Spinel ferrites of the composition Ni1xCuxFe2O4 (x = 0.0–1.0) have been prepared through the thermal
decomposition of their respective impregnated oxalates. The oxalate decomposition process was followed
using differential thermal analysis–thermogravimetry techniques (DTA–TG). The synthesized
nanocrystallites were characterized using X-ray diffraction (XRD), transmission electron microscopy
(TEM) and Fourier transform infrared spectroscopy (FT-IR). The formation of single-phase ferrite is confirmed
by XRD. Tetragonal deformation is observed for samples with composition x 0.7. The increase in
the lattice parameter with increasing Cu content can be explained based on the relative ionic radius. The
TEM image shows spherically non-agglomerated particles with an average crystallite size that agrees well
with that obtained from XRD. FT-IR studies show two absorption bands (m1 and m 2) near to 600 and
400 cm1 for the tetrahedral and octahedral sites, respectively. The hysteresis measurements were done
using a vibrating sample magnetometer (VSM). The cation distribution in these compositions is calculated
from the magnetization data. With increasing Cu content, the saturation magnetization (Ms) was
observed to decrease while the coercivity (Hc) increases. The possible reasons responsible for the composition
dependence of the magnetic properties were discussed. The Curie temperature, measured through
the temperature dependence of the dc-molar magnetic susceptibility, was found to decrease with
increasing Cu content. |
