%0 Journal Article
%T Magnetic and Structural Studies of CoFe2O4 Nanoparticles Suspended in an Organic Liquid
%A Branka Babi£¿-Stoji£¿
%A Vukoman Jokanovi£¿
%A Du£¿an Milivojevi£¿
%A Zvonko Jagli£¿i£¿
%A Darko Makovec
%A Nata£¿a Jovi£¿
%A Milena Marinovi£¿-Cincovi£¿
%J Journal of Nanomaterials
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/741036
%X We present a study of magnetic and structural properties of CoFe2O4 nanoparticles suspended in an organic liquid. Transmission electron microscopy shows that the nanoparticles have a narrow size distribution of average particle size 5.9 ¡À 1.0£¿nm. X-ray diffraction shows that the particles are of cubic spinel crystal structure. Dynamic light scattering measurements reveal the existence of an organic shell around the CoFe2O4 nanoparticles with an average hydrodynamic diameter of 14.4£¿nm. Coercive magnetic field at £¿K is found to be 11.8£¿kOe. Disappearance of the coercive field and remanent magnetization at about 170£¿K suggests that the CoFe2O4 nanoparticles are superparamagnetic at higher temperatures which is confirmed by the room temperature M£¿ssbauer spectrum analysis. Saturation magnetization of the nanoparticles of 80.8£¿emu/g(CoFe2O4) at 5£¿K reaches the value detected in the bulk material and remains very high also at room temperature. The cobalt ferrite nanoparticle system synthesized in this work exhibits magnetic properties which are very suitable for various biomedical applications. 1. Introduction Ferrofluids are stable colloidal suspensions of single domain magnetic particles in a carrier liquid. Stability of the magnetic colloid depends on the thermal contribution and on the balance between attractive and repulsive interactions. Magnetic dipole and van der Waals interactions have tendency to agglomerate the particles. In order to prevent agglomeration, the magnetic particles should be small enough (usually about 10£¿nm in size) and coated with a shell of an appropriate material. This coating can be a sufactant made of long chained molecules or ionic if it is an electric shell [1¨C3]. The particles are usually made of maghemite ¦Ã-Fe2O3, magnetite Fe3O4, and other ferrites of the type MFe2O4, where M = Mn, Co, Ni, Cu. The carrier liquid is usually an organic solvent or water. Ferrofluids respond to an external magnetic field. This enables the ferrofluid¡¯s location to be controlled through the application of a magnetic field. Ferrofluids have a wide range of applications. They can be used to improve the performance of loud speakers [2]. Ferrofluids are also used in high-speed computer disk drives to eliminate harmful dust particles or other impurities that can cause the data-reading heads to crash into the disks. In recent years, a lot of research work has been devoted to biomedical applications of ferrofluids. In magnetic resonance imaging (MRI), ferrofluids are used as contrast agents [3¨C5]. Ferrofluids specially designed can carry drugs to
%U http://www.hindawi.com/journals/jnm/2013/741036/