title: Crystal polymorphism: dependence of oxygen diffusion through 2D ordered Co nanocrystals.
abstract: 8 nm Co nanoparticles with various crystalline structures called polymorphs were produced using different synthetic procedures, such as using reverse micelles, the thermal decomposition of organometallics approach or the hot injection process. These 8 nm Co nanoparticles differing by their crystalline structures are exposed to oxygen at elevated temperature. The fcc Co polycrystalline nanoparticles produce either Co-CoO yolk-shell or CoO hollow structures whereas amorphous Co nanoparticles produce Co-CoO core-shell nanoparticles. Furthermore, single domains with either hcp or ε crystalline structure behave differently upon oxygen diffusion. Co-CoO nanoparticles were produced from the hcp phase while CoO hollow nanoparticles were the product for ε-phase Co nanocrystals.
authors.affiliation: Université Pierre et Marie Curie, UMR 7070, LM2N, 4 place Jussieu, 75005 Paris, France. marie-paule.pileni@upmc.fr.
authors.forename: Zhijie
authors.initials: Z
authors.lastname: Yang
authors.forename: Jianhui
authors.initials: J
authors.lastname: Yang
authors.forename: Johanna
authors.initials: J
authors.lastname: Bergström
authors.forename: Khashayar
authors.initials: K
authors.lastname: Khazen
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Pileni