Coalescence and sintering of Pt nanoparticles: in situ observation by aberration-corrected HAADF STEM

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.

[1]  Andrew M Minor,et al.  Mechanical annealing and source-limited deformation in submicrometre-diameter Ni crystals. , 2008, Nature materials.

[2]  Edward F. Holby,et al.  Instability of Supported Platinum Nanoparticles in Low-Temperature Fuel Cells , 2007 .

[3]  G. Sakai,et al.  Direct observation of dynamic shape transformation and coalescence in platinum nanosheets on graphite surface at room temperature by time-resolved AFM , 2006 .

[4]  Hubert A. Gasteiger,et al.  Instability of Pt ∕ C Electrocatalysts in Proton Exchange Membrane Fuel Cells A Mechanistic Investigation , 2005 .

[5]  P. Perriat,et al.  Sintering of copper nanopowders under hydrogen: an in situ X-ray diffraction analysis , 2003 .

[6]  M. DiBattista,et al.  Determination of diffusion in polycrystalline platinum thin films , 1999 .

[7]  J. Bullard,et al.  Sintering of silver and copper nanoparticles on (001) copper observed by in-situ ultrahigh vacuum transmission electron microscopy , 1998 .

[8]  J. Velasco,et al.  Measurement of surface diffusion coefficients in air of columnar structured platinum near room temperature , 1998 .

[9]  Flemming Besenbacher,et al.  SURFACE DIFFUSION OF PT ON PT(110) : ARRHENIUS BEHAVIOR OF LONG JUMPS , 1997 .

[10]  M. Rahaman.  Ceramic Processing and Sintering , 1995 .

[11]  N. L. Peterson.  Grain-boundary diffusion in metals , 1983 .

[12]  P. Goodhew.  Introduction to analytical electron microscopy: Edited by: J. J. Hren, J.I. Goldstein and D.C. Joy Plenum Press, New York (1979) $35 (in US), $42 (outside US) , 1980 .

[13]  D. Packham.  Essentials of materials science: by A.G. Guy, McGraw-Hill, New York, 1976, 416 pages, 6716 × 914 in., hardback £16.10, paperback £6.20, ISBN 07-025351-X , 1980 .

[14]  David C. Joy,et al.  Introduction to analytical electron microscopy , 1979 .

[15]  Albert G. Guy,et al.  Essentials of materials science , 1976 .

[16]  L. Murr.  Interfacial phenomena in metals and alloys , 1975 .

[17]  P. Rossiter,et al.  Resistivity changes during maraging processes in iron-nickel steels , 1971 .

[18]  J. Blakely,et al.  Surface self diffusion and surface energy measurements on platinum by the multiple scratch method , 1962 .

[19]  Robert L. Coble,et al.  Initial Sintering of Alumina and Hematite , 1958 .

[20]  W. Kingery,et al.  Study of the Initial Stages of Sintering Solids by Viscous Flow, Evaporation‐Condensation, and Self‐Diffusion , 1955 .

[21]  Conyers Herring,et al.  Effect of Change of Scale on Sintering Phenomena , 1950 .