Effects of TiO2 addition on dielectric and energy storage properties of BaO-K2O-Nb2O5-SiO2 glass ceramics

In this work, 25.6BaO-6.4K2O-32Nb2O5-36SiO2-xTiO2 (0 ≤ x ≤10 mol%) (BKNST) glass ceramics were synthesized by conventional melts and controllable crystallization method. The effects of different TiO2 addition on the phase composition, dielectric and energy storage properties of BKNS glass ceramics were systematically evaluated. With the TiO2 concentration increasing, a growing content of Ba2TiO4 phase was observed in the glass ceramics. The microstructures appeared to be homogenous and uniform with very low porosity through the addition of TiO2, for which the maximal breakdown strength of 2112 kV/cm and the corresponding energy storage density of 9.48 J/cm3 were obtained with x = 7.5. The extremely low dielectric loss of less than 1‰ (25 °C, 100 kHz) and the obviously improved microstructure contributed to the increased breakdown strength. In addition, the discharge power density of the glass-ceramic capacitor (x = 7.5) was investigated using the RLC charge-discharge circuit and a relatively high value of 16 MW/cm3 at 300 kV/cm was obtained.