watershed in terms of the soil ion exchange pool, the forest floor has high Sr/Ba and Ca/Sr ratios, mineral soils have intermediate Sr/Ba and low Ca/Sr, and relatively unweathered till in the C horizon has low Sr/Ba and high Ca/Sr. Waters moving through these various compartments will obtain Sr/Ba and Ca/Sr ratios reflecting these characteristics, and thus variations of Sr/Ba and Ca/Sr of streamwater provide evidence of the depth of water flowpaths feeding the streams. 87Sr/86Sr of exchangeable Sr spans a broad range from 0.715 to 0.725, with highest values along the mid-to upper flanks of the catchment and lowest values in a broad zone along the central axis of the catchment associated with numerous groundwater seeps. Thus, variations of 87Sr/86Sr in streamwater provide

  18. Real-time radionuclide identification in γ-emitter mixtures based on spiking neural network.

    PubMed

    Bobin, C; Bichler, O; Lourenço, V; Thiam, C; Thévenin, M

    2016-03-01

    Portal radiation monitors dedicated to the prevention of illegal traffic of nuclear materials at international borders need to deliver as fast as possible a radionuclide identification of a potential radiological threat. Spectrometry techniques applied to identify the radionuclides contributing to γ-emitter mixtures are usually performed using off-line spectrum analysis. As an alternative to these usual methods, a real-time processing based on an artificial neural network and Bayes' rule is proposed for fast radionuclide identification. The validation of this real-time approach was carried out using γ-emitter spectra ((241)Am, (133)Ba, (207)Bi, (60)Co, (137)Cs) obtained with a high-efficiency well-type NaI(Tl). The first tests showed that the proposed algorithm enables a fast identification of each γ-emitting radionuclide using the information given by the whole spectrum. Based on an iterative process, the on-line analysis only needs low-statistics spectra without energy calibration to identify the nature of a radiological threat. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Point-contact tunneling in monophasic and polyphasic Y-Ba-Cu-O samples: Experiment and model

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gonnelli, R.S.; Andreone, D.; Lacquaniti, V.

    1989-02-01

    Tunneling experiments using large-area point-contact structures have been performed on several monophasic polycrystalline Ba/sub 2/Cu/sub 3/O/sub 7-//sub delta/ samples and on polyphasic samples containing, mixed with the previous superconducting phase, also about 11% of the so-called green phase (BaY/sub 2/CuO/sub 5/). Both niobium and Y-Ba-Cu-O tips were used as counterelectrodes and measurements were made at 4.2 and 77 K. Results obtained at different experimental conditions show great reproducibility indicating the presence of the gap voltage at about 20 mV in the dynamic resistance curves. A phenomenological model was then developed to interpret in a quantitative way our data by meansmore » of a decomposition of the experimental conductance into a background component and a superconducting-tunneling component. The former results essentially in a parabolic contribution versus the bias voltage typical of a tunneling between normallike junction electrodes while the latter component is smeared out in voltage by a large amount of broadening. Using the model in a least-squares fit of the experimental data of Nb/Y-Ba-Cu-O junctions, values V/sub G/ = 21.3 +- 0.8 mV and V/sub G/ = 22.0 +- 0.6 mV for the voltage gaps at 4.2 K of monophasic and polyphasic materials, respectively, have been determined. These results have been well confirmed by measurements on Y-Ba-Cu-O/Y-Ba-Cu-O junctions while, at 77 K, there are no indications of a superconducting tunneling. We obtained also the parameters of the background conductance, which indicates the presence of a nonsuperconducting layer at the surface of the material.« less

  20. Enhanced Photocatalytic Activity in Bi1-x Ba x FeO3 Prepared by a PEG400 Assisted Sol-Gel Method

    NASA Astrophysics Data System (ADS)

    Zhang, Chenlan; Chen, Jianguo; Jin, Dengren; Cheng, Jinrong

    2018-03-01

    Ferroelectric Bi1-x Ba x FeO3 nanoparticles for x = 0, 0.01, 0.03, 0.05 and 0.10 were synthesized by a polyethylene glycol 400 (PEG400) assisted sol-gel method. X-ray diffraction reveals that Bi1-x Ba x FeO3 nanoparticles exhibit a distorted rhombohedral structure with the R3c space group, and the diffraction peaks shift upon incorporation of Ba. Transmission electron microscope analysis shows that the particle size of Bi1-x Ba x FeO3 nanoparticles is in the range of 30-60 nm, decreasing with an increase in Ba content. Bi1-x Ba x FeO3 nanoparticles have band gaps in the range of 1.68-2.0 eV, which are capable of responding to visible light irradiation. The rate of the photocatalytic degradation of Bi1-x Ba x FeO3 nanoparticles for x = 0.03 to methyl orange (MO) dye achieves about 81% under visible light irradiation for 3 h, which is higher than that of 66% for pure phase BiFeO3 (BFO). Moreover, the effects of Ba2+ modification on the band gap of BFO crystallites have been investigated and discussed.

  1. Determination of local order in the amorphous precursor to Ba-hexaferrite thin-film recording media

    NASA Astrophysics Data System (ADS)

    Snyder, J. E.; Harris, V. G.; Das, B. N.; Koon, N. C.; Sui, X.; Kryder, M. H.

    1996-04-01

    Ba-hexaferrite thin films for recording media applications are often fabricated by a two-step process: sputter deposition of an amorphous precursor, followed by annealing to crystallize the BaFe12O19 phase. The magnetic anisotropy of the crystalline films can be either in-plane or perpendicular, depending on the sputtering process used in the first step. However, conventional structural characterization techniques have not been able to distinguish between different as-sputtered films. Using polarization-dependent extended x-ray absorption fine structure (PD-EXAFS), we have observed anisotropic local structure around both Ba and Fe atoms in the amorphous precursor films. Comparison of the results suggests that the amorphous films consist of networks of Fe atoms surrounded by their O nearest neighbors, with Ba atoms fitting into in-between spaces as network modifiers (there might also be some minor Fe network modifying contribution). The local structural anisotropy of the amorphous films appears to determine the orientation of the fast-growing basal plane directions during annealing, and thus the directions of the c axes and the magnetic anisotropy.

  2. Why Sn doping significantly enhances the dielectric properties of Ba(Ti1-xSnx)O3

    NASA Astrophysics Data System (ADS)

    Shi, Tao; Xie, Lin; Gu, Lin; Zhu, Jing

    2015-02-01

    Through appropriate doping, the properties of BaTiO3-based ferroelectrics can be significantly enhanced. To determine the physical process induced by the doping of Sn atoms in Ba(Ti0.8Sn0.2)O3, we performed high-resolution scanning transmission electron microscopy experiments and observed that the regions with low Sn content formed polar nano regions (PNRs) embedded in the matrix in Ba(Ti0.8Sn0.2)O3. The interactions among Sn, Ti, Ba and O atoms were determined using first principles calculations. Based on the characteristics of the electronic structure and crystal lattice strain fields, the effects of doping with Sn were investigated. The Sn doping not only changed the electronic structure of the crystal but also increased the dielectric properties of the PNRs. Moreover, the Sn doping was also responsible for the diffuse phase transition of the Ba(Ti1-xSnx)O3 material. The effects mentioned in this paper are universal in lead-free ferroelectrics, and similar elements such as Sb, Mg, and Zr may have the same functions in other systems. Thus, these results provide guidance for the design of the doping process and new systems of ferroelectric or relaxor materials.

  3. Robust antiferromagnetism preventing superconductivity in pressurized (Ba 0.61K 0.39)Mn 2Bi 2

    DOE PAGES

    Gu, Dachun; Dai, Xia; Le, Congcong; ...

    2014-12-05

    BaMn 2Bi 2 possesses an iso-structure of iron pnictide superconductors and similar antiferromagnetic (AFM) ground state to that of cuprates, therefore, it receives much more attention on its properties and is expected to be the parent compound of a new family of superconductors. When doped with potassium (K), BaMn 2Bi 2 undergoes a transition from an AFM insulator to an AFM metal. Consequently, it is of great interest to suppress the AFM order in the K-doped BaMn 2Bi 2 with the aim of exploring the potential superconductivity. Here, we report that external pressure up to 35.6 GPa cannot suppress themore » AFM order in the K-doped BaMn 2Bi 2 to develop superconductivity in the temperature range of 300 K–1.5 K, but induces a tetragonal (T) to an orthorhombic (OR) phase transition at ~20 GPa. Theoretical calculations for the T and OR phases, on basis of our high-pressure XRD data, indicate that the AFM order is robust in the pressurized Ba 0.61K 0.39Mn 2Bi 2. Utlimately, both of our experimental and theoretical results suggest that the robust AFM order essentially prevents the emergence of superconductivity.« less

  4. Why Sn doping significantly enhances the dielectric properties of Ba(Ti1-xSnx)O3

    PubMed Central

    Shi, Tao; Xie, Lin; Gu, Lin; Zhu, Jing

    2015-01-01

    Through appropriate doping, the properties of BaTiO3-based ferroelectrics can be significantly enhanced. To determine the physical process induced by the doping of Sn atoms in Ba(Ti0.8Sn0.2)O3, we performed high-resolution scanning transmission electron microscopy experiments and observed that the regions with low Sn content formed polar nano regions (PNRs) embedded in the matrix in Ba(Ti0.8Sn0.2)O3. The interactions among Sn, Ti, Ba and O atoms were determined using first principles calculations. Based on the characteristics of the electronic structure and crystal lattice strain fields, the effects of doping with Sn were investigated. The Sn doping not only changed the electronic structure of the crystal but also increased the dielectric properties of the PNRs. Moreover, the Sn doping was also responsible for the diffuse phase transition of the Ba(Ti1-xSnx)O3 material. The effects mentioned in this paper are universal in lead-free ferroelectrics, and similar elements such as Sb, Mg, and Zr may have the same functions in other systems. Thus, these results provide guidance for the design of the doping process and new systems of ferroelectric or relaxor materials. PMID:25721479

  5. Strong coercivity reduction and high initial permeability in NiCoP coated BaFe12O19-polystyrene bilayer composite

    NASA Astrophysics Data System (ADS)

    Hamad, Mahmoud A.; El-Sayed, Adly H.; Hemeda, O. M.; Tawfik, A.

    2016-03-01

    Soft-magnetic NiCoP coated hard-magnetic M-type ferrite BaFe12O19 (BaM)-polystyrene (PS) bilayer composite film was successfully synthesized. X-ray diffraction peaks exhibited no change in the structure of BaM after coating with PS. The NiCoP coated BaM-PS composite exhibited a wasp-waisted magnetic hysteretic loop with remarkable reduction in the coercivity, remanence and squareness with respect to BaM-PS, which is useful for the core of a magnetic switching device to control currents so large that they are unmanageable. Moreover, the initial permeability measurement exhibits initial permeability of around 100 000 and thermal stability up to 558 K, which is good for flux-amplifying components of smaller inductors.

  6. Enhanced Photoluminescent Properties and Crystalline Morphology of LiBaPO4:Tm3+ Phosphor through Microwave Sintering Method

    PubMed Central

    Lai, Hsuan-Lin; Weng, Min-Hang; Yang, Ru-Yuan; Chang, Shoou-Jinn

    2016-01-01

    An investigation of the photoluminescent properties and crystalline morphology of blue emitting LiBa1−xPO4:xTm3+ phosphors with various concentrations (x = 0.005–0.030) of Tm3+ ions were synthesized by microwave sintering. For comparison, the LiBa1−xPO4:xTm3+ powders sintered at the same sintering condition but in a conventional furnace were also investigated. LiBaPO4 without second phase was formed no matter which furnace was used. More uniform grain size distributions are obtained by microwave sintering. When the concentration of Tm3+ ion was x = 0.015, the luminescence intensity reached a maximum value, and then decreased with the increases of the Tm3+ concentration due to concentration quenching effect. The microwave sintering significantly enhanced the emission intensity of LiBa1−xPO4:xTm3+ phosphors. Additionally, the d-d interaction is the key mechanism of concentration quenching for LiBaPO4:Tm3+. The chromaticity (x, y) for all LiBa1−xPO4:xTm3+ phosphors are located at (0.16, 0.05), which will be classified as a blue region. PMID:28773483

  7. Defect Chemistry of " BaCuO2" I. Oxygen Non -Stoichiometry, Cation Molecularity and X-ray Diffraction Determinations

    NASA Astrophysics Data System (ADS)

    Spinolo, G.; Anselmi-Tamburini, U.; Arimondi, M.; Ghigna, P.; Flor, G.

    1995-11-01

    "BaCuO2" is the key intermediate in the synthesis of the Ba2YCu3O7-δ superconductor. Its very complex crystal structure is able to accommodate a large change in oxygen content. Oxygen non-stoichiometry of "BaCuO2" materials with 1:1 and 88:90 (Ba :Cu) molecularity has been investigated by polythermal X-ray powder diffraction coupled with isobaric-isothermal gravimetry determinations under different temperature and oxygen partial pressure conditions [300≤ T≤ 820 °C, 1 ≥ P(O2) ≥ 3 • 10-3 atm]. The 1:1 composition does not give well reproducible results, thus suggesting its polyphasic nature, at least in part of the investigated range. The results for the 88:90 ≅ 0.98 (Ba :Cu) composi­ tion are well reproducible and show that the material is single phase. Ba0.98CuO1.98 + δ is oxygen over-stoichiometric in the whole investigated [T, P(O2)] range, with a maximum value δ˜0.21. A Rietveld X-ray profile fitting is in agreement with previous single-crystal data. The trend of δ vs. P(O2) is consistent with the presence of oxygen interstitial defects on (possibly different) crystallographic sites.

  8. 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.

  9. Ba{sub 2}B{sub 2}O{sub 5}:Ce{sup 3+}: A novel blue emitting phosphor for white LEDs

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Panlai, E-mail: li_panlai@126.com; Wang, Zhijun, E-mail: wangzj1998@126.com; Yang, Zhiping

    2014-12-15

    Graphical abstract: Under the 350 nm radiation excitation, Ba{sub 2}B{sub 2}O{sub 5}:Ce{sup 3+} has a broad blue emission band. When the temperature turned up to 150 °C, the emission intensity of Ba{sub 1.97}B{sub 2}O{sub 5}:0.03Ce{sup 3+} is 63.4% of the initial value at room temperature. The activation energy ΔE is calculated to be 0.25 eV, which prove the good thermal stability of Ba{sub 2}B{sub 2}O{sub 5}:Ce{sup 3+}. All the properties indicate that Ba{sub 2}B{sub 2}O{sub 5}:Ce{sup 3+} may have potential application in white LEDs. - Highlights: • Ba{sub 2}B{sub 2}O{sub 5}:Ce{sup 3+} has a broad blue emission band under themore » 350 nm radiation excitation. • Emission intensity of Ba{sub 2}B{sub 2}O{sub 5}:Ce{sup 3+} is 63.4% (150 °C) of the initial value (30 °C). • The activation energy ΔE for thermal quenching is 0.25 eV. - Abstract: A novel blue emitting phosphor Ba{sub 2}B{sub 2}O{sub 5}:Ce{sup 3+} is synthesized by a high temperature solid state method. The luminescent property and the thermal stability of Ba{sub 2}B{sub 2}O{sub 5}:Ce{sup 3+} are investigated. Under the 350 nm radiation excitation, Ba{sub 2}B{sub 2}O{sub 5}:Ce{sup 3+} has a broad blue emission band, and the peak locates at 417 nm which is assigned to the 5d{sup 1}–4f{sup 1} transition of Ce{sup 3+}. It is further proved that the dipole–dipole interaction results in the concentration quenching of Ce{sup 3+} in Ba{sub 2}B{sub 2}O{sub 5}:Ce{sup 3+}. When the temperature turned up to 150 °C, the emission intensity of Ba{sub 1.97}B{sub 2}O{sub 5}:0.03Ce{sup 3+} is 63.4% of the initial value at room temperature. The activation energy ΔE is calculated to be 0.25 eV, which prove the good thermal stability of Ba{sub 2}B{sub 2}O{sub 5}:Ce{sup 3+}. All the properties indicate that Ba{sub 2}B{sub 2}O{sub 5}:Ce{sup 3+} may have potential application in white LEDs.« less

  10. Characteristics of energy harvesting using BaTiO3/Cu laminates with changes in temperature

    NASA Astrophysics Data System (ADS)

    Mori, K.; Takeuchi, H.; Narita, F.

