Magnetoelectric Effect in Cofired Lead‐Free Laminated (Bi0.5Na0.5TiO3‐Bi0.5K0.5TiO3)/(Ni0.8Zn0.2)Fe2O4Composites

Lead‐free magnetoelectric (ME) laminated (80Bi0.5Na0.5TiO3‐20Bi0.5K0.5TiO3)/(Ni0.8Zn0.2)Fe2O4(BNKT/NZFO) composites are prepared via a modified cofiring processing, combining grain refinement and liquid phase sintering with low sintering aid content. The microstructure, dielectric, ferroelectric, magnetic, and magnetoelectric properties are investigated by varying the thickness of NZFO layer. The results show that the coexistence of independent BNKT and NZFO phase and the presence of the morphotopic phase boundary in BNKT phase with high piezoelectric coefficient d33of 131 pC/N are confirmed. Laminated composites have clear and well‐bonded interfaces across the two layers, as well as improved ME properties. The maximum ME voltage coefficient (αE31) of the laminated composite reach 115.1 mV cm−1Oe−1with an optimized BNKT/NZFO layer thickness ratio of 1/2. In addition, a zero‐biased ME response was observed in BNKT/NZFO laminated composites. We propose the lead‐free cofired laminated magnetoelectric composites consisting of piezoelectric(80Bi0.5Na0.5TiO3‐20Bi0.5K0.5TiO3) and magnetostrictive (Ni0.8Zn0.2)Fe2O4. Well‐bonded interfaces and optimized layer thickness ratio provide the evidences for enhanced magnetoelectric coupling. The composite presents large voltage coefficient of 115.1 mV (cm · Oe)−1, which provides the promise for novel magnetoelectric device applications, such as transducers and sensors.