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

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 degrees 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.