    2018-03-01

    The energy harvesting characteristics of piezoelectric/copper (BaTiO3/Cu) laminates rising from sharp temperature changes were investigated both numerically and experimentally. First, a phase field simulation was performed to determine the temperature-dependent piezoelectric coefficient and permittivity values. Then, the output voltages of the BaTiO3/Cu laminates were calculated for variations from room temperature to either a cryogenic temperature (77 K) or a higher temperature (333 K) using a 3D finite element simulation with the properties calculated from the phase field simulation. Finally, the output voltages of the piezoelectric BaTiO3/Cu laminates were measured for the same temperature changes and were compared to the simulation results.

  11. Formation of BaSi2 heterojunction solar cells using transparent MoOx hole transport layers

    NASA Astrophysics Data System (ADS)

    Du, W.; Takabe, R.; Baba, M.; Takeuchi, H.; Hara, K. O.; Toko, K.; Usami, N.; Suemasu, T.

    2015-03-01

    Heterojunction solar cells that consist of 15 nm thick molybdenum trioxide (MoOx, x < 3) as a hole transport layer and 600 nm thick unpassivated or passivated n-BaSi2 layers were demonstrated. Rectifying current-voltage characteristics were observed when the surface of BaSi2 was exposed to air. When the exposure time was decreased to 1 min, an open circuit voltage of 200 mV and a short circuit current density of 0.5 mA/cm2 were obtained under AM1.5 illumination. The photocurrent density under a reverse bias voltage of -1 V reached 25 mA/cm2, which demonstrates the significant potential of BaSi2 for solar cell applications.

  12. Computational Approach to Explore the B/A Junction Free Energy in DNA.

    PubMed

    Kulkarni, Mandar; Mukherjee, Arnab

    2016-01-04

    Protein-DNA interactions induce conformational changes in DNA such as B- to A-form transitions at a local level. Such transitions are associated with a junction free energy cost at the boundary of two different conformations in a DNA molecule. In this study, we performed umbrella sampling simulations to find the free energy values of the B-A transition at the dinucleotide and trinucleotide level of DNA. Using a combination of dinucleotide and trinucleotide free energy costs obtained from simulations, we calculated the B/A junction free energy. Our study shows that the B/A junction free energy is 0.52 kcal mol(-1) for the A-philic GG step and 1.59 kcal mol(-1) for the B-philic AA step. This observation is in agreement with experimentally derived values. After excluding junction effects, we obtained an absolute free energy cost for the B- to A-form conversion for all the dinucleotide steps. These absolute free energies may be used for predicting the propensity of structural transitions in DNA. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Magnetic and Electrical Transport Properties of Dirac Compound BaMnSb2*

    NASA Astrophysics Data System (ADS)

    Huang, Silu; Kim, Jisun; Shelton, William. A.; Plummer, Ward; Jin, Rongying

    BaMnSb2 is a layered compound containing Sb square nets that is theoretically predicted to host Dirac fermions. We have carried out experimental investigations on electrical transport and magnetic properties of BaMnSb2 single crystals. Both in-plane (ρab) and c-axis (ρc) resistivities show metallic behavior with a small bump in ρc located near 40 K, while there is large anisotropy ρc / ρab ( 100 at 300 K) that increases with decreasing temperature to 1500 at 2 K. Interestingly, Shubnikov-de Hass (SdH) oscillations are observed for both ρab and ρc over a wide temperature and magnetic field range. Quantitative analysis indicates that large amplitude SdH oscillations result from nearly massless Dirac Fermions. Furthermore, our magnetic measurements indicate an A-type antiferromagnetic magnetic ordering below 286 K where ferromagnetic ordering is observed in the ab plane with antiferromagnetic coupling along the c direction. These results indicate that BaMnSb2 is a 2D magnetic Dirac material. This work is supported by NSF through Grant Number DMR-1504226.

  14. Structure and magnetism of Fe-doped BaSnO 3 thin films

    DOE PAGES

    Alaan, Urusa S.; N’Diaye, Alpha T.; Shafer, Padraic; ...

    2017-02-28

    BaSnO 3 is an excellent candidate system for developing a new class of perovskite-based dilute magnetic semiconductors. Here in this study, we show that BaSn 0.95Fe 0.05O 3 can be grown from a background pressure of ~2×10-3 mTorr to oxygen pressures of 300 mTorr with high crystallinity and excellent structural quality. When grown in vacuum, the films may be weakly ferromagnetic with a nonzero x-ray magnetic circular dichroism signal on the Fe L 3 edge. Growth with oxygen flow appears to suppress magnetic ordering. Even for very thick films grown in 100 mTorr O 2, the films are paramagnetic. Finally,more » the existence of ferromagnetism in vacuum-grown BaSnO 3 may be attributed to the F-center exchange mechanism, which relies on the presence of oxygen vacancies to facilitate the ferromagnetism. However, other possible extrinsic contributions to the magnetic ordering, such as clusters of Fe 3O 4 and FeO or contamination can also explain the observed behavior.« less

  15. Hydrothermal synthesis and structural analysis of new mixed oxyanion borates: Ba{sub 11}B{sub 26}O{sub 44}(PO{sub 4}){sub 2}(OH){sub 6}, Li{sub 9}BaB{sub 15}O{sub 27}(CO{sub 3}) and Ba{sub 3}Si{sub 2}B{sub 6}O{sub 16}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Heyward, Carla, E-mail: cheywar@clemson.edu; McMillen, Colin D., E-mail: cmcmill@clemson.edu; Kolis, Joseph, E-mail: kjoseph@clemson.edu

    2013-07-15

    Several new borate compounds, Ba{sub 11}B{sub 26}O{sub 44}(PO{sub 4}){sub 2}(OH){sub 6} (1), Li{sub 9}BaB{sub 15}O{sub 27}(CO{sub 3}) (2), and Ba{sub 3}Si{sub 2}B{sub 6}O{sub 16} (3) were synthesized containing other hetero-oxyanion building blocks in addition to the borate frameworks. They were all prepared under hydrothermal conditions and characterized by single crystal and powder X-ray diffraction, and IR spectroscopy. Crystal data: For 1; space group P2{sub 1}/c, a=6.8909 (14) Å, b=13.629 (3) Å, c=25.851 (5) Å, β=90.04 (3)°; For 2; space group P-31c, a=8.8599 (13) Å, c=15.148 (3) Å; For 3; space group P-1, a=5.0414 (10) Å, b=7.5602 (15) Å, c=8.5374 (17)more » Å, α=77.15 (3)°, β=77.84 (3)°, γ=87.41 (3)° for 3. Compounds 1 and 2 contain isolated oxyanions [PO{sub 4}]{sup 3−} and [CO{sub 3}]{sup 2−} respectively, sitting in channels created by the borate framework, while structure 3 has the [SiO{sub 4}]{sup 4−} groups directly bonded to the borate groups creating a B–O–Si framework. - Highlights: • Hydrothermal syntheses of three new mixed oxyanion borates are presented. • Ba{sub 11}B{sub 26}O{sub 44}(PO{sub 4}){sub 2}(OH){sub 6} contains isolated [PO{sub 4}]{sup 3−} in voids of the borate framework. • Li{sub 9}BaB{sub 15}O{sub 27}(CO{sub 3}) contains isolated [CO{sub 3}]{sup 2−} in channels created by the framework. • Ba{sub 3}Si{sub 2}B{sub 6}O{sub 16} has direct bonding of [SiO{sub 4}]{sup 4−} and borates creating a B–O–Si framework.« less

  16. 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... Amendments to Form MA and Form MA-I. (a) When amendment is required—Form MA. A registered municipal advisor...

  17. Tailoring the structure and thermoelectric properties of BaTiO3via Eu2+ substitution.

    PubMed

    Xiao, Xingxing; Widenmeyer, Marc; Xie, Wenjie; Zou, Tianhua; Yoon, Songhak; Scavini, Marco; Checchia, Stefano; Zhong, Zhicheng; Hansmann, Philipp; Kilper, Stefan; Kovalevsky, Andrei; Weidenkaff, Anke

    2017-05-31

    A series of Ba 1-x Eu x TiO 3-δ (0.1 ≤ x ≤ 0.9) phases with ∼40 nm particle size were synthesized via a Pechini method followed by annealing and sintering under a reducing atmosphere. The effects of Eu 2+ substitution on the BaTiO 3 crystal structure and the thermoelectric transport properties were systematically investigated. According to synchrotron X-ray diffraction data only cubic perovskite structures were observed. On the local scale below about 20 Å (equal to ∼5 unit cells) deviations from the cubic structure model (Pm3[combining macron]m) were detected by evaluation of the pair distribution function (PDF). These deviations cannot be explained by a simple symmetry breaking model like in EuTiO 3-δ . The best fit was achieved in the space group Amm2 allowing for a movement of Ti and Ba/Eu along 〈110〉 of the parent unit cell as observed for BaTiO 3 . Density functional calculations delivered an insight into the electronic structure of Ba 1-x Eu x TiO 3-δ . From the obtained density of states a significant reduction of the band gap by the presence of filled Eu 2+ 4f states at the top of the valence band was observed. The physical property measurements revealed that barium-europium titanates exhibit n-type semiconducting behavior and at high temperature the electrical conductivity strongly depended on the Eu 2+ content. Activation energies calculated from the electrical conductivity and Seebeck coefficient data indicate that at high temperatures (800 K < T < 1123 K) the conduction mechanism of Ba 1-x Eu x TiO 3-δ (0.1 ≤ x ≤ 0.9) is a polaron hopping when 0 < x ≤ 0.6 and is a thermally activated process when 0.6 < x < 1. Besides, the thermal conductivity increases with increasing Eu 2+ concentration. Due to a remarkable improvement of the power factor, Ba 0.1 Eu 0.9 TiO 3-δ showed a ZT value of 0.24 at 1123 K.

  18. Localized excitons in fluoroperovskite LiBaF3 crystals

    NASA Astrophysics Data System (ADS)

    Springis, Maris; Trukhin, Anatoly N.; Tale, Ivar

    2003-08-01

    Two radiating processes in LiBaF3 crystals, fast valence-core transitions (5.4 - 6.5 eV) and slow, so called self-trapped exciton luminescence (about 4.3 eV), are important for practical application. Here we present a study of 4.3 eV luminescence under X-ray excitation and photoexcitation as well as under photostimulation after X-irradiation of undoped and Ag-doped LiBaF3 crystals at various temperatures. It is shown that 4.3 eV luminescence appears under X-ray excitation at least from 85 K to 400 K in both undoped and doped crystals. In all samples studied the excitation spectra of 4.3 eV luminescence contain both the main exciton like band at the edge of fundamental absorption at about 10 eV and weaker band in 7.8 - 8.6 eV region. Luminescence spectrum in the 3.8 - 4.8 eV region under 7.8 - 8.6 eV excitation differs slightly from that under 10 eV excitation. Several luminescence bands in 3.8 - 4.8 eV region arises in the temperature range 85 - 230 K under photostimulation in absorption band of F-type center at 2.9 eV created previously under X-irradiation. We propose the luminescence of LiBaF3 crystals in the 3.8 - 4.8 eV region may be caused by localized excitons formed not only under excitation near the fundamental absorption but also in result of electron recombination with localized holes thermally destroyed above 230 K.

  19. An ABO blood grouping discrepancy: Probable B(A) phenotype.

    PubMed

    Jain, Ashish; Gupta, Anubhav; Malhotra, Sheetal; Marwaha, Neelam; Sharma, Ratti Ram

    2017-06-01

    In B(A) phenotype, an autosomal dominant phenotype, there is a weak A expression on group B RBCs. We herein report a case of a probable B(A) phenotype in a first time 20-year old male donor. The cell and serum grouping were done using tube technique and also with blood grouping gel card (Diaclone, ABD cards for donors, BioRad, Switzerland). The antisera used were commercial monoclonal IgM type. To check for the weak subgroup of A, cold adsorption and heat elution was performed. The cell grouping was A weak B RhD positive while the serum grouping was B. There was no agglutination with O cells and the autologous control was also negative. It was a group II ABO discrepancy with or without group IV discrepancy. Results for both the eluate and last wash were negative. Hence, the possibility of weak subgroup of A was unlikely. Blood grouping gel card also showed a negative reaction in the anti-A column. One lot of anti-A was showing 'weak +' agglutination while the other lot was showing 'negative' reaction with the donor RBCs by tube technique. There was no agglutination observed with anti-A1 lectin. Our case highlights the serological characteristics of a B(A) phenotype. This case emphasizes the vital role of cell and serum grouping in detecting such discrepancies especially in donors which can lead to mislabeling of the blood unit and may be a potential risk for the transfusion recipient if not resolved appropriately. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Enhanced strain effect of aged acceptor-doped BaTiO3 ceramics with clamping domain structures

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Zhou, Zhiyong; Zhao, Xiaobo; Liu, Zhen; Liang, Ruihong; Dong, Xianlin

    2017-03-01

    A clamping domain structure is proposed to improve the amount of non-180° domain switching in BaTiO3 based piezoelectric ceramics. Experimental results show a large unipolar strain of 0.23% at 5 kV/mm in aged 0.5 mol. % Mn doped BaTiO3 ceramics with clamping domain structures, and the normalized strain (d33*= Smax/Emax) reaches 600 pm/V at low electric fields of 2 or 3 kV/mm. In contrast, pure BaTiO3 ceramics with clamping domain structures exhibit no clear polarization constriction or strain enhancement at 3 kV/mm. Electron paramagnetic resonance spectra verify the existence of titanium vacancies, Mn2+ and Mn4+, in 0.5 mol. % Mn doped BaTiO3 ceramics. These results indicate that the enhanced strain effect can be attributed to the combined effect of the clamping domain structure and stabilization of defect dipoles. This method provides a general way to obtain large strain in ferroelectrics.

  1. A new oxytelluride: Perovskite and CsCl intergrowth in Ba 3Yb 2O 5Te

    DOE PAGES

    Whalen, J. B.; Besara, T.; Vasquez, R.; ...

