Non-linear effects in diffusion on nanoscale

Research output: Contribution to journalArticle

Abstract

Diffusion on very short distances in amorphous materials, epitaxial multilayers, during dissolution of thin films or kinetics of surface/interface segregation has many challenging features even if the role of structural defects (dislocations, phase or grain/boundaries) can be neglected 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). Even in ideal systems (like Ni/Cu) 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 and thermal as well as diffusional streses) are taken into account. 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 after dissolution of several hundred atomic planes.

Original languageEnglish
Pages (from-to)1031-1042
Number of pages12
JournalDefect and Diffusion Forum
Volume237-240
Issue numberPART 2
Publication statusPublished - Jan 1 2005

Keywords

  • Diffusion
  • Dissolution of thin films
  • Nanomaterials
  • Non-linear effects
  • Shift of interfaces

ASJC Scopus subject areas

  • Radiation
  • Materials Science(all)
  • Condensed Matter Physics

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