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 [((Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 ) 0.65 (Sr 0.5 Ca 0.5 ) 0.35 ](Ti 0.95 Me 0.05 )O 3 (Me = Zr (Zr 0.5 Hf 0.5 ), (Zr 1/3 Hf 1/3 Sn 1/3 ), 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 (Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 TiO 3 composition. In addition, the A-site doping of Sr and Ca and B-site doping of Zr, (Zr 0.5 Hf 0.5 ), and (Zr 1/3 Hf 1/3 Sn 1/3 ) 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 W rec (6.44 J/cm 3 ) and η (73.8 %) under a large E b (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.