Influence of La2O3-doping on structural and dielectric investigations of BaTiO3 borate glasses for high-temperature energy storage applications

New borate glass series 58B₂O₃-5ZnO-(28-x)Na₂O-9BaTiO₃-xLa₂O₃, x = 0–5 mol%, is fabricated using the conventional melt quenching method. The dielectric spectroscopy is used to explore some important aspects of the electronic band structure, dielectric relaxation, and electrical transport in such borate glasses. The X-ray diffraction and Fourier transform infrared spectroscopy are utilized to investigate the structural characteristics of the prepared glasses. The XRD patterns show the disappearance of crystalline peaks and the appearance of two broad humps (30° and 45°), indicating the short-range order and fully amorphous nature of all glasses. FTIR results reveal that the addition of a small amount of La₂O₃ leads to the transformation of BO₃ to BO₄ structural units, while further addition causes the back conversion, indicating the presence of plenty of modifying cations. In the dielectric study, the effects of high temperatures and La₂O₃ content on the dielectric constant, dielectric loss, ac conductivity, and electric modulus are investigated. It is found that in the formed glasses, the conduction mechanism obeys the correlated barrier hopping model. A slight fluctuated reduction in the ac conduction and dielectric loss is observed due to La₂O₃ incorporation. The glasses exhibit the mixed (polaronic and ionic) conductivity behavior, which makes them beneficial for energy storage applications. At high temperatures, it is found that the frequency dependence of the imaginary electric modulus Mʺ obeys the Bergman-modified Kohlrausch–Williams–Watts (KWW) function for all glasses.