Studies on magnetoelectric coupling in lead-free [(0.5) BCT-(0.5) BZT]-NiFe < inf > 2 < /inf > O < inf > 4 < /inf > laminated composites at low and EMR frequencies

Abstract

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.