Narrow Results

Three samples of boro-germanate glass system (GeO₂–B₂O₃) were prepared by cooling the melt from 1473°K in the compositional series containing 40, 35 and 30 mol% B₂O₃. For these glasses the optical absorbance, % transmission, optical band gap, relative permittivity (ε_r), index of refraction (n) and index of dispersion (Abbe No., V_d) have been determined. The position of the absorption edge and hence the optical band gap (E_opt) was found to depend on glass composition. The absorption edge was attributed to indirect transitions. The values of E_opt and n_d were observed to decrease with increasing B₂O₃ content while ε_r and V_d increased with increasing B₂O₃ content.