Ni-Zn ferrites, with the general formula Ni1-xZnxFe2O4 (x = 0.0, 0.3, 0.5,
0.7, 1.0), CoFe2O4, BaTiO3 and PbZr0.52Ti0.48O3 powders were synthesized by
auto-combustion method. The composites were prepared by mixing the
appropriate amounts of individual phases, pressing and conventional
sintering. X-ray analysis, for individual phase and composites, indicated
the formation of crystallized structure of NiZnFe2O4, BaTiO3 and
PbZr0.52Ti0.48O3 without the presence of secondary phases or any impurities.
SEM analyses indicated a formation of uniform grain distribution for
ferromagnetic and ferroelectric phases and formation of two types of grains,
polygonal and rounded, respectively. Magneto-dielectric effect was exhibited
in all samples because of the applied stress occurring due to the
piezomagnetic effect and the magnetic field induced the variation of the
dielectric constant. For all samples the dielectric constant was higher in
applied magnetic field. At the low frequency, the dispersion of dielectric
losses appeared, while at the higher frequency the value of tan ? become
constant (Maxwell-Wagner relaxation). Investigation of J-E relation between
leakage and electric field revealed that both nickel zinc ferrite and
composites have three different regions of conduction: region with ohmic
conduction mechanism, region with the trap-controlled space charge limited
current mechanism and region with space charge limited current mechanism.
Magneto-dielectric properties of ferrites and ferrite/ferroelectric multiferroic composites