1. Inorganic Chemistry Department, Technical University of Dresden, Mommsenstrasse 6, D-01069 Dresden, Germany, Max-Planck-Institute of Coal Research, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim a.d. Ruhr, Germany, Max-Planck-Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, D-01187 Dresden, Germany, Max-Planck-Institut for Metals Research, Heisenbergstrasse 3, D-70569 Stuttgart, Germany, and University of Applied Sciences Münster, Stegerwaldstrasse 39, D-48565 Steinfurt, Germany