Acoustic Evidence of Phase Separation in Lithium Silicate Glasses

Abstract

Ultrasonic measurements of a series of Liz 0-xSiOa (x = 1-6) glass samples are presented. In terms of the model of frozen-in thermal fluctuations in glasses, the analysis of the relationship of temperature coefficient of ultrasonic velocity change versus Liz0 molar fraotion provides evidence of the existence of two-phase separation phenomenon in lithium silicate glasses with a molar fraction of lithium oxide less than 0.25. It also provides some information about the structural change of the glasses from a system of two phases to a single phase, as the molar fraction of Liz0 is further increased.