Modular crystals as modulated structures: the case of the lillianite homologous series

L. Elcoro; J.M. Perez-Mato; K. Friese; V. Petricek; Tonci Balic Zunic; L.A. Olsen

doi:10.1107/s0108768108031492

Modular crystals as modulated structures: the case of the lillianite homologous series

L. Elcoro, J.M. Perez-Mato, K. Friese, V. Petricek, Tonci Balic Zunic, L.A. Olsen

Geology

22 Citations (Scopus)

Abstract

The use of the superspace formalism is extended to the description and refinement of the homologous series of modular structures with two symmetry-related modules with different orientations. The lillianite homologous series has been taken as a study case. Starting from a commensurate modulated composite description with two basic subsystems corresponding to the two different modules, it is shown how a more efficient description can be achieved using so-called zigzag modulation functions. These linear zigzag modulations, newly implemented in the program JANA2006, have very large fixed amplitudes and introduce in the starting model the two orientations of the underlying module sublattices. We show that a composite approach with this type of function, which treats the cations and anions as two separate subsystems forming a misfit compound, is the most appropriate and robust method for the refinements.

Original language	English
Journal	Acta Crystallographica. Section B: Structural Science
Volume	64
Issue number	6
Pages (from-to)	684-701
ISSN	0108-7681
DOIs	https://doi.org/10.1107/s0108768108031492
Publication status	Published - 2008

Keywords

Faculty of Science
modulated structures
misfit compound
superspace formalism
homologous series

Access to Document

10.1107/s0108768108031492

Cite this

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title = "Modular crystals as modulated structures: the case of the lillianite homologous series",

abstract = "The use of the superspace formalism is extended to the description and refinement of the homologous series of modular structures with two symmetry-related modules with different orientations. The lillianite homologous series has been taken as a study case. Starting from a commensurate modulated composite description with two basic subsystems corresponding to the two different modules, it is shown how a more efficient description can be achieved using so-called zigzag modulation functions. These linear zigzag modulations, newly implemented in the program JANA2006, have very large fixed amplitudes and introduce in the starting model the two orientations of the underlying module sublattices. We show that a composite approach with this type of function, which treats the cations and anions as two separate subsystems forming a misfit compound, is the most appropriate and robust method for the refinements.",

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TY - JOUR

T1 - Modular crystals as modulated structures

T2 - the case of the lillianite homologous series

AU - Elcoro, L.

AU - Perez-Mato, J.M.

AU - Friese, K.

AU - Petricek, V.

AU - Balic Zunic, Tonci

AU - Olsen, L.A.

PY - 2008

Y1 - 2008

N2 - The use of the superspace formalism is extended to the description and refinement of the homologous series of modular structures with two symmetry-related modules with different orientations. The lillianite homologous series has been taken as a study case. Starting from a commensurate modulated composite description with two basic subsystems corresponding to the two different modules, it is shown how a more efficient description can be achieved using so-called zigzag modulation functions. These linear zigzag modulations, newly implemented in the program JANA2006, have very large fixed amplitudes and introduce in the starting model the two orientations of the underlying module sublattices. We show that a composite approach with this type of function, which treats the cations and anions as two separate subsystems forming a misfit compound, is the most appropriate and robust method for the refinements.

AB - The use of the superspace formalism is extended to the description and refinement of the homologous series of modular structures with two symmetry-related modules with different orientations. The lillianite homologous series has been taken as a study case. Starting from a commensurate modulated composite description with two basic subsystems corresponding to the two different modules, it is shown how a more efficient description can be achieved using so-called zigzag modulation functions. These linear zigzag modulations, newly implemented in the program JANA2006, have very large fixed amplitudes and introduce in the starting model the two orientations of the underlying module sublattices. We show that a composite approach with this type of function, which treats the cations and anions as two separate subsystems forming a misfit compound, is the most appropriate and robust method for the refinements.

KW - Faculty of Science

KW - modulated structures

KW - misfit compound

KW - superspace formalism

KW - homologous series

U2 - 10.1107/s0108768108031492

DO - 10.1107/s0108768108031492

M3 - Journal article

SN - 2052-5192

VL - 64

SP - 684

EP - 701

JO - Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials

JF - Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials

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