Effect of K2O content on breakdown strength and energy-storage density in K2O-BaO-Nb2O5-SiO2 glass-ceramics

Phase evolution, dielectric properties, breakdown strength, and energy-storage performance were studied by varying K2O content in K2O-BaO-Nb2O5-SiO2 glass-ceramics. It was found that dielectric loss with the increase of K2O content increases owing to the un-crystallized K2O into the glass network, while dielectric breakdown strength firstly increases and then decreases due to the competition between two physical mechanisms, i.e., interfacial polarization and bridging-oxygen bond broken by the non-bridging oxygen ions. With the increase of K2O content, energy-storage density firstly increased up to 12.06±0.69 J/cm3 with a high breakdown strength of 1973 kV/cm, and then decreased. Also, the discharged efficiency is obtained as a high value of 92% from P-E hysteresis loops.