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