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High‐temperature dynamic octahedral tilting in the ionic conductor Sr 11 Mo 4 O 23
Author(s) -
López Carlos A.,
Pedregosa José C.,
Fernández-Díaz María T.,
Alonso José A.
Publication year - 2016
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s160057671502261x
Subject(s) - octahedron , crystallography , ionic bonding , ionic conductivity , atmospheric temperature range , neutron diffraction , crystal structure , delocalized electron , chemistry , strontium , phase (matter) , ion , physics , thermodynamics , organic chemistry , electrode , electrolyte
This work presents the crystal structure evolution of a novel ionic conductor Sr 11 Mo 4 O 23 at high temperature. The formula of this phase can be rewritten as Sr 1.75 □ 0.25 SrMoO 5.75 , highlighting the relationship with double perovskites A 2 B ′ B ′′O 6 . The crystal network contains oxygen‐anion and strontium‐cation vacancies. The structure is complex; Sr, Mo and O atoms are distributed in four, two and six distinct Wyckoff sites, respectively. It was refined from neutron powder diffraction data collected at 473, 673, 873 and 1073 K. The thermal evolution of crystallographic parameters supports the known reversible process of removal/uptake of O‐atom content in the 673–873 K temperature range. Above 873 K, from difference Fourier maps, it was found that the structure exhibits an oxygen delocalization around one of the Mo sites. This delocalization was understood as a dynamical octahedral tilt of the MoO 6 octahedron, yielding an increase in the ionic conductivity at high temperature.