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  • Title/Summary/Keyword: ZrB2

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The Synthesis of Nb2Zr6O17xNx : A New Visible Light Oxynitride Photocatalyst (Nb2Zr6O17xNx의 합성 : Oxynitride계 신규 가시광 광촉매)

  • Kanade, K.G.;Baeg, Jin-Ook;Kale, B.B.;Lee, Sang-Mi;Moon, Sang-Jin;Lee, Chul-Wee;Chang, Hyun-Ju
    • Journal of Hydrogen and New Energy
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    • v.17 no.1
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    • pp.55-61
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    • 2006
  • 신규 Nb2Zr6O17xNx 광촉매를 고상합성법처리(solid state synthesis) 후 암모니아가스(NH3)에 의한 기상처리법(ammonolysis)으로 합성하였다. 합성된 신규 광촉매 및 이를 다시 Pt 및 RuO2를 도핑 하여 H2S를 광분해하여 수소를 발생 실험을 수행하였다. 이 신규 oxynitrid계 광촉매는 가시광하에서 H2S를 광분해하여 수소를 발생하는(Quantum yield = 13.5 %) 우수한 광촉매 활성을 보여주었다.

X-Ray Fluorescence Analysis of Ta2O5,Nb2O5,TiO2,SnO2 and ZrO2 in Tin-Slags (주석-슬랙 중 Ta2O5,Nb2O5,TiO2,SnO2, 및 ZrO2의 X-선 형광분석)

  • Young-Sang Kim;Chong Wook Lee
    • Journal of the Korean Chemical Society
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    • v.27 no.4
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    • pp.273-278
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    • 1983
  • With the synthetic standards, valuable metals (Ta2O5,Nb2O5,TiO2,SnO2, and ZrO2) in the tin slags have been determined by the x-ray fluorescence spectrometry. The powder sample and the standards are homogeneously mixed with anhydrous Li2B4O7 and La_2O_3$ in weight ratio of 15 : 42 : 3 respectively. The mixed material is fused at 1,150C for 30 minutes to be changed into the glass bead. The bead is ground to (-) 325 mesh size and pelletized. The analytical results obtained in this work are consistent with the data obtained by other common methods within allowable error range. The standard deviation for Ta2O5 in PTS-H sample is 0.12 % at level of 3.40 % content.

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X-Ray Fluorescence Analysis of Ta2O5,Nb2O5 and ZrO_2$ in Tin-Slag Samples using Simple Dilution Method (주석 슬랙중 Ta2O5,Nb2O5ZrO_2$의 단일희석법을 이용한 X-선 형광분석)

  • Young-Sang Kim;Hak Je Sung
    • Journal of the Korean Chemical Society
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    • v.28 no.5
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    • pp.293-301
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    • 1984
  • -ray fluorescence analysis of Ta2O5, Nb2O5 and ZrO2 in tin-slag samples using the simple dilution method was studied. The method is to correct mathematically the calibration curve to the linear line by the dilution. One synthesized standard having similar composition to the sample and tin slag samples were diluted with anhydrous Li2B4O7 at the level of 1%, 2% and 3% of the sample content respectively. The diluted samples were fused at 1150C for 30 minutes and these glass beads were finely ground and pelletized. Measuring the X-ray intensities with these pellets, analytical results were calculated by the equation derived from J. Scherman's equation for the characteristic X-ray intensity of an element. Analytical results agreed with the reference values obtained by the standard calibration method within allowable error range and were reproducible.

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X-Ray Spectrometric Determination of Ta2O5,Nb2O5 and ZrO2in Tin-Slag Samples by Double Dilution Technique (주석-슬랙중 Ta2O5,Nb2O5ZrO2의 이중희석법을 이용한 X-선 분광분석)

  • Young-Sang Kim;Kee-Chae Park
    • Journal of the Korean Chemical Society
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    • v.28 no.5
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    • pp.302-308
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    • 1984
  • X-ray spectrometric determination of $Ta_2O_54, Nb2O5 and ZrO2 in tin-slag samples using the double dilution technique was conducted. Tin-slag samples and one synthesized standard sample having similar composition to the samples were diluted with anhydrous Li2B4O7 at the level of 1.00, 2.00 and 3.00% of the sample content, respectively. The diluted samples were fused at 1,150C for 30 minutes, and these glass beads were finely ground and pelletized. With the X-ray intensities measured, analytical results were calculated by the double dilution equation. The results agreed to the reference values obtained by the standard calibration method and the simple dilution technique within allowable error range and were reproducible.

