Influence of the gradual increase of TiO₂-impurities on the structural and optical properties of some calcium sodium borate glasses

The influence of the gradual increase of TiO₂-impurities on the structural and optical properties of some calcium sodium borate glasses was studied to estimate its possibility to use for optoelectronic applications. Where a set of samples were prepared by the fast cooling method, then XRD, and FTIR were used for the characterization and identification of the internal structures of those samples, which exhibited the short-range order structure of the amorphous solids. The introduction of TiO₂ caused BO₃ to convert to BO₄, increase the bulk density of the samples, increase the number of non-bridging oxygen atoms, increase the optical absorbance, and decrease the volume energy loss function. The optical band gaps for the allowed electronic transitions of the study samples showed an anomalous behavior when the Ti-content increase, where the value of the optical bandgap for direct transition increased while that of indirect transition decreased. UV–vis spectral analysis showed the absence of any absorption peaks, which requires that all Ti-cations should be of tetrahedral coordination and have an empty d-subshell.