The scientists used a method known as Z-contrast imaging to examine the oxide layer that forms around a nanoparticle after exposure to the atmosphere, and found that within two years the particles were completely oxidised.
Corresponding author Dr Andrew Pratt, from York's Department of Physics and Japan's National Institute for Materials Science, said: "Oxidation can drastically alter a nanomaterial's properties - for better or worse - and so understanding this process at the nanoscale is of critical importance. This work will therefore help those seeking to use metallic nanoparticles in environmental and technological applications as it provides a deeper insight into the changes that may occur over their desired functional lifetime."
The experimental work was carried out at the York JEOL Nanocentre and the Department of Physics at the University of York, the Department of Physics and Astronomy at the University of Leicester and the Frederick-Seitz Institute for Materials Research at the University of Illinois at Urbana-Champaign.
The scientists obtained images over a period of two years. After this time, the iron nanoparticles, which were originally cube-shaped, had become almost spherical and were completely oxidised.
Professor Chris Binns, from the University of Leicester, said: "For many years at Leicester we have been developing synthesis techniques to produce very well-defined nanoparticles and it is great to combine this technology with the excellent facilities and expertise at York to do such penetrating science. This work is just the beginning and we intend to capitalise on our complementary abilities to initiate a wider collaborative programme."
|Contact: Caron Lett|
University of York