Defects in nanocrystalline Pd and submicrocrystalline Cu by EXAFS

EXAFS spectra of nanocrystalline (nc) Pd and submicrocrystalline (smc) Cu are presented. nc-Pd samples with a grain size of 15 nm have been prepared by gas condensation technique, and submicrocrystalline Cu samples with a grain size of 100 nm have been prepared by severe plastic deformation. EXAFS measurements of powder nc-Pd samples with optimal thickness were performed using synchrotron radiation, and rolled smc-Cu by laboratory EXAFS spectrometer. As a result of mathematical treatment, atomic density distribution functions have been determined. sults obtained show that in comparison with coarse-grained crystalline standards the decrease of the first neighbor coordination numbers N is 5–6% for nc-Pd, and 3% for smc-Cu. For interpretation of the obtained results, the numerical simulation of the atomic structure with modelling to cut off the bond lengths for grain boundary and to create vacancies during sample preparation is performed.