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The Measurements of High Temperature Thermochemical Properties of Rare Earth Manganites with Electrical Conductivity

Research Project

Project/Area Number 62550486
Research Category

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

Allocation TypeSingle-year Grants
Research Field 金属精錬・金属化学
Research InstitutionTOYOHASHI UNIVERSITY OF TECHNOLOGY

Principal Investigator

OHGUSHI Tatsuo  Toyohashi University of Technology, Lecturer, 工学部, 講師 (70126928)

Co-Investigator(Kenkyū-buntansha) KAMEGASHIRA Naoki  Toyohashi University of Technology, Professor, 工学部, 教授 (20023153)
高石 哲男  豊橋技術科学大学, 第5工学系, 教授 (30062425)
Project Period (FY) 1987 – 1988
Project Status Completed (Fiscal Year 1988)
Budget Amount *help
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1988: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1987: ¥1,200,000 (Direct Cost: ¥1,200,000)
Keywordsrare earth manganite / high temperature thermochemical properties / nonstoichiometry / electrical conductivity / 酸素分圧 / 熱力学量
Research Abstract

The aim of this project is to obtain the high temperature thermochemical properties of rare earth manganites. We could obtain these quantities from the measurements of isothermal electrical conductivity and thermogravimetric analysis as a function of oxygen partial pressure. When these manganite phases is annealed under low oxygen partial pressure at high temperature, they decompose into rare earth sesqui oxides and manganese monoxide. Both results from thermogravimetric analysis and electrical conductivity measurements were in good agreement for the temperature and oxygen partial pressure at the decomposition. Therefore the chemical potential diagram for the equilibria between rare earth manganites and the decomposed oxides could be obtained in satisfactory precision. By using these results at several temperatures (900 - 1200 C of temperature and 1 - 10^<-22> atm of oxygen partial pressures), the free energies, enthalpy and entropy changes for LnMnO_3 phases could be obtained from the second law treatment of thermodynamics.
Also heat capacities of several manganites at high temperatures and enthalpy changes of phase transitions of some of these manganites and another type of rare earth manganites with higher structure, e.g. BaLn_2Mn_2O_7, were measured by DSC method. After these measurements are accomplished with a satisfactory precision, the thermochemical properties of these rare earth manganites are to be obtained with more precise from by using the third law treatment of thermodynamics.

Report

(3 results)
  • 1988 Annual Research Report   Final Research Report Summary
  • 1987 Annual Research Report

Research Products

(3 results)

All Other

All Publications (3 results)

  • [Publications] N.Kamegashira,;S.Umeno,;H.Satoh,;M.Horikawa.: Materials Chemistry and Physics. (1989)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] N. Kamegashira; S. Umeno; H. Satoh; M. Horikawa: "Further Study on the Phase Transition of BaTb_2Mn_2O_7" Materials Chemistry and Physics. (1989)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] N.Kamegashira;S.Umeno;H.Satoh;M.Horikawa: Materials Chemistry and Physics. to be. (1989)

    • Related Report
      1988 Annual Research Report

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Published: 1987-03-31   Modified: 2016-04-21  

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