Magnetic and electrical properties of Co1-x Ca-x Fe2O4 nanoparticles synthesized by the auto combustion method

Nano-sized particles of Co-1 x Ca-x Fe2O4 (x = 0.0, 0.01, 0.03, 0.05, 0.07 and 0.09) have been prepared by using the citrate-nitrate auto combustion method. X-Ray diffraction analysis has ensured the formation of the desired ferrites and has been used also to determine some of their structural properties. The particle size of only three samples has been checked out by using both transmission electron microscope (TEM) and particle size analyzer (PSA). Magnetic measurements have been performed by using vibrating sample magnetometer (VSM) at room temperature. The reduction of saturation magnetization of the nano-structured samples in comparison to bulk samples in literature and the effect of Ca addition on saturation magnetization and coercivity of all the samples are discussed. The AC conductivity and dielectric properties of these spinel ferrite nanoparticles have been investigated too as function of frequency at room temperature by using a broadband dielectric spectrometer. The AC conductivity of all the samples has been found to increase with increasing Ca substitution. This behavior is interpreted according to a suggested cationic distribution in agreement with literature and in consistency with the dielectric and loss factor results. (C) 2012 Elsevier B.V. All rights reserved.