The Influence of Pre-processing of TiO2. nH2O Gel on SrTiO3 Powders from Hydrothermal Synthesis

The SrTiO3powders were synthesized from TiO2·nH2O gel under moderate hydrothermal condition. TiO2·nH2O gel was prepared by diluting TiCl4with cold distilled water. The influence of pre-processing of TiO2·nH2O gel and anions (Cl-and NO3-) on the properties of SrTiO3 powders was studied in details by X-ray diffraction (XRD), transition electron microscopy (TEM) and Fourier transform infrared spectrometry (FTIR). The results showed that TiO2·nH2O could be crystallized during the washing and thermal processing. The crystallization of TiO2·nH2O had an important influence on the product particle size and particle size distribution. The SrTiO3powders prepared from amorphous TiO2·nH2O are with big particle size and wide particle size distribution, and those from crystallized TiO2·nH2O are with small particle size and narrow particle size distribution. To get nanometer SrTiO3powders, the suitable crystallization of TiO2·nH2O gel is essential. The chloride and nitrate ions can accelerate the formation of large-grained particles of SrTiO3, but such effect is very small. In a word, the main reason for the effect of washing of TiO2·nH2O on properties of SrTiO3powders is the crystallization of TiO2·nH2O gel during the washing, and the washing process can be substituted by thermal processing neglecting the effect of anions.