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Article Dans Une Revue Science Année : 2008

Hidden Degrees of Freedom in Aperiodic Materials

Bertrand Toudic
Christophe Odin
Philippe Rabiller
Claude Ecolivet
Eric Collet
Philippe Bourges
Mark D. Hollingsworth
  • Fonction : Auteur
Tomasz Breczewski
  • Fonction : Auteur

Résumé

Numerous crystalline materials, including those of bioorganic origin, comprise incommensurate sublattices whose mutual arrangement is described in a superspace framework exceeding three dimensions. We report direct observation by neutron diffraction of superspace symmetry breaking in a solid-solid phase transition of an incommensurate host-guest system: the channel inclusion compound of nonadecane/urea. Strikingly, this phase transition generates a unit cell doubling that concerns only the modulation of one substructure by the other-an internal variable available only in superspace. This unanticipated pathway for degrees of freedom to rearrange leads to a second phase transition, which again is controlled by the higher dimensionality of superspace. These results reveal nature's capacity to explore the increased number of phases allowed in aperiodic crystals.
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Dates et versions

hal-00725179 , version 1 (24-08-2012)

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Citer

Bertrand Toudic, Pilar Garcia, Christophe Odin, Philippe Rabiller, Claude Ecolivet, et al.. Hidden Degrees of Freedom in Aperiodic Materials. Science, 2008, 319 (5859), pp.69-71. ⟨10.1126/SCIENCE.1146745⟩. ⟨hal-00725179⟩
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