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Experimental Phase Diagram Determination and Thermodynamic Assessment of the CeO 2 ‐ Gd 2 O 3 ‐ CoO System
Author(s) -
Ivas Toni,
PovodenKaradeniz Erwin,
Grundy Nicholas,
JudSierra Eva,
Grässlin Jurgen,
Gauckler Ludwig J.
Publication year - 2013
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/jace.12004
Subject(s) - eutectic system , bixbyite , phase diagram , solubility , calphad , materials science , ternary numeral system , ternary operation , perovskite (structure) , ternary compound , phase (matter) , oxide , analytical chemistry (journal) , thermodynamics , crystallography , chemistry , inorganic chemistry , metallurgy , microstructure , physics , organic chemistry , chromatography , computer science , programming language
New phase diagram data and a thermodynamic assessment of the CeO ‐ Gd 2 O 3 ‐ CoO system using the CALPHAD approach are presented. This information is needed to understand the surprisingly low sintering temperature (950°C–1050°C) of CeO 2 ‐based materials doped with small amounts of transition metal oxide (e.g., CoO ). Experimental phase equilibria between 1100°C and 1300°C are reported based on the analysis of annealed and molten samples. No isolated compound exists in the ternary. At 1300°C the Co solubility in the ternary compounds Ce 1− x − y Gd x Co y O 2− x /2− y (fluorite) is 2.7 mol% and is less than 1 mol% in the Gd 2− x Ce x O 3+ x /2 (bixbyite). The Ce solubility in the perovskite GdCoO 3−δ was found to be 1 mol%. The lowest temperature eutectic melt in the ternary has a composition of 57.2 mol% Co and 41.1 mol% Gd melting at an onset temperature of 1303 ± 5°C, which is close to the binary eutectic in the Gd 2 O 3 ‐ CoO system at 60 ± 2 mol% Co and 1348 ± 1°C.