Abstract

The optical band-gap energy (E_g) is an important feature of semiconductors which determines their applications in optoelectronics.  So, it is necessary to investigate the electronic states of ceramic ZnO and effect of doped impurities at different processing conditions.  E_g of the ceramic ZnO + xBi₂O₃ + xTiO₂ where x = 0.5 mol%, was determined using UV-Vis spectrophotometer. The samples was prepared using solid-state route and sintered at the sintering temperatures from 1140 to 1260°C for 45 min in open air.  E_g was decreased with increase of sintering temperature. XRD analysis indicates that there is hexagonal ZnO and few small peaks of inter granular layers of secondary phases, namely, Bi₄Ti₃O₁₂ and Zn₂Ti₃O₈. The relative density of the sintered ceramics decreased and the average grain size increased with the increase of sintering temperature.  The variation of sintering temperatures and XRD findings are correlated with the UV-Vis spectrophotometer results of ZnO doped with 0.5 mol% of Bi₂O₃ and TiO₂ due to the formation of interface states at all sintering temperatures.

Key words: Optical band-gap, ZnO, Bi₂O₃, TiO₂.