Synthesis Method Influence on the Physicochemical Properties and Phase Composition of Zirconium Dioxide

Hydrated zirconium oxides were obtained using precipitation and solid-phase methods of synthesis. Their physicochemical properties and the phase composition of the products of their heat-treatment were studied by means of XRD, IR, and DSC-TG. It was established that (a) the precipitates of hydrated zirconium oxides obtained by means of solid-phase synthesis have a lower moisture content and better filterability compared to the precipitates obtained by the precipitation method and also that (b) the ammonium carbonate used as the main reagent in the synthesis of zirconium oxide precursors effects a significant reduction in the specific surface area compared with the precipitates obtained using a solution of NH4 OH or gaseous ammonia. It is shown that heat-treatment of all synthesized samples of hydrated zirconium oxides at 450 degrees C effects the formation of a mixture of tetragonal and monoclinic modifications of zirconium dioxide. Raising the heat treatment temperature to 600 degrees C effects a sharp reduction in the content of the tetragonal modification of ZrO2 in the product, and the calcination product obtained at 1150 degrees C contains only m-ZrO2.