Issue 45, 2015

Fluoride solid electrolytes: investigation of the tysonite-type solid solutions La1−xBaxF3−x (x < 0.15)

Abstract

Pure tysonite La1−xBaxF3−x solid solutions for x < 0.15 were prepared by solid state synthesis in a platinum tube under an azote atmosphere with subsequent quenching for 0.07 ≤ x < 0.15. The solid solutions were studied by X-ray, electron and neutron diffractions and by 19F NMR and impedance spectroscopy. The evolution of the cell parameters obeying Vegard's rule was determined for 0 < x ≤ 0.15 and atomic position parameters were accurately refined for x = 0.03, 0.07 and 0.10. The chemical pressure induced by large Ba2+ cations leads to an increase of the unit cell parameters. Fluorine environment and mobilities are discussed on the basis of the results of neutron diffraction and 19F solid state NMR. The F1 subnetwork is lacunar; fluorine exchange occurs according to the order: F1–F1 and F1–F2,3. 2D EXSY NMR spectra of La0.97Ba0.03F2.97 reveal, for the first time, a chemical exchange between F2 and F3 sites that requires two successive jumps. The ionic conductivity was evaluated from sintered pellets and different shaping methods were compared. The only structural features which could explain the conductivity maximum are a crossover together with a smaller dispersion of F1–F1,2,3 distances at x = 0.05–0.07.

Graphical abstract: Fluoride solid electrolytes: investigation of the tysonite-type solid solutions La1−xBaxF3−x (x < 0.15)

  • This article is part of the themed collection: Fluorine

Supplementary files

Article information

Article type
Paper
Submitted
18 jun 2015
Accepted
23 jul 2015
First published
23 jul 2015

Dalton Trans., 2015,44, 19625-19635

Author version available

Fluoride solid electrolytes: investigation of the tysonite-type solid solutions La1−xBaxF3−x (x < 0.15)

J. Chable, B. Dieudonné, M. Body, C. Legein, M. Crosnier-Lopez, C. Galven, F. Mauvy, E. Durand, S. Fourcade, D. Sheptyakov, M. Leblanc, V. Maisonneuve and A. Demourgues, Dalton Trans., 2015, 44, 19625 DOI: 10.1039/C5DT02321A

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