TEM diffraction contrast images simulation of dislocations.

Abstract

For end-on screw dislocations and inclined dislocations within thin transmission electron microscopy (TEM) foil, TEM diffraction contrast image is largely modified around piercing point due to free surface relaxation. Based on many-beam Schaeublin-Stadelmann equations, TEM diffraction contrast images simulation of inclined dislocations within thin pure Fe TEM foil are performed and the difference between isotropic and anisotropic dislocation models are studied. Image force are superposed onto bulk elastic field of dislocation in thin foil, the elastic distortions nearby the two emerging points of a straight inclined dislocation located in an elastically isotropic/anisotropic thin foil are expressed as semianalytical solution in Fourier space, and the semianalytical image stress solutions in Fourier space are implemented into CUFOUR for studying free surface relaxation effect on TEM diffraction contrast of dislocation. Simulation results suggest that the diffraction contrast at the ends of dislocation is modified drastically by image forces, and effects of anisotropy cannot be neglected. LAY DESCRIPTION: For end-on screw dislocations and inclined dislocations within thin transmission electron microscopy (TEM) foil, TEM diffraction contrast image is largely modified around piercing point due to free surface relaxation. Based on many-beam Schaeublin-Stadelmann equations, TEM diffraction contrast images simulation of inclined dislocations within thin pure Fe TEM foil are performed and the difference between isotropic and anisotropic dislocation models are studied. Image force are superposed onto bulk elastic field of dislocation in thin foil, the elastic distortions nearby the two emerging points of a straight inclined dislocation located in an elastically isotropic/anisotropic thin foil are expressed as semianalytical solution in Fourier space, and the semianalytical image stress solutions in Fourier space are implemented into CUFOUR for studying free surface relaxation effect on TEM diffraction contrast of dislocation. Simulation results suggest that the diffraction contrast at the ends of dislocation is modified drastically by image forces, and effects of anisotropy cannot be neglected.