Long-lasting luminescence properties of ZnO-B2O3:Tb3+

Tb3+ activated ZnO-B2O3 glass. shows bright and long-lasting phosphorescence (LLP). After irradiation by 254 nm light, a visible greenish light with dominating peak at 542 nm can be observed with naked eyes in the dark for up to 6 h after removal of the activating light. The thermolumineseence spectra of Tb3+-doped glasses illuminated by UV light at room temperature consist of two dominant components with the 382 K peak related to the LLP phenomena. Electron spin resonance (ESR) measurements show that electron trapping centers and hole trapping centers are formed by UV irradiation and their intensity decays slowly in both Tb3+-free and Tb3+-doped glasses. Based on these facts, we suggest that long-lasting phosphorescence is related closely to this UV induced electron and hole traps that serve effectively as electron donor and accepter, and that these defects are controlled by the composition and structure of the glasses.