Correlation between dielectric properties and crystallization treatment in potassium sodium niobate glass-ceramics for energy storage application

•Na2O–K2O–Nb2O5–SiO2–B2O3 glass-ceramic was prepared via melt-quenching and controlled crystallization.•Na0.9K0.1NbO3 and KNbO3 ferroelectric phase and NaNbO3 antiferroelectric phase was crystallized by controlling crystallization.•It was researched that the correlation of crystallization treatment and dielectric properties.•The highest energy storage density for 1.899 J/cm3 is obtained by optimized route.

K2O–Na2O–Nb2O5–SiO2–B2O3 glass-ceramics was prepared via melt-quenching and controlled crystallization route. To investigate the effect of crystallization treatment schedule on the dielectric properties of potassium sodium niobate (KNN) glass-ceramics, this report measured six glass samples with different crystallization treatment by XRD, SEM and LCR measurements. By means of changing heat-treatment schedule, it could be inferred that crystallization process and optimal treatment condition for KNN glass-ceramic with pore-free and high energy density. When the original glass samples crystallized at 707 °C for 2 h and 900 °C for 3 h, this crystallization treatment was beneficial to obtaining the glass-ceramic samples with purer perovskite structure K0.1Na0.9NbO3 crystal phase and finer grains which possessed relative higher energy storage density (1.899 J/cm3). The crystallization behavior and dielectric properties have exhibited a regular change at different crystallization temperature. Comprehensive results and analysis demonstrated that crystallization treatment played a role in dielectric properties of KNN glass-ceramics. In order to optimize energy storage, this experiment controlled transition from matrix glass phase of high breakdown strength (BDS) to ferroelectric crystal phase of high dielectric constant.