Radiation Induced Color Centers in Cr-Doped LiF Phosphor

摘要

The formation of several stable color centers (CCs) at room temperature have been found and investigated in Cr-doped LiF powder phosphors, irradiated in the selective gamma rays doses in the range (0.1-50 kGy). The field emission electron scanning microscope (FE-SEM) results confirms cubical surface morphology; get ruptured either on doping or at high dose irradiation or both. The incorporation of Cr in LiF lattice confirms from the electron dispersive spectroscopy (EDS) spectrum. In non-irradiated Cr-doped LiF lattice, several complex aggregate defects formed at room temperature. However, in gamma irradiated phosphors, F-color centers or F-absorption band at 250 nm and F_2 and F_3~+ color centers at 445 nm i.e., M absorption band are prominent. Among all samples, LiF: Cr (0.02 mol.%) shows maximum concentration of these CCs. On excitation with 325 nm laser sources, the photoluminescence (PL) emission spectrum of optimized phosphor shows broad emission at around 594 nm.