Criterion for estimating the number of phases in phase-separated glass of the Na^sub 2^O-K^sub 2^O-B^sub 2^O3-SiO2 system by dilatometric analysis

• Published in: Glass physics and chemistry 2014-05, Vol.40 (3), p.298
• Main Authors: Stolyar, S V, Konon, M Yu, Drozdova, I A, Anfimova, I N
• Format: Article
• Language: English
• ISSN: 1087-6596; 1608-313X
• DOI: 10.1134/S1087659614030213

The data of dilatometry and electron microscopy of four series of xNa^sub 2^O-(8 - x)K^sub 2^O-32B^sub 2^O3-60SiO2, xNa^sub 2^O-(8 - x)K^sub 2^O-22B^sub 2^O3-70SiO2, xNa^sub 2^O-(6 - x)K^sub 2^O-34B^sub 2^O3-60SiO2, and xNa^sub 2^O-xK^sub 2^O-(40 - 2x)B^sub 2^O3-60SiO2 phase-separated glass heat-treated at 550°C for 144 h (for glass containing 70 mol % SiO2) and 24 h (for glass containing 60 mol % SiO2) for separation on phases are summarized. The comparison of dilatometric data and electron microscopy allow one to conclude that glass with a difference between the onset deformation temperature and a glass transition temperature of more than 100°C is phase-separated; and glass with a difference of less than 65°C is single-phase. Curves for the glass transition temperature as a function of the K^sub 2^O content reveal a mixed alkali effect, namely, minimums for glass containing 60% SiO2, and maximums for glass containing 70% SiO2.[PUBLICATION ABSTRACT]