• Title, Summary, Keyword: Barium carbonate

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Catalytic Effects of Barium Carbonate on the Anodic Performance of Solid Oxide Fuel Cells

  • Yoon, Sung-Eun;Ahn, Jae-Yeong;Park, Jong-Sung
    • Journal of the Korean Ceramic Society
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    • v.52 no.5
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    • pp.350-355
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    • 2015
  • To develop ceramic composite anodes of solid oxide fuel cells without metal catalysts, a small amount of barium carbonate was added to an $(La_{0.8}Sr_{0.2})(Cr_{0.5}Mn_{0.5})O_3(LSCM)$ - YSZ ceramic composite anode and its catalytic effects on the electrode performance were investigated. A barium precursor solution with citric acid was used to synthesize the barium carbonate during ignition, while a barium precursor solution without citric acid was used to create hydrated barium hydroxide. The addition of barium carbonate to the ceramic composite anode caused stable fuel cell performance at 1073 K; this performance was higher than that of a fuel cell with $CeO_2$ catalyst; however, the addition of hydrated barium hydroxide to the ceramic composite anode caused poor stability of the fuel cell performance.

Sedimentary Excess Barium from a Core of the Northwest Pacific Ocean: Geochemical Proxy

  • Suk, Bong-Chool;Park, Chan-Hong;Taira, Asahiko;Hyun, Sang-Min
    • Journal of the korean society of oceanography
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    • v.35 no.2
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    • pp.98-108
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    • 2000
  • A geochemical study on a hemipelagic core sediment taken from the northwest Pacific Ocean (eastern edge of the Shikoku Basin) was conducted to use of excess barium (Ba(ex)) for evaluate the paleoceano-graphic changes. Also, the excursion of sedimentary Ba(ex) was compared with those of biogenic opal, carbonate and organic carbon content in the sediment during the last glacial and interglacial periods. The calculated Ba(ex) derived from the major and minor element shows a distinctive glacial-interglacial variations, and the mass accumulation rate (MAR) of Ba(ex) shows coincident variations with the MARs of biogenic fractions. Especially, strong positive correlation (r$^2$=0.85) between the MAR of Ba(ex) and the MAR of biogenic carbonate is recognized. Based on the strong positive correlation(r$^2$=0.85) between the MAR of Ba(ex) and the MAR of carbonate content, we estimated the degree of carbonate dissolution rate during the glacial and interglacial periods. Assuming the proportional variation and the refractory nature of barium exist between two factors, the variation of index Ca/Ba ratio in sediment indicates the degree of carbonate dissolution. Sedimentary Ca/Ba ratios index clearly show a striking fluctuation between the glacial and interglacial periods with higher positive correlation during glacial and lower correlation during interglacial. This fact indicates enhanced carbonate dissolution during interglacial period. Thus, the sedimentary Ca/Ba ratio in sedimentary records can be used as one of the useful tools for estimation of the relative degree of carbonate dissolution. The excursion of Ba(ex) and the sedimentary Ca/Ba ratio follows the typical pacific carbonate dissolution type(enhanced dissolution during interglacial and reduced dissolution during glacial time) as suggested by previous work (e.g., Wu et al., 1990). Variation in sedimentary Ca/Ba ratio thus strongly supports that glacial-interglacial fluctuation in carbonate dissolution has been prevailed in the northwest Pacific Ocean.

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Studies on Microstructure of Barium Ferrite (Ist. Report) (Barium Ferrite 조직구조(組織構造)에 관(關)한 연구(硏究)(제 1 보)(第 1 報))

  • Ahn, Young-Pil;Lee, Kwang;WhangBo, Han;Doh, Myung-Ki
    • Applied Microscopy
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    • v.1 no.1
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    • pp.43-48
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    • 1969
  • X-ray diffraction intensity of barium ferrite sintered at $1280^{\circ}C$ as first sintering, varing mole ratio of barium carbonate and iron (III) oxide was checked. The results corresponed to of that magnetic coercivity in previous peport. The microstructure and sintering condition were observed-by means of two step replica method without etching by electron microscope.

