Abstract:
MnFe2O4
is one of the iron-based cubic spinel ferrites possessing both magnetic and
electrical properties. In this study, Ni
2+
and Zn
2+
substituted Mn
0.5
Ni0.5-x
Znx
Fe2O4
(where x = 0.05 and 0.1) ferrites are prepared by a solid state reaction method. These ferrites
are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM),
Fourier transform infrared (FT-IR) spectroscopy and complex impedance spectroscopy.
X-ray diffraction patterns of the two samples confirms partial substitution of Ni
2+
and Zn
+2
ions for Mn
2+
ions does not change the basic structure of MnFe
2O4
. It also provides
information about the formation of a single phase spinel structure. The SEM images of the
Mn0.5
Ni0.5-x
Znx
Fe2O4
(where x = 0.05 and 0.1) ferrites reveals that the material synthesized
by solid state reaction method contain agglomerated particles as well as some small particles
are observed in addition to the large particles, which is commonly observed from materials
prepared by solid state reaction method. FT-IR analysis confirms the formation of vibrational
frequency bands associated with the entire spinel structure. The IR spectra of both ferrites
show two clear and sharp absorption bands in the range of 414.28 – 561.04 cm
−1
. And the
two-strong absorption band, which confirms the presence of M-O (Mn, Ni, Zn, Fe) stretching
band in both synthesized ferrites.
From the impedance analysis, it is found that the real and imaginary parts of impedance
values are typically higher at low frequencies and lower at high frequencies. The AC
conductivity analysis confirms that the conduction mechanism is due to small polaron
hopping and follows Jonscher’s law. Dielectric properties, namely dielectric constant (ε′), are
measured at variable temperature using impedance analyzer in the frequency range from 1
kHz to 1 MHz. Both the samples show usual dielectric dispersion which is due to the
formation of interfacial polarization.
