title: Multistep nucleation of nanocrystals in aqueous solution.
abstract: The nucleation and growth of solids from solutions impacts many natural processes and is fundamental to applications in materials engineering and medicine. For a crystalline solid, the nucleus is a nanoscale cluster of ordered atoms that forms through mechanisms still poorly understood. In particular, it is unclear whether a nucleus forms spontaneously from solution via a single- or multiple-step process. Here, using in situ electron microscopy, we show how gold and silver nanocrystals nucleate from supersaturated aqueous solutions in three distinct steps: spinodal decomposition into solute-rich and solute-poor liquid phases, nucleation of amorphous nanoclusters within the metal-rich liquid phase, followed by crystallization of these amorphous clusters. Our ab initio calculations on gold nucleation suggest that these steps might be associated with strong gold-gold atom coupling and water-mediated metastable gold complexes. The understanding of intermediate steps in nuclei formation has important implications for the formation and growth of both crystalline and amorphous materials.
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551.|Centre for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543.
authors.forename: N Duane
authors.initials: ND
authors.lastname: Loh
authors.affiliation: Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, USA.
authors.forename: Soumyo
authors.initials: S
authors.lastname: Sen
authors.affiliation: Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Singapore 138634.|Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575.
authors.forename: Michel
authors.initials: M
authors.lastname: Bosman
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543.
authors.forename: Shu Fen
authors.initials: SF
authors.lastname: Tan
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551.|Centre for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhong
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543.|Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546.
authors.forename: Christian A
authors.initials: CA
authors.lastname: Nijhuis
authors.affiliation: Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, USA.|Department of Physics and Biopharmaceutical Sciences, University of Illinois at Chicago, Chicago, Illinois 60607, USA.
authors.forename: Petr
authors.initials: P
authors.lastname: Král
authors.affiliation: Centre for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543.|MechanoBiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore 117576.
authors.forename: Paul
authors.initials: P
authors.lastname: Matsudaira
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551.|Centre for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543.|Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546.|NanoCore, National University of Singapore, 4 Engineering Drive 3, Singapore 117576.
authors.forename: Utkur
authors.initials: U
authors.lastname: Mirsaidov