Nanoscale effects in diffusion

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Diffusion in nanostructures has many challenging features even if the role of structural defects (dislocations, phase- or grain-boundaries) can be neglected. This can be the case for diffusion in amorphous materials, in epitaxial, highly ideal thin films or multilayers, in dissolution of thin films or in kinetics of surface segregation, where diffusion along short circuits can be ignored and "only" fundamental difficulties, related to nanoscale effects, raise. Different examples for diffusion in such materials will be given with special emphasis on the validity limit of the continuum approach especially if the diffusion coefficient depends strongly on composition (non-linearity). It was shown recently by us that even for ideal systems (like Cu/Ni) this non-linearity leads to linear shift of an originally sharp interface (instead of the parabolic behaviour) and to sharpening of an initially diffuse interface. The sharpening takes place, even if the effects of stresses (built in mismatch, thermal and diffusional stresses) are taken into account. Furthermore deviations from the parabolic law are present in phase separating systems as well, but here the interplay of the strong composition dependence and the phase separation tendency results in a more complex behaviour. These deviations are typical nanoeffects i.e. they diminish with time; in the examples investigated here after dissolution of several hundred atomic planes the parabolic law already fulfills.

Original languageEnglish
Pages (from-to)107-128
Number of pages22
JournalJournal of Metastable and Nanocrystalline Materials
Volume19
DOIs
Publication statusPublished - Jan 1 2004

Keywords

  • Interdiffusion
  • Multilayers
  • Nanoscale
  • Non-Linear Diffusion
  • Segregation
  • Spinodal Decomposition

ASJC Scopus subject areas

  • Materials Science (miscellaneous)
  • Materials Science(all)
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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