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Characterization of nanophase Al‐oxide/Al powders by electron energy‐loss spectroscopy
Author(s) -
A. Fernández,
J.C. Sánchez-López,
A. Caballero,
Martin Jm,
Béatrice Vacher,
Laurence Ponsonnet
Publication year - 1998
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1046/j.1365-2818.1998.00355.x
Subject(s) - electron energy loss spectroscopy , materials science , overlayer , passivation , nanocrystalline material , transmission electron microscopy , energy dispersive x ray spectroscopy , chemical engineering , oxide , x ray photoelectron spectroscopy , nanoparticle , analytical chemistry (journal) , scanning electron microscope , nanotechnology , metallurgy , composite material , layer (electronics) , chemistry , chromatography , engineering
Al nanoparticles were prepared by the inert gas condensation method. After passivation with oxygen and air exposure we obtained a powdered sample of an Al‐oxide/Al nanocomposite material. In the present paper we describe the use of the electron energy‐loss spectroscopy (EELS) technique in a transmission electron microscope to characterize such nanostructured powders compared with a microcrystalline commercial aluminium foil. Energy‐filtered images showed the presence of an alumina overlayer of ≈ 4 nm covering the aluminium nanoparticles (23 nm in diameter). EELS analysis enabled us to determine the total amount of Al 2 O 3 and metallic Al and the structure of the alumina passivation overlayer in the sample. In particular, the extended energy‐loss fine structure analysis of the data showed a major presence of Al tetrahedrally coordinated with oxygen in the alumina passivation layer of Al nanoparticles instead of the octahedral coordination found for a conventional Al foil. This surprising effect has been attributed to the nanoscopic character of the grains. The analysis of the electron‐loss near‐edge structure also determines the presence of a certain degree of aggregation in this kind of powdered sample as result of the coalescence of the nanocrystalline grains. The procedure presented here may have the potential to solve other problems during characterization of nanostructured materials.