ZIRCONIA-CERIA-YTTRIA-BASED MIXED OXIDE AND PROCESS FOR PRODUCING THE SAME

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PROBLEM TO BE SOLVED : To provide a zirconia-ceria-yttria-based mixed oxide maintaining a stable crystal structure after 12 hours of heat treatment at 1, 100°C under a reducing atmosphere, and a process for producing the same. SOLUTION : The process comprises the steps of : (1) mixing a zirconium salt, a yttrium salt and an acid to obtain a zirconium-yttrium-containing acidic solution; (2) adding a sulfating agent and an alkali to the zirconium-yttrium-containing acidic solution to obtain a yttrium hydroxide-zirconium salt-sulfating agent-containing slurry; (3) heating the yttrium hydroxide-zirconium salt-sulfating agent-containing slurry to 65°C or higher to obtain a basic zirconium sulfate-yttrium hydroxide-containing mixed slurry; (4) adding a cerium salt, and, as necessary, one or more salts of rare earth elements other than Ce and Y to the basic zirconium sulfate-yttrium hydroxide-containing mixed slurry to obtain a basic zirconium sulfate-yttrium hydroxide-cerium salt-containing mixed slurry; (5) adding an alkali to the basic zirconium sulfate-yttrium hydroxide-cerium salt-containing mixed slurry to obtain a zirconium hydroxide-cerium hydroxide-yttrium hydroxide-containing mixed oxide; and (6) heat-treating the zirconium hydroxide-cerium hydroxide-yttrium hydroxide-containing mixed hydroxide to obtain a zirconium-ceria-yttria-based mixed oxide. COPYRIGHT : (C)2008, JPO&INPIT