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The inverse perovskite BaLiF 3 : single‐crystal neutron diffraction and analyses of potential ion pathways
Author(s) -
Wiedemann Dennis,
Meutzner Falk,
Fabelo Oscar,
Ganschow Steffen
Publication year - 2018
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520618014579
Subject(s) - neutron diffraction , ion , valence (chemistry) , single crystal , crystallography , materials science , chemistry , crystal structure , organic chemistry
Doped barium lithium trifluoride has attracted attention as component for scintillators, luminescent materials and electrodes. With lithium and fluoride, it contains two possibly mobile species, which may account for its ionic conductivity. In this study, neutron diffraction on oxide‐containing BaLiF 3 single‐crystals is performed at up to 636.2°C. Unfortunately, ion‐migration pathways could not be mapped by modelling anharmonic ion displacement or by inspecting the scattering‐length density that was reconstructed via maximum‐entropy methods. However, analyses of the topology and bond‐valence site energies derived from the high‐temperature structure reveal that the anions can migrate roughly along the edges of the LiF 6 coordination octahedra with an estimated migration barrier of ∼0.64 eV (if a vacancy permits), whereas the lithium ions are confined to their crystallographic positions. This finding is not only valid for the title compound but for ion migration in all perovskites with Goldschmidt tolerance factors near unity.