A comparative investigation of Ce³⁺/Dy³⁺ and Eu²⁺ doped LiAlO₂ phosphors for high dose radiation dosimetry: Explanation of defect recombination mechanism using PL, TL and EPR study

This study describes a comparative analysis of γ-ray irradiated thermoluminescence properties of Ce³⁺/Dy³⁺ and Eu²⁺ doped LiAlO₂ phosphor. LiAlO₂: Ce³⁺/Dy³⁺/Eu²⁺ phosphors were synthesized by solution combustion method. The as synthesized phosphors were characterized by X-ray diffraction (XRD) and Scanning electron microscopy (SEM) for structural and morphological study. Rietveld Refinement of XRD patterns were executed by using Fullprof suit software program. Thermoluminescence characteristics of these phosphors show a linear dose response for a wide range of gamma radiation, especially Eu²⁺ doped LiAlO₂ phosphor. The presence of large number of lithium vacancies in LiAlO₂ phosphor was supposed to be responsible for TL characteristics. Electron paramagnetic resonance (EPR) study of un-doped and Ce³⁺/Dy³⁺/Eu²⁺ doped LiAlO₂ phosphor was carried out to confirm the presence of Eu²⁺ ion and cation, anion vacancies in the host lattice. The responsible defect recombination mechanism for observed TL peak in LiAlO₂ was developed on the basis of TL and EPR study of irradiated and un-irradiated samples. TL kinetics was studied through glow curve deconvolution, Chen's peak shape method and initial rise method. A good match of kinetic parameters was observed between Chen's peak shape method and IR method. The present phosphors may find application in the dosimetry of high dose ionizing radiation.