Synthesis and characterization of new eco-friendly vitreous system Bi2O3-B2O3-BaO: Structural, morphologic, and thermal analysis

In this study, we synthesized new bismuth borate glass materials with a chemical composition of (1-x)(2Bi2O3. B2O3)-xBaO, where x varies from 0 to 0.8mol%. The synthesis was carried out using the conventional meltquenching method. The X-ray diffraction (XRD) patterns confirmed that the prepared glasses were amorphous. The physical parameters namely density (rho), oxygen molar percentage (VO), molar volume (Vm), oxygen packing density (OPD), Poisson's ratio (sigma) and packing density (Vp) of the glassy matrix were studied in relation to the substitution of BaO by Bi2O3 and B2O3. The data obtained indicate that the density and molar volume of the prepared samples decreased as the proportion of BaO increased. The results indicate the formation and modification of non-bridging oxygenated bonds within the samples. Additionally, the oxygen packing density decreases while the compactness density increases, suggesting the presence of a highly compact oxide network. The addition of BaO to all samples resulted in an increase in thermal parameters, including the transition temperature of glass (Tg) and the crystallization temperature (Tc). This confirms that the obtained glass is stiffer and more stable. The IR and Raman spectra demonstrate the depolymerization of the glassy network through the systematic conversion of tri-borate chains to tetra-borate groups, and then to penta-borate groups. Additionally, the IR and Raman spectra confirm the presence of [BO3], [BO4], [BiO3], and [BiO6] units. The introduction of BaO resulted in a gradual conversion from trigonal [BO3] to tetragonal [BO4] units as a result of the rise in the number of non-bridging oxygen atoms, which made the glassy network stiffer. Moreover, the composition, chemical state of the surface as well as binding energies of the various components of the glass were obtained utilizing X-ray photoelectron spectroscopy (XPS). The surface layer morphology and elemental composition of the glasses under study were investigated by the techniques of energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM).