STRONTIUM AND CALCIUM ZIRCONYL CITRATES AS PRECURSORS FOR THE LOW-TEMPERATURE SYNTHESIS OF SRZRO3 AND CAZRO3 FINE POWDERS

Synthesis and the thermal decomposition behavior of new molecular prec ursors, strontium, and calcium zirconyl citrates are presented. The pa thway to the metazirconate formation has been found to proceed through a multistep process. The precursors yield SrZrO3 and CaZrO3 fine powd ers at temperatures as low as 650 degrees C. Physico-chemical, spectro scopic, thermoanalytical, and microscopic techniques have enabled the identification of the sequence of events leading to the perovskite for mation and proposition of a thermolysis scheme. Retention of the molec ular level mixing of the metal ions during the course of the precursor decomposition is supported by these techniques. Prior to the formatio n of MZrO3 (M = Sr and Ca) an ionic oxycarbonate, M2Zr2O5CO3 (M = SI. and Ca), intermediate is produced by the thermal decomposition of the citrate precursors.