Showing papers by "Fabrizio Cleri published in 2010"
TL;DR: In this paper, molecular dynamics simulations of the atomic structure of silicon nanocrystals embedded in a stoichiometric amorphous silica matrix were performed, and the atom-atom interactions were described by a combination of well-assessed potentials for bulk silicon and SiO2, plus a mixing term to allow adjusting the charge transfer at the interface between Si and silica.
17 citations
TL;DR: In this paper, the tensile deformation of polycrystalline Si nanowires is studied by means of molecular dynamics simulations, where the initial microstructure is composed by a network of nanocrystals glued together by a thin layer of amorphous material.
Abstract: We study the tensile deformation of polycrystalline Si nanowires by means of molecular dynamics simulations. The initial microstructure is composed by a network of nanocrystals glued together by a thin layer of amorphous material. Atomistic simulations could clearly identify liquidlike flow in the constrained amorphous Si as the responsible for the observed elongation. After this first stage of nearly constant-stress flow, a necking instability sets in, eventually leading to fracture, at the point when the nanowire diameter becomes comparable to the size of the nanocrystals.
9 citations
TL;DR: In the 2008 EMRS Symposium on Morphology and dynamics of nanostructures and disordered systems via atomic-scale modelling, the authors underlined the use of molecular dynamics as a main tool to describe structural evolution for systems escaping a precise experimental determination of their atomic configurations as discussed by the authors.
3 citations
ENEA1
TL;DR: In this article, the role played by catalysts and interfaces in MgH2-Mg interfaces is investigated by combining accurate SEM observations of samples after partial desorption process and atomic level ab-initio molecular dynamics simulations of interfaces.
Abstract: Magnesium is one of the most promising materials for hydrogen storage due to its high capacity and low cost. Unfortunately, practical applications are for the moment limited by the slow kinetics and the high operating temperature. Nanostructuring magnesium hydride MgH2, generally by ball milling, introduces plastic deformations and catalysts that highly enhances the H2 absorption and desorption. However a fundamental understanding of the role played by catalysts and interfaces in MgH2 is still lacking. Microscopic characterization of MgH2-Mg system with and without heavy metal catalysts, is achieved by combining accurate SEM observations of samples after partial desorption process and atomic level ab-initio molecular dynamics simulations of MgH2-Mg interfaces. The experimental method is based on low voltage SEM observations of cross sectional powder samples, prepared by a new specific metallographic process. Identification of nucleation sites of the sorption reaction and their correlation with the presence of catalyst particles is achieved by suitable experimental conditions. Moreover ab-initio molecular dynamics clarifies the interplay of interfaces and the deformations induced during desorption by the presence of catalysts that are able to lower binding energies and free hydrogen atoms toward interfaces. Both approaches confirm and characterize the nucleation step in the catalysts driven phase transformation.