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Sample records for alloy-yundk 25ba

  1. (La2/5Ba2/5Ca1/5)(Mn(2/5)–NiTi3/5)O3: Rietveld studies, dielectric and magnetic properties of new perovskite-related oxides

    Indian Academy of Sciences (India)

    Pika Jha; Saroj L Samal; Kandalam V Ramanujachary; Samuel E Lofland; Ashok K Ganguli

    2005-10-01

    Oxides of the type (La2/5Ba2/5Ca1/5)(Mn(2/5)–NiTi3/5)O3 (0 ≤ ≤ 0.4) have been synthesized by the ceramic route. All the above oxides have been found to crystallize in the cubic perovskite structure. Rietveld refinement of the Ni-based oxide, (La2/5Ba2/5Ca1/5)(Ni2/5Ti3/5)O3 gave rise to a composition (La0.44Ba0.38Ca0.18) (Ni0.42Ti0.58)O2.85(6) and the refined lattice parameter obtained was 3.9411(2) Å (space group $\\bar{3}$; (2) = 0.026, p = 0.074, p = 0.087). A shift from antiferromagnetic to paramagnetic behaviour is observed with increase in nickel concentration, the Mn-rich phases showing antiferromagnetism around 5 K. There is a systematic decrease in the dielectric constant, and loss tangent with increase in Ni concentration (from = 592 for = 0 to = 78 for = 0.4).

  2. The influence of cation additives on the NIR luminescence intensity of Er3+-doped borate glasses

    Institute of Scientific and Technical Information of China (English)

    Zhou Yong-Liang; Zhang Xiao-Song; Xu Jian-Ping; Zhang Zhong-Peng; Zhang Gao-Feng; Wei Feng-Wei; Li Lan

    2012-01-01

    Er3+-doped 25BaO-(25-x)SiO2-xAl2O3-25B2O3 transparent glasses are prepared with x =0,12.5 and 25 by a solid-state reaction.The Er-related NIR luminescence intensity,which corresponds to the transition of 4I15/2-4I13/2,is obviously altered with different silicon/aluminum ratios.The Judd-Ofelt parameters of the Er3+ ions are adopted to explain the intensity change in the NIR fluorescence,and the Raman scattering intensity versus the amount of Al and/or Si components are discussed.The spectra of the three samples are quite similar in the peak positions,but different in intensity.The maximal phonon density of state for the samples is calculated from the Raman spectra and is correlated to the NIR luminescence efficiency.

  3. Evaluation of the FilmArray® system for detection of Bacillus anthracis, Francisella tularensis, and Yersinia pestis

    Energy Technology Data Exchange (ETDEWEB)

    Seiner, Derrick R.; Colburn, Heather A.; Baird, Cheryl L.; Bartholomew, Rachel A.; Straub, Tim M.; Victry, Kristin D.; Hutchison, Janine R.; Valentine, Nancy B.; Bruckner-Lea, Cindy J.

    2013-04-29

    To evaluate the sensitivity and specificity of the Idaho Technologies FilmArray® Biothreat Panel for the detection of Bacillus anthracis (Ba), Francisella tularensis (Ft), and Yersinia pestis (Yp) DNA, and demonstrate the detection of Ba spores. Methods and Results: DNA samples from Ba, Ft and Yp strains and near-neighbors, and live Ba spores were analyzed using the Biothreat Panel, a multiplexed PCR-based assay for 17 pathogens and toxins. Sensitivity studies with DNA suggest a limit of detection of 250 genome equivalents (GEs) per sample. Furthermore, the correct call of Ft, Yp or Bacillus species was made in 63 of 72 samples tested at 25 GE or less. With samples containing 25 Ba Sterne spores, at least one of the two possible Ba markers were identified in all samples tested. We observed no cross-reactivity with near-neighbor DNAs.

