PREPARATION OF PB-CONTAINING GLASS BY THE SOL-GEL PROCESS - REDUCTION OF PB-MIGRATION DURING DRYING

Conditions for preparing a homogeneous glass of the PbO-B//2O//SiO//2 system by a sol-gel process from silicon methoxide, boric acid and lead acetate have been investigated. The migration of lead ions toward the gel surface during drying was reduced by replacing water in a wet gel with isopropanol. The X-ray transmission of a xerogel obtained by drying a wet gel after the replacement of water with isopropanol was constant at respective points on the diameter of a disk cut out of a cylindrical sample. The X-ray transmission of a xerogel dried without isopropanol treatment, on the other hand, was low at the center and high at the perimeter.