title: Tracing the Surfactant-Mediated Nucleation, Growth, and Superpacking of Gold Supercrystals Using Time and Spatially Resolved X-ray Scattering.
abstract: The nucleation and growth process of gold supercrystals in a surfactant diffusion approach is followed by simultaneous small- and wide-angle X-ray scattering (SAXS/WAXS), supplemented with scanning electron microscopy. The results indicate that supercrystal nucleation can be activated efficiently upon placing a concentrated surfactant solution of a nematic phase on top of a gold nanocrystal solution droplet trapped in the middle of a vertically oriented capillary tube. Supercrystal nuclei comprised of tens of gold nanocubes are observed nearly instantaneously in the broadened liquid-liquid interface zone of a steep gradient of surfactant concentration, revealing a diffusion-kinetics-controlled nucleation process. Once formed, the nuclei can sediment into the naoncrystal zone below, and grow efficiently into cubic or tetragonal supercrystals of ∼1 μm size within ∼100 min. Supercrystals matured during sedimentation in the capillary can accumulate and face-to-face align at the bottom liquid-air interface of the nanocrystal droplet. This is followed by superpacking of the supercrystals into highly oriented hierarchical sheets, with a huge number of gold nanocubes aligned for largely coherent crystallographic orientations.
authors.affiliation: National Synchrotron Radiation Research Center , 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan.
authors.forename: Po-Wei
authors.initials: PW
authors.lastname: Yang
authors.affiliation: Department of Chemistry, National Tsing Hua University , Hsinchu 30013, Taiwan.
authors.forename: Subashchandrabose
authors.initials: S
authors.lastname: Thoka
authors.affiliation: National Synchrotron Radiation Research Center , 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan.
authors.forename: Po-Chang
authors.initials: PC
authors.lastname: Lin
authors.affiliation: National Synchrotron Radiation Research Center , 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan.
authors.forename: Chun-Jen
authors.initials: CJ
authors.lastname: Su
authors.affiliation: National Synchrotron Radiation Research Center , 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan.
authors.forename: Hwo-Shuenn
authors.initials: HS
authors.lastname: Sheu
authors.affiliation: Department of Chemistry, National Tsing Hua University , Hsinchu 30013, Taiwan.
authors.forename: Michael H
authors.identifier: 0000-0002-5648-4345
authors.initials: MH
authors.lastname: Huang
authors.affiliation: National Synchrotron Radiation Research Center , 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan.|Department of Chemical Engineering, National Tsing Hua University , Hsinchu 30013, Taiwan.
authors.forename: U-Ser
authors.identifier: 0000-0002-2247-5061
authors.initials: US
authors.lastname: Jeng