Impact of Low Concentrations of TiO\(_2\) on the Physical and Optical Characteristics in Borobismuthate Glasses

Abstract

A set of glasses was preapred using the melt quenching technique with composition 20 BaO- 10Bi₂O₃-(70-x) B₂O₃ – x TiO₂ (x=0, 0.2, 0.4, 0.6, 0.8 and 1 mol%). X-ray Diffraction (XRD) investigations confirmed that all samples in this batch exhibited an amorphous structure. The parameters, including density, molar volume, and oxygen packing density (OPD), were calculated. It was observed that density ranged from 3.978 to 3.843, and the molar volume showed corresponding changes with variations in density, which were attributed to the creation and alteration of Non-Bridging Oxygen (NBO) sites. Optical absorption investigations were carried out on a series of glass samples. It was observed that the optical bandgap energy (E_opt) increased with the introduction of titanium dioxide, but decreased as the concentration of TiO₂ continued to rise. The metallization criterion (M) showed an initial increase upon the addition of TiO₂, but subsequently remained relatively constant as the TiO₂ content increased. This suggests that these glasses may exhibit characteristics of amorphous semiconductors. Additionally, various other optical parameters, such as refractive index (n), absorption coefficient (\(\alpha\)), extinction coefficient (K), optical conductivity (\(\sigma\)_op), optical polarizability (\(\alpha\)_o), and optical basicity (\(\wedge\)_th), were evaluated for all the samples and analyzed with respect to wavelength.