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Control of phase transition of the rare earth oxyfluorides

Research Project

Project/Area Number 20K05077
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 26020:Inorganic materials and properties-related
Research InstitutionOsaka University

Principal Investigator

TAMURA Shinji  大阪大学, 大学院工学研究科, 准教授 (80379122)

Project Period (FY) 2020-04-01 – 2023-03-31
Project Status Completed (Fiscal Year 2022)
Budget Amount *help
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2022: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2021: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2020: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Keywordsフッ化物イオン / 固体電解質 / 希土類 / 相転移
Outline of Research at the Start

本研究では、希土類オキシフッ化物の構造的、熱力学的特徴とイオン伝導性との相関を明らかにすることを目的として、(1)次世代フッ化物イオン伝導型全固体電池材料の候補として期待できるオキシフッ化ランタン(LaOF)について、相転移に関する知見(相転移温度、雰囲気依存性、合成条件依存性、組成依存性など)を得た上で、(2)他の希土類オキシフッ化物に関する構造的特性とそれらのイオン伝導性を解明する。

Outline of Final Research Achievements

In this study, RO1-xF1+2x (R: rare earths) with intentionally varied anion ratios (O / F) in the samples were synthesized in order to clarify structural properties of rare earth oxyfluorides and their ionic conductivity.
Phase transition of LaO1-xF1+2x can be suppressed at compositions of x higher than equal to 0.1. The maximum conductivity was obtained at x = 0.4. The suppression of the phase transition was also achieved by partial substitution of La sites with divalent cations, and the conductivity increased with increasing the amount of partial substitution. For a series of ROFs, it was found that the formation phase differs depending on the type of rare earths, and that the composition at which the phase transition can be suppressed varies, and that relatively high conductivity can be obtained in ROFs with a tetragonal crystal structure.

Academic Significance and Societal Importance of the Research Achievements

本研究で明らかとなった希土類オキシフッ化物の結晶相と相転移、さらには結晶相とフッ化物イオン伝導性との関係に関する知見は、これまで未解明であったオキシフッ化物の物性を理解する上で極めて重要な基礎的知見を与えた。本知見は、上記学術的な意義のみならず、今後開発が活発となるフッ化物イオン電池への有力候補となる金属オキシフッ化物材料の開発にも多いに貢献できる知見となる。

Report

(4 results)
  • 2022 Annual Research Report   Final Research Report ( PDF )
  • 2021 Research-status Report
  • 2020 Research-status Report
  • Research Products

    (2 results)

All 2023 2022

All Journal Article (1 results) (of which Peer Reviewed: 1 results) Presentation (1 results)

  • [Journal Article] Fluoride ion conducting behavior in nonstoichiometric lanthanum oxyfluoride2023

    • Author(s)
      Momai Mizuki、Tamura Shinji、Imanaka Nobuhito
    • Journal Title

      Ceramics International

      Volume: 49 Issue: 1 Pages: 1502-1506

    • DOI

      10.1016/j.ceramint.2022.10.079

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed
  • [Presentation] オキシフッ化ランタンのフッ化物イオン伝導特性2022

    • Author(s)
      百相瑞貴・田村真治・今中信人
    • Organizer
      第48回固体イオニクス討論会
    • Related Report
      2022 Annual Research Report

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Published: 2020-04-28   Modified: 2024-01-30  

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