Abstract
Spinel ferrite having composition Ni0.5Mg0.3Cu0.2Fe2O4 was prepared by the sol-gel technique at 1473 K. The X-ray diffraction results indicate that the ferrite sample has a cubic spinel-type structure with Fd (3) over barm space group. The electrical properties of the studied sample using complex impedance spectroscopy technique have been investigated in the frequency range 10(2)-10(7) Hz and in the temperature range 300-500 K. The total conductivity curves for sample are found to obey Jonscher power law (sigma(omega) = sigma(dc) + A omega(n)) with an increase in the frequency exponent (n) as temperature increases. The activation energy deduced from the analysis of the conductivity curves matches very well with the value estimated from the relaxation time, indicating that relaxation process and electrical conductivity are attributed to the same defect.
Nyquist plots of impedance show semicircle arcs for sample, and an electrical equivalent circuit has been proposed to explain the impedance results. The effect of frequency and temperature on dielectric constant (epsilon '') and dielectric loss (tan delta) has also been discussed in terms of hopping of charge carriers between Fe2+ and Fe3+ ions.