Study of the dielectric behavior of Co-Ni-Li nanoferrites

The ac conductivity and dielectric properties of Co0.5Ni0.5−2xLixFe2+xO4 nanoparticle ferrite samples (from x=0.00 to 0.25 in step of 0.05) synthesized by the citrate precursor method were studied by using a complex impedance technique. The effect of varying the frequency, temperature and composition on ac conductivity, dielectric constant and dielectric losses was discussed and justified in terms of hopping of charge carriers between Fe+3 and Fe+2 ions, Ni+2 and Ni+3 ions and Co+2 and Co+3 ions. The obtained results of the variation of S parameter with temperature show that the classical barrier hopping model is the most probable mechanism in the samples under investigation. While the results of the Cole-Cole diagrams of M″ vs. M′ at different temperatures ensure the presence of grain and grain boundaries having different but comparable conductivities in the investigated nanoparticle samples and also indicate that the studied ferrites exhibit the so called “electric stiffness”.