One-pot synthesis of high magnetization air-stable FeCo nanoparticles by modified polyol method

High magnetization FeCo nanoparticles with different Fe/Co ratios have been successfully synthesized by surfactant free simple modified polyol method. Polyethylene glycol (PEG) was used as solvent and reducing agent simultaneously in this synthesis process. All the synthesized samples of FeCo nanoparticles were annealed at 600 °C before characterizations. X-ray diffraction (XRD) data on the samples confirm formation of a body-centered-cubic single phase structure in all the compositions. Transmission Electron Microscopy (TEM) data suggest that the annealed FeCo nanoparticles are of 50–90 nm in size. The use of PEG and the annealing procedure employed ensure that the obtained nanoparticles are stable in air. This observation is well supported by both the analysis of Energy Dispersive Spectrometry (EDS) and the images of TEM which establish the formation of a thin passive oxide layer over the FeCo nanoparticles thereby resulting in the stability of the nanoparticles. The physical Property Measurement System (PPMS) reveals that the Fe60Co40 composition among all the samples exhibit highest saturation magnetization of 230.14 emu/g at 5 K.

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► A facile one-pot polyol method used for synthesizing of different Fe/Co ratios.
► The Polyethylene glycol is considered the key point as solvent and also as reducing agent in this method and no need for any surfactant.
► The magnetic characterization of the nanoparticles reveals very high saturation magnetization of 230.14 emu/g at 5 K for the sample Fe60Co40.
► The samples showed air stability because of the thin passive layer of oxide over FeCo nanoparticles which confirmed by TEM and EDS analysis.