Microstructures and energy storage properties of Mn-doped 0.97Bi0.47Na0.47Ba0.06TiO3–0.03K0.5Na0.5NbO3 lead-free antiferroelectric ceramics

Mn-doped 0.97Bi0.47Na0.47Ba0.06TiO3–0.03K0.5Na0.5NbO3 (BNBT–KNN) lead-free energy storage ceramics were prepared by the conventional solid-state reaction methods. Effects of Mn addition on the microstructures and energy storage properties of the ceramics were investigated. XRD analysis revealed that all the ceramics possessed a single perovskite structure. As the Mn content arose from 0 to 3 mol. %, the average grain size of the BNBT–KNN ceramics increased by nearly 4 times (from ~1.6 to ~6.2 µm). The energy storage density of the BNBT–KNN ceramics firstly increased and then decreased with increment of Mn addition. With the rise of external electric field loaded on the ceramics, the energy storage density increased drastically, and a maximum value of 0.938 J/cm3 at 79 kV/cm was achieved by the BNBT–KNN samples with 1.0 mol. % Mn content.