Dielectric responses of glass-added Ba0.95Ca0.05Zr0.3Ti0.7O3 ceramics for energy storage capacitors

The structure and energy storage properties of Ba0.95Ca0.05Zr0.3Ti0.7O3 ceramics with different contents of MgO–CaO–Al2O3–SiO2 glass additive added were examined. The dielectric properties of the specimens were studied as a function of temperature and frequency. The specimens displayed a relaxor-like behavior and the glass addition enhanced the diffuseness degree of the ferroelectric–paraelectric phase transition. With increasing glass additive content, the dielectric loss of the specimens steadily increased. Over several decades of frequency, the ac conductivity data of the specimens agreed with the power-law relation of the universal dielectric response (UDR) model, indicating the presence of hopping motion of polarization carriers. Complex impedance analysis confirmed that oxygen ions are the mobile carriers in the specimens. The origin of oxygen-ion conduction in the glass-added specimens is explained in relation to a chemical reaction between the perovskite grains and the glass additive. It is confirmed that, for the glass-added specimens, polarization response resulting from oxygen-ion hopping is responsible for an overall increase of their dielectric loss in a wide frequency range.