Effect of doping La2O3 on the structure and properties of the titanium barium silicate glass

Glasses with the composition 50SiO2-20TiO2-15BaO-7.5SrO-7.5CaO doped varied content of La2O3 have been prepared by the conventional melt quench technique. The effect of La2O3 on structure of the glasses was investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectra and Raman spectra. The density, thermal stability and dielectric properties of glass were measured and compared by the Archimedes method, differential thermal scanning analysis (DSC) and impedance spectroscopy, respectively. The results showed that the coordination of the titanium remained invariable with the addition of La2O3, while the number of Si-O-Ti bonds increased and the distribution of Qn changed. And the depolymerization of the glass network was observed. The thermal stability and resistance to crystallization increased significantly for glass containing 4 mol% of La2O3 resulting from the strong strength of La O bond and the La3+ clustering. However, the resistance to crystallization for glasses was decreased with further increasing La2O3. The dielectric constant of glass decreased first and then increased with the increase of La2O3 content, while the dielectric loss was almost constant.