Magnetic properties of a novel ceramic ferroelectric-ferromagnetic composite

A series of [0.8Pb(Ni1/3Nb2/3)O-3-0.2PbTiO(3)]/[(Ni0.2Cu0.2 Zn-0.6)Fe2O4] (PNNT/NiCuZn) ferroelectric-ferromagnetic composites were prepared by the conventional solid-state route. The composites show good co-firing behaviors. X-ray diffraction and scanning electron microscope studies confirmed the coexistence of ferroelectric PNNT phase and ferromagnetic NiCuZn phase in the composites. No significant chemical interaction has occurred between PNNT phase and NiCuZn phase. All sintered samples exhibit typical magnetic hysteresis loops at room temperature. The saturation magnetization of composites rises linearly with the increase in NiCuZn content. Frequency dependence of initial permeability was also measured. With an increase in NiCuZn, the initial permeability increases and the cutoff frequency tends to decrease. The Maxwell-Garnett (MG) effective medium theory was used to model the magnetic properties of composites. Although the MG equation cannot give an accurate prediction for the initial permeability of composites because of the oversimplified assumption, it gives upper and lower limits for the initial permeability of compositions.