4.2.2 Essentials to Chapter 4.2: Experimental Techniques for Studying Point Defects in Non-Equilibrium

Non-equilibrium can be obtained in several ways; one always tries to have point defect concentrations far above equilibrium.
What happens during cooling down - rapidly or otherwise?
Question to ponder:
How far can a point defect move during cooling or
what is the total diffusion length Ltotal?
Exercise 4.2-1

Ltotal determines
  • How well quenching works
  • Density of agglomerates
  • Size of agglomerates
Quenching, i.e. freezing-in some equilibrium concentration (or some non-equilibrium concentration) at the low temperature Tquench that was present at the temperature T.  
Irradiation (e.g. with electrons) that mostly produce vacancy - interstitial pairs in a concentration given by the irradiation intensity and thus will be above thermal equilibrium.  
After the point defects have been frozen-in, i.e. immobilized, you measure a property that is sensitive to point defects, most prominently the conductivity at low temperatures, and then study how this property changes upon annealing, i.e. letting your point defects achieve equilibrium (= disappear).  
If you started from equilibrium, you will get equilibrium concentration and diffusion data that must be separated "somehow".  
If you started from a non-equilibrium concentrations, you will only get diffusion data, i.e. migration enthalpies and entropies.  

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© H. Föll (Defects - Script)