49.
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, TiO
2 and ternary metal oxide ZnTiO
3 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 ZnTiO
3 (
a = 8.3948 Å) was obtained on calcination of the precursor at 600°C, and decomposed to the cubic phase Zn
2TiO
4 (
a = 8.4580 Å) and rutile TiO
2 (
a = 4.5955 Å and
c = 2.9593 Å) at 1000°C. The band gap of ZnO (3.28?3.10 eV), TiO
2 (3.37?2.97 eV) and ZnTiO
3 (3.92?3.80 eV) calculated using Tauc’s relation was found to vary inversely with calcination temperature and phase transition.
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