Publication details for Prof. Ivana EvansLewis, James W., Payne, Julia L., Evans, Ivana Radosavljevic, Stokes, Harold T., Campbell, Branton J. & Evans, John S. O. (2016). An Exhaustive Symmetry Approach to Structure Determination: Phase Transitions in Bi2Sn2O7. Journal of the American Chemical Society 138(25): 8031-8042.
- Publication type: Journal Article
- ISSN/ISBN: 0002-7863 (print), 1520-5126 (electronic)
- DOI: 10.1021/jacs.6b04947
- Further publication details on publisher web site
- Durham Research Online (DRO) - may include full text
Author(s) from Durham
The exploitable properties of many materials are intimately linked to symmetry-lowering structural phase transitions. We present an automated and exhaustive symmetry-mode method for systematically exploring and solving such structures which will be widely applicable to a range of functional materials. We exemplify the method with an investigation of the Bi2Sn2O7 pyrochlore, which has been shown to undergo transitions from a parent γ cubic phase to β and α structures on cooling. The results include the first reliable structural model for β-Bi2Sn2O7 (orthorhombic Aba2, a = 7.571833(8), b = 21.41262(2), and c = 15.132459(14) Å) and a much simpler description of α-Bi2Sn2O7 (monoclinic Cc, a = 13.15493(6), b = 7.54118(4), and c = 15.07672(7) Å, β = 125.0120(3)°) than has been presented previously. We use the symmetry-mode basis to describe the phase transition in terms of coupled rotations of the Bi2O′ anti-cristobalite framework, which allow Bi atoms to adopt low-symmetry coordination environments favored by lone-pair cations.