Z Rastegar Mogaddam Gohari - Department of physics, Ferdowsi University, Mashhad
Mohammad Behdani - Department of physics, Ferdowsi University, Mashhad
M Rezaee Roknabadi - Department of physics, Ferdowsi University, Mashhad
A Shakhsi Tavakolian - Exir house of knowledge business engineering company, Mashhad

In this research, we study the structural and magnetic properties of Co1-xZnxFe2O4 (x=0.3, 0.5, 0.7). Thesample was prepared from aqueous salt solutions with respective stoichiometry in an alkaline medium by the coprecipitationmethod. The powder samples were characterized by XRD, Transmission Electron Microscopy (TEM),Fourier transform infrared spectroscopy (FTIR) and Vibrating Sample Magnetometer (VSM). XRD analysis showedthat the sample was single-phase and had the cubic spinel structure in the Fd3m space. With the increase in zincsubstitution, particle size and lattice constant were found to decrease and increase, respectively. In order to preparethe ferrofluild, the precipitated particles were coated with oleic acid and dispersed in kerosene. Magnetic studiesindicated that nanoparticles are super-paramagnetic at room temperature. One of the unique features of this ferrofluidis that, when subjected to an external magnetic field, the fluid increased its apparent viscosity to the point ofbecoming a viscoelastic solid. So we used this in a smart shock absorber. The Mahameter analysis indicated that thisferrofluid has high efficiency in damping vibrations.

Co-Zn ferrite nanoparticles, co- precipitation, super paramagnetic nanoparticles