Formation of SrTiO3 from Sr-oxalate and TiO2

Abstract

SrTiO3 powder has been prepared from Sr-oxalate and TiO2 precursors, instead of using titanyl-oxalate. Sr-oxalate was precipitated from nitrate solution onto the surface of suspended TiO2 powders. Crystallization of SrTiO3 from the precursor was investigated by TGA, DTA and XRD analysis. It is evident that precursor, upon heating, dehydrates in two stages, may be due to the presence of two different types of Sr-oxalate hydrates. Dehydrated precursor then decomposes into SrCO3 and TiO2 mixture. Decomposition of SrCO3 and simultaneous SrTiO3 formation occur at much lower temperature, from 800oC onwards, due to the fine particle size of the SrCO3 and presence of acidic TiO2 in the mixture. The precursor completely transforms into SrTiO3 at 1100oC. About 90 nm size SrTiO3 crystallites are produced at 1100oC/1hr, due to the lower calcination temperature and better homogeneity of the precursor.