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.