title: 3D quantitative analysis of platinum nanocrystal superlattices by electron tomography.
abstract: The work reported herein focuses on the 3D relative arrangement of individual platinum nanocrystals with a size of about 5 nm, and on the structure of the superlattices, they spontaneously form. Electron tomography was systematically used in this study because it allows obtaining quantitative 3D information in real space. Performing tomography in the bright-field TEM mode allowed investigating the short and long-range orderings of the nanoparticles packed as self-organized supercrystals. Systematic fcc pilings were observed with a mean lattice parameter measured to be 19.5 nm, the nature of the arrangement being controlled by the truncated octahedral morphology of platinum nanocrystals and the associated steric effects. A numerical 3D quantitative analysis of the ordering characteristics of the superlattice with a nanometer resolution has been performed that, for the first time, showed a direct correlation between single entities' characteristics and their ordering in periodic arrays. It has been shown that the lattice parameter is different in two orthogonal directions of the fcc structure, which indicates the presence of a slightly compressed superlattice. Inside the superstructure, vacancies and axial defects were observed that would blur the occurrence of potential collective effects from the supercrystals.
authors.affiliation: Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, CNRS-UdS, 23 rue du Lœss BP43, 67034 Strasbourg cedex 2, France.
authors.forename: Ileana
authors.initials: I
authors.lastname: Florea
authors.forename: Arnaud
authors.initials: A
authors.lastname: Demortière
authors.forename: Christophe
authors.initials: C
authors.lastname: Petit
authors.forename: Hervé
authors.initials: H
authors.lastname: Bulou
authors.forename: Charles
authors.initials: C
authors.lastname: Hirlimann
authors.forename: Ovidiu
authors.initials: O
authors.lastname: Ersen