An exhaustive symmetry approach to structure determination: phase transitions in Bi2Sn2O7

DOI: 10.1021/jacs.6b04947

Authors: James W. Lewis (Durham University) , Julia Payne (Durham University) , Ivana Evans (Durham University) , Harold T. Stokes (Brigham Young University) , Branton J. Campbell (Brigham Young University) , John Evans (Durham University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of The American Chemical Society , VOL 138 , PAGES 8031-8042

State: Published (Approved)
Published: June 2016
Diamond Proposal Number(s): 14188

Abstract: 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.

Journal Keywords: Group theory; Chemical structure; Physical and chemical processes; Phase transitions; Lattices

Subject Areas: Chemistry, Materials


Instruments: I11-High Resolution Powder Diffraction

Other Facilities: HRPD at ISIS

Added On: 29/06/2016 10:11

Documents:
jacs.6b04947.pdf

Discipline Tags:

Physical Chemistry Chemistry Materials Science Inorganic Chemistry

Technical Tags:

Diffraction X-ray Powder Diffraction