Unusual heating rates, dose responses and kinetic parameters detected on thermoluminescence from YAl3(BO3)4:Sm3+ phosphors

Abstract

This study focused on the thermoluminescence (TL) characteristics of YAl3(BO3)4 (YAB) phosphors modified with various contents of Sm3+ ions. The TL response of the YAB: Sm3+ phosphors exposed to beta irradiation was measured across the temperature range of 25–500 °C, exhibiting three TL maxima at 70, 235, and 408 °C. Preheating protocol was also carried out to remove the low temperature TL peak followed by further experiments with the two-remaining high-temperature peaks. In the TL measurements conducted with variable heating rates (HR) between 0.1 and 5 °Cs-1, an anomalous heating rate behaviour was observed. A semi-localized transition model was used to address this feature. There was a standard deviation of less than 5% in the reusability measurements. The results of the kinetic parameters obtained by initial rise (IR) and various heating rate (VHR) methods were compared with those obtained by glow curve deconvolution (GCD) method. Tm-Tstop analysis revealed a continuous distribution of trap levels with a trap depth ranging from 1.35 to 2.20 eV. Through the use of GCD, the glow curve was found to demonstrate general order kinetics and consist of seven superimposed traps. The values of the kinetic parameters obtained for the glow curve agreed with those obtained by other methods excluding the VHR method encountering an anomalous impact. The results obtained from these tests showed that the sample could be successfully used for TL dosimetry applications.