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Atomic displacements in the charge ice pyrochlore Bi_{2}Ti_{2}O_{6}O^{?} studied by neutron total scattering

Atomic displacements in the charge ice pyrochlore Bi_{2}Ti_{2}O_{6}O^{?} studied by neutron total scattering
Atomic displacements in the charge ice pyrochlore Bi_{2}Ti_{2}O_{6}O^{?} studied by neutron total scattering
The oxide pyrochlore Bi2Ti2O6O? is known to be associated with large displacements of Bi and O? atoms from their ideal crystallographic positions. Neutron total scattering, analyzed in both reciprocal and real space, is employed here to understand the nature of these displacements.

Rietveld analysis and maximum entropy methods are used to produce an average picture of the structural nonideality. Local structure is modeled via large-box reverse Monte Carlo simulations constrained simultaneously by the Bragg profile and real-space pair distribution function. Direct visualization and statistical analyses of these models show the precise nature of the static Bi and O? displacements.

Correlations between neighboring Bi displacements are analyzed using coordinates from the large-box simulations. The framework of continuous symmetry measures has been applied to distributions of O?Bi4 tetrahedra to examine deviations from ideality. Bi displacements from ideal positions appear correlated over local length scales. The results are consistent with the idea that these nonmagnetic lone-pair containing pyrochlore compounds can be regarded as highly structurally frustrated systems.
1550-235X
144113
Shoemaker, Daniel P.
05ef817f-5b18-4e27-b983-1a63f47f10da
Seshadri, Ram
591864b1-7ea4-418a-953a-be002947842a
Hector, Andrew L.
f19a8f31-b37f-4474-b32a-b7cf05b9f0e5
Llobet, Anna
fbb4b0cd-af50-4624-aff7-4c14641e9063
Proffen, Thomas
edc013bb-6f79-4a4a-8ebe-d031d67e276f
Fennie, Craig J.
a4a4bb04-eeeb-44d2-8cdc-16a420b11207
Shoemaker, Daniel P.
05ef817f-5b18-4e27-b983-1a63f47f10da
Seshadri, Ram
591864b1-7ea4-418a-953a-be002947842a
Hector, Andrew L.
f19a8f31-b37f-4474-b32a-b7cf05b9f0e5
Llobet, Anna
fbb4b0cd-af50-4624-aff7-4c14641e9063
Proffen, Thomas
edc013bb-6f79-4a4a-8ebe-d031d67e276f
Fennie, Craig J.
a4a4bb04-eeeb-44d2-8cdc-16a420b11207

Shoemaker, Daniel P., Seshadri, Ram, Hector, Andrew L., Llobet, Anna, Proffen, Thomas and Fennie, Craig J. (2010) Atomic displacements in the charge ice pyrochlore Bi_{2}Ti_{2}O_{6}O^{?} studied by neutron total scattering. Physical Review B, 81 (14), 144113. (doi:10.1103/PhysRevB.81.144113).

Record type: Article

Abstract

The oxide pyrochlore Bi2Ti2O6O? is known to be associated with large displacements of Bi and O? atoms from their ideal crystallographic positions. Neutron total scattering, analyzed in both reciprocal and real space, is employed here to understand the nature of these displacements.

Rietveld analysis and maximum entropy methods are used to produce an average picture of the structural nonideality. Local structure is modeled via large-box reverse Monte Carlo simulations constrained simultaneously by the Bragg profile and real-space pair distribution function. Direct visualization and statistical analyses of these models show the precise nature of the static Bi and O? displacements.

Correlations between neighboring Bi displacements are analyzed using coordinates from the large-box simulations. The framework of continuous symmetry measures has been applied to distributions of O?Bi4 tetrahedra to examine deviations from ideality. Bi displacements from ideal positions appear correlated over local length scales. The results are consistent with the idea that these nonmagnetic lone-pair containing pyrochlore compounds can be regarded as highly structurally frustrated systems.

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Published date: 2010

Identifiers

Local EPrints ID: 148213
URI: http://eprints.soton.ac.uk/id/eprint/148213
ISSN: 1550-235X
PURE UUID: 970f9934-4b79-439b-b445-f767f20f9117
ORCID for Andrew L. Hector: ORCID iD orcid.org/0000-0002-9964-2163

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Date deposited: 27 Apr 2010 13:42
Last modified: 29 Oct 2019 02:03

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