X-RAY DIFFRACTION METHOD OF THE RADIAL ELECTRON DENSITY DISTRIBUTION. STRUCTURE OF NANOPHASE SUPPORTS AND SUPPORTED CATALYSTS

摘要

X-ray diffraction structural diagnostics of nanomaterials needs the development of special methods taking into account the features of X-ray scattering from small objects. Data on the development of the X-ray diffraction method of the radial electron density distribution (REDD) or the pair distribution function methoda (PDF analysis) based on the integrated analysis of X-ray scattering are presented. The method provides information on interatomic distances and coordination numbers and is primarily used to detect and evaluate the size of nanoassociates (phases) < 3 nm, which are not detected by the usual powder X-ray diffraction analysis of interplanar distances. Being sensitive to changes in the local structure in a region with a length of 1 - 3 unit cells, the REDD method is successfully applied to detect defects in the atomic structure of nanoobjects. Examples of the method application for the structural studies of nanosized supports and supported catalysts are presented.