Octahedral tilting in the polar hexagonal tungsten bronzes RbNbW2O9 and KNbW2O9
Abstract
The ambient temperature structures (orthorhombic, space group, Cmc21) of the polar hexagonal tungsten bronzes RbNbW2O9 and KNbW2O9 have been determined by high-resolution powder neutron diffraction. Displacement of the A-site cation in the polar c-axis, with concomitant octahedral tilting, occurs to optimise the A-cation bonding environment reducing the coordination from 18 to 16. This effect is more evident in KNbW2O9 due to decreased A-cation size. The octahedral tilting in both compositions results in a doubling of the c-axis that has not previously been reported, highlighting the importance of neutron diffraction as a complementary technique for structural determination of such systems.
Citation
McNulty , J A , Gibbs , A , Lightfoot , P & Morrison , F D 2019 , ' Octahedral tilting in the polar hexagonal tungsten bronzes RbNbW 2 O 9 and KNbW 2 O 9 ' , Acta Crystallographica. Section B, Structural Science , vol. 75 , no. Part 5 , B75 . https://doi.org/10.1107/S2052520619009260
Publication
Acta Crystallographica. Section B, Structural Science
Status
Peer reviewed
ISSN
0108-7681Type
Journal article
Rights
Copyright © International Union of Crystallography. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the final published version of the work, which was originally published at https://doi.org/10.1107/S2052520619009260
Description
We thank the Science and Technology Facilities Council (STFC) for the provision of neutron diffraction facilities at ISIS (HRPD experiment RB1710021, doi: 10.5286/ISIS.E.RB1710021) and the School of Chemistry, University of St Andrews for funding of a studentship to JAM through the EPSRC doctoral training grant (EP/K503162/1).Collections
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.