    2013-04-27

    The new oxytelluride Ba 3Yb 2O 5Te was obtained from an alkaline earth flux. Ba3Yb2O5Te crystallizes in the tetragonal space group P4/ mmm (#123), with a=4.3615(3) Å and c=11.7596(11) angstrom, Z=1. The structure combines two distinct building blocks, a Ba 2Yb 2O 5 perovskite-like double layer with square bipyramidal coordination of the ytterbium ions, and a CsCl-type BaTe layer. Short range magnetic order is apparent at below 5 K, with the magnetic behavior above this temperature dominated by crystal field effects. The structure may be considered as an analog to the Ruddlesden-Popper phases, where the NaCl-type layer has been replacedmore » by the CsCl-type layer. Finally, the two-dimensional magnetic behavior is expected based on the highly anisotropic nature of the structure.« less

  2. Luminescence properties of phosphate phosphor Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, Fu; Liu, Yufeng, E-mail: liuyufeng4@126.com; Tian, Xiaodong

    2015-05-15

    A series of reddish orange-emitting phosphate phosphors Ba{sub 3}Y{sub 1−x}(PO{sub 4}){sub 3}:xSm{sup 3+}(0.01≤x≤0.20) were synthesized by solid-state reaction. X-ray diffraction and photoluminescence spectra were utilized to characterize the structure and luminescence properties of as-synthesized phosphors. The optimized phosphors Ba{sub 3}Y{sub 0.95}(PO{sub 4}){sub 3}:0.05Sm{sup 3+} present several excitation bands from 300 to 500 nm, and exhibit intense reddish orange-emitting properties. The energy transfer type between Sm{sup 3+} ions was confirmed as d–d interaction by using Van Uitert model. The chromatic properties of the typical sample Ba{sub 3}Y(PO{sub 4}){sub 3}:0.05Sm{sup 3+} phosphor have been found to have chromaticity coordinates of (0.583, 0.405),more » which are located in reddish orange region under the excitation of 401 nm. These results indicated that Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} phosphors have potential applications in the field of lighting and display due to their effective excitation in the near-ultraviolet range. - Graphical abstract: The color coordinates for 5 mol% Sm{sup 3+} doped Ba{sub 3}Y(PO{sub 4}){sub 3} phosphor were calculated to be (0.583, 0.405), which are located in reddish orange region under the excitation of 401 nm. The peaks of Ba{sub 3}Y{sub 0.95}(PO{sub 4}){sub 3}:0.05Sm{sup 3+} phosphor with the highest emission intensity at 600 nm are broader than those of Y{sub 2}O{sub 3}:Eu{sup 3+} and Y{sub 2}O{sub 2}S:Eu{sup 3+} phosphors. All these characteristics suggest that Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} phosphors are suitable for near-UV (370–410 nm) excitation and can be applicable to near UV-based WLEDs. ▪ - Highlights: • Different concentration Sm{sup 3+}-doped Ba{sub 3}Y(PO{sub 4}){sub 3} phosphors were fabricated by solid state method. • The optimized phosphors present the several excitation bands from 300 to 500 nm. • The Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} shows bright reddish

  3. DECAY OF Ba$sup 13$$sup 3$

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ramaswamy, M.K.; Skeel, W.L.; Jastram, P.S.

    1960-06-01

    The gamma rays following the electron-capture decay of 7.5 year Ba/sup 133/ were studied by means of a coincidence scintillation spectrometer. Gamma rays at 79, 79, 274, presence of a 56 kev gamma ray was confirmed. The resulting decay scheme with levels at 79, 158, 381, and 437 kev is in excellent agreement with previous work. Spin and parity assignments are made for these levels. (auth)

  4. NIR emission using Ce3+→Nd3+ energy transfer in Ba3Ce(PO4)3:Nd3+ phosphor

    NASA Astrophysics Data System (ADS)

    Tumram, P. V.; Moharil, S. V.

    2018-05-01

    In the System CePO4-Ba3(PO4)2, the intermediate compound Ba3Ce(PO4)3, is well known. In recent years, luminescence of rare earths has been studied in this host. However, there are no reports on the NIR emission in Ba3Ce(PO4)3. Here, NIR emission resulting from Ce3+→Nd3+ energy transfer in Ba3Ce(PO4)3 host is reported. This could be relevant for applications in bioimaging, telecommunication, solar photovoltaics, Photodynamic therapy, photostimulated localized hyperthermia, etc.

  5. BACTERICIDAL COATINGS ON TEXTILES FOR REMEDIATION OF INTERMICROBE ACTIVITY (BaCTeRIA) SUMMARY REPORT

    DTIC Science & Technology

    2017-07-07

    Activity by Bacillus sp. P11” Food Bioprocess Technol. 4:822- 828. (2011) Levy, S.B and Marshal,l B.; “ Antibacterial resistance worldwide: causes...TEXTILES FOR REMEDIATION OF INTERMICROBE ACTIVITY (BaCTeRIA) SUMMARY REPORT by Tobyn A. Branck Courtney M. Cowell Jennifer M. Rego and...October 2011 – September 2015 4. TITLE AND SUBTITLE BACTERICIDAL COATINGS ON TEXTILES FOR REMEDIATION OF INTERMICROBE ACTIVITY (BaCTeRIA) SUMMARY REPORT

  6. Thermoelectric properties of AMg 2X 2, AZn 2Sb 2 (A = Ca, Sr, Ba; X = Sb, Bi), and Ba 2ZnX 2 (X = Sb, Bi) Zintl compounds

    DOE PAGES

    Sun, Jifeng; Singh, David J.

    2017-04-03

    In this paper, we report a theoretical investigation of the electronic structure and transport properties of eleven Zintl compounds including nine 122 phases (AMg 2X 2, AZn 2Sb 2 (A = Ca, Sr, Ba; X = Sb, Bi)) and two 212 phases (Ba 2ZnX 2 (X = Sb, Bi)). The electronic structures and electrical transport properties are studied using ab initio calculations and semi-classical Boltzmann theory within the constant relaxation time approximation. All the compounds are semiconducting. We find that the n-type 122 phases with the CaAl 2Si 2 structure type show better performance than p-type materials due to themore » multi-valley degeneracy with anisotropic carrier pockets at and near the conduction band minimum. The pocket anisotropy is beneficial in achieving high conductivity and Seebeck coefficient simultaneously. This mechanism yields substantial improvement in the power factor. Finally, the general performance of 212 phases is inferior to that of the 122 phases, with the Ba 2ZnSb 2 compound showing better performance.« less

  7. Local geometric and electronic structures and origin of magnetism in Co-doped BaTiO3 multiferroics

    NASA Astrophysics Data System (ADS)

    Phan, The-Long; Thang, P. D.; Ho, T. A.; Manh, T. V.; Thanh, Tran Dang; Lam, V. D.; Dang, N. T.; Yu, S. C.

    2015-05-01

    We have prepared polycrystalline samples BaTi1-xCoxO3 (x = 0-0.1) by solid-state reaction. X-ray diffraction and Raman-scattering studies reveal the phase separation in crystal structure as changing Co-doping content (x). The samples with x = 0-0.01 are single phase in a tetragonal structure. At higher doping contents (x > 0.01), there is the formation and development of a secondary hexagonal phase. Magnetization measurements at room temperature indicate a coexistence of paramagnetic and weak-ferromagnetic behaviors in BaTi1-xCoxO3 samples with x > 0, while pure BaTiO3 is diamagnetic. Both these properties increase with increasing x. Analyses of X-ray absorption spectra recorded from BaTi1-xCoxO3 for the Co and Ti K-edges indicate the presence of Co2+ and Co3+ ions. They locate in the Ti4+ site of the tetragonal and hexagonal BaTiO3 structures. Particularly, there is a shift of oxidation state from Co2+ to Co3+ when Co-doping content increases. We believe that the paramagnetic nature in BaTi1-xCoxO3 samples is due to isolated Co2+ and Co3+ centers. The addition of Co3+ ions enhances the paramagnetic behavior. Meanwhile, the origin of ferromagnetism is due to lattice defects, which is less influenced by the changes caused by the variation in concentration of Co2+ and Co3+ ions.

  8. Synthesis and Characterization of an Earth-Abundant Cu2BaSn(S,Se)4 Chalcogenide for Photoelectrochemical Cell Application.

    PubMed

    Shin, Donghyeop; Ngaboyamahina, Edgard; Zhou, Yihao; Glass, Jeffrey T; Mitzi, David B

    2016-11-17

    Cu 2 BaSnS 4-x Se x films consisting of earth-abundant metals have been examined for photocathode application. Films with different Se contents (i.e., Cu 2 BaSnS 4-x Se x with x ≤ 2.4) were synthesized using a cosputter system with post-deposition sulfurization/selenization annealing treatments. Each film adopts a trigonal P3 1 crystal structure, with progressively larger lattice constants and with band gaps shifting from 2.0 to 1.6 eV, as more Se substitutes for S in the parent compound Cu 2 BaSnS 4 . Given the suitable bandgap and earth-abundant elements, the Cu 2 BaSnS 4-x Se x films were studied as prospective photocathodes for water splitting. Greater than 6 mA/cm 2 was obtained under illumination at -0.4 V versus reversible hydrogen electrode for Pt/Cu 2 BaSnS 4-x Se x films with ∼60% Se content (i.e., x = 2.4), whereas a bare Cu 2 BaSnS 4-x Se x (x = 2.4) film yielded ∼3 mA/cm 2 at -0.4 V/RHE.

  9. Pressure-induced photoluminescence in Mn2+-doped BaF2 and SrF2 fluorites

    NASA Astrophysics Data System (ADS)

    Hernández, Ignacio; Rodríguez, Fernando

    2003-01-01

    This work reports an effective way for inducing room temperature photoluminescence (PL) in Mn2+-doped BaF2 and SrF2 using high-pressure techniques. The aim is to understand the surprising PL behavior exhibited by Mn2+ at the cubal site of the fluorite structure. While Mn2+-doped CaF2 shows a green PL with quantum yield close to 1 at room temperature, Mn2+-doped MF2 (M=Ba,Sr) is not PL either at room temperature (SrF2) or at any temperature (BaF2) at ambient pressure. We associate the loss of Mn2+ PL on passing from CaF2 to SrF2 or BaF2 with nonradiative multiphonon relaxation whose thermal activation energy decreases along the series CaF2→SrF2→BaF2. A salient feature of this work deals with the increase of activation energy induced by pressure. It leads to a quantum yield enhancement, which favors PL recovery. Furthermore, the activation energy mainly depends on the crystal volume per molecule irrespective of the crystal structure or the local symmetry around the impurity. In this way, the relevance of the fluorite-to-cotunnite phase transition is analyzed in connection with the PL properties of the investigated compounds. The PL spectrum and the corresponding lifetime are reported for both structural phases as a function of pressure.

  10. Fabrication and Characterization of (100),(001)-Oriented Reduction-Resistant Lead-Free Piezoelectric (Ba,Ca)TiO3 Ceramics Using Platelike Seed Crystals

    NASA Astrophysics Data System (ADS)

    Ichikawa, Hiroki; Sakamoto, Wataru; Akiyama, Yoshikazu; Maiwa, Hiroshi; Moriya, Makoto; Yogo, Toshinobu

    2013-09-01

    The preparation of reduction-resistant (Ba,Ca)TiO3 ceramics as lead-free piezoelectric materials was studied. To improve their electrical properties, (100),(001)-oriented (Ba0.85Ca0.15)TiO3 ceramics were fabricated by the reactive templated grain growth method using a mixture of platelike CaTiO3 and BaTiO3 particles. The platelike CaTiO3 and BaTiO3 particles were prepared through a topochemical microcrystal conversion process using CaBi4Ti4O15 and BaBi4Ti4O15 plate-like precursor crystals. The 100 orientation degree of the grain-oriented (Ba0.85Ca0.15)TiO3 ceramics was 92%, as estimated by Lotgering's equation. In addition, 1 mol % Ba excess and 1 mol % Mn-doped (Ba0.85Ca0.15)TiO3 sintered bodies, which were sintered at 1350 °C in an Ar flow containing H2 (0.3%), had sufficient resistivity to allow the characterization of electrical properties. The ferroelectric and field-induced strain properties of the (Ba0.85Ca0.15)TiO3 ceramics, sintered in the reducing atmosphere, were markedly improved as a result of fabricating grain-oriented samples. The field-induced strain coefficient (estimated from the slope of the unipolar strain loop) of the nonreducible (100),(001)-oriented (Ba0.85Ca0.15)TiO3 ceramics reached 570 pm/V, which was higher than that of polycrystals (260 pm/V) with no preferential orientation.

  11. Microwave dielectric properties of BaO-2CeO{sub 2}-nTiO{sub 2} ceramics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sreemoolanadhan, H.; Sebastian, M.T.; Ratheesh, R.

    2004-11-01

    The BaO-2CeO{sub 2}-nTiO{sub 2} ceramics with n=3, 4 and 5 have been prepared with CeO{sub 2} as starting material. The ceramics have been characterized using scanning electron microscopy, X-ray diffraction, Raman and X-ray photoelectron spectroscopy techniques. The microwave dielectric properties have been measured using standard dielectric resonator techniques. BaO-2CeO{sub 2}-3TiO{sub 2} (123), BaO-2CeO{sub 2}-4TiO{sub 2} (124) and BaO-2CeO{sub 2}-5TiO{sub 2} (125) ceramics showed dielectric constants of 38, 27 and 32, respectively. All the ceramics showed fairly good unloaded Q-factors. 124 and 125 compounds exhibited low {tau}f values, while 123 showed a high {tau}f value.

  12. Ionic-Liquid-Assisted Microwave Synthesis of Solid Solutions of Sr 1–xBa xSnO 3 Perovskite for Photocatalytic Applications

    DOE PAGES

    Alammar, Tarek; Slowing, Igor I.; Anderegg, Jim; ...

    2017-06-06

    Nanocrystalline Sr 1–xBa xSnO 3 (x = 0, 0.2, 0.4, 0.8, 1) perovskite photocatalysts were prepared by microwave synthesis in an ionic liquid (IL) and subsequent heat-treatment. The influence of the Sr/Ba substitution on the structure, crystallization, morphology, and photocatalytic efficiency was investigated and the samples were fully characterized. On the basis of X-ray diffraction results, as the Ba content in the SrSnO 3 lattice increases, a symmetry increase was observed from the orthorhombic perovskite structure for SrSnO 3 to the cubic BaSnO 3 structure. The analysis of the sample morphology by SEM reveals that the Sr 1–xBa xSnO 3more » samples favor the formation of nanorods (500 nm–5 μm in diameter and several micrometers long). The photophysical properties were examined by UV/Vis diffuse reflectance spectroscopy. The band gap decreases from 3.85 to 3.19 eV with increasing Ba 2+ content. Furthermore, the photocatalytic properties were evaluated for the hydroxylation of terephthalic acid (TA). The order of the activities for TA hydroxylation was Sr 0.8Ba 0.2SnO 3 > SrSnO 3 > BaSnO 3 > Sr 0.6Ba 0.4SnO 3 > Sr 0.2Ba 0.8SnO 3. Here, the highest photocatalytic activity was observed for Sr 0.8Ba 0.2SnO 3, and this can be attributed to the synergistic impacts of the modification of the crystal structure and morphology, the relatively large surface area associated with the small crystallite size, and the suitable band gap and band-edge position.« less

  13. AC conduction of Ba1-xCaxTiO3 and BZT-BCTx

    NASA Astrophysics Data System (ADS)

    Khien, Nguyen Van; Huy, Than Trong; Hong, Le Van

    2018-03-01

    Ba1-xCaxTiO3 (BCTx), (x =0.0-0.3) and Ba0.8Zr0.2TiO3-Ba1-xCaxTiO3 (BZT-BCTx), (x=0.15-0.35) were fabricated by the solid state reaction method. Phase structure of the material samples was identified by X-ray diffraction. The impedance versus frequency in a range of 100 Hz to 2.5 MHz was measured for all the samples at room temperature. AC conductivity versus frequency of the BCTx and BZT-BCTx was evaluated and fitted by using the extended Universal Dielectric Response (UDR) equations. The fitting results were discussed in detail and shown that the localized reorientation polarization-based mechanism is most contributed in BCTx matrial samples. Basically both two the hopping polaron and polarization mechanisms play roles in BZT-BCTx material samples. In contrary the short-range polaron hopping is dominated in ac conductivity of BZT-BCTx material samples in low frequency range.

