title: Coalescence and sintering of Pt nanoparticles: in situ observation by aberration-corrected HAADF STEM.
abstract: An aberration-corrected JEOL 2200FS scanning-transmission electron microscope (STEM), equipped with a high-angle annular dark-field detector (HAADF), is used to monitor the coalescence and sintering of Pt nanoparticles with an average diameter of 2.8 nm. This in situ STEM capability is combined with an analysis methodology that together allows direct measurements of mass transport phenomena that are important in understanding how particle size influences coalescence and sintering at the nanoscale. To demonstrate the feasibility of this methodology, the surface diffusivity is determined from measurements obtained from STEM images acquired during the initial stages of sintering. The measured surface diffusivities are in reasonable agreement with measurements made on the surface of nanoparticles, using other techniques. In addition, the grain boundary mobility is determined from measurements made during the latter stages of sintering.
authors: Materials Science and Engineering Program, University of Texas at Austin, Austin, TX 78712, USA.
authors: M A
authors: MA
authors: Asoro
authors: D
authors: D
authors: Kovar
authors: Y
authors: Y
authors: Shao-Horn
authors: L F
authors: LF
authors: Allard
authors: P J
authors: PJ
authors: Ferreira
mesh_terms: D003460:Crystallization / Q000379:methods*; D006358:Hot Temperature; D007089:Image Enhancement / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing / Q000379:methods; D017348:Microscopy, Electron, Scanning Transmission / Q000379:methods*; D008968:Molecular Conformation; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D010984:Platinum / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D010984:Platinum