Occurrence of excess titania in strontium titanate prepared by the oxalate precipitation route

Abstract

Strontium titanyl oxalate has been prepared by allowing a mixed solution of TiCl 4 and SrCl 2 to react with an aqueous solution of oxalic acid under different experimental conditions. Coprecipitation of hydrous TiO 2 with strontium titanyl oxalate is observed at room temperature due to hydrolysis of Ti(OH) 2 2+ species. Calcination of the dried precipitate results in excess TiO 2 as a second phase in SrTiO 3. However, the hydrolysis of Ti(OH) 2 2+ can be nearly eliminated by either increasing the precipitation temperature or adding excess oxalic acid at room temperature, and thereby forming an additionally quantity of Ti()OH) 2C 2O 4 complex which has less tendency to hydrolyse.