  14. P-type field effect transistor based on Na-doped BaSnO3

    NASA Astrophysics Data System (ADS)

    Jang, Yeaju; Hong, Sungyun; Park, Jisung; Char, Kookrin

    We fabricated field effect transistors (FET) based on the p-type Na-doped BaSnO3 (BNSO) channel layer. The properties of epitaxial BNSO channel layer were controlled by the doping rate. In order to modulate the p-type FET, we used amorphous HfOx and epitaxial BaHfO3 (BHO) gate oxides, both of which have high dielectric constants. HfOx was deposited by atomic-layer-deposition and BHO was epitaxially grown by pulsed laser deposition. The pulsed laser deposited SrRuO3 (SRO) was used as the source and the drain contacts. Indium-tin oxide and La-doped BaSnO3 were used as the gate electrodes on top of the HfOx and the BHO gate oxides, respectively. We will analyze and present the performances of the BNSO field effect transistor such as the IDS-VDS, the IDS-VGS, the Ion/Ioff ratio, and the field effect mobility. Samsung Science and Technology Foundation.

  15. Lateral electric-field control of giant magnetoresistance in Co/Cu/Fe/BaTiO{sub 3} multiferroic heterostructure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Savitha Pillai, S.; Kojima, H.; Itoh, M.

    2015-08-17

    We report lateral electric-field-driven sizable changes in the magnetoresistance of Co/Cu/Fe tri-layered wires on BaTiO{sub 3} single crystal. While the observed change is marginal in the tetragonal phase of BaTiO{sub 3}, it reaches over 40% in the orthorhombic and rhombohedral phases with an electric field of 66 kV/cm. We attribute it to possible electric-field-induced variations of the spin-dependent electronic structures, i.e., spin polarization, of the Fe via interfacial strain transfer from BaTiO{sub 3}. The contrasting results for the different phases of BaTiO{sub 3} are discussed, associated with the distinct aspects of the ferroelectric polarization switching processes in each phase.

  16. Temperature dependences of the electromechanical and electrocaloric properties of Ba(Zr,Ti)O3 and (Ba,Sr)TiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Maiwa, Hiroshi

    2017-10-01

    The electrocaloric properties of Ba(Zr,Ti)O3 and (Ba,Sr)TiO3 ceramics (BZT and BST, respectively) were investigated by the indirect estimation and direct measurement of temperature-electric field (T-E) hysteresis loops. The measured T-E loops had shapes similar to those of the strain-electric field (s-E) loops. The measured temperature changes (ΔTs) at around 30 °C of the BZT ceramics sintered at 1450 °C and BST ceramics sintered at 1600 °C upon the release of the electric field from 30 kV/cm to 0 were 0.34 and 0.57 K, respectively. The temperature dependences of the electromechanical and electrocaloric properties were investigated. The BZT ceramics sintered at 1450 °C exhibited the largest electromechanical and electrocaloric properties at around 30 °C, which corresponds to the phase transition temperature. BST is more temperature dependent than BZT. BST ceramics sintered at 1600 °C exhibited the largest electromechanical and electrocaloric properties at around 29 °C, which is about 10 °C higher than the phase transition temperature.

  17. The BaBar detector: Upgrades, operation and performance

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aubert, B.; Barate, R.; Boutigny, D.

    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.

  18. Direct evidence for octupole deformation in Ba 146 and the origin of large E 1 moment variations in reflection-asymmetric nuclei

    DOE PAGES

    Bucher, B.; Zhu, S.; Wu, C. Y.; ...

    2017-04-12

    Despite the more than 1 order of magnitude difference between the measured dipole moments in 144Ba and 146Ba, the octupole correlations in 146Ba are found to be as strong as those in 144Ba with a similarly large value of B(E3;3 – → 0 +) determined as 48( +21 –29) W.u. Here, the new results not only establish unambiguously the presence of a region of octupole deformation centered on these neutron-rich Ba isotopes, but also manifest the dependence of the electric dipole moments on the occupancy of different neutron orbitals in nuclei with enhanced octupole strength, as revealed by fully microscopicmore » calculations.« less

  19. High-pressure studies on Ba-doped cobalt perovskites by neutron diffraction

    NASA Astrophysics Data System (ADS)

    Cao, Huibo; Garlea, Vasile; Wang, Fangwei; Dos Santos, Antonio; Cheng, Zhaohua

    2012-02-01

    Cobalt perovskite possess rich structural, magnetic and electrical properties depending on the subtle balance of the interactions among the spin, charge, and orbital degrees of freedom. Divalent hole-doped cobalt perovskites LaA^2+CoO3 exhibit structural phase transitions, metal-insulator transitions, and multi-magnetic phase transitions. High-pressure measurement is believed to mimic the size effects of the doped ions. We performed neutron diffraction experiments on selected Ba-doped LaCoO3 under pressures up to 6.3 GPa at SNAP at Spallation Neutron Source of ORNL. This work focuses on the high-pressure effects of the selected Ba-doped samples and the change of the phase diagram with pressure.

  20. Dielectric and modulus studies of polycrystalline BaZrO3 ceramic

    NASA Astrophysics Data System (ADS)

    Saini, Deepash S.; Singh, Sunder; Kumar, Anil; Bhattacharya, D.

    2018-05-01

    In the present work, dielectric and modulus studies of polycrystalline BaZrO3 ceramic, prepared by modified combustion method followed by conventional sintering, are investigated over the frequency range of 100 Hz to 106 Hz at different temperatures from 250 to 500 °C in air. The high value of dielectric constant (ɛ' ˜ 103) of BaZrO3 at high temperature and low frequency can be attributed to the Maxwell-Wagner polarization mechanism as well as to the thermally activated mechanism of charge carriers. Electric modulus reveal two type relaxations in the 250 °C to 800 °C temperature region as studied at different frequencies over 100 Hz to 106 Hz in air.

  1. Nonenzymatic detection of glucose using BaCuO2 thin layer

    NASA Astrophysics Data System (ADS)

    Ito, Takeshi; Asada, Tsuyoshi; Asai, Naoto; Shimizu, Tomohiro; Shingubara, Shoso

    2017-01-01

    A BaCuO2 thin layer was deposited on a glassy carbon electrode and used for the direct oxidation of glucose. The crystalline, electrochemical, and physicochemical properties that depend on the deposition temperature and deposition time were studied. X-ray diffraction (XRD) analysis showed that the thin layer was amorphous even at 400 °C. The current density of the glucose oxidation using the thin layer deposited at 200 °C was higher than those at other deposition temperatures. Under this condition, the current density increased with the glucose concentration and deposition time. These results indicate that a BaCuO2 thin layer has potential for measuring the blood glucose level without enzymes.

  2. 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.

  3. BaP (PAH) air quality modelling exercise over Zaragoza (Spain) using an adapted version of WRF-CMAQ model.

    PubMed

    San José, Roberto; Pérez, Juan Luis; Callén, María Soledad; López, José Manuel; Mastral, Ana

    2013-12-01

    Benzo(a)pyrene (BaP) is one of the most dangerous PAH due to its high carcinogenic and mutagenic character. Because of this reason, the Directive 2004/107/CE of the European Union establishes a target value of 1 ng/m(3) of BaP in the atmosphere. In this paper, the main aim is to estimate the BaP concentrations in the atmosphere by using last generation of air quality dispersion models with the inclusion of the transport, scavenging and deposition processes for the BaP. The degradation of the particulated BaP by the ozone has been considered. The aerosol-gas partitioning phenomenon in the atmosphere is modelled taking into a count that the concentrations in the gas and the aerosol phases. If the pre-existing organic aerosol concentrations are zero gas/particle equilibrium is established. The model has been validated at local scale with data from a sampling campaign carried out in the area of Zaragoza (Spain) during 12 weeks. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Experimental and first principle studies on electronic structure of BaTiO{sub 3}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sagdeo, Archna, E-mail: archnaj@rrcat.gov.in; Ghosh, Haranath, E-mail: archnaj@rrcat.gov.in; Chakrabarti, Aparna, E-mail: archnaj@rrcat.gov.in

    2014-04-24

    We have carried out photoemission experiments to obtain valence band spectra of various crystallographic symmetries of BaTiO{sub 3} system which arise as a function of temperature. We also present results of a detailed first principle study of these symmetries of BaTiO{sub 3} using generalized gradient approximation for the exchange-correlation potential. Here we present theoretical results of density of states obtained from DFT based simulations to compare with the experimental valence band spectra. Further, we also perform calculations using post density functional approaches like GGA + U method as well as non-local hybrid exchange-correlation potentials like PBE0, B3LYP, HSE in ordermore » to understand the extent of effect of correlation on band gaps of different available crystallographic symmetries (5 in number) of BaTiO{sub 3}.« less

  5. Ba2Mg(BO3)2:Bi3+ - A new phosphor with ultraviolet light emission

    NASA Astrophysics Data System (ADS)

    Lakshminarasimhan, N.; Jayakiruba, S.; Prabhavathi, K.

    2017-10-01

    Ultraviolet light emission was observed in a new Ba2Mg(BO3)2:Bi3+ phosphor. Bi3+ substitution for Ba2+ in the lattice was supplemented with K+ to maintain the charge neutrality. The samples of the formula Ba2-2xBixKxMg(BO3)2 [x = 0, 0.001, 0.01, 0.02, and 0.05] synthesized by solid state reaction were characterized using powder X-ray diffraction for their phase formation. Raman and diffuse reflectance UV-Vis spectroscopic techniques were used to obtain information on the vibrational modes and optical properties, respectively. The room temperature photoluminescence measurements revealed an ultraviolet emission at 370 nm when excited using 304 nm wavelength and the Stokes shift is 5868 cm-1.

  6. Electron-hole asymmetry, Dirac fermions, and quantum magnetoresistance in BaMnBi 2

    DOE PAGES

    Li, Lijun; Wang, Kefeng; Graf, D.; ...

    2016-03-28

    Here, we report two-dimensional quantum transport and Dirac fermions in BaMnBi 2 single crystals. BaMnBi 2 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. Introduction of BaSnO3 and BaZrO3 artificial pinning centres into 2G HTS wires based on PLD-GdBCO films. Phase I of the industrial R&D programme at SuperOx

    NASA Astrophysics Data System (ADS)

    Chepikov, V.; Mineev, N.; Degtyarenko, P.; Lee, S.; Petrykin, V.; Ovcharov, A.; Vasiliev, A.; Kaul, A.; Amelichev, V.; Kamenev, A.; Molodyk, A.; Samoilenkov, S.

    2017-12-01

    An industrial R&D programme is ongoing at SuperOx, aimed at improving 2G HTS wire performance in magnetic field. We introduce perovskite artificial pinning centres (APC) into the HTS layer matrix. In contrast to most studies described in the literature, we use the high rate production processing parameters and PLD equipment at SuperOx. This paper reports the results of Phase I of this programme. We fabricated 2G HTS wires by pulsed laser deposition of GdBCO films doped with 6%, 12% and 18% (molar) of BaSnO3 and 6% (molar) of BaZrO3, and compared their performance with an undoped reference sample. The depositions were carried out at production growth rates of 375, 560 and 750 nm min-1 by varying laser pulse frequency. BaZrO3 and BaSnO3 formed columnar semi-coherent nanoinclusions in the GdBCO film matrix. The average transverse size of the nanocolumns was about 5 nm, and their volume density correlated with the dopant concentration. All doped samples exhibited much lower angular anisotropy of in-field critical current and higher lift-factors than the undoped sample. Samples containing 6% BaSnO3 and deposited at the lower growth rates, had higher I c than the undoped sample in the entire temperature range, in a wide range of magnetic field (B//c). The sample containing 6% BaZrO3 had higher I c than the undoped sample at 20 and 4.2 K. These results are an encouraging start of our programme, as they show a positive impact of APC introduced into 2G HTS wires fabricated at production throughput. Phase II work will be focussed on maximising the improvements in specific temperature and field conditions, as well as on the verification of reproducibility of the improvements in production wires.

  8. Band-offsets at BaTiO3/Cu2O heterojunction and enhanced photoelectrochemical response: theory and experiment(Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Sharma, Dipika; Satsangi, Vibha R.; Dass Kaura, Sahab; Shrivastav, Rohit; Waghmare, Umesh V.

    2016-10-01

    Band-offsets at BaTiO3/Cu2O heterojunction and enhanced photoelectrochemical response: theory and experiment Dipika Sharmaa, Vibha R. Satsangib, Rohit Shrivastava, Umesh V. Waghmarec, Sahab Dassa aDepartment of Chemistry, Dayalbagh Educational Institute, Agra-282 110 (India) bDepartment of Physics and Computer Sciences, Dayalbagh Educational Institute, Agra-282 110 (India) cTheoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560 064 (India) * Phone: +91-9219695960. Fax: +91-562-2801226. E-mail: drsahabdas@gmail.com. Study on photoelectrochemical activity of pristine BaTiO3, Cu2O and BaTiO3/Cu2O heterojunction has been carried out using DFT based band offsets and charge carriers effective mass calculations and their experimental verification. The results of DFT calculations show that BaTiO3 and Cu2O have staggered type band alignment after the heterojunction formation and high mobility of electrons in Cu2O as compared to the electrons in BaTiO3. Staggered type band edges alignment and high mobility of electrons and holes improved the separation of photo-generated charge carriers in BaTiO3/Cu2O heterojunction. To validate the theoretical results experiments were carried out on pristine BaTiO3, Cu2O and BaTiO3/Cu2O heterojunction with varying thickness of Cu2O. All samples were characterized by X- Ray Diffractometer, SEM and UV-Vis spectrometry. Nanostructured thin films of pristine BaTiO3, Cu2O and BaTiO3/Cu2O heterojunction were used as photoelectrode in the photoelectrochemical cell for water splitting reaction. Maximum photocurrent density of 1.44 mA/cm2 at 0.90 V/SCE was exhibited by 442 nm thick BaTiO3/Cu2O heterojunction photoelectrode Increased photocurrent density and enhanced photoconversion efficiency, exhibited by the heterojunction may be attributed to improved conductivity and enhanced separation of the photogenerated carriers at the BaTiO3/Cu2O interface. The experimental results and first

  9. 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.

