Experimental Phase Diagram Determination and Thermodynamic Assessment of the CeO2‐Gd2O3‐CoO System |
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| Authors: | Toni Ivas Erwin Povoden‐Karadeniz Nicholas Grundy Eva Jud‐Sierra Jurgen Grässlin Ludwig J Gauckler |
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| Affiliation: | 1. Department of Materials, ETH, , Zurich, Switzerland;2. Institut für Werkstoffwissenschaft und Werkstofftechnologie Christian Doppler Laboratory for Early Stages of Precipitation, TU Wien, , Wien, Austria;3. Concast AG, , Zurich, Switzerland;4. Materials Science and Engineering, Drexel University, , Philadelphia, Pennsylvania |
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| Abstract: | New phase diagram data and a thermodynamic assessment of the CeO‐Gd2O3‐CoO system using the CALPHAD approach are presented. This information is needed to understand the surprisingly low sintering temperature (950°C–1050°C) of CeO2‐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 Ce1?x?yGdxCoyO2?x/2?y (fluorite) is 2.7 mol% and is less than 1 mol% in the Gd2?xCexO3+x/2 (bixbyite). The Ce solubility in the perovskite GdCoO3?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 Gd2O3‐CoO system at 60 ± 2 mol% Co and 1348 ± 1°C. |
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