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MI: Fachverband Mikrosonden

MI 2: Analytical Transmission Electron Microscopy and Atom Probe Tomography

MI 2.4: Vortrag

Montag, 16. März 2015, 12:45–13:00, EMH 225

How electrostatic simulations improve the understanding of APT measurement results — •Christian Oberdorfer, Daniel Beinke, and Guido Schmitz — Institute of Materials Science, University of Stuttgart, Germany

Simulations represent a complementary approach to atom probe experiments. By flexible electrostatic modeling, the field evaporation and the ion trajectories are calculated. Important insights into the presence and the origin of measurement artifacts may be revealed in this way.

Numeric treatment is rigidly based on the representation of atoms by Wigner-Seitz cells. Field evaporation is assumed to be induced by polarization forces acting on the atomic cells. Evaluation of the force represents an essential cornerstone to a more realistic prediction of the field evaporation sequence.

Investigated trajectory aberrations show a decisively limited resolution of the computed 3D reconstruction if the standard protocol based on geometric back-projection is followed. The applied point-projection neglects important information of the detailed surface field and fails for this reason.