Coarsening Process of Nucleation-Growth Type Phase-Separated Particles in Binary Germanate Glasses

Abstract

The coarsening process of nucleation-growth type phase-separated particles in a metastable immiscible region of binary GeO2 systems was investigated in detail, and is discussed in terms of the mechanism of connection and coalescence for fluid mixtures. Furthermore, the factors which affect the coarsening process were investigated.At the later stage of the growth of particles, their mean radius \barr changed in proportion to the αth power of time t (\barr(t)∝tα), and the value of growth rate α varied in the range of 0.34∼0.68 depending on the number of connected and coalesced particles n. It was found that nucleation-growth type phase-separated particles grow coarser intermittently by the mechanism of connection and coalescence, and that this coarsening process can not be explained by the usual theory of the 1/3rd power rule.The factors which affect this coarsening process of particles are volume fraction Vf of particles and interfacial tension γA/B between the particles and the dispersed phase. Additionally, it is found that the mean number n of connected and coalesced particles concerning all the measured compositions can be arranged on one line by the cohesive coefficient Vf·γA/B defined in this study.