High Magnetoelectric Coupling in Nano–Microscale Particulate Composites at Low Frequency

Nontoxic lead-free multiferroic magnetoelectric composites are successfully prepared by incorporating the dispersed Ni_0.98Co_0.02Fe₂O₄ (NCF) ferromagnetic nanoparticles into a (K_0.5Na_0.5)NbO₃−LiSbO₃ (KNN−LS) ferroelectric micromatrix. The dependence of the dielectric properties and dc magnetization on NCF phase content has been studied. Variation of dielectric constant and dielectric loss with frequency show dispersion in the low frequency range, and the dielectric constants decrease with the increase in ferrite NCF content. The magnetoelectric (ME) coupling effects including direct ME (DME) and converse ME (CME) effects are investigated in detail at room temperature. The results show that the NCF content significantly affects the ME effects. The CME and DME behaviors are strongly dependent on the driving field frequency and the bias magnetic field. High DME and CME coefficients are obtained at low frequency and at low magnetic bias field. The maximum value of DME and CME coefficients are 197.3 ps/m (12.2 mV⋅cm⁻¹⋅Oe⁻¹) and 314.7 ps/m, respectively.