1. Eduard-Zintl-Institute of Inorganic and Physical Chemistry, Technische Universität Darmstadt, Alarich-Weiss-Str. 12, 64287 Darmstadt, Germany
2. Department of Chemistry & Biochemistry, Materials Department, and Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, California 93106, United States
3. Department of Materials and Earth Sciences, Electron Microscopy Center Darmstadt (EMC-DA), Technische Universität Darmstadt, Alarich-Weiss-Str. 2, 64287 Darmstadt, Germany