  10. Improved osteoblasts growth on osteomimetic hydroxyapatite/BaTiO3 composites with aligned lamellar porous structure.

    PubMed

    Liu, Beilei; Chen, Liangjian; Shao, Chunsheng; Zhang, Fuqiang; Zhou, Kechao; Cao, Jun; Zhang, Dou

    2016-04-01

    Osteoblasts growing into bone substitute is an important step of bone regeneration. This study prepared porous hydroxyapatite (HA)/BaTiO3 piezoelectric composites with porosity of 40%, 50% and 60% by ice-templating method. Effects of HA/BaTiO3 composites with different porosities, with and without polarizing treatment on adhesion, proliferation and differentiation of osteoblasts were investigated in vitro. Results revealed that cell densities of the porous groups were significantly higher than those of the dense group (p<0.05), so did the alkaline phosphate (ALP) and bone gla protein (BGP) activities. Porosity of 50% group exhibited higher ALP activity and BGP activity than those of the 40% and 60% groups. Scanning electron microscopy (SEM) observations revealed that osteoblasts adhered and stretched better on porous HA/BaTiO3 than on the dense one, especially HA/BaTiO3 with porosity of 50% and 60%. However, there was no significant difference in the cell morphology, cell densities, ALP and BGP activities between the polarized group and the non-polarized group (p>0.05). The absence of mechanical loading on the polarized samples may account for this. The results indicated that hierarchically porous HA/BaTiO3 played a favorable part in osteoblasts proliferation, differentiation and adhesion process and is a promising bone substitute material. Copyright © 2015. Published by Elsevier B.V.

  11. Phase equilibria, crystal structure and oxygen content of intermediate phases in the Y-Ba-Co-O system

    NASA Astrophysics Data System (ADS)

    Urusova, A. S.; Cherepanov, V. A.; Aksenova, T. V.; Gavrilova, L. Ya.; Kiselev, E. A.

    2013-06-01

    The phase equilibria in the Y-Ba-Co-O system were systematically studied at 1373 K in air. The intermediate phases formed in the Y-Ba-Co-O system at 1373 K in air were: YBaCo2O5+δ, YBaCo4O7 and BaCo1-yYyO3-δ (0.09≤y≤0.42). It was shown that YBaCo2O5+δ possesses tetragonal structure with the 3ap×3ap×2ap superstructure (sp. gr. P4/mmm). High-temperature X-ray diffraction analysis of the YBaCo2O5+δ in the temperature range from 298 K up to 1073 K under Po2=0.21 аtm has not shown any phase transformations. The value of oxygen content for the YBaCo2O5+δ at room temperature was estimated as 5.40 and at 1323 K it was equal to 5.04. Thermal expansion of sample shows a linear characteristics and the average thermal expansion coefficient (TEC) is about 13.8×10-6, K-1 in the temperature range 298-1273 K. The homogeneity range and crystal structure of the BaCo1-yYyO3-δ (0.09≤y≤0.42) solid solutions were determined by X-ray diffraction of quenched samples. All BaCo1-yYyO3-δ solid solutions were found to have cubic structure (sp. gr. Pm3m). The unit cell parameters were refined using Rietveld full-profile analysis. Oxygen nonstoichiometry of BaCo1-yYyO3-δ solid solutions with 0.1≤y≤0.4 was measured by means of thermogravimetric technique within the temperature range 298-1373 K in air. Thermal expansion of BaCo1-yYyO3-δ (у=0.0; 0.1; 0.2; 0.3) samples was studied within the temperature range 298-1200 K in air. The projection of isothermal-isobaric phase diagram for the Y-Ba-Co-O system to the compositional triangle of metallic components was presented.

  12. Apoptosis of Corneal Epithelial Cells Caused by Ultraviolet B-induced Loss of K+ is Inhibited by Ba2+

    PubMed Central

    Glupker, Courtney D.; Boersma, Peter M.; Schotanus, Mark P.; Haarsma, Loren D.; Ubels, John L.

    2017-01-01

    UVB exposure at ambient outdoor levels triggers rapid K+ loss and apoptosis in human corneal limbal epithelial (HCLE) cells cultured in medium containing 5.5 mM K+, but considerably less apoptosis occurs when the medium contains the high K+ concentration that is present in tears (25 mM). Since Ba2+ blocks several K+ channels, we tested whether Ba2+-sensitive K+ channels are responsible for some or all of the UVB-activated K+ loss and subsequent activation of the caspase cascade and apoptosis. Corneal epithelial cells in culture were exposed to UVB at 80 or 150 mJ/cm2. Patch-clamp recording was used to measure UVB-induced K+ currents. Caspase-activity and TUNEL assays were performed on HCLE cells exposed to UVB followed by incubation in the presence or absence of Ba2+. K+ currents were activated in HCLE cells following UVB-exposure. These currents were reversibly blocked by 5 mM Ba2+. When HCLE cells were incubated with 5 mM Ba2+ after exposure to UVB, activation of caspases-9, -8, and -3 and DNA fragmentation were significantly decreased. The data confirm that UVB-induced K+ current activation and loss of intracellular K+ leads to activation of the caspase cascade and apoptosis. Extracellular Ba2+ inhibits UVB-induced apoptosis by preventing loss of intracellular K+ when K+ channels are activated. Ba2+ therefore has effects similar to elevated extracellular K+ in protecting HCLE cells from UVB-induced apoptosis. This supports our overall hypothesis that elevated K+ in tears contributes to protection of the corneal epithelium from adverse effects of ambient outdoor UVB. PMID:27189864

  13. Further considerations of the Ce/Yb vs. Ba/Ce plot in volcanology and tectonics

    USGS Publications Warehouse

    Doe, B.R.

    2002-01-01

    A plot of Ce/Yh vs. Bd/Ce, for locality averages, effectively separates mid-ocean ridge basalts (MORB) (Ce/Yb 10, Ba/Ce 4.2). The conventional interpretation is that these three types of volcanic environments involve oceanic rift-related, large-volume partial melts (???20-30%) of a depleted source. (MORB), small volume melts (???5% for alkalic volcanics) of enriched sources related to plumes (OIV), and melts of hydrous-enriched sources during subduction, especially for Ba (IAV). There OIV sites, however, have average ratios that fall in the MORB field (e.g., Krafla Volcano, Iceland), and these localities also tend to have other geochemical data similar to MORB. Average ratios of Hawaiian tholeiitic shield basalts of Mauna Kea and Koolau volcanoes occupy a restricted field on a plot of Ce/Yb vs. Ba/Ce of 1O-18 for Ce/Yb and 2.8-3.1 for Ba/Ce, a field toward which other shield basalts and cone-building volcanics regress. In general, post-shield alkalic rocks have higher values of Ce/Yb than do tholeiites. Peralkalic basalts (basanites, melilitites, and phonolites) have even higher values of Ce/Yb, reflecting smaller degrees of partial melting (perhaps 1-2%) and melting of sources containing phlogopite that were enriched by CO2-dominated fluids. The minor post-erosion nephelinitic suites of Hawaii (e.g., the Honolulu Series on Oahu, and the Koloa suite on Kauai) generally have values both greater than IAV for Ce/Yb and greater than other kinds of OIV for Ba/Ce in a part of the plot previously not found to be occupied by data. Alkali basalts of both these nephelinitic series have the lowest and similar ratios (Ce/Yb ??? 25; Ba/Ce ??? 10). In the Hawaiian Islands. there are two trends. One (a), where phlogopite has heen interpreted tp remain in the source. generally has Ba/Ce decrease away from the alkali basalts as Ce/Yb increases. The other (b), where phlogopite has heen interpreted to enter the melt, occupies a field that is high in both Ce/Yb (>30) relative to IAV

  14. On the symmetry and crystal structures of Ba{sub 2}LaIrO{sub 6}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fu, W.T., E-mail: w.fu@chem.leidenuniv.n; Goetz, R.J.; IJdo, D.J.W.

    2010-02-15

    Accurate profile analysis of X-ray diffraction data was carried out to settle recent dispute on the symmetry and crystal structures of the double perovskite Ba{sub 2}LaIrO{sub 6}. Even through careful comparison of the full-width at half-maximum values, we found no evidence for Ba{sub 2}LaIrO{sub 6} adopting either monoclinic (I2/m) or mixed rhombohedral (R3-bar) and monoclinic (I2/m) structures at room temperature, becoming triclinic (I1-bar) at below about 200 K. The correct space group is just R3-bar at temperatures between 82 and 653 K. Furthermore, the R3-bar->Fm3-barm phase transition does occur in Ba{sub 2}LaIrO{sub 6}, but the transition temperature is found tomore » be much higher than the reported value. - Graphical abstract: Observed (crosses) and calculated (continuous line) profiles of Ba{sub 2}LaIrO{sub 6} at some selected temperature showing the region containing the basic (222), (321) and (400) reflections. Tick marks below indicate the positions of the allowed Bragg's reflections.« less

  15. The Role of Annealing Process in Ag-Based BaSnO3 Multilayer Thin Films.

    PubMed

    Wu, Muying; Yu, Shihui; He, Lin; Yang, Lei; Zhang, Weifeng

    2016-12-01

    The BaSnO3/Ag/BaSnO3 multilayer structure was designed and fabricated on a quartz glass by magnetron sputtering, followed by an annealing process at a temperature from 150 to 750 °C in air. In this paper, we investigated the influence of the annealing temperature on the structural, optical, and electrical properties of the multilayers and proposed the mechanisms of conduction and transmittance. The maximum value of the figure of merit of 31.8 × 10(-3) Ω(-1) was achieved for the BaSnO3/Ag/BaSnO3 multilayer thin films annealed at 150 °C, while the average optical transmittance in the visible ranges was >84 %, the resistivity was 5.71 × 10(-5) Ω cm, and the sheet resistance was 5.57 Ω/sq. When annealed at below 600 °C, the values of resistivity and transmittance of the multilayers were within an acceptable range (resistivity <5.0 × 10(-4) Ω cm, transmittance >80 %). The observed property of the multilayer film is suitable for the application of transparent conductive electrodes.

  16. 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.

  17. p-BaSi2/n-Si heterojunction solar cells on Si(001) with conversion efficiency approaching 10%: comparison with Si(111)

    NASA Astrophysics Data System (ADS)

    Deng, Tianguo; Sato, Takuma; Xu, Zhihao; Takabe, Ryota; Yachi, Suguru; Yamashita, Yudai; Toko, Kaoru; Suemasu, Takashi

    2018-06-01

    B-doped p-BaSi2 epitaxial layers with a hole concentration of 1.1 × 1018 cm‑3 were grown on n-Si(001) using molecular beam epitaxy to fabricate p-BaSi2/n-Si solar cells. The thickness (d) of the p-BaSi2 layer was varied from 20 to 60 nm to investigate its effect on the solar cell performance. The conversion efficiency under an AM1.5 illumination increased with d reaching a maximum of 9.8% at d = 40 nm, which is nearly equal to the highest efficiency (9.9%) for p-BaSi2/n-Si solar cells on Si(111). This study indicated that Si(001) substrates are promising for use in BaSi2 solar cells.

  18. Ba{sub 6}Nb{sub 4}RuO{sub 18}” and “LaBa{sub 4}Nb{sub 3}RuO{sub 15}” – The structural consequences of substituting paramagnetic cations into A{sub n}B{sub n−1}O{sub 3n} cation-deficient perovskite oxides

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kamil, Elynor L.; Morgan, Harry W.T.; Hayward, Michael A., E-mail: michael.hayward@chem.ox.ac.uk

    The B-cation deficient perovskite phases Ba{sub 6}Nb{sub 4}RuO{sub 18} and LaBa{sub 4}Nb{sub 3}RuO{sub 15} were prepared by ceramic synthesis. Neutron powder diffraction analysis indicates that rather than the 6-layer and 5-layer cation-deficient perovskite structures expected for these phases (by analogy to the known structures of Ba{sub 6}Nb{sub 4}TiO{sub 18} and LaBa{sub 4}Nb{sub 3}TiO{sub 15}) they adopt 5-layer and 4-layer B-cation deficient perovskite structures respectively, and are better described as Ba{sub 5}Nb{sub 3.33}Ru{sub 0.81}O{sub 15} and Ba{sub 3.16}La{sub 0.84}Nb{sub 2.36}Ru{sub 0.72}O{sub 12}. The factors that lead to the compositionally analogous Nb/Ru and Nb/Ti phases adopting different structures are discussed on themore » basis of the difference between d{sup 0} and non-d{sup 0} transition metal cations. - Graphical abstract: The ruthenium-containing B-cation deficient perovskite phases, Ba{sub 5}Nb{sub 3.33}Ru{sub 0.81}O{sub 15} and Ba{sub 3.16}La{sub 0.84}Nb{sub 2.36}Ru{sub 0.72}O{sub 12}, adopt 5-layer and 4-layer structures respectively, rather than the 6-layer and 5-layer cation-deficient structures adopted by the analogous titanium-containing phases Ba{sub 6}Nb{sub 4}TiO{sub 18} and LaBa{sub 4}Nb{sub 3}TiO{sub 15}. Display Omitted - Highlights: • B-cation deficient perovskite containing paramagnetic cations. • B-cation deficient structure determined by neutron powder diffraction. • Low ‘solubility’ of BaRuO{sub 3} in Ba{sub 5}Nb{sub 4}O{sub 15} leads to novel structure.« less

  19. One-step fabrication of BaMoO4 microstructures with controlled morphologies via a simple EDTA-mediated route

    NASA Astrophysics Data System (ADS)

    Yin, Yongkui; Li, Ying; Zhang, Haifeng; Ren, Fengyun; Zhang, Dawei; Feng, Wenxu; Shao, Lili; Li, Kaijun; Liu, Yang; Sun, Zhanpeng; Li, Miaojing; Song, Gaochen; Wang, Guan

    2013-03-01

    A facile strategy has been developed to synthesize BaMoO4 microcrystals with different morphologies, such as octopus-like, flower-like, and Chinese-cabbage-like, by using ethylenediaminetetraacetic acid as chelating and capping reagent at room temperature. X-ray diffraction, field emission scanning electron microscopy, and Fourier transformer infrared spectroscopy were introduced to characterize the composition, morphology, and chemical information of the as-obtained products. The effects of a series of experimental parameters, such as ethylenediaminetetraacetic acid quantity and the reagent concentrations, on the morphology and photoluminescence properties of the consequential BaMoO4 microcrystals were investigated in detail. The photoluminescence spectra of the obtained BaMoO4 microstructures exhibited different emission intensities. This method could be readily extended to synthesize BaWO4 microstructures with various morphologies.

  20. Direct Observation of Surface Potential Distribution in Insulation Resistance Degraded Acceptor-Doped BaTiO3 Multilayered Ceramic Capacitors

    NASA Astrophysics Data System (ADS)

    Hong, Kootak; Lee, Tae Hyung; Suh, Jun Min; Park, Jae-Sung; Kwon, Hyung-Soon; Choi, Jaeho; Jang, Ho Won

    2018-05-01

    Insulation resistance (IR) degradation in BaTiO3 is a key issue for developing miniaturized multilayer ceramic capacitors (MLCCs) with high capacity. Despite rapid progress in BaTiO3-based MLCCs, the mechanism of IR degradation is still controversial. In this study, we demonstrate the Al doping effect on IR degradation behavior of BaTiO3 MLCCs by electrical measurements and scanning Kelvin probe microscopy (SKPM). As the Al doping concentration in BaTiO3 increases, IR degradation of MLCCs seems to be suppressed from electrical characterization results. However, SKPM results reveal that the conductive regions near the cathode become lager with Al doping after IR degradation. The formation of conducting regions is attributed to the migration of oxygen vacancies, which is the origin of IR degradation in BaTiO3, in dielectric layers. These results imply that acceptor doping in BaTiO3 solely cannot suppress the IR degradation in MLCC even though less asymmetric IR characteristics and IR degradation in MLCCs with higher Al doping concentration are observed from electrical characterization. Our results strongly suggest that observing the surface potential distribution in IR degraded dielectric layers using SKPM is an effective method to unravel the mechanism of IR degradation in MLCCs.

