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High-entropy ceramic materials usually refer to the multi-principal solid solution formed by 5 or more ceramic components. Due to its novel “high-entropy effect” and excellent performance, it has become one of the research hotspots in the field of ceramics in recent years. As the research system of high-entropy ceramics has gradually expanded from the initial rock salt oxides (Mg-Ni-Co-Cu-Zn)O to fluorite oxides, perovskite oxides, spinel oxides, borides, carbides and silicates, its special mechanical, electrical, magnetic and energy storage properties have been continuously discovered. Based on the basic principle of high-entropy materials, this paper mainly introduces the prominent perovskite-type oxide high-entropy ceramics in recent years from the perspective of ceramic structure and properties, and predicts the development trend of high-entropy perovskite-type ceramics in the next few years.

Multiferroic fluids are novel fluid-based multiferroic composites in which particles can change their magnetization/polarization direction with an external field. In this study, CoFe2O4–PbZr0.52Ti0.48O3 (CFO-PZT) multiferroic fluids were prepared by the milling method, and the effects of PZT particle size on settlement stability and magnetoelectric properties were systematically investigated. Crystal structure analysis shows that pure-phase CFO and PZT particles were successfully prepared. The microscopic morphology analysis indicates that the PZT particle size decreases as the carbon template size increases. Settlement stability is better when the particle size is 1.36 ± 0.04 μm. As the particle size decreases, the dielectric constant first increases then decreases, and finally increases. The residual polarization intensity decreases with decreasing particle size, but the saturation polarization intensity first increases and then decreases. After the magnetic field is applied, dielectric characteristics and ferroelectric properties decrease, showing the "negative magnetoelectric effect". When the particle size is 1.89 ± 0.04 μm, the CFO-PZT multiferroic fluid has the maximum magnetodielectric and magnetoelectric coupling coefficients of 3.36% and − 3.39 V/(cm·Oe), respectively. Therefore, multiferroic fluids are expected to broaden the application fields of multiferroic materials. [ABSTRACT FROM AUTHOR]

The potential applications of magnetoelectric composites in capacitors, sensors, memory electronic devices, and energy harvesting devices have aroused great interest due to their mutual coupling between ferroelectric and ferromagnetic phases. In this paper, BFO/CFO composite films were prepared by the sol–gel method, and the regulation of magneto-photoelectric and coupling properties of BFO/CFO films with different compositions was studied. The results show that with the increase of BFO composition, the interface between BFO layer and BFO layer also appears, the dielectric constant of the film decreases with increasing the content of BFO, and the photoelectric conversion efficiency of the film increases at first and then decreases with the increase of BFO content. When the composition is 4BFO/6CFO, the photoelectric conversion efficiency of the composite film is the highest, which is 2.02 × 10−3%. With the increase of CFO content, the remanent magnetization and saturation magnetization of the film increase gradually. However, when the compositions are 4BFO/6CFO and 3BFO/7CFO, their leakage current is high, resulting in the degradation of ferroelectric properties. The composition 5BFO/5CFO has the highest magnetodielectric and photo induced magnetodielectric response, the corresponding values are 2.21% and 3.88%, respectively. The magnetoelectric coupling coefficient of the film is greatly increased under the action of light, reaching 115%, which could plausibly relate to the photovoltaic effect and the photostriction effects of the film. These results may provide good guidance on designing new photoelectromagnetic detector. [ABSTRACT FROM AUTHOR]

Multiferroic materials have recently as a new useful material because they can exhibit a potent magnetoelectric interaction between the ferroelectric and ferromagnetic orders above ambient temperature. In this paper, BiFeO3/CoFe2O4(BFO/CFO) thin films were prepared by the spin-coating method, and the effects of composition on the crystal structure, surface morphology, electrical properties, magnetic properties, photovoltaic properties as well as magnetic and photoelectric coupling properties of the composite films were systematically investigated. The results show that the main crystal phases of the composite films are BFO and CFO, and there are no other heterozygous phases that can be observed. The AFM results show that the roughness of thin films ranges from 8 to 10 nm, and it increases with the increase of CFO composition on the whole. SEM results confirm that there is a clear interface between different phases of different constituent films, and no obvious diffusion phenomenon occurs. The saturation and residual magnetization values increase gradually with the increase of CFO content, and the magnetic properties are stronger. With the increase of BFO composition, the dielectric constant of the composite film gradually decreases. The photoelectric conversion efficiency of the composite film decreases with the increase of BFO content, and the maximum photoelectric conversion efficiency is 5.63 × 10−5% when the composition is 3BFO/7CFO. The maximum photomagnetic dielectric response is found when the composition of the film is 5BFO/5CFO. [ABSTRACT FROM AUTHOR]