Research on Effect of Li2O on the Properties of Bismuth Borate Glasses

Borate glasses containing Li2O and fixed concentration of heavy metal oxide Bi2O3 are prepared by melt quenching technique. The effect of addition of Li2O on borobismuthate glasses has been studied. Density of the glasses has been found to increase slightly with Li2O content whereas molar volume and glass transition temperature decreases. IR spectroscopy was used for structural studies of these glasses in the range from 400 to 4000 cm-1. IR analysis showed that Bi3+cations are incorporated in the glass structure as (BiO6) octahedral units and boron ions are incorporated as (BO3) and (BO4) units. As the Li2O content increases in the glass, some of the BO3 trigonal units get converted into BO4 tetrahedral units and non-bridging oxygens have been formed. The optical transmittance spectra have been recorded at room temperature. The cut-off wavelength shows a red shift, the optical band gap decreases and polarizability increases with Li2O content. The compositional dependence of different physical properties such as density, molar volume optical band gap and optical basicity has been studied and correlated with the glass structure.