preparation of surface modified magnetic iron oxide nanoparticles and study of their colloidal behavior

in this work, we report synthesis of surface modified superparamagnetic iron oxide nanoparticles (spion) by co-precipitation method using feso4.7h2o and fe2(so4)3.5h2o as precursors and trisodium citrate dihydrate as surfactant. surface modification of the as prepared samples was performed in pot by sol-gel precipitation method using tetraethoxysilane (teos). the structure, morphology, and magnetic properties of the products were characterized by x-ray powder diffraction (xrd), scanning electron microscopy (sem), fourier transform infrared spectroscopy (ft-ir), and vibrating sample magnetometer (vsm) at room temperature. the results revealed formation of iron oxide nanoparticles, with an average size parameter of 8.5 nm for naked and 37nm for silica coated particles, with a superparamagnetic behavior and fast response to applied magnetic fields with zero remanence and coercivity.