Landolt-Börnstein - Group III Condensed Matter

1.5 Atomistic mechanisms of diffusion


This chapter provides a brief introduction to atomistic mechanisms of diffusion, namely, direct interstitial mechanism, direct exchange and ring mechanisms, vacancy mechanism, divacancy mechanism, interstitialcy mechanism, and interstitial-substitutional mechanism. Foreign atoms that are located exclusively in interstitial sites of an otherwise perfect crystal may diffuse simply by jumping from interstitial site to interstitial site. This mechanism is denoted as the direct interstitial mechanism. The direct diffusion of substitutionally incorporated foreign atoms or host atoms on regular lattice sites would involve the exchange of two atoms on neighbouring lattice sites or of a ring of atoms. This mechanism is called as the direct exchange and ring mechanisms. In the vacancy mechanism vacant lattice sites act as diffusion vehicles. A substitutional foreign atom or a self-atom diffuses by jumping into a neighbouring vacancy. In divacancy case bound pairs of vacancies on neighbouring lattice sites act as diffusion vehicles. In the interstitialcy mechanism, self interstitial atom act as diffusion vehicles. The self-interstitial atom replaces a substitutional atom which then in turn replaces a neighbouring lattice atom. Some foreign atoms may be dissolved on interstitial atom and also on substitutional sites. Such atoms may diffuse via the dissociative mechanism or via the kick-out mechanism.

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1.5 Atomistic mechanisms of diffusion
Book Title
Diffusion in Solid Metals and Alloys
1 General introduction
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Landolt-Börnstein - Group III Condensed Matter
  • H. Mehrer
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  • H. Mehrer
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