Coalescence of silver nanoparticles at room temperature: Unusual crystal structure transformation and dendrite formation induced by self-assembly

It was found that during the evaporation of water from a droplet of a silver nanoparticles dispersion a self-assembly process leads to the coalescence of the nanoparticles at room temperature and eventually results in a 3D, micrometer-sized dendrite. Direct in situ HR-TEM observation of coalescence events of individual nanoparticles revealed that during this process a transformation of the nanoparticles' crystal structure takes place, from the common fee silver structure to the unusual hcp structure. It was found that even-though a majority of the nanoparticles in the dispersion have the fee structure the obtained dendrites are characterized by the hep structure, reflecting the crystal structure transformation due to the coalescence process.