Dielectric and Ferroelectric Properties of In Situ Synthesized Co(Fe1−xMnx)2O4/BaTiO3 Composite Ceramics

Magnetoelectric composite materials have attracted increasing attention because of their coupling between ferroelectricity and ferromagnetism. In this work, a new method has been used to prepare composite ceramics. Ferromagnetic phase Co(Fe1−xMnx)2O4 (x = 0.2, 0.4, 0.6, 0.8) with porous surfaces were prepared by annealing a metal organic framework (MOF) precursor (Fe1−xMnx)3[Co(CN)6]2·nH2O, and the ferroelectric phase BaTiO3 was grown in situ in the pores of Co(Fe1−xMnx)2O4 by a hydrothermal method. The structure, dielectric and ferroelectric properties of Co(Fe1−xMnx)2O4-BaTiO3 composite ceramics have been comparatively studied. XRD results indicate that with the increase of x, the crystalline structure of the ferromagnetic phase changes from CoFe2O4 (x = 0.2, 0.4) to CoMn2O4 (x = 0.6, 0.8) and SEM results show that the compactness of ceramics is better with increasing x. Because the conductivity of CoMn2O4 is far larger than that of CoFe2O4, the dielectric and ferroelectric properties of composite ceramics with x = 0.2 and 0.4 are better than that of x = 0.6 and 0.8. With the increase in the ratio of ferromagnetic and ferroelectric phases, the compactness of the ceramics was enhanced. Meanwhile, due to the higher conduction loss and leakage current of the ferromagnetic phase, the dielectric and ferroelectric properties of composite ceramics weaken with the increase of the ferromagnetic phase.