Novel magnetoelectric composites of cobalt iron alloy and barium titanate

Magnetoelectric barium titanate ceramics with embedded cobalt iron alloy particles (Co 1/3 Fe 2/3 ) x –(BaTiO 3 ) (1− x ) , with x =0.2, 0.4, and 0.6, were prepared by a polyol‐mediated synthesis with subsequent sintering in a reducing forming gas atmosphere. The samples were characterized by XRD and SEM / EDX measurements. The sizes of the Co 1/3 Fe 2/3 grains increase with x . Impedance spectroscopy showed a behavior similar to pure BaTiO 3 , in particular the occurrence of the ferroelectric‐paraelectric phase transition, and high permittivities for the sample with x =0.6, that is, near the percolation threshold. The samples exhibit soft ferromagnetic properties with large saturation magnetizations of 2.5 μ B /atom and narrow hystereses. Detailed magnetoelectric investigations revealed a unique DC ‐field dependence of α ME for all three compositions. Most remarkably, the sample with x =0.4 possesses a broad ME hysteresis and an inversion of the sign of α ME at 5 kO e.