title: Neutron Laue and X-ray diffraction study of a new crystallographic superspace phase in n-nonadecane-urea.
abstract: Aperiodic composite crystals present long-range order without translational symmetry. These materials may be described as the intersection in three dimensions of a crystal which is periodic in a higher-dimensional space. In such materials, symmetry breaking must be described as structural changes within these crystallographic superspaces. The increase in the number of superspace groups with the increase in the dimension of the superspace allows many more structural solutions. This is illustrated in n-nonadecane-urea, revealing a fifth higher-dimensional phase at low temperature.
authors.affiliation: Institut de Physique de Rennes, UMR UR1-CNRS 6251, Université de Rennes 1, 35042 Rennes, France.
authors.forename: S
authors.initials: S
authors.lastname: Zerdane
authors.affiliation: Institut de Physique de Rennes, UMR UR1-CNRS 6251, Université de Rennes 1, 35042 Rennes, France.
authors.forename: C
authors.initials: C
authors.lastname: Mariette
authors.affiliation: Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights NSW 223, Australia.
authors.forename: G J
authors.initials: GJ
authors.lastname: McIntyre
authors.affiliation: Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble CEDEX 9, France.
authors.forename: M-H
authors.initials: MH
authors.lastname: Lemée-Cailleau
authors.affiliation: Institut de Physique de Rennes, UMR UR1-CNRS 6251, Université de Rennes 1, 35042 Rennes, France.
authors.forename: P
authors.initials: P
authors.lastname: Rabiller
authors.affiliation: Institut de Physique de Rennes, UMR UR1-CNRS 6251, Université de Rennes 1, 35042 Rennes, France.
authors.forename: L
authors.initials: L
authors.lastname: Guérin
authors.affiliation: Institut de Physique de Rennes, UMR UR1-CNRS 6251, Université de Rennes 1, 35042 Rennes, France.
authors.forename: J C
authors.initials: JC
authors.lastname: Ameline
authors.affiliation: Institut de Physique de Rennes, UMR UR1-CNRS 6251, Université de Rennes 1, 35042 Rennes, France.
authors.forename: B
authors.initials: B
authors.lastname: Toudic
keywords: aperiodic composite crystals; crystallographic superspace; neutron Laue diffraction; symmetry