Electrical transport properties of V2O5-added Ni-Co-Zn ferrites

Abstract

Frequency-dependent dielectric constant, dielectric loss, AC conductivity values and complex impedance spectra of V2O5-added Ni-Co-Zn ferrites (Ni0.62Co0.03Zn0.35Fe2O4+ xV2O5, where x = 0, 0.5, 1 and 1.5 wt.%) have been investigated at room temperature. The dielectric properties of the samples follow the Maxwell-Wagner polarization model. An inverse relationship was found between dielectric constant and AC electrical resistivity for all the samples. The dielectric constants decreased with the addition of V2O5, while the electrical resistivities of V2O5-added Ni-Co-Zn ferrites are found to be larger than that of pure Ni-Co-Zn ferrite. The AC conductivity was reduced with the addition of V2O5to Ni-Co-Zn ferrite at lower-frequency region. However, AC conductivity shows a sharp increase at higher-frequency region, which could be attributed to the enhancement of electron hopping between the Fe2+ and Fe3+ ions in the ferrite matrix due to the activity of the grains. The complex impedance spectroscopy results through Cole-Cole/Nyquist plot have demonstrated a single semicircular arc. It indicates that conduction mechanism takes place predominantly through the grain/bulk property, which could be ascribed to the larger grain size of V2O5-added Ni-Co-Zn ferrites.