Effect of Electric Field on Phase Separation of Glass

Abstract

IN the manufacture of fine-grained and void-free glass ceramics, the first step is the separation of the parent glass into two or more metastable phases. This occurs either by the classical nucleation and growth mechanism to give spherical particles of secondary phase¹, or by spinodal decomposition² which gives a more continuous glass in glass separation. In either mechanism, diffusion must be important. It has been shown³ that both formation and growth of nuclei of a second phase depend on the diffusion coefficients of ions present, and, like other diffusion-controlled phenomena, these processes should be influenced by electric fields. We describe here experimental results which indicate that the application of an electric field permits controlled nucleation of glass at temperatures below the normal nucleation range and increases the growth rate of nuclei at higher temperatures.