The effect of lead oxide on structural and elastic properties of strontium lead silicate glass from deteriorated silica gel

Preparation of glass samples in the system, 10SrO – xPbO – (90-x)SGD, where SGD stands for deteriorated silica gel and x = 20, 25, 30, 35, 40 and 45 mol%, were prepared by a melted quenching technique at a temperature of 1250 °C. The Archimedes principle was used to measure density of the glass samples, and then these data were used to calculate their molar volumes. Ultrasonic velocities of this glass system were investigated using the pulse echo technique at room temperature. Both velocities and density of the system were further used to estimate the elastic moduli. The results showed that the concentration of PbO has an effect on the glass structure. The elastic moduli of the glass samples were varied by changing the concentration of PbO and its maximum appeared at 35 mol% of PbO. The structural properties of the glass samples were studied using FTIR spectroscopy, measuring in the range of 400-2000 cm-1. It was found that higher contents result in the breakdown of Si-O bonds and the formation of NBOs. The average strength of the bonds was related to the elastic moduli of the glass samples. Therefore, the information about the bonds obtained from FTIR spectroscopy supported the measurements of the elastic moduli from the pulse echo technique. Moreover, these data showed that deteriorated silica gel can be recycled into a potential glass product.