Preparation And Properties Of (Ni_0.8Zn_0.1Cu_0.1)Fe₂O₄/Pb(Ni_1/3Nb_2/3)O₃-Pb(Zn_1/3Nb_2/3)O₃-PbTiO₃ Magnetoelectric Ceramic Compo

Magnetoelectric ceramic composites (Ni0.8Zn0.1Cu0.1)Fe2O4/Pb(Ni1/3 Nb2/3)O3-Pb(Zn1/3Nb2/3)O3-PbTiO3 (NZCF/PNN-PZN-PT) composed of rhombohedral and tetragonal perovskite ferroelectrics with the composition around the morphotropic phase boundary (MPB) and ferrite were prepared by conventional ceramic processing. The influences of sintering conditions and the phase structure of ferroelectrics on the phase composition, microstructure, electrical properties and magnetoelectric property of the magnetoelectric ceramic composites were investigated. The effect of WO3 sintering additive on the sintering capability, phase structure and magnetoelectric property was also discussed. It is found that the addition of WO3 in the ferroelectric phase decreases sintering temperature of the magnetoelectric ceramics greatly from 1180℃to 950℃. X-ray diffraction (XRD) measurement, scanning electron microscope (SEM) observation and energy dispersive X-ray analysis (EDX) indicate that the ferroelectric phase and the ferrite phase coexist in the sintered ceramic composites, where no additional intermediate phases are observed. Dielectric properties and magnetoelectric property of the (1-x)NZCF/xPNN-PZN-Pb(Ni1/2W1/2)O3-0.40PT((1-x)NZCF/xPNN-PZN-PNW-0.40PT) ceramic composites are improved greatly as compared to those of the undoped (1-x)NZCF/xPNN-PZN-0.40PT ceramic composites. However, with the increase of the ferrite content, electrical and magnetoelectric properties of the sintered ceramic composites deteriorate. A maximum magnetoelectric voltage coefficient of 13.1 mV/cm/Oe is obtained in the 0.1NZCF /0.9PNN-PZN-PNW-PT ceramic composite at 400 Oe d.c. bias magnetic field superimposed 1 kHz a.c. magnetic field. The addition of 5 mol% WO3 in the ferroelectric phase can decrease sintering temperature of the ceramic composites greatly, therefore, dielectric loss of the sintered ceramic composites decreases sharply leading to the increase of the magnetoelectric voltage coefficient. Due to the difference of composition and phase structure of the ferroelectrics, electrical and magnetoelectric properties of the (1-x)NZCF/xPNN-PZN -PNW-0.35PT and (1-x)NZCF/xPNN-PZN-PNW-0.45PT magnetoelectric ceramic composites exhibit different values. From the results of the magnetoelectric property of the (1-x)NZCF/xPNN-PZN-PNW-PT ceramic composites, it is found that the magnetoelectric coefficient of the ceramic composites is correlated with the piezoelectric property of the magnetoelectric ceramic composites. The larger the value of piezoelectric constant d33 of the ceramic composites has, the bigger the magnetoelectric coefficient will be.