Photoluminescence and thermoluminescence properties of ZnGa2O4 prepared by a microwave assisted solid state reaction

Abstract

A novel microwave assisted solid state chemical reaction was used to synthesize ZnGa2O4, from stoichiometric amounts of ZnO and Ga2O3 that were calcined at 1100 °C for 8 h under the assistance of 1200 W microwave power. The formation of a single phase was confirmed by X-ray diffractometry (XRD). The optical properties were probed using UV–Vis–NIR absorption, photoluminescence (PL) and Thermoluminescence (TL) spectroscopic techniques. The energy band gap of the compound was approximated to 4.68 eV from diffuse reflectance spectrum using the Kubelka-Munk model. The displayed greenish emission was centred at 528 nm, and the thermoluminescence measurements proved that the electron trapping and de-trapping mechanisms followed second-order kinetics. The variable heating rate (VHR) and initial rise (IR) methods were used to determine the depth of the electron trapping centres.