Anomalous heating rate response of beta irradiated Sm3+ and Tb3+ doped BaAl2O4 phosphors

The stuffed derivative of the tridymite structure, the oxide BaAl2O4 has been regarded as a long persistent phosphor. Thermoluminescence (TL) glow curve peaks of thin pellet samples of undoped and, Sm3+ and Tb3+ doped BaAl2O4 prepared by combustion method was reported. The structure of the compounds was monitored by X-ray diffraction and found a single-phase compound with a hexagonal structure. Performing a series of TL measurements for the temperature range from room temperature to 400 degrees C, the effect of beta radiation dose on TL response, various TL heating rate (HR) properties of undoped and Sm3+ and Tb3+ doped BaAl2O4 phosphors were investigated. Peak shape method was also utilized to assess the trap parameters. The activation energy of the main peak at 128 degrees C was found to be 0.97 eV. TL glow curves obtained from undoped and Tb3+ doped BaAl2O4 decrease with increasing HR value (varying from 0.5 to 15 degrees C s(-1)) in a way matching with thermal quenching effect. Contrary to expectations, anomalous HR dependence was observed on Sm3+ doped BaAl2O4 sample and a semi-localized transition model has been used in order to explain such behaviour. (C) 2018 Elsevier B.V. All rights reserved.