Small angle X-ray scattering study of spinodal decomposition in B2O3---PbO---Al2O3 glass

SAXS measurement for 80B₂O₃·15PbO·5Al₂O₃ (wt%) glass can be performed with high accuracy. SAXS spectra were obtained for glasses which had been heat-treated for different lengths of time at 380°C and 400°C. A converging point k′_c and a common curve for k >k′_c were observed in the SAXS spectra of glasses subjected to appropriate aging. This suggests the validity of Cook's modification of Cahn's theory. At the very early stage of the decomposition a relaxation takes place of $\text{?″}\text{and}\text{D}\text{?}$ and the spectra of Cahn-Cook's amplification factor show a typical aspect of the early stage of decomposition after the relaxation. Plots of k³I(k) versus k³ suggest that the interface between the two phases is diffuse and the demixing process is in the early stage of the spinodal decomposition.