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SUMMARY:Diffusion-controlled agglomeration (dewetting) of thin metal films
DTSTART:20140915T131500
DTEND:20140915T141500
DTSTAMP:20260428T074735Z
UID:e2886f23a161d27e63c8eb1fadee9a7cc94d6f11cb798ce68a70c595
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Eugen Rabkin\, Department of Materials Science and Engin
 eering Technion\, Israel Institute of Technology\, Haifa\nWe report the re
 sults of our studies of solid state dewetting (agglomeration) of thin Au\,
  Fe\, and Ni films\, and of Au-Fe bi-layers deposited on sapphire substrat
 e. At the final stages of agglomeration an array of single crystalline fac
 eted nanoparticles is produced. These particles exhibit stable faceted sha
 pes that are far from those predicted by equilibrium considerations. We di
 scuss high thermal stability of faceted particles in terms of slow mass tr
 ansport along the singular atomically flat facets [1]. In the case of hete
 roepitaxial Ni films and Au-Fe bilayers\, the formation of highly faceted 
 pinholes to the substrate is accompanied by the nucleation and growth of t
 win boundaries parallel to the substrate. These boundaries allow nucleatin
 g of defects at the side facets of the pinhole\, thus enabling its growth.
  A slow pace of self-diffusion along the singular facets increases the imp
 ortance of alternative short-circuit diffusion paths\, such as grain bound
 aries and film-substrate interface. We demonstrate that holes expansion an
 d simultaneous growth of hillocks in Fe thin films during initial stages o
 f dewetting can be described in terms of grain boundary diffusion of Fe at
 oms from the holes to the hillocks. We also describe the initial stages of
  dewetting of thin Au and Ni films in terms of a combination of grain boun
 dary and film-substrate interface diffusion\, and grain boundary sliding. 
 Our results indicate that a classical hierarchy of short-circuit diffusion
  paths is not applicable on the nanoscale [2].\nReferences:\n1. O. Malyi\,
  E. Rabkin\nThe effect of evaporation on size and shape evolution of facet
 ed gold nanoparticles on sapphire\nActa mater. 60 (2012) 261-268\n2. D. Am
 ram\, L. Klinger\, N. Gazit\, H. Gluska\, E. Rabkin\nGrain boundary groovi
 ng in thin films revisited: the role of interface diffusion\nActa mater. 6
 9 (2014) 386-396\nBio: Eugen Rabkin was born in Gomel\, Byelorussia (forme
 r USSR). He studied materials science in Moscow\, and obtained his Ph.D. f
 rom the Institute of Solid State Physics of the Russian Academy of Science
 s in 1991. Between 1992 and 1997 he was a Post-doctoral researcher at the 
 Max Planck Institute for Metal Research in Stuttgart\, Germany. Since 1997
  he is a faculty member in the Department of Materials Science and Enginee
 ring at the Technion-Israel Institute of Technology. He co-authored about 
 200 papers in peer-reviewed journals. His research interests include diffu
 sion and phase transformations in solids\, mechanical properties of materi
 als at the nanoscale\, and hydrogen storage in nanocrystalline solids.\nht
 tp://materials.technion.ac.il/eugen-rabkin-metals-interfaces-diffusion/
LOCATION:MXF 1 https://plan.epfl.ch/?room==MXF%201
STATUS:CONFIRMED
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