Cooling Dodecanethiol-Capped 2 nm Diameter Gold Nanocrystal Superlattices below Room Temperature Induces a Reversible Order–Disorder Structure Transition
mediaposted on 17.11.2016 by Yixuan Yu, Adrien Guillaussier, Vikas Reddy Voggu, William Pineros, Thomas M. Truskett, Detlef-M. Smilgies, Brian A. Korgel
Media is any form of research output that is recorded and played. This is most commonly video, but can be audio or 3D representations.
We recently observed that a disordered assembly of octadecanethiol-capped gold (Au) nanocrystals can order when heated from room temperature to 60 °C [Yu, Y.; Jain, A.; Guillaussier, A.; Voggu, V. R.; Truskett, T. M.; Smilgies, D.-M.; Korgel, B. A. Faraday Discuss. 2015, 181, 181–192]. This “inverse melting” structural transition was reversible and occurred near the melting-solidification temperature of the capping ligands. To determine the generality of this phenomenon, we studied by in situ grazing incidence small-angle X-ray scattering (GISAXS) the structure of assemblies of Au nanocrystals with shorter C12 and C5 alkanethiol capping ligands that form ordered superlattices at room temperature and have a ligand melting-solidification temperature below room temperature. Superlattices of dodecanethiol-capped Au nanocrystals disorder when cooled below 260 K, which is the melting-solidification temperature for dodecanethiol. Au nanocrystals capped with even shorter pentanethiol ligands that have a melting transition below 100 K (the lowest experimentally accessible temperature) do not undergo the disorder transition.