Synthesis and Characterization of Magnetic Nanoparticles

Abstract

Magnetic single-domain nanoparticles (quotsuperspins) are very interesting not only for potential applications, e.g. high density storage devices, but also for fundamental research in magnetism. In an ensemble of nanoparticles in which the interparticle magnetic interactions are sufficiently small, the system shows superparamagnetic (SPM) behavior as described by the Neel-Brown model. On the contrary, when interparticle interactions are non-negligible, the system eventually shows collective behavior, which overcomes the individual anisotropy properties of the particles. In order to address the effect of interactions, we have investigated two different multicomponent magnetic nanoparticles systems (Coo.sZno.sFe204 and NiesZno.sFe204) newlineThe correlationship between structure and magnetic properties has been established by investigations of various cubic spinel ferrite nanoparticles. Initially, a general reverse microemulsion synthetic route for size and shape ferrite nanoparticles is described by taking Coo.sZettsFe20.4 and NioiZnosFe204 nanoparticles as examples. The effect of temperature on the magnetic properties of the ferrite nanoparticles has been studied in detail. The size dependent superparamagnetic properties are discussed. These results are the first experiments that report the synthesis of spinet ferrite nanoparticles with shape and size control capability. A comparative study with chemical co-precipitation route reveals that reverse microemulsion route yield small and monodisperse superparamagnetic particles with diameter in the range 2-5 nm at low temperature. newline