Expansion characteristics of some Li2Osingle bondBaOsingle bondAl2O3single bondSiO2 glasses and glass-ceramics

The thermal expansion characteristics of some glasses and glass-ceramics within the system LiAlSi2O6single bondBaAl2Si2O8 are described. The expansion coefficient of glass decreases with the increase of BaAl2Si2O8 content, while both the transformation (Tg) and softening (Ts) temperatures increased. The thermal expansion coefficients of glass-ceramics exhibited a wide range depending upon the type and relative proportions of the crystalline phases present. The α-values of the studied glass ranged from 58.34 to 75.03 × 10−7/°C in the 20–300 °C temperature range and those of the crystalline products ranged from 3 to 80 × 10−7/°C in the same temperature range. The break in the expansion curves of the crystalline samples at about 300 °C defined the reversible transformation temperature of the orthorhombic ⇆ hexagonal-celsian.