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### 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. |

© H. Föll (Defects - Script)