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Distorted f.c.c. arrangement of gold nanoclusters: a model of spherical particles with microstrains and stacking faults
Author(s) -
Longo Alessandro,
Martorana Antonino
Publication year - 2008
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889808004846
Subject(s) - icosahedral symmetry , nanoclusters , stacking , crystallography , materials science , diffraction , absorption (acoustics) , absorption spectroscopy , superposition principle , analytical chemistry (journal) , chemistry , nanotechnology , physics , optics , organic chemistry , chromatography , composite material , quantum mechanics
The structures of two samples of gold nanoclusters supported on silica were studied by X‐ray powder diffraction (XRD) and X‐ray absorption spectroscopy. The data relative to both techniques were analysed by an approach involving simulation based on structural models and fitting. The XRD model concerned a distorted f.c.c. (face‐centred cubic) arrangement, with microstrains and parallel stacking faults in approximately spherical particles; as an alternative possibility, a linear combination of ordered f.c.c. and noncrystalline (decahedral and icosahedral) particles was also taken into account. Both approaches gave calculated patterns closely resembling the experimental data. X‐ray absorption spectra were fitted on the basis of f.c.c. and noncrystalline arrangements. The best results were obtained by the f.c.c. motif, while a simulation consisting in the superposition of f.c.c. and noncrystalline components in the relative amounts determined by XRD analysis gave a poor agreement with the experimental data. It was concluded that the good XRD fitting obtained by linear combination of lognormal size‐distributed f.c.c. cuboctahedral, decahedral and icosahedral contributions was a result of the flexibility of the basis set of functions, but that the complementary analysis of X‐ray absorption data did not confirm the presence of a noteworthy fraction of noncrystalline particles.