Magnetoelectric effect in two-layer composites with a graded magnetic phase

The samples of homogeneous ($x$ = 0; 0.1; 0.2) and multilayer ceramics with compositional gradient ($x$ =0.2 $\to$ 0.1 $\to$ 0 $\to$ 0.1 $\to$ 0.2) based on solid solutions of nickel – zinc ferrites (Ni$_{1-x}$Zn$_{x}$)Fe$_{2}$O$_{4}$ have been prepared by thick-film technology. The graded samples had smooth inhomogeneous distribution of chemical elements (Zn, Ni) throughout the thickness after sintering by the two-stage mode. The longitudinal ($\alpha_{E33}$) and transverse ($\alpha_{E31}$) magnetoelectric effects in bilayer PZT – nickel – zinc ferrite composites were studied. Magnetoelectric coefficients were not significant in the absence of an external constant magnetic field. The maximum value of the longitudinal magnetoelectric coefficient in composites with graded magnetic phase was almost two times higher than the value of $\alpha_{E33}$ in homogeneous structures.