The inherent displacive flexibility of the hexacelsian tetrahedral framework and its relationship to polymorphism in Ba-hexacelsian

R. L. Withers; Y. Tabira; J. A. Valgoma; M. Aroyo; M. T. Dove

doi:10.1007/s002690000112

The inherent displacive flexibility of the hexacelsian tetrahedral framework and its relationship to polymorphism in Ba-hexacelsian

R. L. Withers^*, Y. Tabira, J. A. Valgoma, M. Aroyo, M. T. Dove

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

10 Citations (Scopus)

Abstract

The results of a rigid unit mode (RUM) analysis of the inherent displacive structural flexibility of the tetrahedral framework of the ideal hexacelsian structure type are presented. One of the three types of RUM found to exist is characterized by modulation wave vectors perpendicular to 〈110〉 and atomic displacement patterns involving tetrahedral rotation around the parent c axis while a second type of RUM is found to be soft at any modulation wave vector and to involve tetrahedral rotation about in-plane rotation axes. It is shown how a combination of these two types of RUM motion associated with the same q = 1/2〈1101〉* modulation wave vector enables the outstanding crystal chemical problems and apparently mutually contradictory results as regards polymorphism in Ba-hexacelsian to be resolved.

Original language	English
Pages (from-to)	747-756
Number of pages	10
Journal	Physics and Chemistry of Minerals
Volume	27
Issue number	10
DOIs	https://doi.org/10.1007/s002690000112
Publication status	Published - 2000

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title = "The inherent displacive flexibility of the hexacelsian tetrahedral framework and its relationship to polymorphism in Ba-hexacelsian",

abstract = "The results of a rigid unit mode (RUM) analysis of the inherent displacive structural flexibility of the tetrahedral framework of the ideal hexacelsian structure type are presented. One of the three types of RUM found to exist is characterized by modulation wave vectors perpendicular to 〈110〉 and atomic displacement patterns involving tetrahedral rotation around the parent c axis while a second type of RUM is found to be soft at any modulation wave vector and to involve tetrahedral rotation about in-plane rotation axes. It is shown how a combination of these two types of RUM motion associated with the same q = 1/2〈1101〉* modulation wave vector enables the outstanding crystal chemical problems and apparently mutually contradictory results as regards polymorphism in Ba-hexacelsian to be resolved.",

keywords = "Correlated tetrahedral rotation, Diffuse distribution, Dynamical disorder, Hexacelsian, Phase transition",

author = "Withers, {R. L.} and Y. Tabira and Valgoma, {J. A.} and M. Aroyo and Dove, {M. T.}",

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T1 - The inherent displacive flexibility of the hexacelsian tetrahedral framework and its relationship to polymorphism in Ba-hexacelsian

AU - Withers, R. L.

AU - Tabira, Y.

AU - Valgoma, J. A.

AU - Aroyo, M.

AU - Dove, M. T.

PY - 2000

Y1 - 2000

N2 - The results of a rigid unit mode (RUM) analysis of the inherent displacive structural flexibility of the tetrahedral framework of the ideal hexacelsian structure type are presented. One of the three types of RUM found to exist is characterized by modulation wave vectors perpendicular to 〈110〉 and atomic displacement patterns involving tetrahedral rotation around the parent c axis while a second type of RUM is found to be soft at any modulation wave vector and to involve tetrahedral rotation about in-plane rotation axes. It is shown how a combination of these two types of RUM motion associated with the same q = 1/2〈1101〉* modulation wave vector enables the outstanding crystal chemical problems and apparently mutually contradictory results as regards polymorphism in Ba-hexacelsian to be resolved.

AB - The results of a rigid unit mode (RUM) analysis of the inherent displacive structural flexibility of the tetrahedral framework of the ideal hexacelsian structure type are presented. One of the three types of RUM found to exist is characterized by modulation wave vectors perpendicular to 〈110〉 and atomic displacement patterns involving tetrahedral rotation around the parent c axis while a second type of RUM is found to be soft at any modulation wave vector and to involve tetrahedral rotation about in-plane rotation axes. It is shown how a combination of these two types of RUM motion associated with the same q = 1/2〈1101〉* modulation wave vector enables the outstanding crystal chemical problems and apparently mutually contradictory results as regards polymorphism in Ba-hexacelsian to be resolved.

KW - Correlated tetrahedral rotation

KW - Diffuse distribution

KW - Dynamical disorder

KW - Hexacelsian

KW - Phase transition

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U2 - 10.1007/s002690000112

DO - 10.1007/s002690000112

M3 - Article

SN - 0342-1791

VL - 27

SP - 747

EP - 756

JO - Physics and Chemistry of Minerals

JF - Physics and Chemistry of Minerals

IS - 10

ER -

The inherent displacive flexibility of the hexacelsian tetrahedral framework and its relationship to polymorphism in Ba-hexacelsian

Abstract

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