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.
|Number of pages||7|
|Journal||Journal of the American Ceramic Society|
|Publication status||Published - 1998 Apr 1|
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Materials Chemistry