The phase relations for the Sc2O3-Ta2O5 system in the composition range of 50-100 mol% Sc2O3 have been studied by using solid-state reactions at 1350°, 1500°, or 1700°C and by using thermal analyses up to the melting temperatures. The Sc5.5Ta1.5O12 phase, defect-fluorite-type cubic phase (F-phase, space group Fm3m), ScTaO4, and Sc2O3 were found in the system. The Sc5.5Ta1.5O12 phase formed in 78 mol% Sc2O3 at <1700°C and seemed to melt incongruently. The F-phase formed in approx. 75 mol% Sc2O3 and decomposed to Sc5.5Ta1.5O12 and ScTaO4 at <1700°C. The F-phase melted congruently at 2344° ± 2°C in 80 mol% Sc2O3. The eutectic point seemed to exist at approx. 2300°C in 90 mol% Sc2O3. A phase diagram that includes the four above-described phases has been proposed, instead of the previous diagram in which those phases were not identified.
|Number of pages||4|
|Journal||Journal of the American Ceramic Society|
|Publication status||Published - 1999 Jan 1|
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Materials Chemistry