ISSN print edition: 0366-6352
ISSN electronic edition: 1336-9075
Registr. No.: MK SR 9/7
Freeze-drying synthesis and characterisation of Na composites of ZnO, TiO2 and ZnTiO3 semiconductor oxides
Budigi Lokesh, Nasina Madhusudhana Rao, Shaik Kaleemulla, and Amaravadi Sivakumar
Shaik Kaleemulla, bAmaravadi Sivakumar aThin Films Laboratory, Materials Physics Division School of Advanced Sciences VIT University, Vellore – 632 014, Tamil Nadu, India
Abstract: 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 Å) was obtained on calcination of the precursor at 600°C, and decomposed to the cubic phase Zn2TiO4 (a = 8.4580 Å and rutile TiO2 (a = 4.5955 Å and c = 2.9593 Å) at 1000°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.
Keywords: zinc titanates – freeze-drying – phase transformation – diffuse reflectance spectroscopy – optical bandgap
Full paper is available at www.springerlink.com.
Chemical Papers 69 (11) 1481–1490 (2015)