  1. T cell regulation of the thymus-independent antibody response to trinitrophenylated-Brucella abortus (TNP-BA)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tanay, A.; Strober, S.

    The authors have previously observed a reduction of the T cell-dependent primary antibody response to dinitrophenylated keyhole limpet hemocyanin, and an enhancement of the T cell-independent response to trinitrophenylated Brucella abortus (TNP-BA) in BALB/c mice after treatment with total lymphoid irradiation (TLI). To elucidate the relative contribution of T and B cells to the enhanced T cell-independent antibody responses after TLI, a syngeneic primary adoptive transfer system was utilized whereby irradiated hosts were reconstituted with unfractionated spleen cells or a combination of purified T and B cells from TLI-treated and untreated control mice. Antibody responses of purified splenic B cellsmore » from TLI-treated BALB/c mice (TLI/B) to TNP-BA were enhanced 10-fold as compared with those of unfractionated (UF) spleen cells or B cells from normal (NL) BALB/c mice (NL/UF and NL/B, respectively). Splenic T cells from normal animals (NL/T) suppressed the anti-TNP-BA response of TLI/B by more than 100-fold. NL/T neither suppressed nor enhanced the response of NL/B. On the other hand, T cells from TLI-treated mice (TLI/T) enhanced by 100-fold the anti-TNP-BA response of NL/B, but neither suppressed nor enhanced the response of TLI/B. Thus, T cells can regulate the T cell-independent antibody response to TNP-BA. However, experimental manipulation of the T and B cell populations is needed to demonstrate the regulatory functions.« less

  2. Barite recrystallization in the presence of 226Ra and 133Ba

    NASA Astrophysics Data System (ADS)

    Heberling, Frank; Metz, Volker; Böttle, Melanie; Curti, Enzo; Geckeis, Horst

    2018-07-01

    Despite the long history of studies on (Ba,Ra)SO4, various recent investigations aimed at improving our understanding of its formation processes and thermodynamics. Accumulation of natural Ra isotopes (mainly 226Ra and 228Ra) in (Ba,Ra)SO4 plays an important role in many geotechnical applications and water desalination facilities. In the near field of a nuclear waste repository, barite formation may be expected e.g. as a consequence of contact of spent nuclear fuel or vitrified high level waste with sulfate containing ground water, and may control the potential release of Ra from waste forms upon leakage. Here, we present results of long term batch-type barite recrystallization experiments conducted in the simultaneous presence of 226Ra and 133Ba as a function of initial Ra2+ concentration and pH with the same type and charge of barite powder as used in previous studies (Curti et al., 2010; Klinkenberg et al., 2014; Brandt et al., 2015). Due to the simultaneous measurement of 133Ba and 226Ra our data allow for a direct relation of 226Ra uptake with barite recrystallization, which leads to more accurate partition coefficients compared to previous studies. During a reaction period of five years, barite is continuously recrystallizing. Within the investigated radium concentration range (Ba(1-X)RaXSO4 with X < 0.0006), we measure a partition coefficient of D = 2.1 ± 0.5. The partition coefficient is constant within uncertainty during almost five years (1793 days) of experimental duration. This value is in line with a description of (Ba,Ra)SO4 as an ideal solid solution based on the solubility products (KSP) of the endmembers barite (log10(KSP(barite)) = -9.97) and radium sulfate (log10(KSP(RaSO4)) = -10.26; dimensionless Guggenheim parameter, a0 = 0.0 ± 0.3). Apparent discrepancies to previous theoretical results (a0 = 1.0 ± 0.4) may be resolved when the uncertainties related to the solubility of RaSO4 are considered. Compared to results of previous publications

  3. Direct synthesis of ultrafine tetragonal BaTiO3 nanoparticles at room temperature

    PubMed Central

    2011-01-01

    A large quantity of ultrafine tetragonal barium titanate (BaTiO3) nanoparticles is directly synthesized at room temperature. The crystalline form and grain size are checked by both X-ray diffraction and transmission electron microscopy. The results revealed that the perovskite nanoparticles as fine as 7 nm have been synthesized. The phase transition of the as-prepared nanoparticles is investigated by the temperature-dependent Raman spectrum and shows the similar tendency to that of bulk BaTiO3 materials. It is confirmed that the nanoparticles have tetragonal phase at room temperature. PMID:21781339

  4. Electronic phase diagram of disordered Co doped BaFe2As2-δ

    NASA Astrophysics Data System (ADS)

    Kurth, F.; Iida, K.; Trommler, S.; Hänisch, J.; Nenkov, K.; Engelmann, J.; Oswald, S.; Werner, J.; Schultz, L.; Holzapfel, B.; Haindl, S.

    2013-02-01

    Superconducting and normal state transport properties in iron pnictides are sensitive to disorder and impurity scattering. By investigation of Ba(Fe1-xCox)2As2-δ thin films with varying Co concentrations we demonstrate that in the dirty limit the superconducting dome in the electronic phase diagram of Ba(Fe1-xCox)2As2-δ shifts towards lower doping concentrations, which differs significantly from observations in single crystals. We show that especially in the underdoped regime superconducting transition temperatures higher than 27 K are possible.

  5. Pressure-Stabilized Cubic Perovskite Oxyhydride BaScO2H.

    PubMed

    Goto, Yoshihiro; Tassel, Cédric; Noda, Yasuto; Hernandez, Olivier; Pickard, Chris J; Green, Mark A; Sakaebe, Hikari; Taguchi, Noboru; Uchimoto, Yoshiharu; Kobayashi, Yoji; Kageyama, Hiroshi

    2017-05-01

    We report a scandium oxyhydride BaScO 2 H prepared by solid state reaction under high pressure. Rietveld refinements against powder synchrotron X-ray and neutron diffraction data revealed that BaScO 2 H adopts the ideal cubic perovskite structure (Pm3̅m), where oxide (O 2- ) and hydride (H - ) anions are disordered. 1 H nuclear magnetic resonance (NMR) spectroscopy provides a positive chemical shift of about +4.4 ppm, which can be understood by the distance to the nearest (and possibly the next nearest) cation from the H nucleus. A further analysis of the NMR data and calculations based on ab initio random structure searches suggest a partial cis preference in ScO 4 H 2 octahedra. The present oxyhydride, if compositionally or structurally tuned, may become a candidate for H - conductors.

  6. Tin doped PrBaFe 2O 5+δ anode material for solid oxide fuel cells

    DOE PAGES

    Dong, Guohui; Yang, Chunyang; He, Fei; ...

    2017-04-25

    Ceramic anodes have many advantages over cermet anodes for solid oxide fuel cells. We report the synthesis and characterization of Sn doped double perovskite PrBaFe (2-x)Sn xO 5+δ (x = 0–0.3) anode materials. Different crystal structures were observed depending on the Sn doping level and gas atmosphere. The materials demonstrated excellent stability in both reducing and redox atmospheres at elevated temperatures. The oxygen content in the as-prepared PrBaFe (2-x)Sn xO 5+δ was nonlinearly correlated to the Sn doping level and reached maximum values around x = 0.1. After the reducing treatment, the oxygen content linearly decreased with increasing Sn dopingmore » level. The electrical conductivity of bulk PrBaFe (2-x)Sn xO 5+δ (x = 0.1) reached 63.6 S cm -1 at 800 °C in humidified hydrogen. At 750 °C, the surface exchange coefficient and bulk diffusivity of PrBaFe (2-x)Sn xO 5+δ reached the maximum values of 4.42 × 10 -6 m s -1 and 6.04 × 10 -7 m 2 s -1, respectively, in the reducing process when the Sn doping level was x = 0.1. The activation energies of surface exchange coefficient and bulk diffusivity of PrBaFe (2-x)Sn xO 5+δ (x = 0.1) were 0.22 eV and 0.16 eV, respectively, in the reducing process. The area specific resistance of the PrBaFe (2-x)Sn xO 5+δ (x = 0.1) anode was 0.095–0.285 Ω cm 2 from 850–750 °C in humidified hydrogen, better than or comparable to the best ceramic anodes in the literature.« less

  7. 1-mJ Q-switched diode-pumped Nd:BaY2F8 laser

    NASA Astrophysics Data System (ADS)

    Agnesi, Antonio; Carraro, Giovanni; Guandalini, Annalisa; Reali, Giancarlo; Sani, Elisa; Toncelli, Alessandra; Tonelli, Mauro

    2004-08-01

    We report what is to our knowledge the first high repetition rate Q-switched Nd:BaY2F8 (Nd:BaYF) laser pumped with a multiwatt fiber-coupled diode array tuned at 806 nm. As much as 2.42 W of average power and up to 1.05 mJ of pulse energy were obtained with 6.1 W of absorbed pump power, with excellent beam quality (M2<1.2) and linear polarization.

  8. Development of BaO-ZnO-B2O3 glasses as a radiation shielding material

    NASA Astrophysics Data System (ADS)

    Chanthima, N.; Kaewkhao, J.; Limkitjaroenporn, P.; Tuscharoen, S.; Kothan, S.; Tungjai, M.; Kaewjaeng, S.; Sarachai, S.; Limsuwan, P.

    2017-08-01

    The effects of the BaO on the optical, physical and radiation shielding properties of the xBaO: 20ZnO: (80-x)B2O3, where x=5, 10, 15, 20 and 25 mol%, were investigated. The glasses were developed by the conventional melt-quenching technique at 1400 °C with high purity chemicals of H3BO3, ZnO, and BaSO4. The optical transparency of the glasses indicated that the glasses samples were high, as observed by visual inspections. The mass attenuation coefficients (μm), the effective atomic numbers (Zeff), and the effective electron densities (Ne) were increased with the increase of BaO concentrations, and the decrease of gamma-ray energy. The developed glass samples were investigated and compared with the shielding concretes and glasses in terms of half value layer (HVL). The overall results demonstrated that the developed glasses had good shielding properties, and highly practical potentials in the environmental friendly radiation shielding materials without an additional of Pb.

  9. Interplay of magnetism and superconductivity in the compressed Fe-ladder compound BaFe 2 Se 3

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ying, Jianjun; Lei, Hechang; Petrovic, Cedomir

    High pressure resistance, susceptibility, and Fe K β x-ray emission spectroscopy measurements were performed on Fe-ladder compound BaFe 2 Se 3 . Pressure-induced superconductivity was observed which is similar to the previously reported superconductivity in the BaFe 2 S 3 samples. The slope of local magnetic moment versus pressure shows an anomaly across the insulator-metal transition pressure in the BaFe 2 Se 3 samples. The local magnetic moment is continuously decreasing with increasing pressure, and the superconductivity appears only when the local magnetic moment value is comparable to the one in the iron-pnictide superconductors. Our results indicate that the compressedmore » BaFe 2 C h 3 ( C h = S , Se) is a new family of iron-based superconductors. Despite the crystal structures completely different from the known iron-based superconducting materials, the magnetism in this Fe-ladder material plays a critical role in superconductivity. This behavior is similar to the other members of iron-based superconducting materials.« less

  10. CARNAÚBA: The Coherent X-Ray Nanoprobe Beamline for the Brazilian Synchrotron SIRIUS/LNLS

    NASA Astrophysics Data System (ADS)

    Tolentino, Hélio C. N.; Soares, Márcio M.; Perez, Carlos A.; Vicentin, Flávio C.; Abdala, Dalton B.; Galante, Douglas; Teixeira, Verônica de C.; de Araújo, Douglas H. C.; Westfahl, Harry, Jr.

    2017-06-01

    The CARNAÚBA beamline is the tender-to-hard X-ray (2 - 15 keV) scanning nanoprobe planned for the 4th generation storage ring SIRIUS at the LNLS. CARNAÚBA uses an undulator source with vertical linear polarization in a low-beta straight section and grazing incidence-focusing mirrors to create a nanoprobe at 143 m from the source. The beamline optic is based on KB mirrors and provides high brilliance at an achromatic focal spot down to the diffraction limit diameter of ˜30 nm with a working distance of ˜6 cm. These characteristics are crucial for studying nanometric samples in experiments involving complex stages and environments. The CARNAÚBA beamline aims to perform raster scans using x-ray fluorescence, x-ray absorption spectroscopy, x-ray diffraction and coherent x-ray imaging techniques. Computed tomography will extend these methods to three dimensions.

  11. Superconductivity and fluctuations in Ba 1–pK pFe 2As 2 and Ba(Fe 1–nCo n) 2As 2

    DOE PAGES

    Böhm, T.; Hosseinian Ahangharnejhad, R.; Jost, D.; ...

    2016-08-11

    In this paper, we study the interplay of fluctuations and superconductivity in BaFe 2As 2 (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),more » we find 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 A 1g and B 1g 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. Evidence for a common gene pool and frequent recombinational exchange of the tbpBA operon in Mannheimia haemolytica, Mannheimia glucosida and Bibersteinia trehalosi

    PubMed Central

    Lee, Inkyoung; Davies, Robert L.

    2012-01-01

    SUMMARY The tbpBA operon was sequenced in 42 representative isolates of Mannheimia haemolytica (32), Mannheimia glucosida (6) and Bibersteinia trehalosi (4). A total of 27 tbpB and 20 tbpA alleles were identified whilst the tbpBA operon was represented by 28 unique alleles that could be assigned to seven classes. There were 1566 (34.8% variation) polymorphic nucleotide sites and 482 (32.1% variation) variable inferred amino acid positions among the 42 tbpBA sequences. The tbpBA operons of serotype A2 M. haemolytica isolates are, with one exception, substantially more diverse than those of the other M. haemolytica serotypes and most likely have a different ancestral origin. The tbpBA phylogeny has been severely disrupted by numerous small- and large-scale intragenic recombination events. In addition, assortative (entire gene) recombination events, involving either the entire tbpBA operon or the individual tbpB and tbpA genes, have played a major role in shaping tbpBA structure and it’s distribution in the three species. Our findings indicate that a common gene pool exists for tbpBA in M. haemolytica, M. glucosida and B. trehalosi. In particular, B. trehalosi, M. glucosida and ovine M. haemolytica isolates share a large portion of the tbpA gene and this probably reflects selection for a conserved TbpA protein that provides effective iron-uptake in sheep. Bovine and ovine serotype A2 lineages have very different tbpBA alleles. Bovine-like tbpBA alleles have been partially, or completely, replaced by ovine-like tbpBA alleles in ovine serotype A2 isolates suggesting that different transferrin receptors are required by serotype A2 isolates for optimum iron uptake in cattle and sheep. Conversely, the tbpBA alleles of bovine-pathogenic serotype A1 and A6 isolates are very similar to those of closely related ovine isolates suggesting a recent and common evolutionary origin. PMID:20884693

  13. Thermodynamic properties of ternary oxides in the system Ba-Fe-O using solid-state electrochemical cells with oxide and fluoride ion conducting electrolytes

    NASA Astrophysics Data System (ADS)

    Rakshit, S. K.; Parida, S. C.; Singh, Ziley; Prasad, R.; Venugopal, V.

