Abstract:
Magnetoelectric (ME) composites with nominal chemical compositions
(y)Mn0.45Ni0.05Zn0.50Fe2O4+(1-y)BaZr0.52Ti0.48O3 ( where y = 0.00, 0.20, 0.40, 0.60, 0.80 and
1.0) were prepared by a standard solid state reaction technique. The aim of this research is
to develop magnetoelectric composites consisting of piezoelectric and magnetostrictive
components. Barium-zirconium-titanate (BZT) was selected as piezoelectric phase and
manganese-nickel-zinc (MNZ) ferrite as magnetostrictive phase for these composites. The
properties of component phases were optimized in order to enhance the ME effect in the
composite. X-ray diffraction (XRD) patterns confirm the presence of the constituent phases,
i.e. ferroelectric and ferrite phases in the composites. XRD analysis also confirms cubic
spinel structure with lattice constant 8.4441 Å and tetragonal perovskite structure with lattice
constants a = 4.1132 Å and c = 4.1144 Å. The maximum bulk density for tetragonal
peroveskite structure is 5.37 g-cm-3 while for cubic spinel structure is 4.01 g-cm-3 for the
composites sintered at 1300 ºC temperature . ME effect is resistivity–dependent property.
The maximum ME voltage coefficient viz. 50.51 mV/cm.Oe is observed for the composite
containing 20% ferrite sintered at 1300 ºC. The resonance frequency, fr, increases with
increasing ferrite content, which is observed from the admittance spectra. The maximum
dielectric constant viz. 4429 is observed at frequency 20 Hz for the composite containing
80% ferrite sintered at 1150 ºC. The dielectric loss is high at low frequency and that is low
above 1 MHz. The maximum conductivity viz. 1.9x10-5(Ω-cm)-1 is observed at frequency 20
Hz for the sample of 80% ferrite content sintered at 1300 ºC. Real part of the initial
permeability , μi
/, for all composites increases with increasing ferrite content and also
increases with increasing temperature up to 1300 ºC and thereafter decreases. The magnetic
loss is high for ferrite and low for composites at high frequency.
