Study of the Influence of R2O3 (R = Al, La, Y) on the Structure, Thermal and some Physical Properties of Magnesium Borosilicate Glasses

Abstract

The influence of R2O3 (R = Al, La, Y) on the structure, thermal and some physical properties of 40MgO–30B2O3–30SiO2 glass has been investigated by differential thermal analysis, X-ray diffraction, scanning electron microscopy 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 change in properties associated with the substituting ions largely correlates with the structural role of these ions in the glass structure. The experimental results suggest that Al3+ ions act as network formers in the investigated composition range, while La3+ and Y3+ ions act as network modifiers and increase the number of non-bridging oxygen in the glass network. The obtained results showed that the glass transition temperature (640–700 ºС), thermal expansion coefficient (5.6–7.5 ppm/ºС), density (2.60–3.34 g/cm3), and molar volume (21.17–24.15 cm3/mol) values of the investigated glasses were increased with increasing R2O3 content. The increase in density is due to the relatively larger molar mass of the substitution oxides than other glass components, while the large ionic radius of the substitution ions causes an increase in the molar volume. The obtained results for the glass transition temperature and thermal expansion coefficient showed an increase in the values for these properties with a decreasing field strength of the substitution ions. These results can be used to develop new materials with the required properties for advanced aerospace and electronic applications.