Single-phase multiferroic materials of rare-earth orthoferrites with magnetism and ferroelectricity are of great technological importance in storage devices. However, the polarization (P) of these materials is generally weak (0.01 μC·cm⁻²), and the ferroelectricity is reported to exist below room temperature (25 ℃). Here, (Bi_0.2La_0.2Y_0.2Dy_0.2Tb_0.2)FeO₃ (BLYDTFO) high-entropy oxides that exhibit a saturation P of 5.3 μC·cm⁻² at the electric field (E) of 45 kV·cm⁻¹ 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 BO₆ octahedron, which facilitates non-centrosymmetric distortion and ferroelectricity at room temperature compared with other single components (LaFeO₃, YFeO₃, DyFeO₃, and TbFeO₃). This high-entropy approach expands the compositional window of the rare-earth orthoferrites to enhance the ferroelectricity in multiferroic applications.

High-entropy oxides with complex compositions can be designed as novel ferroelectric materials with interesting physical consequences. A single-phase (K_0.5Bi_0.5)_0.2Ba_0.2Sr_0.2Ca_0.2Mg_0.2TiO₃ high-entropy ceramic with a perovskite structure was synthesized by a conventional high-temperature solid-state method, and the dielectric and ferroelectric properties of the ceramic were investigated. The results show that there are no relaxation peaks in the test temperature range because of the multi-element doping. The dielectric constant of ceramic has a high-temperature stability at < 300 ℃ . The maximum dielectric constant of 8887 is obtained at 100 Hz and 650 ℃ . The introduction of high-entropy oxide in the ceramic can have high-entropy ferroelectrics in complex materials, and modify the properties of electronic ceramic.