Structural and electrical properties of Cu substituted Ni-Cd nanoferrites for microwave applications

A series of Ni0.7-xCuxCd0.3Fe2O4 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) were synthesized by sol-gel auto combustion technique. The X-ray diffraction (XRD) analysis confirms the creation of cubic spinel structure of single-phase ferrites with crystallite size from 11 to15 nm. The lattice constant and grain size of the ferrite nanoparticles are found to increase with Cu content. The dielectric study of the materials at room temperature unveils a typical dispersion behavior in the lower frequency region (20 Hz - 1 KHz) and the dielectric constants remain constant at higher frequencies. The minimum loss tangent of ~0.019 at 13 MHz is found in the composition of x = 0.1. Both the complex impedance and electric modulus analysis confirms the presence of non-Debye type of relaxation phenomenon in the prepared ferrites. The ac conductivity bands suggest the hopping type of conduction and the ionic conduction relaxation mechanism in the investigated materials.