Date of Original Version
Copyright 2009 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article may be found at http://dx.doi.org/10.1063/1.3054376.
Abstract or Description
We report the oxidation products and qualitative rates for polydisperse FeCo magnetic nanoparticles (MNPs) synthesized using an induction plasma torch. X-ray diffraction(XRD) and TEM showed MNPs to have a thin ferrite shell. Nanopowders were isochronally annealed to promote oxidation and XRD was used to follow the evolution of the FeCo core and the Fe3O4and FeO oxide shells. Isothermal anneals were used to follow oxidation kinetics at 350 and 500°C. High resolution transmission electron microscopy(HRTEM) revealed faceted morphologies terminated at (100) and (110) FeCo faces with (110)FeCo∥(111)oxide and (100)FeCo∥(100)oxide, and FeCo∥oxide orientation relationships between the FeCo core and oxide shell. We show HRTEM images of MNP chaining and compare the rf heating of samples of aqueous ferrofluids similarly loaded with as synthesized and oxidized MNPs.
Journal of Applied Physics, 105, 7, 07A328.