Magnetic multiresonance behavior of Fe@Al2O3 nanoembedments and microstructural evolution during mechanosynthesis

The embedding of metal nanoparticles into an insulating ceramic matrix can provide encapsulation and prevent their oxidation and agglomeration. A nanoembedment powder with the Fe nanoparticles embedded into Al2O3 matrix is prepared by high-energy ball milling. Starting from the highly exothermic reactant mixture of magnetite and aluminum, Fe nanoparticles were in situ formed in Al2O3 matrix by mechanochemical reaction. It is found that a post-reaction milling significantly narrows the size distribution of Fe nanoparticles. The mechanism for the two-stage milling process was proposed. The microwave permeability of nanoembedments exhibited a multiresonance behavior, which was the evidence for monodispersed Fe nanoparticles. The Fe@Al2O3 nanoembedments are potential candidates as microwave absorber and left-handed materials.

A nanoembedment powder with the Fe nanoparticles embedded into Al2O3 matrix is prepared by high-energy ball milling. It is found that extensive milling after mechanochemical reaction significantly narrows the size distribution of Fe nanoparticles, which is evidenced by a multiresonance behavior in the microwave permeability spectra. And the mechanism for the two-stage milling process is proposed.Figure optionsDownload as PowerPoint slideHighlights
► Fe nanoparticles were added to Al2O3 by high-energy ball milling.
► Post-reaction milling distinctly narrows the size distribution of Fe nanoparticles.
► Monodispersed Fe nanoparticles were evidenced by multiresonance behavior.
► The mechanism for the two-stage milling process is proposed.