title: Evolution of atomic structure during nanoparticle formation.
abstract: Understanding the mechanism of nanoparticle formation during synthesis is a key prerequisite for the rational design and engineering of desirable materials properties, yet remains elusive due to the difficulty of studying structures at the nanoscale under real conditions. Here, the first comprehensive structural description of the formation of a nanoparticle, yttria-stabilized zirconia (YSZ), all the way from its ionic constituents in solution to the final crystal, is presented. The transformation is a complicated multi-step sequence of atomic reorganizations as the material follows the reaction pathway towards the equilibrium product. Prior to nanoparticle nucleation, reagents reorganize into polymeric species whose structure is incompatible with the final product. Instead of direct nucleation of clusters into the final product lattice, a highly disordered intermediate precipitate forms with a local bonding environment similar to the product yet lacking the correct topology. During maturation, bond reforming occurs by nucleation and growth of distinct domains within the amorphous intermediary. The present study moves beyond kinetic modeling by providing detailed real-time structural insight, and it is demonstrated that YSZ nanoparticle formation and growth is a more complex chemical process than accounted for in conventional models. This level of mechanistic understanding of the nanoparticle formation is the first step towards more rational control over nanoparticle synthesis through control of both solution precursors and reaction intermediaries.
authors: Center for Materials Crystallography, Department of Chemistry, and iNANO, Aarhus University , Langelandsgade 140, Aarhus, DK-8000, Denmark.
authors: Christoffer
authors: C
authors: Tyrsted
authors: Center for Materials Crystallography, Department of Chemistry, and iNANO, Aarhus University , Langelandsgade 140, Aarhus, DK-8000, Denmark ; Faculty of Chemistry, Georg-August-Universitat Gottingen , Tammannstrasse 4, D-37077 Gottingen, Germany.
authors: Nina
authors: N
authors: Lock
authors: Center for Materials Crystallography, Department of Chemistry, and iNANO, Aarhus University , Langelandsgade 140, Aarhus, DK-8000, Denmark ; Department of Applied Physics and Applied Mathematics, Columbia University , New York, NY 10027, USA.
authors: Kirsten M Ø
authors: KM
authors: Jensen
authors: Center for Materials Crystallography, Department of Chemistry, and iNANO, Aarhus University , Langelandsgade 140, Aarhus, DK-8000, Denmark.
authors: Mogens
authors: M
authors: Christensen
authors: Center for Materials Crystallography, Department of Chemistry, and iNANO, Aarhus University , Langelandsgade 140, Aarhus, DK-8000, Denmark.
authors: Espen D
authors: ED
authors: Bøjesen
authors: SNBL, European Synchrotron Radiation Facility , 6 rue Horowitz, F-38043 Grenoble, France.
authors: Hermann
authors: H
authors: Emerich
authors: ID11, European Synchrotron Radiation Facility , 6 rue Horowitz, F-38043 Grenoble, France.
authors: Gavin
authors: G
authors: Vaughan
authors: Department of Applied Physics and Applied Mathematics, Columbia University , New York, NY 10027, USA ; Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory , Upton, New York, NY 11973, USA.
authors: Simon J L
authors: SJ
authors: Billinge
authors: Center for Materials Crystallography, Department of Chemistry, and iNANO, Aarhus University , Langelandsgade 140, Aarhus, DK-8000, Denmark.
authors: Bo B
authors: BB
authors: Iversen
keywords: EXAFS; PDF; in situ; nanoparticle; total scattering