title: Disorder in Ag7GeSe5I, a superionic conductor: temperature-dependent anharmonic structural study.
abstract: A temperature-dependent structural investigation of the substituted argyrodite Ag(7)GeSe(5)I has been carried out on a single crystal from 15 to 475 K, in steps of 50 K, and correlated to its conductivity properties. The argyrodite crystallizes in a cubic cell with the F\bar 43m space group. The crystal structure exhibits high static and dynamic disorder which has been efficiently accounted for using a combination of (i) Gram-Charlier development of the Debye-Waller factors for iodine and silver, and (ii) a split-atom model for Ag(+) ions. An increased delocalization of the mobile d(10) Ag(+) cations with temperature has been clearly shown by the inspection of the joint probability-density functions; the corresponding diffusion pathways have been determined.
authors.affiliation: Institut Charles Gerhardt Montpellier, UMR 5253, CNRS Université Montpellier 2 CC 1503, Place E. Bataillon, F-34095 Montpellier CEDEX 5, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Albert
authors.forename: Sébastien
authors.initials: S
authors.lastname: Pillet
authors.forename: Claude
authors.initials: C
authors.lastname: Lecomte
authors.forename: Annie
authors.initials: A
authors.lastname: Pradel
authors.forename: Michel
authors.initials: M
authors.lastname: Ribes