Effect of Additives on Absorption Edge Energy in Bismuth Phosphate Glass

The effect of third-additive oxides on absorption edge energy was studied in binary bismuth phosphate glass. The edge energy was shifted toward lower energies by the substitution of third-additive oxides for P2O5. The substitutions of glass-network-forming (NWF) oxides and glass-network-modifying (NWM) oxides resulted in distinct linear relationships between the edge energy and Duffy's ideal basicity. The energy shift against the calculated basicity was larger for the substitution of NWF oxides than for that of NWM oxides. Moreover, the substitution of intermediate oxides gave a similar tendency to the substitution of NWF oxides rather than to that of NWM oxides for both relationships. It was deduced that electron donation is more sensitive to the substitution of NWF oxides than to that of NWM oxides. On the other hand, a 238 cm-1 Raman band, which is attributed to the Bi–O vibration mode, shifted toward higher wave numbers by the substitution of all of the oxides. The 238 cm-1 band showed a linear relationship with the ideal basicity similar to the relationship between the edge energy and the basicity. Sensitivity against electron donation was consistent with both the Bi–O bond strength and the absorption edge energy.