The dependence of luminescence on reduction of Sm2+ ions doped in lithium barium borate glasses

Sm³⁺-doped Li₂O–BaO–B₂O₃ glass was prepared by the conventional melt quenching method in air atmosphere. Sm²⁺ ions were obtained by two methods, i.e. heating the as-made glass in a reducing atmosphere and irradiating the sample under X-rays. The two obtained samples were investigated by luminescence spectra and lifetime measurements. It was found that the conversion of Sm³⁺→Sm²⁺ after X-ray irradiation is efficient in this borate glass. Photo-stability of Sm²⁺ ions was evaluated by the photo-bleaching method. Furthermore, thermo-luminescence was also measured. The different defects and the reduction mechanism of Sm²⁺ ions in this borate glass were discussed. This would be helpful to understand the reduction mechanism of Sm²⁺ ions in borate glasses.