High-entropy enhanced room-temperature ferroelectricity in rare-earth orthoferrites
Bo Ni, Ateer Bao, Yaohang Gu, Xiaoyan Zhang, Xiwei Qi
Abstract
Single-phase multiferroic materials of rare-earth orthoferrites with magnetism and ferroelectricity are of great technological importance in storage devices. However, the polarization (<i>P</i>) of these materials is generally weak (0.01 μC·cm<sup>−2</sup>), and the ferroelectricity is reported to exist below room temperature (25 ℃). Here, (Bi<sub>0.2</sub>La<sub>0.2</sub>Y<sub>0.2</sub>Dy<sub>0.2</sub>Tb<sub>0.2</sub>)FeO<sub>3</sub> (BLYDTFO) high-entropy oxides that exhibit a saturation <i>P</i> of 5.3 μC·cm<sup>−2</sup> at the electric field (<i>E</i>) of 45 kV·cm<sup>−1</sup> at room temperature was designed and fabricated by the conventional solid-phase method. The results show that configurational entropy introduces atomic disorder and a larger tilt of BO<sub>6</sub> octahedron, which facilitates non-centrosymmetric distortion and ferroelectricity at room temperature compared with other single components (LaFeO<sub>3</sub>, YFeO<sub>3</sub>, DyFeO<sub>3</sub>, and TbFeO<sub>3</sub>). This high-entropy approach expands the compositional window of the rare-earth orthoferrites to enhance the ferroelectricity in multiferroic applications.