Effect of Mn/Co substitutions on the resistivity and dielectric properties of nickel–zinc ferrites

Nickel-zinc ferrite nanoparticles with suitable chemical modifications by Mn or Co substitutions for Zn as two systems (namely, Ni–Zn–Mn and Ni–Zn–Co) were synthesized by sol-gel autocombustion method. X-ray diffraction measurements on the synthesized nanoparticles confirm that the samples attain single phase cubic spinel structures only. The powders were then used to obtain pellets in desired dimensions by employing usual ceramic procedure for carrying out measurements of resistivity and dielectric properties. The variations of dc resistivity as a function of composition and temperature, and the corresponding variation of activation energies for both the systems are presented and discussed. Also, the results of dielectric constant as a function of substituent concentration, dielectric dispersion and dielectric loss tangent are discussed. Effect of Mn/Co substitutions in Ni–Zn ferrites and possible mechanisms responsible for variations in resistivity and dielectric properties of both the ferrite systems have been evolved independently. Also, comparison of the trends between the dielectric constant and the resistivity with substituents’ concentration and their inter-relation with conduction mechanisms has been thoroughly analyzed for both the ferrite systems.