Detail Hidden Degrees of Freedom in Aperiodic Materials   Oleh:  Toudic, Bertrand ; Garcia, Pilar ; Odin, Christophe ; Rabiller, Philippe ; Ecolivet, Claude ; Collet, Eric ; Bourges, Philippe ; McIntyre, Garry J. ; Breczewski, Tomasz Jenis: Article from Bulletin/Magazine Dalam koleksi: SCIENCE (keterangan: ada di Proquest) vol. 319 no. 5859 (Jan. 2008), page 69. Ketersediaan Perpustakaan FK Nomor Panggil: S01.K.2008.01 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada     Lihat Detail Induk Isi artikel 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. Opini Anda Klik untuk menuliskan opini Anda tentang koleksi ini! Kembali

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