Formation and properties of nitrogen-rich strontium silicon oxynitride glasses

Glass formation in the system Sr–Si–O–N was investigated and properties of obtained glasses evaluated. The glass-forming region was determined for glasses prepared by melting mixtures of Sr metal, SiO₂ and Si₃N₄ powders in Nb crucibles at 1600–1750 °C in nitrogen atmosphere using a radio frequency furnace. The glasses were found to be homogenous, translucent gray to opaque black, and to contain high contents of N (up to 45 e/o) and Sr (up to 36 e/o). The glass transition temperature (790–973 °C), density (2.99–4.07 g/cm³), microhardness (8.10–10.50 GPa), and refractive index (1.65–1.93) are strongly correlated with the amounts of Sr and N. The properties are compared with findings in other oxynitride silicate glass systems.