Abstract:
Synthesis and characterization of nanoparticles, which is less than 100 nm ferrite materials
have gained much attention in recent years because of their unique properties and potential
for many applications such as magnetic storage systems, magnetic resonance imaging,
spintronics etc. Cu substitute Co
0.7-x
Ni0.3
Cux
Fe2O4
for x = 0.05 and 0.1 ferrite materials are
successfully synthesized by sol-gel method processing at pH value of 7. The synthesized
ferrites are annealed at a temperature of 800 °C for 8 hrs. The structure, chemical
composition, electrical and dielectric properties of both ferrites are characterized by the x-ray
powder diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Fourier transform
infrared (FT-IR) spectroscopy and complex impedance spectroscopy (CIS).
XRD analysis reveals that both ferrites show cubic spinel structure with space group Fd3m.
The lattice parameter decreases from 8.447Å to 8.441 Å with increasing Cu content from x =
0.05 to x = 0.1. The average crystallite sizes of the synthesized samples are determined by
using the X-ray analysis broadening of the (311) diffraction peak by using Debye-Scherrer’s
formula and it is found in the values of 72 and 70.90 nm. The elemental analysis as obtained
from the EDX measurement indicates the quantitative presence of Co, Ni, Cu, Fe and O in
the synthesized samples. It also confirms the absence of impurities in Co
0.65
Ni0.3
Cu0.05
Fe2O4
and Co
0.6
Ni0.3
Cu0.1
Fe2O4
ferrite samples. The FT-IR spectra show the tetrahedral stretching
vibration modes of Co0.65
Ni0.3
Cu0.05
Fe2O4
and Co0.6
Ni0.3
Cu0.1
Fe2O4
ferries. The two strong
frequency bands appeared at wavenumber 569.02 and 572.90 cm
−1
are responsible for the
formation of Co
0.65
Ni0.3
Cu0.05
Fe2O4
and Co
0.6Ni0.3
Cu0.1
Fe2O4
ferrites, respectively.
From the electrical and dielectric properties studies, it is found that the value of the dielectric
constant as well as the real impendence of both samples decreases exponentially with an
increasing frequency due to interfacial polarization. For the case of conductivity, the effect of
the variation of frequency on the electrical conductivity of both synthesized sample are
identified. Their conduction mechanism is explained on the basis of hopping of charge
carriers between Fe
2+
- Fe
3+
ions on octahedral sites.
