1. Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA
2. Department Structure and Dynamics of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109, Berlin, Germany
3. Department of Physics, Dalhousie University, 6310 Coburg Road, Halifax, Nova Scotia, B3H 4R2, Canada
4. IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
5. Department of Chemistry, Duke University, Durham, North Carolina 27708, USA