    2004-04-01

    The standard molar Gibbs energy of formations of BaFe 12O 19(s), BaFe 2O 4(s), Ba 2Fe 2O 5(s), Ba 3Fe 2O 6(s) and Ba 5Fe 2O 8(s) have been determined using solid-state electrochemical technique employing CaF 2(s) as an electrolyte. The reversible e.m.f. values have been measured in the temperature range from 970 to 1151 K. The oxygen chemical potential corresponding to three phase equilibria involving technologically important compound BaFe 12O 19(s) has been determined using solid-state electrochemical technique employing CSZ as an electrolyte from 1048 to 1221 K. The values of Δ fGm0( T) for the above ternary oxides are given by ΔfG m0( BaFe12O19, s)/ kJ mol -1(±0.6)=-5431.3+1.5317 (T/ K) (970⩽T/ K⩽1151) ΔfG m0( BaFe2O4, s)/ kJ mol -1(±1.3)=-1461.4+0.3745 (T/ K) (970⩽T/ K⩽1151) ΔfG m0( Ba2Fe2O5, s)/ kJ mol -1(±1.4)=-2038.3+0.4433 (T/ K) (970⩽T/ K⩽1149) ΔfG m0( Ba3Fe2O6, s)/ kJ mol -1(±1.5)=-2700.1+0.6090 (T/ K) (969⩽T/ K⩽1150) and ΔfG m0( Ba5Fe2O8, s)/ kJ mol -1(±1.6)=-3984.1+0.9300 (T/ K) (973⩽T/ K⩽1150) The uncertainty estimates for Δ fGm0 includes the standard deviation in the e.m.f. and uncertainty in the data taken from the literature. An isothermal oxygen potential diagram for the system Ba-Fe-O was constructed at 1100 K based on the thermodynamic data obtained in this study.

  14. Absorption of Dy3+ and Nd3+ ions in Ba R 2F8 single crystals

    NASA Astrophysics Data System (ADS)

    Apollonov, V. V.; Pushkar', A. A.; Uvarova, T. V.; Chernov, S. P.

    2008-09-01

    The Dy3+ absorption and excitation spectra of BaY2F8 and BaYb2F8 single crystals are investigated in the ultraviolet, vacuum ultraviolet, and visible ranges at a temperature of 300 K. These crystals exhibit intense broad absorption bands due to the spin-allowed 4 f-5 d transitions in the range (56-78) × 10-3 cm-1 and less intense absorption bands that correspond to the spin-forbidden transitions in the range (50-56) × 10-3 cm-1. The Nd3+ absorption spectra of BaY2F8 single crystals are studied in the range (34-82) × 10-3 cm-1 at 300 K for different crystal orientations.

  15. Acoustic nonlinearity parameter B/A determined by means of thermodynamic method under elevated pressures for alkanediols.

    PubMed

    Zorębski, Edward; Zorębski, Michał

    2014-01-01

    The so-called Beyer nonlinearity parameter B/A is calculated for 1,2- and 1,3-propanediol, 1,2-, 1,3-, and 1,4-butanediol, as well as 2-methyl-2,4-pentanediol by means of a thermodynamic method. The calculations are made for temperatures from (293.15 to 318.15) K and pressures up to 100 MPa. The decrease in B/A values with the increasing pressure is observed. In the case of 1,3-butanediol, the results are compared with corresponding literature data. The consistency is very satisfactory. A simple relationship between the internal pressure and B/A nonlinearity parameter has also been studied. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. 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.

  17. Potential variation around grain boundaries in BaSi{sub 2} films grown on multicrystalline silicon evaluated using Kelvin probe force microscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Baba, Masakazu; Tsukahara, Daichi; Toko, Kaoru

    2014-12-21

    Potential variations across the grain boundaries (GBs) in a 100 nm thick undoped n-BaSi{sub 2} film on a cast-grown multicrystalline Si (mc-Si) substrate are evaluated using Kelvin probe force microscopy (KFM). The θ-2θ X-ray diffraction pattern reveals diffraction peaks, such as (201), (301), (410), and (411) of BaSi{sub 2}. Local-area electron backscatter diffraction reveals that the a-axis of BaSi{sub 2} is tilted slightly from the surface normal, depending on the local crystal plane of the mc-Si. KFM measurements show that the potentials are not significantly disordered in the grown BaSi{sub 2}, even around the GBs of mc-Si. The potentials are highermore » at GBs of BaSi{sub 2} around Si GBs that are formed by grains with a Si(111) face and those with faces that deviate slightly from Si(111). Thus, downward band bending occurs at these BaSi{sub 2} GBs. Minority carriers (holes) undergo a repelling force near the GBs, which may suppress recombination as in the case of undoped n-BaSi{sub 2} epitaxial films on a single crystal Si(111) substrate. The barrier height for hole transport across the GBs varies in the range from 10 to 55 meV. The potentials are also higher at the BaSi{sub 2} GBs grown around Si GBs composed of grains with Si(001) and Si(111) faces. The barrier height for hole transport ranges from 5 to 55 meV. These results indicate that BaSi{sub 2} GBs formed on (111)-dominant Si surfaces do not have a negative influence on the minority-carrier properties, and thus BaSi{sub 2} formed on underlayers, such as (111)-oriented Si or Ge and on (111)-oriented mc-Si, can be utilized as a solar cell active layer.« less

  18. Surface reaction characteristics at low temperature synthesis BaTiO 3 particles by barium hydroxide aqueous solution and titanium tetraisopropoxide

    NASA Astrophysics Data System (ADS)

    Zeng, Min

    2011-05-01

    Well-crystallized cubic phase BaTiO 3 particles were prepared by heating the mixture of barium hydroxide aqueous solution and titania derived from the hydrolysis of titanium isopropoxide (TTIP) at 328 K, 348 K or 368 K for 24 h. The morphology and size of obtained particles depended on the reaction temperature and the Ba(OH) 2/TTIP molar ratio. By the direct hydrolytic reaction of titanium tetraisopropoxide, the high surface area titania (TiO 2) was obtained. The surface adsorption characteristics of the titania particles had been studied with different electric charges OH - ions or H + ions. The formation mechanism and kinetics of BaTiO 3 were examined by measuring the concentration of [Ba 2+] ions in the solution during the heating process. The experimental results showed that the heterogeneous nucleation of BaTiO 3 occurred on the titania surface, according to the Avrami's equation.

  19. 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.

  20. 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.

  1. Phase equilibria, crystal structures, and dielectric anomaly in the BaZrO 3-CaZrO 3 system

    NASA Astrophysics Data System (ADS)

    Levin, Igor; Amos, Tammy G.; Bell, Steven M.; Farber, Leon; Vanderah, Terrell A.; Roth, Robert S.; Toby, Brian H.

    2003-11-01

    Phase equilibria in the (1- x)BaZrO 3- xCaZrO 3 system were analyzed using a combination of X-ray and neutron powder diffraction, and transmission electron microscopy. The proposed phase diagram features two extended two-phase fields containing mixtures of a Ba-rich cubic phase and a tetragonal, or orthorhombic Ca-rich phase, all having perovskite-related structures. The symmetry differences in the Ca-rich phases are caused by different tilting patterns of the [ZrO 6] octahedra. In specimens quenched from 1650°C, CaZrO 3 dissolves only a few percent of Ba, whereas the solubility of Ca in BaZrO 3 is approximately 30 at% . The BaZrO 3-CaZrO 3 system features at least two tilting phase transitions, Pm3 m→ I4/ mcm and I4/ mcm→ Pbnm. Rietveld refinements of the Ba 0.8Ca 0.2ZrO 3 structure using variable-temperature neutron powder diffraction data confirmed that the Pm3 m→ I4/ mcm transition corresponds to a rotation of octahedra about one of the cubic axes; successive octahedra along this axis rotate in opposite directions. In situ variable-temperature electron diffraction studies indicated that the transition temperature increases with increasing Ca-substitution on the A-sites, from approximately -120°C at 5 at% Ca to 225°C at 20 at% Ca. Dielectric measurements revealed that the permittivity increases monotonically from 36 for BaZrO 3 to 53 for Ba 0.9Ca 0.1ZrO 3, and then decreases to 50 for Ba 0.8Ca 0.2ZrO 3. This later specimen was the Ca-richest composition for which pellets could be quenched from the single-phase cubic field with presently available equipment. Strongly non-monotonic behavior was also observed for the temperature coefficient of resonant frequency; however, in this case, the maximum occurred at a lower Ca concentration, 0.05⩽ x⩽0.1. The non-linear behavior of the dielectric properties was attributed to two competing structural effects: a positive effect associated with substitution of relatively small Ca cations on the A-sites, resulting

  2. Potential variations around grain boundaries in impurity-doped BaSi₂ epitaxial films evaluated by Kelvin probe force microscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tsukahara, D.; Baba, M.; Honda, S.

    2014-09-28

    Potential variations around the grain boundaries (GBs) in antimony (Sb)-doped n-type and boron (B)-doped p-type BaSi₂ epitaxial films on Si(111) were evaluated by Kelvin probe force microscopy. Sb-doped n-BaSi₂ films exhibited positively charged GBs with a downward band bending at the GBs. The average barrier height for holes was approximately 10 meV for an electron concentration n ≈ 10¹⁷ cm⁻³. This downward band bending changed to upward band bending when n was increased to n = 1.8 × 10¹⁸cm⁻³. In the B-doped p-BaSi₂ films, the upward band bending was observed for a hole concentration p ≈ 10¹⁸cm⁻³. The average barriermore » height for electrons decreased from approximately 25 to 15 meV when p was increased from p = 2.7 × 10¹⁸ to p = 4.0 × 10¹⁸ cm⁻³. These results are explained under the assumption that the position of the Fermi level E{sub f} at GBs depends on the degree of occupancy of defect states at the GBs, while E{sub f} approached the bottom of the conduction band or the top of the valence band in the BaSi₂ grain interiors with increasing impurity concentrations. In both cases, such small barrier heights may not deteriorate the carrier transport properties. The electronic structures of impurity-doped BaSi₂ are also discussed using first-principles pseudopotential method to discuss the insertion sites of impurity atoms and clarify the reason for the observed n-type conduction in the Sb-doped BaSi₂ and p-type conduction in the B-doped BaSi₂.« less

  3. Antiferromagnetism in semiconducting SrMn2Sb2 and BaMn2Sb2 single crystals

    NASA Astrophysics Data System (ADS)

    Sangeetha, N. S.; Smetana, V.; Mudring, A.-V.; Johnston, D. C.

    2018-01-01

    Crystals of SrMn2Sb2 and BaMn2Sb2 were grown using Sn flux and characterized by powder and single-crystal x-ray diffraction, respectively, and by single-crystal electrical resistivity ρ , heat capacity Cp, and magnetic susceptibility χ measurements versus temperature T , and magnetization versus field M (H ) isotherm measurements. SrMn2Sb2 adopts the trigonal CaAl2Si2 -type structure, whereas BaMn2Sb2 crystallizes in the tetragonal ThCr2Si2 -type structure. The ρ (T ) data indicate semiconducting behaviors for both compounds with activation energies of ≳0.35 eV for SrMn2Sb2 and 0.16 eV for BaMn2Sb2 . The χ (T ) and Cp(T ) data reveal antiferromagnetic (AFM) ordering at TN = 110 K for SrMn2Sb2 and 450 K for BaMn2Sb2 . The anisotropic χ (T ≤TN) data also show that the ordered moments in SrMn2Sb2 are aligned in the hexagonal a b plane, whereas the ordered moments in BaMn2Sb2 are aligned collinearly along the tetragonal c axis. The a b -plane M (H ) data for SrMn2Sb2 exhibit a continuous metamagnetic transition at low fields 0 BaMn2Sb2 exhibits no metamagnetic transitions up to 5.5 T. The χ (T ) and C p(T ) data for both SrMn2Sb2 and BaMn2Sb2 indicate strong dynamic short-range AFM correlations above their respective TN up to at least 900 K within a local-moment picture, corresponding to quasi-two-dimensional magnetic behavior. The present results and a survey of the literature for Mn pnictides with the CaAl2Si2 and ThCr2Si2 crystal structures show that the TN values for the CaAl2Si2 -type compounds are much smaller than those for the ThCr2Si2 -type materials.

  4. Synthesis, Crystal and Electronic Structures of the Pnictides AE 3TrPn 3 (AE = Sr, Ba; Tr = Al, Ga; Pn = P, As)

    DOE PAGES

    Stoyko, Stanislav; Voss, Leonard; He, Hua; ...

    2015-09-24

    New ternary arsenides AE 3TrAs 3 (AE = Sr, Ba; Tr = Al, Ga) and their phosphide analogs Sr 3GaP 3 and Ba 3AlP 3 have been prepared by reactions of the respective elements at high temperatures. Single-crystal X-ray diffraction studies reveal that Sr 3AlAs 3 and Ba 3AlAs 3 adopt the Ba 3AlSb 3-type structure (Pearson symbol oC56, space group Cmce, Z = 8). This structure is also realized for Sr 3GaP 3 and Ba 3AlP 3. Likewise, the compounds Sr 3GaAs 3 and Ba 3GaAs 3 crystallize with the Ba 3GaSb 3-type structure (Pearson symbol oP56, space groupmore » Pnma, Z = 8). Both structures are made up of isolated pairs of edge-shared AlPn 4 and GaPn 4 tetrahedra (Pn = pnictogen, i.e., P or As), separated by the alkaline-earth Sr 2+ and Ba 2+ cations. In both cases, there are no homoatomic bonds, hence, regardless of the slightly different atomic arrangements, both structures can be rationalized as valence-precise [AE 2+] 3[Tr 3+][Pn 3-] 3, or rather [AE 2+] 6[Tr 2Pn 6] 12-, i.e., as Zintl phases.« less

  5. Study of the electronic structure and half-metallicity of CaMnO3/BaTiO3 superlattice

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Jiang, Wei; Chen, Jun-Nan; Huang, Jian-Qi

    2016-09-01

    In this paper, the electronic structure, magnetic properties and half-metallicity of the CaMnO3/BaTiO3 superlattice are investigated by employing the first-principle calculation based on density functional theory within the GGA or GGA + U exchange-correlation functional. The CaMnO3/BaTiO3 superlattice is constructed by the cubic CaMnO3 and the tetragonal ferroelectric BaTiO3 growing alternately along (0 0 1) direction. The cubic CaMnO3 presents a robust half-metallicity and a metastable ferromagnetic phase. Its magnetic moment is an integral number of 3.000 μB per unit cell. However, the CaMnO3/BaTiO3 superlattice has a stable ferromagnetic phase, for which the magnetic moment is 12.000 μB per unit cell. It also retains the robust half-metallicity which mainly results from the strong hybridization between Mn and O atoms. The results show that the constructed CaMnO3/BaTiO3 superlattice exhibits superior magnetoelectric properties. It may provide a theoretical reference for the design and preparation of new multiferroic materials.

