Optical Study of Lithium-Bismuth-Borate Glasses

Glasses with compositions xBi(2)O(3)(75-x)B(2)O(3)25Li(2)O(3) for 0 <= x <= 40 mol% have been prepared using the normal melt-quenching technique. The optical absorption and reflection spectra were recorded at room temperature in the wavelength range 190-1100 nm. From the absorption edge studies, the values of the optical band gap (E-opt) and Urbach energy (Delta E) have been evaluated. Optical parameters such as refractive index and complex dielectric constant have been determined. The dispersion of the refractive index is discussed in terms of the single-oscillator Wemple-DiDomenico model. Color parameters and color difference data L-*, U-*, V-*, C-*, h(ue), W, Y-e, Delta L-*, Delta U-*, Delta V-*, Delta C-*, and Delta E have been calculated.