Dielectric and magnetic properties of BaTiO3 –NiFe2O4 multiferroic composites

Multiferroic composites with the general formula x BaTiO 3 –(1− x ) NiFe 2 O 4 ( x =0.5, 0.7, 0.8) were prepared by mixing chemically obtained nickel ferrite and barium titanate powders. Optimum processing parameters for a reduction of chemical reactions at the interfaces between ferroelectric-ferrite phases were found. The presence of the nickel ferrite and barium titanate single phases was detected by X-ray measurements. Good quality of the homogenized ceramics containing both phases was confirmed by use of scanning electron microscopy. Dielectric measurements showed the superposition of the multiple conductivity mechanisms responsible for the dielectric dispersion at frequencies up to 1 MHz. Calculated activation energies for DC conductivity showed the contribution of oxygen vacancies and Maxwell-Wagner related phenomena. Magnetic measurements of the composite materials were performed showing the coercivity increase and saturation of the magnetization moment decrease with the increase of barium titanate content.