An international team of researchers has used pioneering electron microscopy techniques to discover an important mechanism behind the reaction of metallic nanoparticles with the environment.
Crucially, the research led by the University of York and reported in Nature Materials, shows that oxidation of metals - the process that describes, for example, how iron reacts with oxygen, in the presence of water, to form rust - proceeds much more rapidly in nanoparticles than at the macroscopic scale. This is due to the large amount of strain introduced in the nanoparticles due to their size which is over a thousand times smaller than the width of a human hair.
Improving the understanding of metallic nanoparticles particularly those of iron and silver - is of key importance to scientists because of their many potential applications. For example, iron and iron oxide nanoparticles are considered important in fields ranging from clean fuel technologies, high density data storage and catalysis, to water treatment, soil remediation, targeted drug delivery and cancer therapy.
The research team, which also included scientists from the University of Leicester, the National Institute for Materials Science, Japan and the University of Illinois at Urbana-Champaign, USA, used the unprecedented resolution attainable with aberration-corrected scanning transmission electron microscopy to study the oxidisation of cuboid iron nanoparticles and performed strain analysis at the atomic level.
Lead investigator Dr Roland Krger, from the University of York's Department of Physics, said: "Using an approach developed at York and Leicester for producing and analysing very well-defined nanoparticles, we were able to study the reaction of metallic nanoparticles with the environment at the atomic level and to obtain information on strain associated with the oxide shell on an iron core.
"We found that the oxide film grows much faster on a nanopart
|Contact: Caron Lett|
University of York