Anomalous electrical properties of nanocrystalline Ni–Zn ferrite

Nanocrystalline powders of Ni–Zn ferrite (NZFO) having the chemical formula Ni_xZn_1−xFe₂O₄, where x varies as 1, 0.8, 0.6, 0.4, 0.2, and 0, were synthesized by chemical co-precipitation technique. The samples synthesized were characterized by X-ray diffraction (XRD) technique at several stages. As prepared samples at room temperature show absence of Bragg peak indicating that there was no crystalline phase formation of ferrite. The XRD pattern of the samples sintered at 400 °C clearly showed the characteristic Bragg peaks of spinel cubic structure. XRD patterns were further analyzed to calculate the lattice constant, porosity, and jump length of charge carriers. Electrical dc resistivity measurements were carried out with respect to temperature using two probe method. NZFO samples showed abnormal electrical behavior at room temperature. Also abnormal electrical behavior with increase in temperature in the range 600–800 K was observed. Variation of dielectric constant and loss tangent with frequency were studied at room temperature. The electrical and dielectric behavior of the Ni–Zn samples is discussed in the light of literature.