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Fabrication of YBa_2Cu_3O_{7-x}$ceramic using the Sol-Gel process (졸-겔 법으로 YBa_2Cu_3O_{7-x}$세라믹의 제조)

  • Kim, Hyun-Taek;Kang, Hyung-Boo;Kim, Bong-Heup
    • Proceedings of the KIEE Conference
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    • pp.299-301
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    • 1989
  • This study presents a method of preparing $YBa_2Cu_3O_{7-x}$ ceramic and chlorine doping in it for the purpose of Jc enhancement us ins sol-gel process.Tetramethylammonium-hydroxide and pottasium carbonate solution were added to the aqueous solution of Yttrium nitrate, Barium chloride and Copper nitrate for pH control as well as forming hydroxy-carbonate precipitation. Instead of Barium nitrate, Barium chloride was used for doping chloride impurities in the specimen. The resulted materal showed good high Tc-superconductivity after calcination. Tc and Jc value are 92 K and 120.8 $A/cm^2$ respectively.

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EFFECT of PREPARATION METHODS and CONDITIONS of PRECURSORS on the PROPERTIES of $BATIO_3$ ALKOXIDE FILMS

  • N., Korobova;Soh, Dea-Wha
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.714-718
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    • 2003
  • Usually for the commercial preparation of barium titanate films or ceramics the reaction atmosphere must be preferably in air. However, normally air is not used because it contains carbon dioxide, which can easily react with barium to form the undesired product barium carbonate, leading to unwanted second-phase formation in the (mal stages of the process. In the present work a series of perovskite barium titanate films was prepared by the sol-gel method, using a metal alkoxide solutions in the electrophoretic deposition (EPD). The influence of several process parameters, like sintering temperature of sol preparation before EPD and heat-treatment temperature and non-oxidized atmosphere, on the film properties is described.

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Enhancement of the Crystallinity of Barium Titanate by Using a Uniform Barium-Carbonate Surface Coating

  • Chung, Nak-Kwan;Yun, Ju-Young;Kim, Jin-Tae;Park, Jiho
    • Journal of the Korean Physical Society
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    • v.70 no.9
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    • pp.861-865
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    • 2017
  • In this work, we modified the surfaces of $BaTiO_3$ particles by using barium acetate and ammonium bicarbonate, and we studied the characteristics and sintering behaviors of the coated $BaTiO_3$ particles. Transmission electron microscopy showed that the resultant coating layer was smooth and uniform without agglomerates. X-ray photoemission spectroscopy analysis also revealed that the surface coating layer was composed of $BaCO_3$. After calcination at $950^{\circ}C$ for 5 hours, the c/a ratio of the coated particles was found to have increased without size growth while the uncoated particles showed size growth. We finally found that the $BaCO_3$ layer acted as a barrier to inhibit particle growth during calcination.

Effects of Alkaline Earth Oxides on Electrical Characteristics of Steatite Porcelain (Steatite 자기의 전기적 특성에 미치는 알칼리 토금속 산화물의 영향)

  • 이종근;이병하;전승관
    • Journal of the Korean Ceramic Society
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    • v.16 no.1
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    • pp.31-37
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    • 1979
  • The middle point of composition within the system $MgO-Al_2O_3-SiO_2$ has been studied for applicability as ceramics dielectrics. A Kyul Sung Tale of high purity, magnesia clinker of Sam-wha chemical company, C.P. aluminium oxide, calcium carbonate, red lead, barium carbonate which was made into frit were used the raw materials. A number of steatite ceramics were prepared under carefully controlled condition and the water absorption, linear shrinkage, power factor, dielectric constant and dielectric loss were measured at elevated temperature. When we used magnesia clinker as flux, the quantity of this flux was 0.05mole, sintering temperature was continued for 2 hrs. at 1, 27$0^{\circ}C$. From this conditions, we could get the data whose power factor was 0.142%, water absorption was zero, linear shrinkage was 8.76%, dielectric constant was 5.63, dielectric loss was 0.00799. When we used red lead as flux, the quantity of this flux was 0.033mole and 0.066mole, sintering temperature was continued for 2hrs. at 1, 26$0^{\circ}C$. From this conditions, we could get the data whose water absorption was zero, linear shrinkage was 8.03%, and 8.48%, power factor was 0.136% and 0.062%, dielectric loss was 0.0072 and 0.0037. When we used barium carbonate made into frit as flux, the quantity of this flux was 0.02mole, sintering temperature was continued for 2hrs. at 1, 27$0^{\circ}C$. From this conditions, we could get the data whose water absoption was zero, linear shrinkage was 8.44%, power factor was 0.138%, dielectric constant was 5.69, dielectric loss was 0.0074.

