Effects of Sintering Temperature on Microstructural, Magnetic, and Impedance Spectroscopic Properties of Ni_0.4Cd_0.3Zn_0.3Fe₂O₄ Ferrites

Ni_0.4Cd_0.3Zn_0.3Fe₂O₄ ferrites have been prepared through the use of sol-gel method at 900 °C and 1100 °C. Rietveld refinements of XRD patterns indicate that the prepared samples crystallize in the cubic spinel structure. Lattice constant and grain size are found to increase with sintering temperature. Magnetic measurements show that the maximum magnetization (M_s) rises, whereas both coercivity (H_c) and remanence (M_r) decrease when increasing the sintering temperature. Frequency and temperature dependence of electrical conductivity, electrical modulus, and electrical impedance have been studied using impedance spectroscopy technique. As the sintering temperature increases, the conductivity of the samples increases. The variation of imaginary part of modulus (M″) displays the presence of an electrical relaxation phenomenon and non-Debye nature. Nyquist representations have been analyzed using an electrical equivalent circuit. The obtained results reveal that the conduction mechanism of the samples is achieved basically of the grain boundary contribution.