Phase formation of zinc titanate precursor prepared by a hydrothermal route at pH 5

The phase formation and microstructure of zinc titanate precursors prepared at pH 5 by hydrothermal routes using TiCl₄ and Zn(NO ₃)₂·6H₂O as the initial materials were studied. When the zinc titanate precursors were calcined at 773 K for 1 h, only the single phase anatase TiO₂ was obtained. The Zn₂Ti ₃O₈ phase first appeared at 873 K and decomposition started at 1073 K. After calcination at 1073 K for 1 h, only the Zn ₂TiO₄ and rutile TiO₂ appeared. The crystalline size of Zn₂Ti₃O₈ increased from 11.9 nm to 38.6 nm with increasing the calcination temperature from 873 K to 1173 K. The crystalline size of anatase TiO₂ also increased from 15.3 nm to 50.8 nm when the calcination temperature increased from 773 K to 1173 K. However, the crystalline size of rutile TiO₂ stayed at about 57.5 nm for calcination temperature between 1173 K and 1273 K.