[1] Univ Karlsruhe, Inst Anorgan Chem, D-76128 Karlsruhe, Germany
[2] Int Ctr Young Scientists, Natl Inst Mat Sci, Tsukuba, Ibaraki 3050044, Japan
[3] Forschungszentrum Karlsruhe, Inst Mat Forsch, D-76344 Eggenstein Leopoldshafen, Germany
[4] Forschungszentrum Karlsruhe, Inst Nanotechnol, D-76344 Eggenstein Leopoldshafen, Germany
[5] Natl Inst Mat Sci, Adv Mat Lab, Tsukuba, Ibaraki 3050044, Japan