  6. 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

  7. HPHT synthesis, structure and electrical properties of type-I clathrates Ba{sub 8}Al{sub x}Si{sub 46−x}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Binwu; Jia, Xiaopeng; Sun, Hairui

    2016-01-15

    Clathrate compounds Ba{sub 8}Al{sub x}Si{sub 46−x} were successfully synthesized using the method of high-pressure and high-temperature (HPHT). In this process, we used BaSi{sub 2} 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.more » 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. - Graphical abstract: Left: The cavity structure diagram of a China-type large volume cubic high-pressure apparatus, and the Type-I clathrate structure of sample synthesized using HPHT. Middle: X-ray Rietveld refinement profile for Ba{sub 8}Si{sub 46} and element mapping for Ba{sub 8}Al{sub 16}Si{sub 30}. Right: Temperature dependence of Seebeck coefficient for Ba{sub 8}Al{sub x}Si{sub 46−x} prepared by HPHT. - Highlights: • HPHT is a simple and rapid synthetic approach. • We use BaSi{sub 2} as one of the starting materials replacing Ba metals. • The processing time reduces from few days to an hour. • Structure determination is refined by Rietveld analysis of XRD data. • Variable temperature electrical properties are characterized.« less

  8. In situ investigation of complex BaSO4 fiber generation in the presence of sodium polyacrylate. 1. Kinetics and solution analysis.

    PubMed

    Wang, Tongxin; Cölfen, Helmut

    2006-10-10

    Simple solution analysis of the formation mechanism of complex BaSO(4) fiber bundles in the presence of polyacrylate sodium salt, via a bioinspired approach, is reported. Titration of the polyacrylate solution with Ba(2+) revealed complex formation and the optimum ratio of Ba(2+) to polyacrylate for a slow polymer-controlled mineralization process. This is a much simpler and faster method to determine the appropriate additive/mineral concentration pairs as opposed to more common crystallization experiments in which the additive/mineral concentration is varied. Time-dependent pH measurements were carried out to determine the concentration of solution species from which BaSO(4) supersaturation throughout the fiber formation process can be calculated and the second-order kinetics of the Ba(2+) concentration in solution can be identified. Conductivity measurements, pH measurements, and analytical ultracentrifugation revealed the first formed species to be Ba-polyacrylate complexes. A combination of the solution analysis results and optical microscopic images allows a detailed picture of the complex precipitation and self-organization process, a particle-mediated process involving mesoscopic transformations, to be revealed.

  9. Precipitation method for barium metaborate (BaB{sub 2}O{sub 4}) synthesis from borax solution

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Akşener, Eymen; Figen, Aysel Kantürk; Pişkin, Sabriye

    2013-12-16

    In this study, barium metaborate (BaB{sub 2}O{sub 4}, 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−BaB{sub 2}O{sub 4} 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 (Na{sub 2}B{sub 4}O{sub 7⋅}10H{sub 2}O, BDH) and barium chloride (BaCI{sub 2⋅}2H{sub 2}O, Ba) in the glass-batch reactor with stirring.more » 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.« less

  10. Synthesis of high-oxidation Y-Ba-Cu-O phases in superoxygenated thin films

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Gauquelin, N.; McMahon, C.; Hawthorn, D. G.; Botton, G. A.; Wei, J. Y. T.

    2018-03-01

    It is known that solid-state reaction in high-pressure oxygen can stabilize high-oxidation phases of Y-Ba-Cu-O superconductors in powder form. We extend this superoxygenation concept of synthesis to thin films which, due to their large surface-to-volume ratio, are more reactive thermodynamically. Epitaxial thin films of YBa2Cu3O7 -δ grown by pulsed laser deposition are annealed at up to 700 atm O2 and 900 ∘C , in conjunction with Cu enrichment by solid-state diffusion. The films show the clear formation of Y2Ba4Cu7O15 -δ and Y2Ba4Cu8O16 as well as regions of YBa2Cu5O9 -δ and YBa2Cu6O10 -δ phases, according to scanning transmission electron microscopy, x-ray diffraction, and x-ray absorption spectroscopy. Similarly annealed YBa2Cu3O7 -δ powders show no phase conversion. Our results demonstrate a route of synthesis towards discovering more complex phases of cuprates and other superconducting oxides.

  11. Preparation and Stoichiometry Effects on Microstructure and Properties of High Purity BaTiO3.

    DTIC Science & Technology

    1986-03-27

    oxalate , citrate) salt solutions, from mixed alkoxide precursors or from hydrothermal solutions. Typical starting materials and reaction sequences...decomposition and calcination reactions to form the BaTiO compound. Both the oxalate and 3 hydrothermal processes show commnercial promise and are briefly...thermal decomposition of oxalates and by hydrothermal synthesis. As-received lots of mixed oxide and oxalate -derived powders had Ba:TI ratios of 0.997 and

  12. 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 ...

  13. Luminescence properties of Eu2+ in M2MgSi2O7 (M=Ca, Sr, and Ba) phosphors

    NASA Astrophysics Data System (ADS)

    Kim, T.; Kim, Y.; Kang, S.

    2012-03-01

    The photoluminescence properties of alkali-earth magnesium silicates (M2MgSi2O7, M=Ca, Sr, and Ba) doped with Eu2+ were investigated. Solid solutions of Ba x Sr2- x Si2O7, Ca2MgSi2O7, and Sr2MgSi2O7 were prepared. Ba x Sr2- x Si2O7 retained a tetragonal crystal structure similar to the structure of the other compounds up to a stoichiometry of x=1.6, which enabled a systematic study of the common structure. Monoclinic Ba2MgSi2O7 was prepared, and the luminescence properties were compared with those of other samples. The emission and excitation spectra of tetragonal M2MgSi2O7 (M=Ca, Sr, and Ba) changed as a function of the covalency, site symmetry, and crystal field strength. The luminescence properties showed excellent agreement with theoretical predictions based on these factors. The Stokes shift differentiated the emission behaviors of the tetragonal and monoclinic structures.

  14. A novel tunable white light emitting multiphase phosphor obtained from Ba2TiP2O9 by introducing Eu3+

    NASA Astrophysics Data System (ADS)

    Zhou, Zhenzhen; Liu, Guanghui; Wan, Jieqiong; Ni, Jia; Lu, Zhouguang; Ma, Ruguang; Zhou, Yao; Wang, Jiacheng; Liu, Qian

    2016-04-01

    Tunable white light was realized in samples Ba2(1- x)TiP2O9:2 xEu ( x = 0-0.80) by introducing orange-red light emitting Eu3+ in self-activated blue-green light emitting matrix Ba2TiP2O9. The sample Ba2(1- x)TiP2O9:2 xEu is a multiphase system consisting of Ba2TiP2O9, EuPO4 and TiO2 when x is greater than or equal to 0.20. The tunable light from blue-green to bluish-white, to white, and eventually to pinky-white of samples Ba2(1- x)TiP2O9:2 xEu under UV light excitation is attributed to the light mixture of tunable blue-green light from Ti4+-O2- charge transfer transition in Ba2TiP2O9 and orange-red light from Eu3+ 4f-4f transition mostly in EuPO4. The Commission International de l'Eclairage chromaticity coordinates, correlated color temperature and color rendering index were tuned from (0.262, 0.339), 9492 K and 74 for matrix sample Ba2TiP2O9 to (0.324, 0.346), 5876 K and 87 for sample Ba2(1- x)TiP2O9:2 xEu ( x = 0.40) under UV light excitation. Therefore, a kind of promising UV-excited white light emitting multiphase phosphor was obtained.

  15. Sub-10 nm lanthanide doped BaLuF{sub 5} nanocrystals: Shape controllable synthesis, tunable multicolor emission and enhanced near-infrared upconversion luminescence

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rao, Ling; Lu, Wei; Wang, Haibo

    2015-04-15

    Highlights: • Sub-10 nm cubic phase BaLuF{sub 5} nanocrystals were synthesized by a hydrothermal method for the first time. • Tunable multicolor from yellow to yellow-green was achieved by controlling Gd{sup 3+} content in BaLuF{sub 5}:Yb/Er system. • Intense near-infrared upconversion luminescence in BaLuF{sub 5}:Gd/Yb/Tm nanocrystal. • The enhancement near-infrared luminescence can be realized by adjusting the content of Gd{sup 3+} in BaLuF{sub 5}:Gd/Yb/Tm system. - Abstract: In this study, sub-10 nm BaLuF{sub 5} nanocrystals with cubic phase structure were synthesized by a solvothermal method using oleic acid as the stabilizing agent. The as-prepared BaLuF{sub 5} nanocrystals were characterized bymore » transmission electron microscopy (TEM), X-ray diffraction (XRD), and analyzed by the upconversion (UC) spectra. The TEM results reveal that these samples present high uniformity. Compared with Gd-free samples, the size of BaLuF{sub 5}:Yb/Er doped with 10% Gd{sup 3+} decreased to 5.6 nm. In addition, BaLuF{sub 5}:Yb/Tm/Gd upconversion nanoparticles (UCNPs) presented efficient near-infrared (NIR)-NIR UC luminescence. Therefore, it is expected that these ultra-small BaLuF{sub 5} nanocrystals with well-controlled shape, size, and UC emission have potential applications in biomedical imaging fields.« less

  16. PLATFORM DEFORMATION PHASE CORRECTION FOR THE AMiBA-13 COPLANAR INTERFEROMETER

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liao, Yu-Wei; Lin, Kai-Yang; Huang, Yau-De

    2013-05-20

    We present a new way to solve the platform deformation problem of coplanar interferometers. The platform of a coplanar interferometer can be deformed due to driving forces and gravity. A deformed platform will induce extra components into the geometric delay of each baseline and change the phases of observed visibilities. The reconstructed images will also be diluted due to the errors of the phases. The platform deformations of The Yuan-Tseh Lee Array for Microwave Background Anisotropy (AMiBA) were modeled based on photogrammetry data with about 20 mount pointing positions. We then used the differential optical pointing error between two opticalmore » telescopes to fit the model parameters in the entire horizontal coordinate space. With the platform deformation model, we can predict the errors of the geometric phase delays due to platform deformation with a given azimuth and elevation of the targets and calibrators. After correcting the phases of the radio point sources in the AMiBA interferometric data, we recover 50%-70% flux loss due to phase errors. This allows us to restore more than 90% of a source flux. The method outlined in this work is not only applicable to the correction of deformation for other coplanar telescopes but also to single-dish telescopes with deformation problems. This work also forms the basis of the upcoming science results of AMiBA-13.« less

  17. Controlled synthesis and novel photoluminescence properties of BaTiO{sub 3}:Eu{sup 3+}/Eu{sup 2+} nanocrystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Feng, Li; Li, Ying; Wang, Guofeng, E-mail: wanggf75@gmail.com

    2015-01-15

    Highlights: • Tetragonal phase BaTiO{sub 3}:Eu nanocrystals were successfully synthesized using a hydrothermal method. • Under 398 nm excitation, the emissions from Eu{sup 2+} and Eu{sup 3+} ions were observed. • The emission band of Eu{sup 2+} from BaTiO{sub 3}:Eu was observed to broaden with increasing Eu concentration. - Abstract: Tetragonal phase BaTiO{sub 3}:Eu nanocrystals were successfully synthesized using a hydrothermal method and a subsequent calcination treatment. The structures and morphologies of nanocrystals were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy. The photoluminescence properties of BaTiO{sub 3}:Eu were investigated in detail. Under 398 nmmore » excitation, the emissions from Eu{sup 2+} and Eu{sup 3+} ions were observed, indicating that Eu{sup 2+} and Eu{sup 3+} ions coexisted in BaTiO{sub 3}:Eu nanocrystals. Especially, the emission band of Eu{sup 2+} from BaTiO{sub 3}:Eu was observed to broaden with increasing Eu concentration. When the Eu concentration was 0.5 mol%, the {sup 5}D{sub 0} → {sup 7}F{sub 0} and {sup 5}D{sub 1} → {sup 7}F{sub 0} emissions were observed. In addition, under 537 nm excitation, the emission intensity increased with increasing Eu concentration.« less

  18. Manipulation of Optical Transmittance by Ordered-Oxygen-Vacancy in Epitaxial LaBaCo 2O 5.5+δ Thin Films

    DOE PAGES

    Cheng, Sheng; Lu, Jiangbo; Han, Dong; ...

    2016-11-23

    Giant optical transmittance changes of over 300% in wide wavelength range from 500 nm to 2500 nm were observed in LaBaCo 2O 5.5+δ thin films annealed in air and ethanol ambient, respectively. The reduction process induces high density of ordered oxygen vacancies and the formation of LaBaCo 2O 5.5 (δ = 0) structure evidenced by aberration-corrected transmission electron microscopy. Moreover, the first-principles calculations reveal the origin and mechanism of optical transmittance enhancement in LaBaCo 2O 5.5 (δ = 0), which exhibits quite different energy band structure compared to that of LaBaCo 2O 6 (δ = 0.5). The discrepancy of energymore » band structure was thought to be the direct reason for the enhancement of optical transmission in reducing ambient. Thus, LaBaCo 2O 5.5+δ thin films show great prospect for applications on optical gas sensors in reducing/oxidizing atmosphere.« less

  19. Manipulation of Optical Transmittance by Ordered-Oxygen-Vacancy in Epitaxial LaBaCo2O5.5+δ Thin Films.

    PubMed

    Cheng, Sheng; Lu, Jiangbo; Han, Dong; Liu, Ming; Lu, Xiaoli; Ma, Chunrui; Zhang, Shengbai; Chen, Chonglin

    2016-11-23

    Giant optical transmittance changes of over 300% in wide wavelength range from 500 nm to 2500 nm were observed in LaBaCo 2 O 5.5+δ thin films annealed in air and ethanol ambient, respectively. The reduction process induces high density of ordered oxygen vacancies and the formation of LaBaCo 2 O 5.5 (δ = 0) structure evidenced by aberration-corrected transmission electron microscopy. Moreover, the first-principles calculations reveal the origin and mechanism of optical transmittance enhancement in LaBaCo 2 O 5.5 (δ = 0), which exhibits quite different energy band structure compared to that of LaBaCo 2 O 6 (δ = 0.5). The discrepancy of energy band structure was thought to be the direct reason for the enhancement of optical transmission in reducing ambient. Hence, LaBaCo 2 O 5.5+δ thin films show great prospect for applications on optical gas sensors in reducing/oxidizing atmosphere.

  20. γ -soft Ba 146 and the role of nonaxial shapes at N ≈ 90

    DOE PAGES

    Mitchell, A. J.; Lister, C. J.; McCutchan, E. A.; ...

    2016-01-12

    Low-spin states in the neutron-rich, N = 90 nuclide 146Ba were populated following β decay of 146Cs , with the goal of clarifying the development of deformation in barium isotopes through delineation of their nonyrast structures. Fission fragments of 146Cs were extracted from a 1.7-Ci 252Cf source and mass selected using the CAlifornium Rare Ion Breeder Upgrade (CARIBU) facility. Low-energy ions were deposited at the center of a box of thin β detectors, surrounded by a highly efficient high-purity Ge array. The new 146Ba decay scheme now contains 31 excited levels extending up to ~2.5 MeV excitation energy, double whatmore » was previously known. These data are compared to predictions from the interacting boson approximation (IBA) model. It appears that the abrupt shape change found at N = 90 in Sm and Gd is much more gradual in Ba and Ce, due to an enhanced role of the γ degree of freedom.« less