1. Inorganic Chemistry II, Faculty of Chemistry and Biochemistry; Ruhr-University; Bochum 44801 Bochum (Germany)
2. Institute for Materials; Ruhr-University; Bochum 44801 Bochum (Germany)
3. Applied Solid State Physics; Ruhr-University; Bochum 44801 Bochum (Germany)
4. Materials Research Department; Ruhr-University; Bochum 44801 Bochum (Germany)