Effects of Co Substitution on the Microstructural, Infrared, and Electrical Properties of Mg_{0.6 − x}Co _xZn_0.4Fe₂O₄ Ferrites

Spinel ferrites having Mg_{0.6 − x}Co_xZn_0.4Fe₂O₄ (0 ≤ x ≤ 0.6) compositions were prepared using the sol–gel method. XRD patterns show that samples have the cubic phase of the spinel ferrite with the Fd3 ̄ m space group. The obtained values of the lattice constant and porosity increase with increasing cobalt concentration. FTIR spectra show only the tetrahedral stretching peaks that are shifting towards higher frequencies with increasing Co content. The substitution of Mg by Co leads to the decrease of conductivity of the samples. The behaviors of the real part of permittivity and loss tangent have been investigated using Maxwell theory. Electrical modulus and impedance results show the presence of the electrical relaxation phenomenon for the samples with non-Debye type. The Nyquist representations have been analyzed using a proposed electrical circuit, and the results show that the resistances of the prepared samples resulted mostly from the grain boundary effect.