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1986 Fiscal Year Final Research Report Summary

Studies on the Composition-Structure-Property Relations in Ceramic Grain-Boundaries

Research Project

Project/Area Number 60550543
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 無機工業化学
Research InstitutionThe University of Tokyo

Principal Investigator

KOUMOTO Kunihito  Faculty of Engineering, The University of Tokyo, 工学部, 講師 (30133094)

Co-Investigator(Kenkyū-buntansha) FUJITSU Satoru  Faculty of Engineering, The University of Tokyo, 工学部・工業化学科, 助手 (20165400)
MIYAYAMA Masaru  Faculty of Engineering, The University of Tokyo, 工学部・工業化学科, 助手 (20134497)
Project Period (FY) 1985 – 1986
KeywordsGrain Boundary / Ceramics / Humidity-Sensing / Electrical breakdown / Diffusion / I-V Characteristics / バリスタ
Research Abstract

TEM observations of the grain boundary areas were made on semiconductng <BaTiO_3> Thick film. The 180 domains across the grain boundary could not be ovserved the possibility of the existence of 90 domains was suggested. Exsolution method was applied to the NiO-ZnO ceramics to control the microstructure in which the grain-boundary regions were rich in ZnO and the grains were NiO rich phase, as detected by XMA. The change in V-I characteristics with the change in relative humidity was measured at 25゜c. <Ni_(0.2)Zn_(0.8)O> sintered at 1300゜c and further annealed at 800゜c for 336h was found to be the most sensitive to humidity. The electrical breakdown strength of single crystal MgO at 1000-1400゜c decreased with increase in the dislocation density and that of polycrystalline MgO indicated a significant effect of the grain boundaries. A high correlation between the ionic conductivity and the breakdown strength was found, which together with the observed melted track suggested that the electrolytic decomposition took place. The varistor properties were examined for porous ZnO containing no dopants such as <Bi_2O_3> or <Pr_6O_(11)> . Comparison of I-V curves for the oxidized and unoxidized samples indicated that oxygen, which had chemisorbed and diffused into the grain boundary, played a role in giving rise to varistor characteristics.

  • Research Products

    (8 results)

All Other

All Publications (8 results)

  • [Publications] 河本邦仁: Japanese Journal of Applied Physics. 23. L305-L307 (1984)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 村田弘: Journal of Materials Science. 20. 4507-4513 (1985)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 崔勝哲: 日本化学会誌. 6. 1192-1193 (1985)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 藤津悟: Journal of the American Ceramic Society. (1987)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kunihito Koumoto: "TEM Observations of the Grain Boundaries in a Semiconducting Barium Titanate Thick Film" Japanese Journal of Allpied Physics. 23. L305-L307 (1984)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Hiroshi Murata: "High-Temperature Electrical Breakdown in Single Crystal and polycrystalline MgO" Journal of Materials Science. 20. 4507-4513 (1985)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Seung Chul Choi: "Humidity-Sensing Characteristics of the Grain-Boundary-Controlled NiO-ZnO Ceramics" Nippon Kagaku Kaishi. 6. 1192-1193 (1985)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Satoru Fujitsu: "Origin of ZnO Varistor" Journal of the American Ceramic Society. (1978)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1988-11-09  

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