ZnO-P₂O₅-SiO₂ Long-lasting Phosphorescence Glasses Doped With Rare Earth Ions

ZnO-P₂O₅-SiO₂ was selected to be host materials of long-lasting phosphorescence glasses and Tb³⁺ ions were doped in host materials. The long-lasting phosphorescence glasses with the composition (in mol %) of ZnO-P₂O₅-SiO₂: Tb³⁺ were prepared in a conventional melt-quenched method and sol-gel. The histories, applications and open questions of long-lasting phosphorescence glasses were generalized.The long-lasting phosphorescence glasses were prepared by conventional melt-quenched method. The results showed as follows: A visible greenish light can be observed with naked eyes after the glasses were irradiated by 254nm light. It can last for up to 9h in the dark after removal of the activating light. The masses of SiO₂ were definite and the luminescent properties of the glasses became better with masses of ZnO increasing. The luminescent properties of glasses were affected by different concentrations of Tb³⁺. The luminescent properties of glasses were optimum when the concentrations of Tb³⁺ were up to 5%. The luminescent properties of glasses became worse and worse in the sequence of CaO, SrO, BaO when 2% of ZnO was replaced by 2% of RO (RO= CaO, SrO, BaO). The luminescent properties of glasses became worse with the contents of RO (RO= CaO, SrO, BaO) increasing.The glasses were prepared by sol-gel. The effects of technological conditions on formation of gels and glasses were discussed. The results showed as follows: The calcination temperature of the glasses was 1200℃,which was lower by 200℃than that of conventional melt-quenched method. Formation of gels and glasses was affected by different ratios of citric acid and ZnO, solvents, pH values and heat treatment temperatures. The gels and glasses can be prepared on the conditions that solvents were 75¹25ml, pH values were 0.5², heat treatment temperatures were 70⁹0℃, ratios of citric acid and ZnO were 1.5².The long-lasting phosphorescence glasses were prepared by sol-gel. The effects of technological conditions on the properties of long-lasting phosphorescence glasses were discussed. The results were showed as follows: The properties of long-lasting phosphorescence glasses were affected by different concentrations of Tb³⁺, ratio of citric acid and ZnO, solvents and pH values. The optimum long-lasting phosphorescence glasses were prepared on the condition that the solvent was 100ml, the pH value was 1.5, the heat treatment temperature was 80℃and the ratio of citric acid and ZnO was 1.5. Compared with long-lasting phosphorescence glasses which were prepared by conventional melt-quenched method, the fluorescent and luminescent properties of long-lasting phosphorescence glasses which were prepared by sol-gel were better because of homogeneous compositions and no aliquation of metallic ions of the glasses.