Abstract:
Magnetic spinel ferrites are important materials owing to their outstanding electrical and
magnetic properties. Their distinctive qualities such as high electrical resistivity, high
permeability and negligible eddy current losses for high-frequency electromagnetic wave
propagation make them suitable for many technological applications. In this study,
ZnFe2O4 and Zn0.9Cu0.05Mg0.05Fe2O4 nanoferrite materials were synthesized by sol-gel
combustion method. The effect of Cu2+and Mg2+ for Zn2+
substitution on thermal
structural, optical, electrical and dielectric properties of ZnFe2O4 were investigated using
thermogravimetric analysis (TGA), differential thermal analysis (DTA), x-ray powder
diffraction (XRD),Ultra violet visible (UV-Vis) spectroscopy, Fourier-transform infrared
(FT-IR) spectroscopy and Impedance spectroscopy (IS).
From TGA/DTA analysis, compound formation, temperatures as well as the weight loss
regions were identified. The XRD results confirmed that all XRD peaks appeared from
both ferrites were very sharp and well-defined, which indicates a high crystallinity of both
compounds. The average crystal sizes were found to be 48.31nm and 48.65 nm for
ZnFe2O4 and Zn0.9Cu0.05Mg0.05Fe2O4, respectively. This confirmed that the substitution
of Cu and Mg cations into ZnFe2O4 causes an increase in crystal size. In FT-IR study, two
strong absorption bands between metal-oxygen ions were identified in both compounds.
These absorption bands revealed the formation of the cubic spinel structure, which is in
agreement with XRD results of the compounds. The optical band gap values were found to
be 2.78ev and 2.7eV for ZnFe2O4 and Zn0.9Cu0.05Mg0.05Fe2O4ferrites, respectively. At
room temperature, the complex-plane impedance analysis and the effect of frequency on
the impedance and dielectric properties were also investigated in this study. The real and
imaginary impendence for both compounds were found to decrease with increase in
frequency. It was also found that the dielectric constant decreases continuously with
increasing frequency and becomes constant at higher frequency regions, which indicates
that the major contribution to the polarization comes from orientation polarization.
