Multiferroicity and magnetoelectric coupling in ferrite-ferroelectric particulate ceramics

Nontoxic lead-free magnetoelectric ceramics were successfully prepared by incorporating the dispersed ferromagnetic Ni-ferrite particles into (K_0.5Na_0.5)NbO₃-based ferroelectric matrix. The multiferroicity of the ceramics were verified by P-E loops and magnetic hysteresis loops. Dielectric properties and magnetoelectric coefficients as a function of frequency were measured in the range of 100 Hz to 100 kHz. The relative dielectric constant, loss tangent and magnetoelectric coefficients decrease rapidly with very high values at lower frequencies and decrease slowly with very low values at higher frequencies. The dependence of the magnetoelectric effects on dc bias magnetic field shows that both the direct and converse magnetoelectric effects increases initially with the increase in magnetic field and then decreases with the further increase in the field. It is still observed that the frequency and field dependence of direct and converse magnetoelectric effects display almost the same behaviors.