High energy storage properties achieved in 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 based relaxor ferroelectric ceramics via high-entropy design

Perovskite high-entropy ceramics (HECs) are favorable for energy storage performance due to the novel high-entropy effects. However, highly disordered states of HECs with equal molar ratio at the same site greatly reduce polarization intensity, yielding unsatisfactory energy storage properties. Herein, non-equiatomic [((Bi0.5Na0.5)0.94Ba0.06)0.65(Sr0.5Ca0.5)0.35](Ti0.95Me0.05)O3 (Me = Zr (Zr0.5Hf0.5), (Zr1/3Hf1/3Sn1/3), abbreviated as BNBSCT-Zr, BNBSCT-ZrHf, BNBSCT-ZrHfSn), HECs have been designed and prepared by a hydrothermal method. As-prepared HECs exhibit high maximum polarization, which are related to the morphotropic phase boundary (MPB) induced by the (Bi0.5Na0.5)0.94Ba0.06TiO3 composition. In addition, the A-site doping of Sr and Ca and B-site doping of Zr, (Zr0.5Hf0.5), and (Zr1/3Hf1/3Sn1/3) rooted in high configuration entropy improves the degree of dielectric relaxation, decreases the grain size, increases the resistivity, and enlarges the band gap, resulting in a higher breakdown electric field. As a result, BNBSCT-ZrHfSn ceramics exhibit the significant energy storage properties with a high Wrec (6.44 J/cm3) and η (73.8 %) under a large Eb (477 kV/cm), as well as good temperature, frequency, and fatigue stability. The results show that the "entropy engineering + MPB" strategy provided in this study can remarkablely develop the energy storage properties of dielectric ceramics.