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Synthesis and Crystal Chemistry of New Actinide Pyrochlores (새로운 파이로클로어의 합성 및 결정화학적 특징)

  • ;;;Sergey V. Yudintsev
    • Journal of the Mineralogical Society of Korea
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    • v.15 no.1
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    • pp.78-84
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    • 2002
  • New pyrochlore-type phases(A2B2O7) were synthesized in the systems: CaO-CeO2-TiO2, CaO-UO2(ThO2)-ZrO2, CaO-UO2(ThO2)-Gd2O3-TiO2-ZrO2, 및 CaO-ThO2-SnO2. The starting materials were pressed with the pressure of 200~400 MPa and sintered at 1500~ 1550C for 4~8 hours in air and at 1300~ 1350C for 5 ~50 hours under oxygen atmosphere. The products were characterized using XRD, SEM/EDS and TEM. In the bulk compositions of CaCeTi2O7, CaThZr2O7,(Ca0.5 GdTh0.5)(ZrTi)O7) (Ca0.5GdTh0.5)(ZrTi)O7, (Ca0.5GdU0.5)(ZrTi)O7 and CaThSn2O7 , pyrochlore was the major phase, together with other oxide phase of2O7 fluorite structure. In the samples with target compositions CaUZr2O2Ca0.5 GdU0.5)Zr2TiO7 pyrochlore was not identified, but a fluorite-structured phase was detected. The formation factor as the stable phase depended on crystal chemical characteristics of the actinide and lanthanide elements of the system concerned.

Electromagnetic Properties of Bulk High-Tc Superconductor (벌크형 초전도체의 전기자기적 특성)

  • Lee, Sang-Heon
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.2
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    • pp.111-114
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    • 2017
  • In this research, the development of fabrication technique of bulk YBaCuO superconductors for application was studied. In fluence of BaZrO3 addition on magnetization characteristics of thermal pyrolysis textured YBaCuO superconductor was investigated. Fine BaZrO3 particle were dispersed within the textured YBaCuO matrix by means of the thermal pyrolysis processing. Magnetic levitation force for YBaCuO superconductors were obtained using Nd-B-Fe permanent magnet, at 77 K and at the magnetic field from 0 to 5.3 K gauss. In the unadded superconductor and 5 wt% BaZrO3 addition, anomalous magnetization behavior, which is characterized by the intermediate magnetic field, was observed at 77 K. Critical current density was about few hundreds A/cm2 and the magnetic characteristics increased slightly by addition of BaZrO3 powder. Maximum magnetic force was obtained in the YBaCuO superconducting bulk with 3 wt.% BaZrO3 addition.

The Oxidation of Functionally Gradient NiCrAlY/YSZ Coatings

  • Park, K.B.;Park, H.S.;Kim, H.J.;Lee, D.B.
    • Journal of Surface Science and Engineering
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    • v.34 no.5
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    • pp.499-502
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    • 2001
  • Functionally gradient NiCrAlY/ZrO2-Y2O3 and NiCrAlY/ZrO2- CeO2-Y2O3 coatings were prepared by APS. The as-sprayed microstructure consisted of metal-rich and ceramic-rich regions, between which Al2O3-rich layers existed owing to the oxidation during APS. During oxidation between 900 and 1100C in air, the pre-existing Al2O3-rich scales grew, due mainly to the preferential reaction of Al with inwardly transporting oxygen along the heterogeneous phase boundaries. As the amount of ceramics in the coating increased, the oxidation resistance increased.

