Synthesis and Characterization of Iron-Magnesium Bimetallic Particles

Abstract

The clusters of two immiscible metals, iron and magnesium, were prepared by atom clustering in cold pentane(Solvated-Metal-Atom-Dispersion). Very small α-Fe crystallites embedded in a matrix of magnesium and organic fragments were obtained. Stable Fe-Mg particles containing small α-Fe crystallites in a range of 3 to 20 nm in size were formed by heat-treatment followed by oxidative passivation. Fe-Mg bimetallic materials were also prepared by a vacuum co-evaporation method. The Fe-Mg SMAD particles have over-all sizes in a range of 40 to 85 nm, and specific surface areas in a range of 17 to 26 m²/g, while the vacuum co-evaporated Fe-Mg materials are considered as bulk materials.

Magnetic properties were studied by Mössbauer spectroscopy and SQUID magnetrometry. After being heat-treated at temperatures above 200°C, the Fe-Mg SMAD particles have corrected saturation magnetization values of about 2 00 emu/gram of iron, which is nearly the bulk value of pure iron. These materials have coercivities ranging from 10 to 200 Oe, which are much lower than those of small Fe particles coated with surface iron oxides.