Spinodal decomposition during continuous cooling of a PbOB 2O 3Al 2O 3 glass

Abstract

Spinodal decomposition during continuous cooling of the PbOB 2O 3Al 2O 3 quasi-binary glass system was analysed by numerical integration of Cook's differential equation (which includes the contribution of random density fluctuations) for small angle X-ray scattering (SAXS) intensity. The SAXS curves derived from the calculations have a wide range of k-Fourier components (0 < k < k c) for which a positive amplification factor occurs and they show a “crossover” point at k c = 0.155 A ̊ −1 . The wavenumber which receives maximal amplification, k m, increases with the cooling rate, Q, as Q 1 n , with n = 10.9. This Q dependence of k m is similar to that predicted by Huston et al., however our results show a higher value of n. The dependence on Q and k m of the SAXS intensity I( k m) was also deduced. The measurements of SAXS curves were performed on glass samples prepared by the splat-cooling technique. Because of the difficulties which arise in the determination of the cooling rate of the samples, the only experimental results that could be compared with the theory are the k m dependence of I and the value of k c. These results are satisfactorily understood in terms of the present analysis.