Structural, magnetic and electrical properties of Co1-xZnxFe2O4 synthesized by co-precipitation method

Nanoparticles of Co1-xZnxFe2O4 with stoichiometric proportion (x) varying from 0.0 to 0.6 were prepared by the chemical co-precipitation method. The samples were sintered at 600 degrees C for 2h and were characterized by X-ray diffraction (XRD), low field AC magnetic susceptibility, DC electrical resistivity and dielectric constant measurements. From the analysis of XRD patterns, the nanocrystalline ferrite had been obtained at pH = 12.5-13 and reaction time of 45 min. The particle size was calculated from the most intense peak (3 1 1) using the Scherrer formula. The size of precipitated particles lies within the range 12-16 nm, obtained at reaction temperature of 70 degrees C. The Curie temperature was obtained from AC magnetic susceptibility measurements in the range 77-850 K. It is observed that Curie temperature decreases with the increase of Zn concentration. DC electrical resistivity measurements were carried out by two-probe method from 370 to 580 K. Temperature-dependent DC electrical resistivity decreases with increase in temperature ensuring the semiconductor nature of the samples. DC electrical resistivity results are discussed in terms of polaron hopping model. Activation energy calculated from, the DC electrical resistivity versus temperature for all the samples ranges from 0.658 to 0.849 eV. The drift mobility increases by increasing temperature due to decrease in DC electrical resisitivity. The dielectric constants are studied as a function of frequency in the range 100 Hz-1 MHz at room temperature. The dielectric constant decreases with increasing frequency for all the samples and follow the Maxwell-Wagner's interfacial polarization. (C) 2006 Elsevier B.V. All rights reserved.