Determination of thermoluminescence kinetic parameters of thulium doped lithium calcium borate

Abstract

For the first time kinetic parameters of thulium doped Lithium calcium borate (LCB) Thermoluminescence (TL) material are reported here. Irradiated LCB:Tm 3+ powder has revealed two intense TL glow peaks one at 510 (peak 1) and the other at 660 K (peak 2). Activation energy ( E ), frequency factor ( s ) and order of kinetics ( b ) of these peaks were determined by various heating rate (VHR), initial rise (IR), and peak shape (PS) methods. The trap depth and frequency factor determined for peaks 1 and 2 of LCB:Tm phosphor using VHR and IR methods are in good agreement. The average activation energy of peaks 1 and 2 obtained by these methods is 1.62 and 1.91 eV respectively. The frequency factors of peaks 1 and 2 are in the range of 10 13–16 and 10 12–14 sec −1 respectively. The E and s values estimated using the glow peak shape dependent parameters are relatively less compared to the values obtained from other methods. The large difference in these values is due to the complex nature of the glow curves. The order of the kinetics process for complex glow curve peaks could not be assigned on the basis of shape parameters alone but T m response on absorbed dose is to be considered for final confirmation. Glow peaks 1 and 2 of LCB:Tm 3+ obey first and general order kinetics respectively. ► Trap depth and frequency factor are determined for the peaks at 510 and 660 K of LCB:Tm. ► Parameters obtained by various heating rate and initial rise methods are in good agreement. ► Trap depth of peak 1 and peak 2 is 1.61 eV and 1.91 eV respectively. ► T m response to absorbed dose is used to distinguish a first order or non-first order kinetics.