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High‐Temperature Phase Relations in the System Gd 2 O 3 ‐Ta 2 O 5
Author(s) -
Yokogawa Yoshiyuki,
Ishizawa Nobuo,
Sōmiya Shigeyuki,
Yoshimura Masahiro
Publication year - 1991
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1991.tb08261.x
Subject(s) - orthorhombic crystal system , phase diagram , fluorite , phase (matter) , crystallography , composition (language) , materials science , melting temperature , chemistry , crystal structure , metallurgy , composite material , organic chemistry , linguistics , philosophy
The Phase relations of the system Gd 2 O 3 ‐Ta 2 O 5 in the composition range 50 to100 mol% Gd2O3 was studied by solidstate reactions at 1350°, 1500°, or 1700°C and by thermal analyses up to the melting temperatures. Weberite‐type orthorhombic phase (W2 phase, space group C2221) with the composition of Gd3 TaO7 seems to melt incongruently; at about 2040°C, although this Gd 3 TaO 7 Phase was previously reported to melt congruently. A new fluorite‐type cubic phase (F phase, space group Fm3m ) was found for the first time above 1500°C in the system. It melts congruently with the composition of about 80mol% Gd2O3at 2318° 3°C. A phase diagram was proposed for the system Gd 2 O3–Ta2O 5 in the Gd 2 O 3 –rich portion