Magnetoelectric properties of lead-free (80Bi_0.5Na_0.5TiO₃-20Bi_0.5K_0.5TiO₃)-Ni_0.8Zn_0.2Fe₂O₄ particulate composites prepared by in situ sol-gel

Lead-free multiferroic ceramics consisting of (1-x) (80Bi0.5Na0.5TiO3-20Bi0.5K0.5TiO3) (BNT-BKT)-xNi0.8Zn0.2Fe2O4 (NZFO) (x = 0, 0.15, 0.25, 0.35, and 0.45) were synthesized by the in situ sol-gel method. The structural, ferroelectric, piezoelectric, ferromagnetic, and magnetoelectric (ME) properties were measured as a function of the NZFO content x. The results showed that the coexistence of BNT-BKT and NZFO phases and the presence of the morphotropic phase boundary in the BNT-BKT phase with a high piezoelectric coefficient d33 (∼131 pC/N) were confirmed. The composites exhibited a homogeneous microstructure and well-combined interfaces between the magnetostrictive and piezoelectric phases, as well as an improved ME response. The largest ME voltage coefficient (αME) of 42.41 mV/cm Oe was achieved for the 0.65(BNT-BKT)-0.35NZFO composite, which is in fact the highest one reported so far for lead-free particulate ME composites fabricated via in situ processing.