title: Synthèse et étude structrale de lyonsite-type (Na0,4,Li0,6)(Fe,Li2)(MoO4)3.
abstract: The new compound (Na0.4,Li0.6)(Fe,Li2)(MoO4)3 was synthesized by cooling from the melt. Its anionic framework is built up from two distinct MO6 octa-hedra, each containing disordered Li(+) and Fe(3+) ions in 0.6:0.4 and 0.7:0.3 ratios, and two MoO4 tetra-hedra, which link by vertex-sharing of their O atoms. These tetra-meric units are further linked by sharing edges between octa-hedra and by formation of M-O-Mo (M = Fe/Li) bridges, forming ribbons propagating in the [100] direction. The ribbons are cross-linked in both the b- and c-axis directions, giving rise to a three-dimensional framework having [100] tunnels in which the monovalent Na(+)/Li(+) cations (0.4:0.6 ratio) lie. Bond-valence calculations are consistent with the disorder model for the cations. The structure of the title compound, which is isotypic with Li3Fe(MoO4)3 and Li3Ga(MoO4)3, is compared briefly with those of LiFeMo2O8 and Li1.6Mn2.2(MoO4)3.
authors.affiliation: Laboratoire de Matériaux et Cristallochimie, Faculté des Sciences de Tunis, Université de Tunis ElManar, 2092 Manar II Tunis, Tunisie.
authors.forename: Amira
authors.initials: A
authors.lastname: Souilem
authors.affiliation: Laboratoire de Matériaux et Cristallochimie, Faculté des Sciences de Tunis, Université de Tunis ElManar, 2092 Manar II Tunis, Tunisie.
authors.forename: Mohamed Faouzi
authors.initials: MF
authors.lastname: Zid
authors.affiliation: Laboratoire de Matériaux et Cristallochimie, Faculté des Sciences de Tunis, Université de Tunis ElManar, 2092 Manar II Tunis, Tunisie.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Driss
keywords: bond-valence calculations; crystal structure; lyonsite-type; monovalent cation molybdate