Coprecipitation and hydrothermal synthesis of ultrafine 5.5 mol% CeO2-2 mol% YO1.5-ZrO2 powders

Ultrafine 5.5 mol% CeO2-2 mol% YO1.5-ZrO2 powders with controllable crystallite size were synthesized by two kinds of coprecipitation methods and subsequent crystallization treatment. The amorphous gel produced by ammonia coprecipitation and hydrothermal treatment at 200 degrees C for 3.5 h results in an ultrafine powder with a surface area of 206 m(2)/g and a crystallite size of 4.8 nm. The powder produced by urea hydrolysis and calcination exhibits a purely tetragonal phase. In addition, the powders crystallized by hydrothermal treatment exhibit high packing density and can be sintered at lower temperature (<1400 degrees C) with nearly 100% tetragonal phase achieved.