[1] Max Planck Inst Chem Phys Fester Stoffe, D-01178 Dresden, Germany
[2] Max Planck Inst Festkorperforsch, D-70506 Stuttgart, Germany
[3] Univ Santiago Chile, Fac Quim & Biol, Dept Quim Mat, Santiago 2, Chile
[4] Univ Stuttgart, Inst Anorgan Chem, D-70569 Stuttgart, Germany