Influence of R2O3 (R=Al, La, Y) on the structure and properties of strontium borosilicate glasses

Abstract

The influence of R2O3 (R=Al, La, Y) on the structure, thermal, and some physical properties of strontium borosilicate glasses have been investigated by differential thermal analysis, X-ray diffraction, and Fourier-transform infrared spectroscopy. Fourier-transform infrared spectroscopy results showed that the network of the investigated glasses consists mainly of BO3, BO4, and SiO4 structural units. The influence of R2O3 on the properties of strontium borosilicate glasses depends on the structural role of R3+ ions. The experimental results suggest that Al3+ ions act as intermediate in the investigated composition range, while La3+ and Y3+ ions act as modifiers and depolymerize the glass network. The obtained results showed that the glass transition temperature (610–6600С), dilatometric softening temperature (640–6750С), and molar volume (25.03–29.22 cm3/mol) values of the investigated glasses were increased with equimolar substitution of SrO by R2O3. The thermal expansion coefficient (6.8–9.5 ppm/K) of the investigated glasses was found to decrease with increasing the R2O3 content. The obtained results showed that the density (3.03–3.68 g/cm3) values of the investigated glasses were increased with increasing the Y2O3 and La2O3 content and decreased with increasing the Al2O3 content. The tendency to crystallize is higher in glasses containing La2O3 compared to glasses containing Y2O3 or Al2O3. The results obtained in this study indicate that the investigated glasses can be potential candidates for advanced aerospace and electronic applications as heat-resistant electrical insulating glass- and glass-ceramic-to-metal seals and coatings.