EXAFS study of changes in atomic structure of silver nanoparticles in soda-lime glass caused by annealing

Atomic structure of silver nanoparticles in soda-lime glass at T = 10 K before and after annealing was studied by Ag K-edge EXAFS. To overcome ambiguities in the structure determination by the Fourier-transform analysis of these spectra, caused by the presence of various species of the absorbing silver atoms in the sample, the refinements of the fitting technique of the Fourier transforms F(R) have been implemented. The F(R) of Ag K-edge EXAFS in as prepared and annealed glasses were analyzed in the extended range of interatomic distances (R) up to ~ 6.5 Ǻ using Ag K-edge EXAFS in Ag-foil at the same temperature as the reference. The proposed technique of the fit enabled to go beyond the averaged description of silver nanoparticles structure in glass and to reveal the atomic structure of the core region of nanoparticles, the structural characteristics of their near-surface region, parameters of AgO bonds inside the glass matrix and the percentage of Ag atoms in each of these species before and after the annealing process. The mean size of silver nanoparticles in as prepared and annealed glasses was estimated and the mechanism of nanoparticles growth after the thermal treatment was suggested.