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Synthesis and Water Adsorption Properties of Perovskite-type Oxides Containing Manganese

Research Project

Project/Area Number 63470062
Research Category

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

Allocation TypeSingle-year Grants
Research Field 無機工業化学
Research InstitutionOkayama University

Principal Investigator

NAGAO Mahiko (1989)  Okayama University, Faculty of Science Professor, 理学部, 教授 (30032816)

田口 秀樹 (1988)  岡山大学, 理学部, 助教授 (20188139)

Project Period (FY) 1988 – 1989
Project Status Completed (Fiscal Year 1989)
Budget Amount *help
¥6,100,000 (Direct Cost: ¥6,100,000)
Fiscal Year 1989: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1988: ¥4,900,000 (Direct Cost: ¥4,900,000)
KeywordsPerovskite / Metal oxide / Electrical property / Solid state reaction / Co-precipitation / Hopping conduction / Adsorption / Sintering / 固相反応法 / 金属ー絶縁体転移 / 磁気的性質 / 半導体
Research Abstract

Perovskite-type (Ln_<1-x>Ca_x)MnO_3 (Ln: La, Nd, Gd) were synthesized at 1300-1350゚C in the flow of pure oxygen gas. X-ray powder diffraction patterns of these manganates were indexed as the perovskite-type structure. At low temperature, manganates are n-type semiconductors and the electrical resistivity follows Mott's T^<-1/4> law, indicating the possible occurrence of variable range hopping of electron due to Anderson localization. Above room temperature, manganates have positive temperature coefficient, and exhibit a metal-insulator transition without any crystallographic change. The magnetic susceptibility measurement suggests that spin state of Mn^<3+> ions change from low to high at the metal-insulator transition temperature. From these results, it is considered that the metal-insulator transition is caused by a change in the spin state of Mn^<3+> ion in (Ln_<1-X> Ca_X)MnO_3.
Fine particle (La^<1-x> Ca_x)MnO_3 was synthesized as follows: one is the decomposition of the precursor a … More nd the other is the solid state reaction by using acetates. The precursor was prepared from the co-precipitation method and its formula was found to be (Ca_<0.5> Mn_<0.5>)CO_3.
Fine particle (La_<1-X> Ca_X)MnO_3 was synthesized as follows: one is the decomposition of the precursor and the other is the solid state reaction by using acetated. The precursor was prepared from the co-precipitation method and its formula was found to be (Ca_<0.5> Mn_<0.5>)CO_3. Firing this precursor at 950゚C, CaMnO_3 was obtained. On the other hand, acetates were weighted and mixed, then fired at 900゚C. The particle size of manganates thus obtained was 0.8-0.9 m, and the specific surface area was 3-5 m^2/g. By using these methods, the synthesis temperature of (La_<1-x> Ca_x)MnO_3 was lowered by 300-400゚C compared with the conventional solid state reaction.
The electrical resistivity of (La_<1-x> Ca_x)MnO_3 under various relative pressure of H_2O vapor was measured. Only the electrical resistivity of CaMnO_3 decreased with increasing vapor pressure of H_2O, and this decrease was assumed to be ascribed to the ionic conductivity of water layer adsorbed on CaMnO_3. Less

Report

(3 results)
  • 1989 Annual Research Report   Final Research Report Summary
  • 1988 Annual Research Report
  • Research Products

    (15 results)

All Other

All Publications (15 results)

  • [Publications] H.Taguchi: "High-Temperature Phase Transition of CaMnO_<3-δ>" Journal of Solid State Chemistry. 78. 312-315 (1989)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] H.Taguchi: "Synthesis of CaMnO_3 from(Ca_<0.5> Mn_<0.5>)CO_3" Journal of Materials Science Letters. 8. 963-964 (1989)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] H.Taguchi: "Metal-Insulator Transition in the System(Gd_<1-x>Ca_x)MnO_<2.98>" Journal of Solid state Chemistry. 82. 8-13 (1989)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] H.Taguchi: "Metal-Insulator Transition in the System(Ca_<1-x>Sr_x)MnO_3" Journal of Solid State Chemistry(投稿予定).

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] H. Taguchi: "High Temperature Phase Transition of CaMnO_<3-delta>" J. Solid State Chem., 78, 312-315 (1989).

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] H. Taguchi: "Synthesis of CaMnO_3 from (Ca_<0.5>Mn_<0.5>)CO_3" J. Mater. Sci. Lett., 8, 963-964 (1989).

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] H. Taguchi: "Metal-Insulator Transition in the System (Gd_<1-X>Ca_X)MnO_<2.98>" J. Solid State Chem., 82, 8-13 (1989).

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] H. Taguchi: "Metal-Insulator Transition in the System (Ca_<1-X>Sr_X)MnO_3 (in preparation)" J. Solid State Chem.

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] H.Taguchi: "High-Temperature Phase Transition of CaMnO_<3-5>" Journal of Solid State Chemistry. 78. 312-315 (1989)

    • Related Report
      1989 Annual Research Report
  • [Publications] H.Taguchi: "Synthesis of CaMnO_3 from(Ca_<0.5>Mn_<0.5>)CO_3" Journal of Materials Science Letters. 8. 963-964 (1989)

    • Related Report
      1989 Annual Research Report
  • [Publications] H.Taguchi: "Metal-Insulator Transition in the System(Gd_<1-x>Ca_x)MnO_<2.98>" Journal of Solid State Chemistry. 82. 8-13 (1989)

    • Related Report
      1989 Annual Research Report
  • [Publications] H.Taguchi: "Metal-Insulator Transition in the System(Ca_<1-x>Sr_x)MnO_3" Journal of Solid State Chemistry.

    • Related Report
      1989 Annual Research Report
  • [Publications] H.Taguchi: Joural of Solid State Chemistry.

    • Related Report
      1988 Annual Research Report
  • [Publications] H.Taguchi: Journal of Materials Science Letter.

    • Related Report
      1988 Annual Research Report
  • [Publications] H.Taguchi: Journal of Solid State Chemistry.

    • Related Report
      1988 Annual Research Report

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Published: 1988-04-01   Modified: 2016-04-21  

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