Abstract

The synchrotron X-ray absorption spectroscopy (XAS) revealed that magnetic nanoparticles synthesized from the reaction between Fe(acac)<inf>3</inf> and Pt(acac)<inf>2</inf> in the modified polyol process were composed of iron oxides and Pt metallic phases. By virtue of thermal treatment at 650 °C for 1 hour, this iron oxide phase was reduced to Fe metallic phase shown by X-ray absorption near edge structure (XANES) spectra. Interestingly, the difference between annealed nanoparticles in the case of 3.5 and 4.5 mmol surfactants was observed exclusively from the extended X-ray absorption fine structure (EXAFS) spectra. The reduction of iron oxide was evidently facilitated by the products decomposed from the surfactants during the thermal annealing. The fraction of oxygen in the elemental composition was therefore reduced. The annealing also transformed magnetic nanoparticles around 5 nm in diameter into ferromagnetic aggregates with the size over 30 nm. Copyright © 2013 American Scientific Publishers All rights reserved.