Glass doped with Ni2+ and Mn2+ was prepared by using the sol–gel process. Very strong visible light (the fluorescence efficiency was about 4 times that of undoped sol-gel SiO2 glass and about 160 times that of ZnS nanocrystallites) from SiO2 glass doped with Ni2+ and Mn2+ was observed. The emission wavelength of Ni2+-doped, Mn2+-doped and undoped glass samples was about 450nm. However, co-doping with Ni2+ and Mn2+ shifted the emission wavelength to 420nm. The sol-gel SiO2 glass was a porous phosphor material. Very strong photoluminescence of the sol-gel SiO2 glass came mainly from structural defects. Because the doped samples contained more Si dangling bonds, non-bridging O, and O vacancies, the fluorescence efficiency of doped samples was remarkably increased. Because the doped ions affected the band-gap structure of the host materials, the emission wavelength of the co-doped samples was different to that of Ni2+- and Mn2+-doped samples. Because the emission wavelength of Ni2+ and Mn2+

luminescent centers in the sol–gel silica glass was almost the same as that of undoped samples, the fluorescence intensities of Ni2+- and Mn2+-doped samples were higher than those of the co-doped samples.

Defects and Photoluminescence of Ni2+ and Mn2+-Doped Sol–Gel SiO2 Glass. P.Yang, C.F.Song, M.K.Lü, J.Chang, Y.Z.Wang, Z.X.Yang, G.J.Zhou, Z.P.Ai, D.Xu, D.L.Yuan: Journal of Solid State Chemistry, 2001, 160[1], 272-7