Co/Ag binary nanoparticle superlattices were engineered. It is demonstrated that the Ag/Co nanoparticle size ratio is the dominating factor in the formation of binary nanoparticle superlattices. However, regardless of the relative ratio concentration of Co and Ag nanoparticles, the deposition temperature, Td markedly changes the crystalline structure of binary superlattices. A systematic study of these parameters is presented in order to shed light on the driving force in the formation of binary metallic nanoparticle superlattices. For metal Co and Ag nanoparticles, the interparticle potential pairs areconsidered to be strong, but entropy is still the main driving force for the assembling into binary nanoparticle superlattices, rather than the energy arising from the interparticle interactions.
Source : Metal−Metal Binary Nanoparticle Superlattices: A Case Study of Mixing Co and Ag Nanoparticles. Z. Yang, J. Wei and M.P. Pileni Chem Mater. 2015, 27, 2152−2157.