Studies on magnetoelectric coupling in lead-free [(0.5) BCT-(0.5) BZT]-NiFe2O4 laminated composites at low and EMR frequencies

The possibility of achieving significantly higher magnetoelectric (ME) coupling in lead-free [(0.5)BCT-(0.5)BZT]/NiFe2O4 and NiFe2O4/[(0.5)BCT-(0.5)BZT]/NiFe2O4 laminates, processed by epoxy bonding using 1 mm -thick [(0.5)BCT-(0.5)BZT] and NiFe2O4 layers was reported. The effect of coupling modes in these bi- and tri-layer laminates was investigated through evaluating transverse (αE,31) and longitudinal (αE,33) ME coefficients both at low (1 kHz) and at electromechanical resonance frequencies (300-380 kHz) under external bias field. Measurements on frequency dependence of ME coefficients revealed resonance enhancement due to bending and radial acoustic modes. A maximum ME response of 0.98 and 1.1 V/cm⋅Oe was obtained for the [(0.5)BCT-(0.5)BZT]/NiFe2O4 and NiFe2O4/[(0.5)BCT-(0.5)BZT]/NiFe2O4 composites, respectively at the radial mode resonance, and these finding are explained on the basis of mechanical coupling exists at the interfaces of [(0.5)BCT-(0.5)BZT] and NiFe2O4 phases.