Effect of crystallization temperature on dielectric and energy-storage properties in SrO-Na2O-Nb2O5-SiO2 glass-ceramics

The SrO-Na2O-Nb2O5-SiO2 (SNNS) glass-ceramics were prepared through the melt-quenching combined with the controlled crystallization technique. XRD results showed Sr6Nb10O30, SrNb2O6, NaSr2Nb5O15 with tungsten bronze structure and NaNbO3 with the perovskite structure. With the decrease of crystallization temperature, dielectric constant firstly increased and then decreased, while breakdown strength (BDS) was increased. High BDS of the glass-ceramics is attributed to the dense and uniform microstructure at low crystallization temperature. The optimal dielectric constant of 140±7 at 900 °C and BDS of 2182±129 kV/cm at 750 °C were obtained in SNNS glass-ceramics. The theoretical energy-storage density was significantly improved up to the highest value of 15.2±1.0 J/cm3 at 800 °C, which is about 5 times than that at 950 °C. The discharged efficiency increased from 65.8% at 950 °C to 93.6% at 750 °C under the electric field of 500 kV/cm by decreasing crystallization temperature.