Sol–Gel Synthesis of Rare-Earth and Phosphorus Codoped Monolithic Silica Glasses from a Cosolvent-Free Phase-Separating System

Abstract

A cosolvent-free sol–gel method to prepare monolithic transparent silica glasses doped by rare-earth ions at high concentrations has been developed. Despite the simple solution composition, the reaction mixture undergoes a macroscopic phase separation in parallel with the gelation, and the resultant macropores make it possible to considerably shorten the processing time by facilitating the drying and sintering of gels. The addition of a small amount of phosphorus significantly enhances the dissolution of rare-earth ions, demonstrating a notable effect of phosphorus on the solvation of rare-earth ions in silica glasses.