Structural Equilibria in Silicate Glass Melts Investigated by Raman Spectroscopy

Abstract

Structural equilibria of alkali silicate glasses and melts are investigated based on the Q n fractions ( n =number of bridging oxygen in SiO 4 tetrahedron) obtained from high‐temperature Raman spectra. A mathematical treatment of the entropy of mixing, Δ S mix , of structural groups of Q n is conducted and applied to the investigation of phase transformation and phase separation. Characteristics of Q n traces and the counter‐map of Δ S mix on Q n diagram are found to possess useful information to understand their mechanisms. An extended Q n diagram is also proposed to understand the melt structure and properties for the wide composition range.