1. NEEP 541 – Diffusion
Fall 2003
Jake Blanchard

2. Outline Diffusion of point defects Mechanisms Vacancy Interstitial
Etc.

3. Diffusion of Defects
Defect motion is the key to many aspects of radiation damage
The motion allows clustering, leading to larger defects that are better able to affect macroscopic properties
Defect diffusion can generally be described by Fick’s law

4. Fick’s Law

5. Fick’s Law g=geometry factor =jump frequency G=free energy H=enthalpy
S=entropy

6. Diffusion Mechanisms There are many ways for defects to diffuse
Vacancy
Direct interstitial
Indirect interstitial
Kick-out
Frank-Turnbull
other

7. Vacancy

8. Direct Interstitial

9. Indirect interstitial

10. Kick-Out

11. Frank-Turnbull

12. Direct Exchange
Other similar mechanisms exist