Anomalous luminescent properties in ZnO and SrAl2O4 composites

作者：Singh V P^*; Mohanty P; Lochab S P; Rath Chandana

来源：RSC Advances, 2014, 4(69): 36765-36770.

DOI：10.1039/c4ra05730a

We have reported previously in a ZnO-SrAl2O4 composite synthesized through a solution combustion route that by dispersing 20 wt% of ZnO in the SrAl2O4 matrix and calcining at 700 degrees C, a stable hexagonal phase of SrAl2O4 at RT is established which is generally a high temperature phase of SrAl2O4 reported in the literature [Singh et al. 2014 Dalton Transactions]. By increasing the calcination temperature of the composite to 1200 degrees C, the hexagonal phase transforms into a stable, monoclinic phase of SrAl2O4. In addition, we have observed anomalous luminescent properties in these composites. In photoluminescence spectra, we observe near band edge emission and defect band emission (DBE) corresponding to ZnO without any signature of emission corresponding to SrAl2O4 in both the composites. The DBE peak is found to be stronger in the monoclinic phase than that observed in the hexagonal phase of SrAl2O4, indicating more defects in the former composite. Combining the excitation and emission properties, we propose a tentative model to illustrate the mechanism of excitation and emission processes involved in the composites. Thermoluminescence studies show a common glow peak at similar to 323 degrees C in both composites and an additional glow peak at similar to 158 degrees C in the composite with the monoclinic phase. An additional glow peak further confirms more defects in the monoclinic phase than in the hexagonal phase corroborating with PL and XRD results. With increasing g-irradiation dose, the additional glow peak shows a linear dosimetric response. The composite with the monoclinic phase seems to be suitable for dosimetric application which will be confirmed after doing more measurements in future.

• 出版日期2014