Structural effects on Au and Ag colloidal nanoparticles

Abstract

On the nanometer scale, size reduction effects affect materials properties. Au and Ag nanoparticles are interesting cases owing to a structural transition that occurs at nanometric sizes; this has been explored, for example, to change material properties. Here, we present structural studies on dodecanethiol-capped Au and Ag colloidal nanoparticles synthesized at room temperature and 80 °C. For the same synthesis conditions, Au nanoparticle sizes are smaller than Ag ones. From the structure point of view, the synthesis temperature has a minor effect on Au nanoparticles but it induces stacking faults and twin planes in the Ag case. These results suggest that hexagonal close-packed symmetry may be favored for Ag for certain synthesis conditions, but this has not been identified for Au.

Acknowledgements: LNLS is acknowledged for the use of LME (HRTEM); SAXS and XRD1 beamlines. This work was funded by FAPESP (01/07715-8), CNPq (470904/2001-1) and CAPES (M.S.L. scholarship).