Glass additive in barium titanate ceramics and its influence on electrical breakdown strength in relation with energy storage properties

Glass additive was employed to improve the microstructures and energy storage properties of barium titanate ceramics using liquid phase sintering technology. Microstructural observation indicated that the average grain size reduced obviously with increasing glass concentration. Also, the dielectric constant decreased and the dielectric breakdown strength increased as glass concentration increased. The increase in the breakdown strength with decreasing grain size was consistent with the well-known relationship for the mechanical failure. The activation energies of bulk grain and grain boundary as well as their differences were calculated using measured impedance values. Good inverse dependence of the dielectric breakdown strength on the difference between activation energies of bulk grain and grain boundary was obtained for the glass-added BaTiO3 ceramics. It was also found that the energy storage density of the ceramics increased gradually with increasing glass concentration. Possible effect of the interfacial polarization in degrading the energy storage property was discussed.