DIEUDONNÉ, Belto; CHABLE, Johann; BODY, Monique; LEGEIN, Christophe; DURAND, Etienne; MAUVY, Fabrice; FOURCADE, Sébastien; LEBLANC, Marc; MAISONNEUVE, Vincent; DEMOURGUES, Alain

doi:10.1039/c6dt04714a

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DIEUDONNÉ, Belto
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]

CHABLE, Johann
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
Institut des Molécules et Matériaux du Mans [IMMM]

BODY, Monique
Institut des Molécules et Matériaux du Mans [IMMM]

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Article de revue

Ce document a été publié dans

Dalton Transactions. 2017-03-14, vol. 46, n° 11, p. 3761-3769

Royal Society of Chemistry

Résumé en anglais

Pure tysonite-type Ce1-xSrxF3-x solid solutions for 0 ≤ x < 0.15 were prepared by a solid-state route at 900 °C. The cell parameters follow Vegard's laws for 0 ≤ x ≤ 0.10 and the solubility limit is identified (0.10 < xlimit < 0.15). For 0 ≤ x ≤ 0.05, the F2-(Ce,Sr) and F3-(Ce,Sr) bond distances into [Ce1-xSrxF]((2-x)+) slabs strongly vary with x. This slab buckling is maximum around x = 0.025 and strongly affects the more mobile F1 fluoride ions located between the slabs. The (19)F MAS NMR spectra show the occurrence of F1-F2,3 exchange at 64 °C. The fraction of mobile F2,3 atoms deduced from the relative intensity of the NMR resonance is maximum for Ce0.99Sr0.01F2.99 (22% at 64 °C) while this fraction linearly increases with x for La1-xAExF3-x (AE = Ba, Sr). The highest conductivity found for Ce0.975Sr0.025F2.975 (3 × 10(-4) S cm(-1) at RT, Ea = 0.31 eV) is correlated to the largest dispersion of F2-(Ce,Sr) and F3-(Ce,Sr) distances which induces the maximum sheet buckling. Such a relationship between composition, structural features and fluoride ion conductivity is extended to other tysonite-type fluorides. The key role of the difference between AE(2+) and RE(3+) ionic radii and of the thickness of the slab buckling is established and could allow designing new ionic conductors.< Réduire

DOI

http://dx.doi.org/10.1039/c6dt04714a

Project ANR

Batteries tout solide à ions fluorure - ANR-12-PRGE-0009

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Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB) - UMR 5026