Temperature Dependence of the Density of Stabilized Magnesium-Aluminoborate Glass at Temperatures below the Glass Transition Temperature

Abstract

The density of the glass of the composition 32MgO ∙ 20Al₂O₃ ∙ 48B₂O₃ (mol %) (the glass transition temperature is 644°С) in the course of the stabilization process in the temperature range 635−580°С and the temperature dependence of the stabilized glass density d_s in the range 700–580°С are investigated. The study aims to examine the temperature dependence of the stabilized glass density at temperatures below the glass transition point. The density is measured upon quenching the samples at room temperature via hydrostatic weighing in kerosene with an accuracy of ±0.001 g/cm³. It is established that in the temperature range 650−610°С the density d_s increases linearly with the temperature decrease. Deviation from the linear dependence d_s(T) towards lower density values is observed in the temperature range 610−580°С. Therefore, for the stabilized glass of the composition mentioned above in the investigated range below T_g the density first increases linearly with decreasing temperature, after which its growth gradually slows.