Electron paramagnetic resonance, photo-acoustic spectroscopy and thermally stimulated luminescence for identification of thermally stimulated processes in gamma-irradiated LaBa2F7

Thermally stimulated luminescence (TSL), electron paramagnetic resonance (EPR) and photo-acoustic spectroscopy (PAS) techniques were used to investigate the radiation induced centers in polycrystalline LaBa2F7 containing trace amounts of other rare-earths particularly Gd3+ and Sm3+. The TSL glow curve of LaBa2F7 after g-irradiation to a dose of 3 kGy had shown a weak TSL glow peak at 390 K and a much stronger one at 495 K. The EPR spectra of the g-irradiated LaBa2F7 samples showed the presence of O- and O2- ions. Temperature dependence study of the EPR spectra showed that the thermal destruction of O- ion occurs in the 460-490 K temperature range. In g-irradiated samples, O- and F-centers were identified by PAS. The correlation of EPR and PAS results indicate that the prominent TSL glow at 495 K is associated with the thermal destruction of O- radical ion. The trap parameters viz. trap depth and frequency factor have been determined from TSL data.