Long-range modulation of a composite crystal in a five-dimensional superspace.

Autor:	Guérin L; Institut de Physique de Rennes, UMR UR1-CNRS 6251, Université de Rennes 1, 35042 Rennes, France., Mariette C; Institut de Physique de Rennes, UMR UR1-CNRS 6251, Université de Rennes 1, 35042 Rennes, France., Rabiller P; Institut de Physique de Rennes, UMR UR1-CNRS 6251, Université de Rennes 1, 35042 Rennes, France., Huard M; Institut de Physique de Rennes, UMR UR1-CNRS 6251, Université de Rennes 1, 35042 Rennes, France., Ravy S; Synchrotron SOLEIL, L'Orme des merisiers, Saint-Aubin BP 48, 91192 Gif-sur-Yvette cedex, France., Fertey P; Synchrotron SOLEIL, L'Orme des merisiers, Saint-Aubin BP 48, 91192 Gif-sur-Yvette cedex, France., Nichols SM; Department of Chemistry, 213 CBC Building, Kansas State University, Manhattan, Kansas 66506-0401, USA., Wang B; Department of Chemistry, 213 CBC Building, Kansas State University, Manhattan, Kansas 66506-0401, USA., Mannsfeld SC; Center for Advancing Electronics Dresden, Dresden University of Technology, 01062 Dresden, Germany., Weber T; Laboratory of Crystallography, Eidgenössische Technische Hochschule (ETH) Zurich, CH-8093 Zurich, Switzerland., Hollingsworth MD; Department of Chemistry, 213 CBC Building, Kansas State University, Manhattan, Kansas 66506-0401, USA., Toudic B; Institut de Physique de Rennes, UMR UR1-CNRS 6251, Université de Rennes 1, 35042 Rennes, France.
Jazyk:	angličtina
Zdroj:	Physical review. B, Condensed matter and materials physics [Phys Rev B Condens Matter Mater Phys] 2015 May 01; Vol. 91 (18).
DOI:	10.1103/PhysRevB.91.184101
Abstrakt:	The intergrowth crystal of n -tetracosane/urea presents a misfit parameter, defined by the ratio γ = c h / c g ( c host / c guest ), that is very close to a commensurate value ( γ ≅ 1/3). High-resolution diffraction studies presented here reveal an aperiodic misfit parameter of γ = 0.3369, which is found to be constant at all temperatures studied. A complex sequence of structural phases is reported. The high temperature phase (phase I) exists in the four-dimensional superspace group P 6 1 22(00 γ ). At T c 1 = 179(1) K, a ferroelastic phase transition increases the dimension of the crystallographic superspace. This orthorhombic phase (phase II) is characterized by the five-dimensional (5D) superspace group C 222 1 (00 γ )(10 δ ) with a modulation vector a o * + c m * = a o * + δ · c h * , in which the supplementary misfit parameter is δ = 0.025(1) in host reciprocal units. This corresponds to the appearance of a modulation of very long period (about 440 ± 16 Å). At T c 2 = 163.0(5) K, a 5D to 5D phase transition leads to the crystallographic superspace group P 2 1 2 1 2 1 (00 γ )(00 δ ) with a very similar value of δ . This phase transition reveals a significant hysteresis effect.
Databáze:	MEDLINE
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