  4. A New Family of Perovskite Catalysts for Oxygen-Evolution Reaction in Alkaline Media: BaNiO3 and BaNi(0.83)O(2.5).

    Science.gov (United States)

    Lee, Jin Goo; Hwang, Jeemin; Hwang, Ho Jung; Jeon, Ok Sung; Jang, Jeongseok; Kwon, Ohchan; Lee, Yeayeon; Han, Byungchan; Shul, Yong-Gun

    2016-03-16

    Establishment of a sustainable energy society has been strong driving force to develop cost-effective and highly active catalysts for energy conversion and storage devices such as metal-air batteries and electrochemical water splitting systems. This is because the oxygen evolution reaction (OER), a vital reaction for the operation, is substantially sluggish even with precious metals-based catalysts. Here, we show for the first time that a hexagonal perovskite, BaNiO3, can be a highly functional catalyst for OER in alkaline media. We demonstrate that the BaNiO3 performs OER activity at least an order of magnitude higher than an IrO2 catalyst. Using integrated density functional theory calculations and experimental validations, we unveil that the underlying mechanism originates from structural transformation from BaNiO3 to BaNi(0.83)O(2.5) (Ba6Ni5O15) over the OER cycling process. PMID:26910187

  5. Correlation between temperature-dependent permittivity dispersion and depolarization behaviours in Zr4+-modified BiFeO3–BaTiO3 piezoelectric ceramics

    Indian Academy of Sciences (India)

    Weidong Zeng; Changrong Zhou; Jianrong Xiao; Jiafeng Ma

    2015-12-01

    The correlation between permittivity frequency dispersion and depoling process upon heating was investigated in Zr4+-modified 0.75BiFeO3–0.25BaTiO3 (BF–BZT) ceramics. The temperature-dependent permittivity r() and the piezoelectric coefficient 33 for poled samples were measured under heating conditions to clarify the depolarization mechanism. The results indicate that the poling temperature plays a crucial role in the domains' alignment process, as expected. The temperature-dependent permittivity frequency dispersion and depolarization behaviours may have same origin. The aligned domains' break up into random state/nanodomains at depoling temperature ( d), which causes strong frequency dependence of the permittivity, simultaneously, induces the loss of piezoelectricity. It suggests that the temperature-dependent permittivity measurements method is a simple way to determine the depolarization temperature.

  6. Magnetoresistance hysteresis in granular HTSCs as a manifestation of the magnetic flux trapped by superconducting grains in YBCO + CuO composites

    International Nuclear Information System (INIS)

    Hysterestic behavior of the magnetoresistance of granular HTSCs and its interaction with the magnetic hysteresis are studied by measuring magnetoresistance R(H) and critical current Ic(H) of composites formed by HTSC Y0.75Lu0.25Ba2Cu3O7 and CuO. A network of Josephson junctions is formed in such composites, in which the nonsuperconducting component plays the role of barriers between HTSC grains. Hysteretic dependences R(H) of magnetoresistance are studied in a wide range of transport current density j and are analyzed in the framework of the two-level model of a granular superconductor, in which dissipation takes place in the Josephson medium and the magnetic flux can be pinned both in grains and in the Josephson medium. The interrelation between the hysteresis of critical current Ic(H) and the evolution of the hysterestic dependence R(H) of the magnetoresistance upon transport current variation is demonstrated experimentally. The effect of the magnetic past history on the hysteretic behavior of R(H) and the emergence of a segment with a negative magnetoresistance are analyzed. It is shown for the first time that the R(H) dependences are characterized by a parameter that is independent of the transport current, viz., the width of the R(H) hysteresis loop

  7. Dynamic Assessment of Incidental Vocabularies: A Case of Iranian ESP Learners

    Directory of Open Access Journals (Sweden)

