Physical and optical investigations of Bi2O3-TeO2-B2O3-GeO2 glasses

Anew series of quaternary glasses with chemical composition xBi(2)O(3)-(80-x)TeO2-10B(2)O(3)-10GeO(2) where 40 <= x <= 65 have been prepared by melt quenching technique. X-ray diffraction measurements have been achieved to check the amorphous nature of the glasses. The effect of Bi2O3 content on the physical, thermal and optical properties of the prepared glasses was studied. It is observed that oxygen packing density decreased with the increase of molar volume with increasing Bi2O3 content implying the formation of non-bridging oxygen's and expands the glass. The glass transition temperature (T-g) increased whereas the glass stability decreased with Bi2O3. In addition to that, indirect optical band gap and Urbach energy values of the titled glasses have been calculated from Tauc plots using absorption spectra. The indirect optical band gap (E-opt) decreased with the increase of Bi2O3 concentration in the present glass system. The Raman spectroscopy at room temperature was employed to study the influence of bismuth oxide on the boron-oxygen network structure. The analysis of Raman spectra shows the presence of fundamental vibrations of TeO3, GeO6, BO3, BO4, BiO6 structural units.