Thermoluminescence and electron paramagnetic resonance correlation studies in lithium silicate phosphor

Lithium silicate phosphor, synthesized by the solid-state reaction method, displays three thermoluminescence (TL) peaks at 155 degrees C, 240 degrees C and 430 degrees C. Activation energy, frequency factor and kinetic order associated with the TL peaks have been determined using E-T-STOP and glow curve deconvolution (GCD) methods. Electron Paramagnetic Resonance (EPR) studies have been carried out to identify the defect centers induced in the phosphor by gamma irradiation and also to find the centers responsible for the TL process in the system. The observed EPR spectrum arises from a superposition of three defect centers. One of the centers (center I) with a g-value 2.0097 is identified as the O- ion. Center II with an isotropic g-value 2.0002 is assigned to a F+-type center (singly ionized oxygen vacancy). The F+ center is likely to be associated with the TL peak at 156 degrees C. Center III characterized by a rhombic g-tensor with g(1) = 1.9831, g(2) = 1.9676, and g(3) = 1.9208 is identified as a Ti3+ center. The Ti3+ center relates to the low temperature TL peak at 155 degrees C.

Automated summary

The lithium silicate phosphor synthesized by solid-state reaction method exhibits three thermoluminescence peaks at different temperatures, with associated parameters determined by E-T-STOP and GCD methods. EPR studies were conducted to identify defect centers induced by gamma irradiation and their role in the TL process. The observed EPR spectrum is a combination of three defect centers, each linked to a specific TL peak.