Interstitial defects migration properties

For ceramic materials, defects within the lattice are inextricably linked with transport properties. The diffusion of a cation in a ceramic, for example, involves the formation of vacancy or interstitial states within the crystal, and the migration of these species leads to a net transport of material through the lattice. These processes may be modeled by means of ion pair potentials in conjunction with the Mott-Littleton defect approach, direct molecular dynamics techniques, 24 or Monte Carlo methods to describe overall transport on the basis of calculated individual process statistics. 

The same arguments apply to interstitials. In pure metals of simple (f.c.c. or b.c.c.) crystal structure, the structure and properties of interstitials are well-known for example, in many f.c.c. metals, it consists of a dumbbell oriented in a <1 OOHype direction, with a large formation energy (several eV) and a small migration energy (typically 0.2 eV). In intermetallic compounds, the structure of interstitials is generally not known in some cases, several types of complex defects occur... 

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