Microstructure and ferroelectric properties of high-entropy perovskite oxides with A-site disorder

Abstract

High-entropy oxides with complex compositions can be designed as new ferroelectric materials with interesting physical consequences. Here, a series of high-entropy perovskite ceramics (Bi0.2Na0.2Ba0.2Sr0.2Ca0.2TiO3, Bi0.2Li0.2Ba0.2Sr0.2Pb0.2TiO3, Bi0.2Na0.2Ba0.2Sr0.2Pb0.2TiO3, Bi0.2K0.2Ba0.2Sr0.2Pb0.2TiO3, and Bi0.2Ag0.2Ba0.2Sr0.2Pb0.2TiO3) was proposed, which selected various elements to diminish the formational enthalpy and thus to achieve a single-phase structure. Detailed crystal structure and microstructure characterizations indicated that the high-entropy perovskites exhibited a single tetragonal phase with excellent chemical homogeneity. The equiatomic ratios of the A-site cations in perovskites could be used to maximize the entropy stabilization effect and effectively disordered the symmetry of the crystal structure. A robust ferroelectric polarization reaching 20 μC/cm2 under 50 kV/cm was achieved in Bi0.2Na0.2Ba0.2Sr0.2Pb0.2TiO3 high-entropy ferroelectrics. This work provides an effortless approach to discover new high-entropy ferroelectrics in materials with unexplored compositional complexity and gives additional opportunities to design and tailor the functional properties in entropy-stabilized ferroelectrics.