1. Institute for Mineralogy, Crystallography and Materials Science, Leipzig University, 04275 Leipzig, Germany
2. Leibniz-Institute for Solid State and Materials Research, 01069 Dresden, Germany
3. Experimentelle Physik VII, Universität Würzburg, 97074 Würzburg, Germany
4. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
5. Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany