Persistent phosphorescence and photo-stimulated luminescence were observed in reduced calcium aluminate glasses which were activated with Tb3+ ions. The phosphorescence from Tb3+ was observed by illuminating the Tb3+ 4f → 5d charge-transfer band with ultra-violet 254nm light. The photo-stimulated luminescence was observed upon stimulating the ultraviolet-illuminated glass with 633nm light. An electron paramagnetic resonance signal, which was attributed to an F+-like center, associated with ions, was induced by illumination with ultra-violet light, and its intensity decay obeyed first-order kinetics. The appearance of the photo-stimulated luminescence under illumination was accompanied by a distinct intensity reduction of the electron paramagnetic resonance signal, due to the F+-like center. The thermoluminescence spectra of specimens which were illuminated with ultra-violet light at 77K consisted of 2 components which peaked at about 240 and 390K. The low-temperature and high-temperature components were attributed to an F-like center and to an F+-like center, respectively. The results led to the conclusion that electrons of the F-like center and the F+-like center made the main contribution to the occurrence of persistent phosphorescence and photo-stimulated luminescence, respectively.

Long-Lasting Phosphorescence and Photostimulated Luminescence in Tb Ion-Activated Reduced Calcium Aluminate Glasses. T.Kinoshita, M.Yamazaki, H.Kawazoe, H.Hosono: Journal of Applied Physics, 1999, 86[7], 3729-33