Dielectric and magnetoelectric characterization of CoFe2O4/Ba0.55Sr0.25Ca0.2Nb2O6 composites

(1 − x)CoFe2O4/xBa0.55Sr0.25Ca0.2Nb2O6 magnetoelectric (ME) composites were prepared and characterized. Co-presence of two end-members was confirmed by SEM and X-ray diffraction analysis. A very high dielectric constant was obtained at low frequencies and an interesting temperature dependence of dielectric constant was observed in the present composite ceramics. All composites after post-densification annealing in oxygen could be electrically and magnetically poled to exhibit significant magnetoelectric effect. The ME effect of the composites was greatly dependent on the frequency of ac magnetic field. With increasing frequency, the magnetoelectric coefficient dE/dH increased firstly and then decreased. dE/dH also depended on the dc bias magnetic field. The highest dE/dH value of 9.51 mV/cm/Oe was observed in 0.2CoFe2O4/0.8Ba0.55Sr0.25Ca0.2Nb2O6 composites under 1 kOe and at 90 kHz.