    Sepideh Hanifi

    2016-04-01

    Full Text Available Dynamic assessment (DA, stemmed from both Vygotsky’s (1978 learning theory and Feuerstein’s (1979 theory of mediated learning experiences, is an alternative to static assessment. It focuses on both instruction and assessment aiming at promoting learning through mediation.  DA has been widely researched in different linguistic areas, but there is paucity of research on its practice in ESP contexts. Accordingly, this study investigated the effectiveness of DA on incidental vocabularies emerging in technical reading textbooks, written for electronic engineering students. The study employed a quasi-experimental research design. Due to sample selection problems, an intact group of 25 BA electronic students were selected from the University of Zanjan. A pre-test was administered to check whether they had previous knowledge of the target words, incidentally acquired during the reading activity. As for the instrument stage, DA procedures were utilized in order to individualize participants’ assessment. Following DA implementation, a post-test similar in content to pre-test, was administered to the same participants. The significance of DA for the enhancement of incidental vocabularies was to make participants aware of the strategies of identifying, evaluating and monitoring vocabularies (Nassaji, 2003 through mediation process.  The results indicated that participants' incidental vocabulary learning promoted dramatically using DA, which employed structured hints for the mediation process.  The results of this study can inform both teachers and learners to provide a step by step procedure to promote both teaching and assessment of ESP learners' vocabulary.Keywords: Dynamic Assessment, Incidental Vocabulary Learning, ESP Learners, ZPD, mediation 

  8. Phase transition, piezoelectric, and multiferroic properties of La(Co{sub 0.5}Mn{sub 0.5})O{sub 3}-modified BiFeO{sub 3}-BaTiO{sub 3} lead-free ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Lingling; Jiang, Na; Zou, Xiao; Sun, Ting; Zheng, Qiaoji; Xu, Chenggang; Lin, Dunmin [College of Chemistry and Materials Science, Sichuan Normal University, Chengdu (China); Shi, Dongliang; Lam, Kwok Ho [Department of Electrical Engineering, The Hong Kong Polytechnic University, Kowloon (China)

    2015-09-15

    (0.75-x)BiFeO{sub 3}-0.25BaTiO{sub 3}-xLa(Co{sub 0.5}Mn{sub 0.5})O{sub 3} + 1 mol% MnO{sub 2} lead-free ceramics (x = 0-0.10) were synthesized by a conventional solid-state reaction route and the effects of La(Co{sub 0.5}Mn{sub 0.5})O{sub 3} on phase transition, piezoelectric, ferroelectric, and multiferroic properties of the ceramics were investigated. The ceramics can be well sintered at 960 C for 2 h. After the addition of La(Co{sub 0.5}Mn{sub 0.5})O{sub 3}, the crystal structure of the ceramics is transformed from rhombohedral (space group R3c) to orthorhombic symmetry (space group Amm2), and the morphotropic phase boundary (MPB) of rhombohedral and orthorhombic phases is formed at x = 0.01-0.03. The dielectric peak of the ceramics was found to become diffusive with increasing x. The ceramics with x = 0-0.03 possess strong piezoelectricity with d{sub 33} of 95-108 pC N{sup -1}, strong ferroelectricity with P{sub r} of 2.2-18.1 μC cm{sup -2}, considerable magnetoelectric coefficient of 372-672 mV/cmOe, and high Curie temperature of 523-659 C, showing potential applications in multiferroic devices. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Pure and Y-substituted BaZrO3 ceramics. A possible support material for fabrication of YBa2Cu3O7-x high-Tc superconductors

    International Nuclear Information System (INIS)

    This thesis concerns the preparation and characterization of cuprate based high-Tc superconductors (Y-123 and Bi-2223) and especially development and testing of BaZrO3 based materials. The formation of YBa2Cu3Oy (Y-123) by a CO2-free route involving reaction sintering of stoichiometric mixtures of chemically prepared fine powders of Y2BaCuO5, BaCuO2 and CuO have been studied by thermal and XRD analysis. The synthesis and sintering of BaZrO3 powders prepared by the hydroxide-alkoxide-methanol sol-gel route have been studied. The phase relations in the system BaO-Y2O3-ZrO2 have been studied to determine the solid solubility limits for the perovskite phase BaXYYZrZON (X+X+Z=3) at 1500 deg. C. In the binary system Y2O3-BaZrO3 the solubility limit was found to be ≅19 mol% Y2O3, i.e. Ba0.81Y0.42Zr0.81O3. along the joint BaYO2.5-Ba the boundary was determined to be at BaY0.21Zr0.79O2.895. evidence for a new solid solution series between Ba3Y4O9 and ZrO2 are given, and a partial 1500 deg. C phase diagram for the ternary system BaO-Y2O3-ZrO2 is presented. The growth of BaZrO3 single crystals have been attempted both by a laser zone floating technique and flux methods. The compatibility between YBa2Cu3O7-X and BaZrO3, BaXYYZrZO3-δ as well as BaHfO3 have been studied at 950 deg. and 1050 deg. C. The results show the four most promising candidates as support materials for fabrication of YBa2Cu3Oy to be BaHfO3, BaY0.05Zr0.95O2.975, , BaZrO3 and BaY0.1Zr0.9O2.95. (EG)

