An Exhaustive Symmetry Approach to Structure Determination: Phase Transitions in Bi2Sn2O7.
J Am Chem Soc
; 138(25): 8031-42, 2016 06 29.
Article
en En
| MEDLINE
| ID: mdl-27248317
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 ß and α structures on cooling. The results include the first reliable structural model for ß-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, ß = 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.
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Colección:
01-internacional
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MEDLINE
Idioma:
En
Revista:
J Am Chem Soc
Año:
2016
Tipo del documento:
Article
País de afiliación:
Reino Unido