title: How can the nanocrystallinity of 7 nm spherical Co nanoparticles dispersed in solution be improved?
abstract: We report a solution-phase annealing of spherical Co nanocrystals synthesized in reverse micelles and coated with dodecanoic acid. The deposition of a drop of solution on a transmission electron microscope grid shows that a progressive increase in the temperature to 316 °C results in the progressive crystallographic transition from a polycrystalline and probably face-centered cubic Co phase to the single-crystalline hexagonal close-packed (hcp) Co phase. These nanocrystals are highly stable against oxidation and coalescence. We stress that, to our knowledge, this constitutes the first example in the literature of pure hcp-Co spherical single crystals dispersed in solution. These nanocrystals can be freely manipulated and, due to their low size dispersion, can self-organize on various substrates.
authors.affiliation: Laboratoire des Matériaux Mésoscopiques et Nanométriques, UMR CNRS 7070, Université Pierre et Marie Curie, Bât. F, 4 Place Jussieu, 75005 Paris, France.
authors.forename: Manon
authors.initials: M
authors.lastname: Cavalier
authors.forename: Michael
authors.initials: M
authors.lastname: Walls
authors.forename: Isabelle
authors.initials: I
authors.lastname: Lisiecki
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Pileni
mesh_terms: D003035:Cobalt; D003460:Crystallization; D007850:Lauric Acids; D053768:Metal Nanoparticles / Q000737:chemistry*; D008823:Micelles; D012996:Solutions
chemical_list: D007850:Lauric Acids; D008823:Micelles; D012996:Solutions; C030358:lauric acid; D003035:Cobalt