The influence of Bi2O3 on structural and enhancing physical properties of Li2O–Fe2O3–In2O3–P2O5 glasses

Glasses based on the Li2O–Fe2O3–In2O3–Bi2O3–P2O5 system were prepared as potential low-melting sealing glasses. The modifications of the glass structure were characterized by means of XRD and FTIR spectroscopy as a function of Bi2O3/P2O5 substitutions. The bulk density, together with other parameters, was also calculated. The amorphous nature was observed for all glass samples except the highest Bi-content. FTIR and Raman spectrum reveal that the prompt polymerization of the phosphate chains by increasing the Bi2O3 content and forming P–O–Bi bonds and the existence of different structural groups FeO6, FeO4, BiO6, PO4, PO3 and PO. The dilatometry measurements showed an increase in both transition (Tg) and softening (Ts) temperatures with Bi-content. Conversely, coefficients of thermal expansion decreased from 120 × 10−7/°C to 80 × 10−7/°C. The dissolution rate of the prepared glasses was tested, and the results showed significantly improved glass stability. Finally, the obtained glasses have a suitable working temperature, suitable thermal expansion values, and good thermal and chemical stability, making them a prospective candidate for low-temperature sealing materials.