Lewis, James W. and Payne, Julia L. and Evans, Ivana Radosavljevic and Stokes, Harold T. and Campbell, Branton J. and Evans, John S. O. (2016) 'An exhaustive symmetry approach to structure determination : phase transitions in Bi2Sn2O7.', Journal of the American Chemical Society., 138 (25). pp. 8031-8042.
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.
|Full text:||(AM) Accepted Manuscript|
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|Publisher Web site:||http://dx.doi.org/10.1021/jacs.6b04947|
|Publisher statement:||This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.|
|Date accepted:||13 May 2016|
|Date deposited:||05 August 2016|
|Date of first online publication:||01 June 2016|
|Date first made open access:||26 August 2016|
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