Thermal Stability of Photostimulated Luminescence Centers in BaFBr and BaFBr:Eu^<2+> Single Crystals

概要

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The thermal stabilities and mutual conversion processes of photostimulated luminescence (PSL) centers in BaFBr and BaFBr:Eu^<2+> crystals have been studied by measuring the changes of PSL spectra with a pulse-annealing technique after exposure to X-rays at 20 K. The O^<2-> PSL band in BaFBr was found to exhibit two thermal stages, i.e., enhancement during pulse annealing at temperatures around 116 K and decrement after annealing at temperatures above 200 K. On the other hand, the Eu^<2+> PSL band in BaFBr:Eu^<2+> remains constant after the enhancement during pulse annealing at around 116 K. These facts are well explained by that O^--F(Br^-) pair defects and Eu^<3+> centers are responsible for O^<2-> and Eu^<2+> PSL processes at 20 K, respectively. In addition to this, the decrement of the Eu^<2+> emission yield after X-ray irradiation at RT indicates that Eu^<3+> centers converted from Eu^<2+> ions by capturing holes are responsible for the PSL process operating at RT in BaFBr:Eu^<2+>.
社団法人応用物理学会の論文
1999-12-15