Grain size engineering enhanced dielectric, ferroelectric and energy storage properties in SnO2 modified BCZT lead-free ceramics

Grain size engineering is considered as an extremely effective method to realize high electric breakdown strength and enhance the recoverable energy density. In this work, the SnO2 additive is proposed to drive the grain size smaller and enhance the energy storage performance of the (Ba0.85Ca0.15)(Zr0.2Ti0.8)O3 lead-free ceramics. The (Ba0.85Ca0.15)(Zr0.2-xSnxTi0.8)O3 with x = 0.05, 0.10, 0.15, and 0.20 for energy storage application are fabricated via the conventional solid phase reaction method. The influence of Sn4+ addition on the microstructure, dielectric, ferroelectric and energy storage properties of (Ba0.85Ca0.15)(Zr0.2-xSnxTi0.8)O3 ceramics are investigated. As expected, the smallest average grain size and highest diffused phase transition are obtained when x = 0.10. Meanwhile, a maximum electric breakdown field strength 92.08 kV/cm and a recoverable energy storage of 422 mJ/cm3 accompanied with the improved energy storage efficiency of 83.3% are noted. The mentioned results suggest that the effective control of Sn4+ amount in BCZT ceramics is helpful to reduce the grain size and then obtain higher energy storage density and efficiency at relatively low electric field strength.