title: Noncrystalline-to-crystalline transformations in Pt nanoparticles.
abstract: We show that the noncrystalline-to-crystalline transition of supported Pt nanoparticles (NPs) in the subnanometer to nanometer size range is statistical in nature, and strongly affected by particle size, support, and adsorbates (here we use H2). Unlike in the bulk, a noncrystalline phase exists and is stable in small NPs, reflecting a general mesoscopic feature. Observations of >3000 particles by high-resolution transmission electron microscopy show a noncrystalline-to-crystalline transition zone that is nonabrupt; there is a size regime where disordered and ordered NPs coexist. The NP size at which this transition occurs is strongly dependent on both the adsorbate and the support, and this effect is general for late 5d transition metals. All results are reconciled via a statistical description of particle-support-adsorbate interactions.
authors.affiliation: Chemical and Petroleum Engineering, and Physics, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States.
authors.forename: Long
authors.initials: L
authors.lastname: Li
authors.forename: Lin-Lin
authors.initials: LL
authors.lastname: Wang
authors.forename: Duane D
authors.initials: DD
authors.lastname: Johnson
authors.forename: Zhongfan
authors.initials: Z
authors.lastname: Zhang
authors.forename: Sergio I
authors.initials: SI
authors.lastname: Sanchez
authors.forename: Joo H
authors.initials: JH
authors.lastname: Kang
authors.forename: Ralph G
authors.initials: RG
authors.lastname: Nuzzo
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Anatoly I
authors.initials: AI
authors.lastname: Frenkel
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.forename: James
authors.initials: J
authors.lastname: Ciston
authors.forename: Eric A
authors.initials: EA
authors.lastname: Stach
authors.forename: Judith C
authors.initials: JC
authors.lastname: Yang
mesh_terms: D003460:Crystallization; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D010984:Platinum / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D010984:Platinum