Reduction of Sm3+ and Eu3+ ions-co-doped Al2O3-SiO2 glasses and photoluminescence properties

The reduction process of Sm3+ and Eu3+ ions doped in Al2O3-SiO2 glasses and the energy transfer phenomena between Sm2+ and Eu2+ ions were investigated. When the glass was heated with H-2 gas, the H-2 gas molecules diffused through the glass structure, followed by the reduction of Sm3+ to Sm2+ without forming AlOH bonds, whereas the Eu3+ ions reduced and formed AlOH bonds. The activation energy for the H-2 gas diffusion in Sm3+-doped glass was higher than that of Eu3+-doped glass and the reduction of Sm3+ ions was suppressed as the Eu2O3 content increased. The photoluminescent properties caused by the energy transfer between Eu2+ and Sm2+ ions were also examined. The energy of the Eu2+:4f(7) -> 4f(6)5 d(1) transition effectively transferred to excite the Sm2+: 4f(6) -> 4f(5)5 d(1) transition, resulting in strongly enhanced emission intensities of the Sm2+: D-5(0)-> F-7(J) transitions.