Studies on X-ray and thermally stimulated luminescence properties of Li (Gd,Tb)F4 crystals grown by Bridgman method

초록

The crystallization process of LiGdF4 and LiTbF4 was done using the Bridgman-Stockbarger technique. The phase purity of the synthesized compound was monitored through the powder X-ray diffraction pattern technique. The Rietveld refinement process was done using Fullprof software and found the samples crystallize in a Tetragonal crystal system with the space group of I41/a. The Energy Dispersive Spectroscopy (EDS) spectral analysis was carried out to confirm the presented elements. The LiTbF4 sample exhibits strong host emission of Tb3+ bands in the wavelength range from 480 to 640 nm with a peak maximum at 545 nm (5D4 -> 7F5), under the X-ray excitation. Similarly, the LiGdF4 sample exhibits a very strong host emission of Gd3+ ion peak at 311 nm, which is corresponds to the transition of 6P7/2 excited state to the 8S7/2 ground state. The effective atomic number (Zeff) of LiGdF4 and LiTbF4 was estimated. The thermoluminescence (TL) glow peaks were recorded for the X-ray irradiated samples. Both samples produce a similar glow curve structure, which is complex, and it confirms the presence of several trap centers. TL kinetic parameters, such as activation energy (E, eV) and frequency factor (S, s-1) of the TL peak were calculated using standard methods such as deconvolution and initial rise methods. The calculated kinetic parameters by two different methods were compared and found to be in good agreement.

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