Freeze-drying synthesis and characterisation of Na composites of ZnO, TiO2 and ZnTiO3 semiconductor oxides

摘要

The freeze-drying method of metal oxides synthesis has a number of advantages such as high homogeneity, varying porous structures, morphologies and uniform particle size distribution, etc. Because of these advantages, the binary metal oxides ZnO, TiO2 and ternary metal oxide ZnTiO3 were synthesised by the freeze-drying method. The synthesised materials were characterised by X-ray diffraction (XRD), Fourier transform-infra red spectroscopy (FT-IR), UV-VIS spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). The as-synthesised metal oxides were calcined at different temperatures to study the phase evolution and morphological changes. The crystalline cubic-phase ZnTiO3 (a = 8.3948 angstrom) was obtained on calcination of the precursor at 600 degrees C, and decomposed to the cubic phase Zn2TiO4 (a = 8.4580 angstrom) and rutile TiO2 (a = 4.5955 angstrom and c = 2.9593 angstrom) at 1000 degrees C. The band gap of ZnO (3.28-3.10 eV), TiO2 (3.37-2.97 eV) and ZnTiO3 (3.92-3.80 eV) calculated using Tauc's relation was found to vary inversely with calcination temperature and phase transition. (C) 2015 Institute of Chemistry, Slovak Academy of Sciences