Diffraction anomalous fine structure study of iron/iron oxidenanoparticles

Abstract

Diffraction anomalous fine structure is a recently developed techniquewhich can provide a measurement of the local structure of a givenelement in a particular phase or crystallographic site. Most previousinvestigations have applied the technique to bulk solids, thin films,and nano-dots or wires on crystalline substrates. In this paper, thetechnique is applied to highly disordered nanometre-sized Fe/Fe oxidecore-shell nanocrystalline powders, the diffraction patterns of whichexhibit weak and greatly broadened diffraction peaks. Focusing on theoxide shell diffraction peaks, a qualitative analysis of the near-edgespectral region and a quantitative analysis of the extended energyregion are provided; in particular, good quality fittings of theextended range spectra are obtained. The local structure is selectivelyprobed around the tetrahedral and octahedral sites of the oxide shell,finding the presence of a high degree of structural disorder. Thisstudy demonstrates that diffraction anomalous fine structure can now befruitfully applied to nanocrystalline powders.