Low-Temperature Direct Synthesis of Nanoparticles of Fluorite-Type Ceria–Zirconia Solid Solutions by “Forced Cohydrolysis” at 100°C

Author： Hirano M. Miwa T. Inagaki M.

Publisher： Academic Press

ISSN： 0022-4596

Source： Journal of Solid State Chemistry, Vol.158, Iss.1, 2001-04, pp. : 112-117

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Abstract

Nanometer-sized particles ranging from 2 to 3 nm of CeO₂ (ceria)–ZrO₂ (zirconia) solid solutions with cubic and/or tetragonal fluorite-type structure in the wide composition range from 20 to 100 mol% CeO₂, without a trace of monoclinic ZrO₂ phase, could be directly synthesized at low temperature of 100°C from acidic aqueous solutions of ZrOCl₂ and (NH₄)₂Ce(NO₃)₆ by forced simultaneous hydrolysis, i.e., “forced cohydrolysis.” Analytical values of CeO₂/ZrO₂ ratio in the as-precipitated solid solutions showed fairly good agreement with starting compositions in the solutions. The proceeding of the hydrolysis and formation rate of fluorite-type solid solutions tended to slow down at near median composition. Any change in crystalline phase of as-precipitated solid solutions was not observed by powder X-ray diffractometry after heat treatment in air below 1000°C. Ceria–zirconia solid solutions with fluorite structures containing large amount of ZrO₂ maintained high surface area after heat treatment at 1000°C.