LONG LUMINESCENT GLASS - TB3-ACTIVATED ZNO-B2O-SIO2 GLASS()

It has been found that zinc borosilicate glasses 60ZnO-20B(2)O(3)-20Si O(2) doped with 0.2 mol% Tb2O3 exhibit phosphorescence after exciting with 254 nm light. This phosphorescence arises from f-f transitions of Tb3+ ions and is observable by the eye, in the dark for up to 1 h aft er stopping the UV-illumination. Electron spin resonance (ESR) measure ments show that electron trapping centers, associated with Zn ions, ar e formed by the UV irradiation and the phosphorescent centers decay af ter the irradiation was stopped. We suggest that this UV induced cente r is the photoinduced electron trap, which serves effectively as an el ectron donor, in the dark. (C) 1998 Elsevier Science B.V. All rights r eserved.