1. Central Facility of Electron Microscopy, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
2. Carl Zeiss Microscopy GmbH, Carl-Zeiss-Str. 22, 73447 Oberkochen, Germany
3. Institut des Matériaux Jean Rouxel, UMR6502, CNRS - Université de Nantes, 2 rue de la Houssinière, B.P.32229, 44322 Nantes Cedex, France
4. Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70579 Stuttgart, Germany