High-temperature phase relations in the Sc2O3-Ta2O5 system

Yoshiyuki Yokogawa, Masahiro Yoshimura

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)1585-1588
Number of pages4
JournalJournal of the American Ceramic Society
Issue number6
Publication statusPublished - 1999

All Science Journal Classification (ASJC) codes

  • Ceramics and Composites
  • Materials Chemistry


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