High-Temperature Phase Relations in the System Y2O3-Ta2O5 |
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Authors: | Yoshiyuki Yokogawa Masahiro Yoshimura |
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Affiliation: | Research Laboratory of Engineering Materials, Tokyo Institute of Technology, Yokohama 227, Japan |
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Abstract: | The phase relations for the system y2o3–Ta2o5 in the composition range 50 to 100 mol% Y2O3 have been studied by solid-state reactions at 1350°, 1500°, or 17000C and by thermal analyses up to the melting temperatures. Weberite-type orthorhombic phases (W2 phase, space group C2221), fluorite-type cubic phases (F phase, space group Fm3m )and another orthorhombic phase (O phase, space group Cmmm )are found in the system. The W2 phase forms in 75 mol% Y2O3 under 17000C and O phase in 70 mol% Y2O3 up to 1700°C These phases seem to melt incongruently. The F phase forms in about 80 mol% Y2O3 and melts congruently at 2454° 3°C. Two eutectic points seem to exist at about 2220°C 90 mol% Y2O3, and at about 1990°C, 62 mol% Y2O3. A Phase diagram including the above three phases were not identified with each other. |
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Keywords: | phases yttria tantalum oxide systems thermal analysis |
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