Effect of Li2O on the heterogeneous structure of equi-molar lead borate glasses

Different glass samples in the Li₂O, PbO and B₂O₃ system have been prepared by melt quenching method. These glasses were classified in two groups such as 0.5 B₂O₃, (0.5 ? x) PbO, xLi₂O and (0.5 + y) B₂O₃; (0.25 ? y)PbO; 0.25Li₂O. The IR spectra almost show broad bands in the frequency range (800–1050) cm^?1 and (1100–1500) cm^?1, together with different weak bands over the range of investigation (2400–3000) cm^?1. The deconvolution analyses of these IR spectra reveals presence of multi structure arrangements from BO₄ and BO₃ groups, such as penta, tri, and diborates grouping together with meta; ortho borates as well as PbO_n groups. Partial replacement of PbO by Li₂O causes decrease in microhardness, a change which is attributed to the decrease in the concentration of ortho borate groups as is it revealed from the bands area analysis. The IR analysis shows also that the total concentration of (meta + ortho) borates is nearly constant while their individual concentrations is proportional depending on the relative concentration of PbO and Li₂O.