Glasses in the Ba–Si–O–N System

Abstract

The preparation and properties of Ba–Si–O–N glasses are reported. These oxynitride glasses were prepared by melting mixtures of BaH2, SiO2, and Si3N4 powders in a nitrogen atmosphere at 1550°–1700°C. The glasses were characterized by X‐ray powder diffraction, differential thermal analysis, and scanning electron microscopy. Final glass compositions were calculated from analyses obtained by energy dispersive X‐ray (EDX) spectroscopy and combustion analysis, for cation and anion compositions, respectively. The glasses were found to be homogenous, translucent gray to opaque black, and consists of N contents of up to 42 equiv% and Ba contents of up to 36 equiv%. Determined glass densities varied between 3.27 and 4.18 g/cm3, and calculated molar volumes varied between 10.28 and 11.11 cm3/mol. Both density and molar volume increase with Ba content. Glass compactness (0.45–0.49), glass transition temperature (786°–905°C), and microhardness (7.93–9.56 GPa) were found to increase linearly with N content. The refractive index increased from 1.66 to 1.91 and was found to be strongly correlated with the amounts of Ba and N.