Interstitial substitution

For interstitial substitution of CaCl2 in KCl, the defect reaction equation is... 

The diffusion of dopants in semiconductors has been briefly discussed in Sect. 2.1.3. At an atomic scale, the diffusion of a FA in a crystal lattice can take place by different mechanisms, the most common being the vacancy and interstitial mechanisms in silicon and germanium (see for instance [25]). The interstitial/substitutional or kick-out mechanism, which is an interstitial mechanism combined with the ejection of a lattice atom (self-interstitial) and its replacement by the dopant atom is also encountered for some atoms like Pt in silicon. 

FIGURE 17 Effect of imperfections on interstitial-substitutional diffusion (a) the interstitial to substitutional impurity conversion in a perfect crystal is limited by intrinsic point defect transport, (b) a crystal imperfection promotes the conversion. The subscripts 1 and S denote interstitial and substitutional positions, (c) Diffusion... 

Kozl] Kozeschnik, E., Vitek, J.M., Ortho-Equilibrium and Para-Equilibrium Phase Diagrams for Interstitial/Substitutional Iron Alloys , Calphad, 24(4), 495-502 (2000) (Phase Diagram, Phase Relations, Thermodyn., Calculation, 10)... 

Interstitially substituted C atoms in a cubic close-packed Fe lattice play an important part in determining the properties of steel (see below). (Vacancies and interstitial atoms of B, Al, P, As, Sb, etc. occurring in C or Si lattices have an essential role in semiconductors and other electronic devices (Section 12.20).)... 

The results were interpreted within the framework of interstitial-substitutional diffusion. 

The Au was found to diffuse via a complex mechanism involving a vacancy-controlled interstitial-substitutional equilibrium. This led to very complex diffusion concentration profiles. The experimental data on the self-diffusion coefficient of Si was described by ... 

They interpreted the marked effect of the simultaneous addition of carbon and La on the creep life due to the I-S (interstitial-substitutional) interaction, which forms clusters by chemical affinity around dislocations (Monma and Suto 1966). That is, carbon and La (which has a large atomic radius) form clusters with a large apparent size of the solute atmosphere around dislocations, which markedly decrease the moving velocity of dislocations by anchoring them to the atmosphere. Dislocations can move, however, by a process in which the solute atoms migrate with dislocations, and this will be controlled by the diffusion rate of the solute. The diffusion rate of La atoms is considered to be small, especially when they form clusters by the I-S interaction. Further detailed research is required on this diffusion controlled mechanism. 

Define the following point defects and identify them as atomic defects or electronic defects vacancy, interstitial, substitutional impurity, misplaced atoms, electron, hole, dopant. 

We can examine point defects, defects that occur at single atomic site, by applying the principles of chemical reaction equilibrium from this chapter. Atomic point defects include vacancies, interstitials, substitutional impurities, and misplaced atoms. Electronic point defects include mobile electrons and holes. From this approach, we can study carrier concentrations in semiconductors and see the effect of gas partial pressure on defect concentrations at equilibrium. The Brouwer diagram is a particularly useful tool in seeing the effect of gas partial pressure on defect concentration over many orders of magnitude. 

---