1. Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634, USA
2. Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA
3. Electron Microscope Facility, Clemson Research Park, Clemson University, Clemson, South Carolina 29634, USA
4. Materials Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 29634, Saudi Arabia