Effect of sol—gel processing on luminescence of Sm-doped silica

Abstract

The changes in the properties of pure and Sm-doped silica in the process of sol—gel and gel—glass transitions was studied. It was shown that the sol—gel transition (20°C) is influenced by the starting ratio of H 2O to si(OC 2H 5) 4 (silicon tetraethoxide). The gel—glass transition is mainly influenced by the temperature. The basic physical and chemical properties of gel—glasses were similar to the properties of melted glasses at a temperature of about 750°C independent of the ratio of the starting components. The evolution of Sm 3+ luminescence in Sm-doped silica was investigated at every stage of formation of gel—glass from liquid sol to the glassy state. On the basis of the transformation of Sm 3− luminescence during sol—gel processing some conclusions about the structural states of doped ions in the silica matrix were made. The effect of Al 2O 3 and K 2O on the luminescence and structural state of Sm 3+ ions was also considered.