Highly stable alumina-coated iron nanocomposites synthesized by wet chemistry method

Highly stable Fe/Al2O3 nanocomposite, which was Fe nanoparticles coated with a thin shell of alumina, has been successfully fabricated by a simple wet chemistry procedure. The formation of these powders was confirmed by X-ray power diffraction (XRD) and transmission electron microscopy (TEM). The effect of the alumina shell on the properties of the nanocomposite was studied. The magnatizations of Fe cores in the Fe/Al2O3 nanocomposites with 20% and 30% Al/Fe molar ratio were as high as 210 emu/g, and almost did not change after being exposed in air at least 60 days. It indicates that these alumina-coated Fe nanocomposites were very stable. The complex permeability study of the as-prepared samples shows that Al2O3 shell could improve the soft magnetic property, especially in the high-frequency range. The real part μ of the permeability of the sample with Al molar content of 20% (Al/Fe) was as high as 13 and independent of frequency up to at least 1 GHz.