Irradiation induced defects in nanocrystalline Cu

Cu nanocrystals were synthesized in a thin layer of amorphous silica (SiO2) by ion implantation and thermal annealing. Subsequently the nanocrystals and a bulk Cu film standard were irradiated with high-energy Sn ions to induce structural disorder. We quantify the disorder by extended X-ray absorption fine structure (EXAFS) spectroscopy. Irradiation is found to increase the structural disorder in the nanocrystals, while the structural parameters of the irradiated film remain the same as those for the unirradiated crystalline standard. We explain this difference by the high regeneration rate in elemental bulk metals and the effect thereupon of a finite crystal size