Hysteretic magnetoelectric behavior of CoFeO-BaTiO composites prepared by reductive sintering and reoxidation

Magnetoelectric composites (CoFe 2 O 4 ) x -(BaTiO 3 ) 1− x with x = 0.1, 0.2, 0.3, 0.4 and 0.5 were prepared by a polyol mediated synthesis route. The densification step was performed in a reducing forming gas atmosphere at 1250 °C. Under these conditions Co 2+ and Fe 3+ are reduced to the corresponding metals and thus a reaction of these elements with the BaTiO 3 matrix is prevented. Reoxidation in air to CoFe 2 O 4 at a rather low temperature of 800 °C leads to samples free of secondary phases. While the course of the synthesis was monitored by TGA, XRD and photometric analysis, the final composites were characterized via SEM, EDX, impedance spectroscopy and magnetic and magnetoelectric (ME) measurements. All samples show pronounced ME hystereses and α ME maxima dependent on the H dc field sweep direction. The sample with x = 0.4 exhibits the highest maximum α ME of 420 μV Oe −1 cm −1 . Magnetoelectric composites (CoFe 2 O 4 ) x -(BaTiO 3 ) 1− x with x = 0.1, 0.2, 0.3, 0.4 and 0.5 were prepared by a polyol mediated synthesis route followed by reactive densification.