Theory and Analysis of Early Stage of Spinodal Decomposition of Vitreous Systems with Relaxing Structure

Abstract

The interaction distance R in 80B₂O₃·15PbO·5Al₂O₃ glass and 0.132Na₂O·0.868SiO₂ glass is obtained as 15.8 Å which satisfies R>>r₀ (r₀: nearest neighbor distance). The parameter f₀ of Langer’s scaling analysis is obtained to be very large for these glasses. Therefore, the linearized Cahn theory holds for the early stages.The relaxation of ∂²f⁄∂c² besides \ ildeD is introduced to take place during aging the severely quenched glass. The theory taking into consideration of thermal fluctuations and the relaxation of ∂²f⁄∂c² and \ ildeD is developed.
In the above two glasses with the very different thermal history each other, time evolution kinetics in SAXS spectra can be elucidated by this theory. Cahn-Cook’s amplification factor spectra after the termination of all the relaxation processes show the typical characteristics of the early stage of the decomposition.