Structural units distribution, phase separation and properties of PbO-TiO2-B2O3 glasses

Glasses of the formula 50PbO·xTiO2·(50 − x)B2O3·0.5CuO (0 ≤ x ≤ 30 mol%) have been investigated by XRD, FTIR, SEM. Phase separation is observed in as-prepared glasses, but there are no crystalline species. Crystalline PbTiO3 and PbB2O7 phases are formed in 50PbO·30TiO2·20B2O3·0.5CuO glass samples after thermal treatment at 530 °C for 8 h. The IR spectra do not show peaks related to structural units of TiO2. The fraction of BO4 units decreases slightly with increasing TiO2 content. This change is assumed due to formation of TiO6 units at the expense of TiO4 units. Both the density and molar volume do not change with composition. Calculations based on the concentration and volume of the structural units indicate that the molar volume has mostly the same value between 0 and 30 mol% TiO2.