Phase diagram and oxygen-ion conductivity in the Y 2O 3-Nb 2O 5 system

Jin Ho Lee, Masatomo Yashima, Masato Kakihana, Masahiro Yoshimura

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21 Citations (Scopus)

Abstract

The phase equilibria in the Y 2O 3-Nb 2O 5 system have been studied at temperatures of 1500° and 1700°C in the compositional region of 0-50 mol % Nb 2O 5. The solubility limits of the C-type Y 2O 3 cubic phase and the YNbO 4 monoclinic phase are 2.5 (±1.0) mol% Nb 2O 5 and 0.2 (±0.4) mol% Y 2O 3, respectively, at 1700°C. The fluorite (F) single phase exists in the region of 20.1-27.7 mol% Nb 2O 5 at 1700°C, and in the region of 21.1-27.0 mol% Nb 2O 5 at 1500°C, respectively. Conductivity of the Y 2O 3-x mol% Nb 2O 5 system increases as the value of x increases, to a maximum at x = 20 in the compositional region of 0 ≤ x ≤ 20, as a result of the increase in the fraction of F phase. In the F single-phase region, the conductivity decreases in the region of 20-25 mol% Nb 2O 5, because of the decrease in the content of oxygen vacancies, whereas the conductivity at x = 27 is larger than that at x = 25. The conductivity decreases as the value of x increases in the region of 27.5 ≤ x ≤ 50, because of the decrease in the fraction of F. The 20 mol% Nb 2O 5 sample exhibits the highest conductivity and a very wide range of ionic domain, at least up to log p o2 = -20 (where p o2 is given in units of atm), which indicates practical usefulness as an ionic conductor.

Original languageEnglish
Pages (from-to)894-900
Number of pages7
JournalJournal of the American Ceramic Society
Volume81
Issue number4
Publication statusPublished - 1998 Apr 1

All Science Journal Classification (ASJC) codes

  • Ceramics and Composites
  • Materials Chemistry

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