Long lasting phosphorescence (LLP) and photostimulated luminescence (PSL) were found in reduced calcium aluminate glasses activated with Tb3+ ions. The LLP from Tb3+ was observed by illuminating the Tb3+ 4f→5d charge transfer band with ultraviolet (UV) 254 nm light, while the PSL was seen by stimulating the UV-illuminated glasses with 633 nm light. The decay curve of the LLP was fitted with a second-order kinetic for the initial period (0<t<20 min) and a first-order kinetic for the later (t>30 min). An electron paramagnetic resonance (EPR) signal, which is attributed to an F+-like center associated with Ca2+ ions, was induced by illumination with UV light and its intensity decay was fitted with a first-order kinetic similarly to the later stage of the LLP. The appearance of the PSL by illumination is accompanied by a distinct intensity reduction of the EPR signal due to the F+-like center. The thermoluminescence spectra of the specimen illuminated with UV light at 77 K consist of two components peaking at ∼240 and ∼390 K. The low temperature component and the high temperature component were attributed to an F-like center and an F+-like center, respectively. These results lead to a conclusion that electrons of the F-like center and the F+-like center contribute predominantly to the emergence of the LLP and the PSL, respectively.

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A long lasting green phosphorescence was found in -doped calcium aluminate glasses prepared under a strongly reducing atmosphere. An electron-trapped centre giving an EPR signal at g = 1.999, an analogue of the centre in CaO, was induced by illumination with ultraviolet (uv) radiation and decayed slowly after the illumination was stopped. A partial oxidation of ions to ions by uv illumination was observed. A mechanism of the long lasting phosphorescence was suggested to consist of recombination of an electron released thermally from the -like centre with the photo-oxidized .

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