Synthesis and characterizations of BNT–BT–KNN ceramics for energy storage applications

Abstract

Dielectric, ferroelectric and piezoelectric properties of the (0.94–x) Bi0.5Na0.5TiO3–0.06BaTiO3–xK0.5Na0.5NbO3/BNT–BT–KNN ceramics with x = 0.02 and 0.05 (2KNN and 5KNN) were studied in detail. Dielectric study and temperature-dependent polarization hysteresis loops indicated a ferroelectric-to-antiferroelectric transition at depolarization temperature (Td). The low Td in both the ceramic samples suggested the dominant antiferroelectric ordering at room temperature (RT), which was also confirmed by RT polarization and strain hysteresis loops studies. Antiferroelectric-to-paraelectric phase transition temperature (Tm) was nearly same for both systems. The 5KNN ceramic samples showed the relaxor behaviour. The values of the dielectric constant, Td, and maximum strain percentage increased, whereas the coercive field and remnant polarization decreased with the increase of the KNN percentage in the BNT–BT–KNN system. High-energy storage density ∼0.5 J/cm3 at RT hinted about the suitability of the 5KNN system for energy storage applications.