Effects of Fe2+ on dielectric and magnetic properties in rare earth garnet type high entropy oxides

Given the important role played by the valence state of the transition metal in determining material this paper investigates the effect of Fe2+ content on the structure and dielectric properties of garnet-structured high entropy oxides (Y0.2Eu0.2Er0.2Dy0.2Lu0.2)3(Al0.5Fe0.5)5O12 through Fe2+ doping. The results of XPS and Mӧssbauer spectra showed that the Fe2+ content in the tetrahedron increased with Fe2+ doping. With increasing Fe2+ content, the dielectric constants gradually increased, and the maximum dielectric constant reached 2.78×104 at 100 Hz under 30ºC. The analysis of the AC impedance spectrum and electrical conductivity revealed that the difference between the activation energy of grain boundary and grain conductivity resulted in increased dielectric constants of the samples. In addition, the doping of Fe2+ increased the maximum magnetization of the samples. This work provides a new idea for designing giant dielectric materials and magnetic materials with a high entropy strategy.