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The true structural periodicities and superspace group descriptions of the prototypical incommensurate composite materials: Alkane/urea inclusion compounds

DOI: 10.1209/0295-5075/116/56001 DOI Help

Authors: Michel Couzi (Université de Bordeaux) , François Guillaume (Université de Bordeaux) , Kenneth .d.m. Harris (University of Cardiff) , Benjamin A. Palmer (University of Cardiff, Weizmann Institute of Science, Israel) , Kirsten Christensen (Diamond Light Source; University of Oxford) , Stephen P. Collins (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Epl (europhysics Letters) , VOL 116

State: Published (Approved)
Published: December 2016
Diamond Proposal Number(s): 6365 , 6361

Abstract: The prototypical family of incommensurate composite materials are the n-alkane/urea inclusion compounds, in which n-alkane guest molecules are arranged in a periodic manner along one-dimensional tunnels in a urea host structure, with an incommensurate relationship between the periodicities of the host and guest substructures along the tunnel. We develop interpretations of the structural periodicities, superspace group descriptions and symmetry properties of the low-temperature phases of n-alkane/urea inclusion compounds, based in part on a high-resolution synchrotron single-crystal X-ray diffraction study of n-nonadecane/urea. Specifically, we prove that, on passing from phase I to phase II, the C-centering of the orthohexagonal unit cell is lost for both the host and guest substructures, and that the symmetries of all phases I, II and III are described completely by (3 + 1)-dimensional superspace groups.

Subject Areas: Chemistry

Instruments: I16-Materials and Magnetism , I19-Small Molecule Single Crystal Diffraction

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