Microstructure, Magnetodielectric, and Multiferroic Properties of xCo_0.8Cu_0.2Fe₂O_4−y(0.8BaTiO₃–0.2BiAlO₃) Composite Ceramics

Abstract

Herein, xCo 0.8 Cu 0.2 Fe 2 O 4Ày (0.8BaTiO 3 -0.2BiAlO 3 ) [xCCFO-y(BTO-BA)] (x ¼ 0, y ¼ 1; x ¼ 1, y ¼ 1; x ¼ 1, y ¼ 2; x ¼ 1, y ¼ 4; x ¼ 1, y ¼ 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 BaFe 12 O 19 . 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 %0.47 μm, 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 C, but this value increases (higher than 150 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.