1. Graz Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz, Austria
2. Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
3. Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
4. Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, 8010 Graz, Austria