Microstructure, Magnetodielectric, and Multiferroic Properties of xCo0.8Cu0.2Fe2O4-y (0.8BaTiO3-0.2BiAlO3) Composite Ceramics

Herein, xCo(0.8)Cu(0.2)Fe(2)O(4-y )(0.8BaTiO(3)-0.2BiAlO(3)) [xCCFO-y(BTO-BA)] (x = 0, y = 1; x = 1, y = 1; x = 1, y = 2; x = 1, y = 4; x = 1, y = 6) magnetoelectric composite ceramics are synthesized by solid-state method. The effects of composition on the microstructure, dielectric, ferroelectric and magnetic properties are systematically investigated. Two-phase structures were confirmed by X-ray diffraction patterns, which correspond to (BTO-BA) and CCFO phases; a little impurity can be found, and this low-concentration secondary phase is indexed as BaFe12O19. By scanning electron microscopy, it is found that all the samples show a uniform and relatively dense surface, while the grains show two different kinds of shapes and sizes, which are related with ferroelectric-phase BTO-BA and magnetic-phase CCFO. The average grain size of BTO-BA is approximate to 0.47 mu m, and that of CCFO increases with increasing concentration of BTO-BA, and the size of BTO-BA is suppressed with the addition of CCFO. With decreasing the concentration of CCFO, the composites show more and more obvious magnetodielectric effect. The Curie temperature of BTO-BA ceramics is around 150 degrees C, but this value increases (higher than 150 degrees C) with the addition of CCFO, implying practical application in high-temperature devices. The ferroelectric properties of composite ceramics can be optimized by adding BTO-BA.