  10. Characterization and activity of alkaline earth metals loaded CeO{sub 2}–MO{sub x} (M = Mn, Fe) mixed oxides in catalytic reduction of NO

    Energy Technology Data Exchange (ETDEWEB)

    Mousavi, Seyed Mahdi [Department of Applied Chemistry and Chemical Engineering, Faculty of Chemistry, University of Tabriz, 5166616471 Tabriz (Iran, Islamic Republic of); Niaei, Aligholi, E-mail: niaei@yahoo.com [Department of Applied Chemistry and Chemical Engineering, Faculty of Chemistry, University of Tabriz, 5166616471 Tabriz (Iran, Islamic Republic of); Illán Gómez, María José [Carbon Materials and Environment Research Group, Department of Inorganic Chemistry, Faculty of Science, Universidad de Alicante, Alicante (Spain); Salari, Dariush; Nakhostin Panahi, Parvaneh [Department of Applied Chemistry and Chemical Engineering, Faculty of Chemistry, University of Tabriz, 5166616471 Tabriz (Iran, Islamic Republic of); Abaladejo-Fuentes, Vicente [Carbon Materials and Environment Research Group, Department of Inorganic Chemistry, Faculty of Science, Universidad de Alicante, Alicante (Spain)

    2014-02-14

    Nanocrystalline CeO{sub 2}–MO{sub x} mixed oxides (M = Mn, Fe) with different M/(M + Ce) molar ratio are prepared by sol–gel combustion method. X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Temperature Programmed Reduction with H{sub 2} (H{sub 2}-TPR) and N{sub 2}-adsorption (BET) analyses are conducted to characterize the physical–chemical properties of the catalysts. The activity of catalysts for reduction of NOx with ammonia has been evaluated. The CeO{sub 2}–MnO{sub x} catalysts showed better low temperature activity than CeO{sub 2}–FeO{sub x}. The superior activity of CeO{sub 2}–MnO{sub x} with Mn/(Mn + Ce) molar ratio of 0.25 respect to other catalysts (with 83% NO conversion and 68% N{sub 2} yield at 200 °C) is associated to nanocrystalline structure, reducibility at low temperature and synergistic effect between Ce and Mn that are observed by XRD, TEM and H{sub 2}-TPR. The CeO{sub 2}–FeO{sub x} catalysts were found to be active at high temperature, being Ce–Fe the best catalyst yielded 82% NO conversion at 300 °C. The effect of alkaline earth metals (Ca, Mg, Sr and Ba) loading on the structure and catalytic activity of cerium mixed oxides are also investigated. Loading of Ba enhanced the NO reduction activity of mixed oxides due to the increase of number of basic sites. Highest performance with 91% NO conversion and 80% N{sub 2} yield attained over CeO{sub 2}–MnO{sub x} (0.25)-Ba (7%) catalyst at 200 °C. - Highlights: • CeO{sub 2}–MO{sub x} mixed oxides (M = Mn, Fe) were synthesized by sol–gel combustion method. • The activity of mixed oxides is evaluated in catalytic reduction of NO with NH{sub 3}. • The CeO{sub 2}–MnO{sub x} showed better activity than CeO{sub 2}–FeO{sub x} due to better redox properties. • Ba loading enhanced the activity due to the increase of number of basic sites. • 91% NO conversion and 80% N{sub 2} yield attained over 7%Ba–Ce{sub 0.75}Mn{sub 0.25}O{sub 2} at 200 °C.