Core-shell (Ag)Au bimetallic nanoparticles:: Analysis of transmission electron microscopy images

Layered core-shell bimetallic silver-gold colloids in the size range of 10-16 nm have been prepared by the seed-growth method. Silver nuclei were covered by gold shells of various thicknesses without any stabilization agent. Interfacial (Ag)Au colloid-2,2'-bipyridine films were prepared from these bimetallic colloids and used for the purpose of analysis of transmission electron microscopy (TEM) images and electron diffraction. Both observed and calculated TEM images were used to characterize the prepared nanoparticles. On the basis of the analysis of TEM images, the calculated TEM image contrast, and results obtained by electron diffraction, energy-dispersive X-ray analysis, and other experiments, the core-shell structure of the prepared (Ag)Au nanoparticles was revealed. Particles were found to consist of a silver core and a gold shell enriched with silver.