Structure and properties of ZnO-BaO-Bi2O3-B2O3 glasses for low temperature sealing applications

ZnO-BaO-Bi2O3-B2O3 glasses for low temperature sealing applications have been prepared using the conventional melt quenching technique. The effects of Bi2O3/B2O3 ratio on the glass structure and properties have been systematically investigated using Fourier transform infrared (FT-IR) spectroscopy, x-ray photoelectron spectroscopy (XPS) and physical measurements. The FT-IR and XPS spectra show that the glass network is mainly constituted by [BO3], [BiO3] and [BiO6]. With increasing Bi2O3/B2O3 ratio, the relative fraction of bridging oxygen (BO) decreases gradually, whereas the concentration of Bi3+ increases compared to Bi5+ in the glasses. Accordingly, the bulk density, glass transition temperature (T-g) and softening temperature (T-s) increase, coefficient of thermal expansion (CTE), bend strength and Vickers hardness decrease. The sealing experiment suggests that ZnO-BaO-Bi2O3-B2O3 glasses area potential matched sealing material for Kovar 4J50 alloy.