Small-Angle X-ray Scattering of Heat-Treated Flame-Fused Silica Glass from Amorphous and Crystalline Powders

High-quality as-fused silica glass, heat treated at 1523 K and prepared by the flame-fusion process using natural crystalline quartz and high-purity amorphous silica glass powders, was investigated by small-angle X-ray scattering (SAXS). The X-ray scattering intensity amplitude from the amorphous structure after heat treatment was analysed in terms of viscosity, density and metallic impurity content. It is shown that SAXS scattering of the amorphous sample is sensitive to the structural change induced by annealing.