Structural and electrical properties of Cu doped NiFe2O4 nanoparticles prepared through modified citrate gel method

Nanoparticles of polycrystalline NiFe2-xCuxO4 (0.0 <= x <= 0.05) ferrites were prepared through the modified citrate-gel method. The samples were obtained as dried gel after the successful chemical reaction of their respective metal nitrate solutions in the midst of citric acid as catalyst. X-ray diffraction (XRD) and selective area electron diffraction (SAED) confirmed the single phase nature of all the samples with an average particle size of 19.8 ( +/- 1). Fourier transformation infrared spectroscopy (FTIR) shows the presence of two broad vibrational bands between 400 and 1000 cm(-1) corresponding to the tetrahedral and the octahedral sites. The variation of dielectric properties (epsilon', epsilon '', tan delta) and ac conductivity (sigma(ac)), with frequency reveals that the dispersion is due to the Maxwell-Wagner type of interfacial polarization in general and due to hopping of charges between Fe+2 and Fe+3 as well as between Ni+2 and Ni+3 ions at B-sites. The complex impedance spectroscopy has been used to study the effect of grain and grain boundary on the electrical properties of all the ferrite nanoparticles. (C) 2011 Elsevier Ltd. All rights reserved.