title: New insights into the structural and dynamical features of lithium hexaoxometalates Li7MO6 (M = Nb, Ta, Sb, Bi).
abstract: We present a (re)investigation of the hexaoxometalates Li(8)MO(6) (M = Sn, Pb, Zr, Hf) and Li(7)MO(6) (M = Nb, Ta, Sb, Bi). Lithium motion and ionic conductivity in the hexaoxometalates were studied using impedance spectroscopy (for Li(7)MO(6), M = Sb, Bi, Ta) and (6)Li and (7)Li solid-state nuclear magnetic resonance (for Li(7)TaO(6)). The NMR data indicate a considerable exchange of Li among the tetrahedral and octahedral voids even at ambient temperature. In an investigation of the crystal structures using laboratory and synchrotron X-ray powder diffraction techniques, the structures of Li(7)TaO(6), Li(7)NbO(6), and Li(7)SbO(6) could be solved and refined. All three reveal a triclinic metric (Li(7)SbO(6), triclinic, P1, a = 5.38503(6) A, b = 5.89164(7) A, c = 5.43074(6) A, alpha = 117.2210(6) degrees, beta = 119.6311(6) degrees, gamma = 63.2520(7) degrees, V = 127.454(3) A(3), Z = 1; Li(7)NbO(6), triclinic, P1, a = 5.37932(9) A, b = 5.91942(11) A, c = 5.37922(9) A, alpha = 117.0033(9) degrees, beta = 119.6023(7) degrees, gamma = 63.2570(9) degrees, V = 126.938(4) A(3), Z = 1; Li(7)TaO(6), triclinic, P1, a = 5.38486(2) A, b = 5.92014(3) A, c = 5.38551(2) A, alpha = 117.0108(2) degrees, beta = 119.6132(2) degrees, gamma = 63.2492(2) degrees, V = 127.208(1) A(3), Z = 1.
authors.affiliation: Max-Planck-Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
authors.forename: Claus
authors.initials: C
authors.lastname: Mühle
authors.forename: Robert E
authors.initials: RE
authors.lastname: Dinnebier
authors.forename: Leo
authors.initials: L
authors.lastname: van Wüllen
authors.forename: Georg
authors.initials: G
authors.lastname: Schwering
authors.forename: Martin
authors.initials: M
authors.lastname: Jansen