Phase evolution in preparing ZnSnO₃ powders by precipitation method

Previous studies on the preparation of ZnSnO₃ under normal pressure and non-epitaxy conditions are ambiguous and contradictory. Therefore, the phase evolution in preparing ZnSnO₃ powder with different calcination temperatures was systematically studied by precipitation method under normal pressure in the present work. The phase of the samples was characterized by XRD and Raman spectroscopy. Due to lacking the reliable Raman data of ZnSnO₃ in previous literatures, the Raman spectra of ZnSnO₃ with LiNbO₃-type structure and ilmenite-type structure were simulated by first principle based on CASTEP module of Materials Studio. Moreover, the TG-DSC analysis was carried out for the as-dried precursor powder to further clarify the phase evolution. The results indicated that the phase of the as-dried precursor powder was ZnSn(OH)₆ with cubic structure and a series of decomposition reactions occurred with increasing calcination temperature. Wherein, ZnSn(OH)₆ began to decompose into ZnSnO₃ at about 170 °C, and then ZnSnO₃ began to decompose into Zn₂SnO₄ and SnO₂ at about 320 °C. Namely, the thermal stability temperature of ZnSnO₃ should be lower than 320 °C under normal pressure. Furthermore, the beginning crystallization temperature for the decomposition-achieved Zn₂SnO₄ and SnO₂ was about 670 °C. In addition, the morphologies of all the samples were detected by SEM, and mainly determined by the crystal structures of the phases in the samples.