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Synthesis, Characterization and Catalytic Application of MoO3/CeO2-ZrO2 Solid Heterogeneous Catalyst for the Synthesis of Benzimidazole Derivatives

  • Rathod, Sandip B.;Lande, Machhindra K.;Arbad, Balasaheb R.
    • Bulletin of the Korean Chemical Society
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    • v.31 no.10
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    • pp.2835-2840
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    • 2010
  • A series of MoO3/CeO2ZrO2 catalysts with different Mo content (8 - 20 wt %) were prepared by simple co-precipitation followed by impregnation method and were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), energy dispersive spectroscopic (EDS) techniques. The prepared materials were tested for catalytic activity by the synthesis of benzimidazole derivatives using condensation of aromatic aldehydes and o-phenylenediamine by conventional and microwave method. Obtained results reveal that the catalytic activity increases with increase in Mo wt % loading. The best catalytic activity was obtained with 20 wt % MoO3/CeO2ZrO2. The particle size or crystallite size was estimated using Debye-Scherrer equation. After completion of reaction, the catalyst can be recovered efficiently and reused with consistent activity.

The Effect of BaF2 Particle Size for Zirconium Recycling by Precipitation from Waste Acid and Ba2ZrF8 Vacuum Distillation Property (폐 산세 용액으로부터 공침 반응에 의한 지르코늄 회수 시 BaF2 입도 영향 및 Ba2ZrF8의 진공증류 특성)

  • Choi, Jeong Hun;Nersisyan, Hayk;Han, Seul Ki;Kim, Young Min;Park, Cheol-Ho;Kahng, Jong Won;Na, Ki Hyun;Kim, Jeong hun;Lee, Jong Hyeon
    • Resources Recycling
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    • v.26 no.6
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    • pp.29-37
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    • 2017
  • Nuclear fuel cladding tube is fabricated by pilgering and annealing process. In order to remove impurity and oxygen layer on the surface, pickling process is carried out. When Zirconium(Zr) is dissolved and saturated in acid solution during the pickling process, all the waste acid including Zr is disposed. Therefore, BaF2 is added into the waste acid to extract Zr and Ba2ZrF8 is subsequently formed. To recycle Zr by electrowinning process, Ba2ZrF8 is used as electrolyte, but it has high melting point (1053C). ZrF4 should be added into Ba2ZrF8 to decrease the melting point. In this paper, it was investigated that Ba2ZrF8 was separated to BaF2 and ZrF4 by vacuum distillation. Firstly, BaF2 with different particle size (1μm, 35μm, 110μm) was added into the waste acid and the respective precipitation property was estimated. BaF2 obtained by vacuum distillation was shattered by ball-milling with different time. The precipitation efficiency was compared with 1μm of BaF2s one, which was not used as precipitation agent.

Dielectric properties and microstructures of (CaxSr1-x)ZrO3 ceramics

  • Li, Yu-De;Chen, Jian-Ming;Lee, Ying-Chieh
    • Journal of Ceramic Processing Research
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    • v.19 no.6
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    • pp.461-466
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    • 2018
  • The effects of Ca/Sr ratio and the sintering temperature on the properties of (CaxSr(1x))ZrO3 (CSZ) ceramics were investigated in this study. CSZ ceramics were prepared using solid-state reaction process, which were sintered in air at temperatures ranging from 1350C to 1450C. Their structures were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The change in Ca/Sr ratio significantly affected the crystalline phase and the dielectric properties of the (CaxSr(1x))ZrO3 ceramics. The secondary phase, Ca0.15Zr0.85O1.85, was observed and increased correspondingly with the rising of sintering temperatures. In order to understand the effects of secondary phase on the dielectric properties of CSZ ceramics, the Ca0.15Zr0.85O1.85 phase was prepared individually using solidstate method. The Ca0.15Zr0.85O1.85 ceramics sintered at 1500C for 2 hours possessed a dielectric constant (εr) of 21.7, a dielectric loss (tanδ) of 49.5104 and an Insulation Resistance (IR) of 2.1×1010Ω. The (Ca0.7Sr0.3)ZrO3 ceramics exhibited the best dielectric properties, with a permittivity of 29, a dielectric loss (tanδ) of 2.7×104, and an Insulation Resistance (IR) of 2.6×1012Ω.