Determination of nanoparticle structure type, size and strain distribution from X-ray data for monatomic f.c.c.-derived non-crystallographic nanoclusters

Whole-profile fitting least-squares techniques are successfully applied to simulated X-ray diffraction patterns of monoatomic fcc-derived non-crystallographic nanoclusters to extract structure and size information. Three main structure types have been considered (cuboctahedral, icosahedral and decahedral). Nanocluster structure models have been generated within an original mathematical approach so as to be independent of a specific material. For each structure type, a log-normal size distribution is assumed and a suitable phenomenological function is introduced to model size- and structure type-related strain effects. The Debye function method (modified to increase computational efficiency) has been used to obtain the nanoclusters diffracted intensities. Tests revealed the effectiveness of the method to correctly recognize the structure types and to estimate with good accuracy structure concentrations and size distributions.