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Crystal Chemistry of Yttrium-Barium-Copper Oxycarbonate Ceramics

  • Vatolin, Nikolay;Dubrovina, Iring;Balakirev, Viacimir;Zubkov, Vladimir;Tyutyunik, Alexander
    • The Korean Journal of Ceramics
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    • v.6 no.2
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    • pp.164-167
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    • 2000
  • The barium rich region of the Y-Ba-Cu-O-C system includes a tetragonal perovskite-like phase, which possesses a wide homogeneity region toward yttrium, copper and carbonate ion on the one hand, and toward oxygen, on the other hand. Accounting for vacancies ($\square$-vacancy) this phase could be described by the general formula per unit cell: {Ba$_8$}[Y$_{3-z}$Cu$_{5-x}$$(CO_3)_n$ $\square$$_{x+x-n}$]O$_{y{\pm}{\delta}y}$ (*). Here, cube-octahedral sites are represented in braces, while quasioctahedral ones with proper octahedral (Y, Cul), square (Cu2) and triangular (CO$_3$) configuration are shown in square brackets. The formula (*) was confirmed by full-profile Rietveld refinement based on X-ray diffraction data of YBa$_{5}$Cu$_2$O$_y$ (1-5-2 phase). Homogeneity region limits of the phase (*) at 96$0^{\circ}C$ in air were determined to be -0.33$\leq$x$\leq$1.80, 0.33$\leq$z$\leq$2.00, 0$\leq$n$\leq$3.

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Peculiarities of SHS and solid state synthesis of $ReBa_{2}Cu_{3}O_{7-x}$ materials

  • Sho, Dea-Wha;Li, Yingmei;Cho, Yong-Joon;Kim, Tae-Wan;Korobova, N.;Isaikina, O.;Mansurov, Z.;Baydeldinova, A.;Ksandopoulo, G.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.620-623
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    • 2001
  • The peculiarities of using Self-propagating High-temperature Synthesis (SHS) and solid state phase synthesis for production of high temperature superconductor materials are discussed. Oxide superconductors with general formula $ReBa_2$$Cu_3$$O_{7-x}$ (Re= Y, Yb, Sm, Nd) have been made with using barium oxide initial powder instead of traditional barium carbonate. X-ray powder diffraction showed a single phase orthorhombic perovskite structure was produced in all reactions. Phenomena observed during the grinding of the reactant mixture are presented. Mechano-chemical activation - as a pretreatment of the reactant mixture - strongly influences the kinetic parameters, the reaction mechanism, and the composition and structure of the final product.

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Peculiarities of SHS and Solid State Synthesis of ReBa2Cu3O7-x Materials

  • Soh, Deawha;Natalya, Korobova
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.3
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    • pp.275-280
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    • 2002
  • The peculiarities of using Self-propagating High-temperature Synthesis (SHS) and solid-stave chase synthesis for production of high temperature superconductor materials were discussed. Oxide superconductors with general formula of $ReBa_2Cu_3O_{7-x}$ (Re=Y, Sm) haute been made by using barium oxide initial powder instead of traditional barium carbonate. Phenomena observed during the grinding of the reactants mixture are presented. Mechano-chemical activation - as a pre-treatment of the reactants mixture - strongly influences the kinetic parameters, the reaction mechanism, and the composition and structure of the final product.