title: Enhanced oxidation of nanoparticles through strain-mediated ionic transport.
abstract: Geometry and confinement effects at the nanoscale can result in substantial modifications to a material's properties with significant consequences in terms of chemical reactivity, biocompatibility and toxicity. Although benefiting applications across a diverse array of environmental and technological settings, the long-term effects of these changes, for example in the reaction of metallic nanoparticles under atmospheric conditions, are not well understood. Here, we use the unprecedented resolution attainable with aberration-corrected scanning transmission electron microscopy to study the oxidation of cuboid Fe nanoparticles. Performing strain analysis at the atomic level, we reveal that strain gradients induced in the confined oxide shell by the nanoparticle geometry enhance the transport of diffusing species, ultimately driving oxide domain formation and the shape evolution of the particle. We conjecture that such a strain-gradient-enhanced mass transport mechanism may prove essential for understanding the reaction of nanoparticles with gases in general, and for providing deeper insight into ionic conductivity in strained nanostructures.
authors.affiliation: 1] Department of Physics, University of York, York YO10 5DD, UK [2] International Center for Young Scientists, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
authors.forename: Andrew
authors.initials: A
authors.lastname: Pratt
authors.affiliation: 1] Department of Physics, University of York, York YO10 5DD, UK [2] York JEOL Nanocentre, University of York, York YO10 5BR, UK.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Lari
authors.affiliation: 1] Department of Physics, University of York, York YO10 5DD, UK [2] Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, UK.
authors.forename: Ondrej
authors.initials: O
authors.lastname: Hovorka
authors.affiliation: University of Illinois at Urbana-Champaign, Frederick Seitz Materials Research Laboratory, Illinois 61801, USA.
authors.forename: Amish
authors.initials: A
authors.lastname: Shah
authors.affiliation: Department of Physics, University of York, York YO10 5DD, UK.
authors.forename: Charles
authors.initials: C
authors.lastname: Woffinden
authors.affiliation: Department of Physics, University of York, York YO10 5DD, UK.
authors.forename: Steve P
authors.initials: SP
authors.lastname: Tear
authors.affiliation: Department of Physics and Astronomy, University of Leicester, Leicester LH1 7RH, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Binns
authors.affiliation: Department of Physics, University of York, York YO10 5DD, UK.
authors.forename: Roland
authors.initials: R
authors.lastname: Kröger
mesh_terms: D005290:Ferric Compounds / Q000737:chemistry*; D017136:Ion Transport; D007501:Iron / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D005290:Ferric Compounds; C000499:ferric oxide; D007501:Iron