Frustrated pretransitional phenomena in aperiodic composites

Article

关键词: UREA INCLUSION-COMPOUNDS;    X-RAY-DIFFRACTION;    DIFFUSE-SCATTERING;    PHASE-TRANSITION;    N-PARAFFINS;    COMPOUNDS OC(NH2)2+CNH2N+2;    COMPOUND;    DISORDER;    ADDUCTS;    MOLECULES;   

DOI  :  10.1103/PhysRevB.94.184105

来源: SCIE

【 摘 要 】

This paper reports on symmetry breaking in the aperiodic inclusion compound n-octadecane/urea and its isotopomer n-octadecane/urea-d(4). The high-symmetry phase is described by a hexagonal rank-4 superspace group. Pretransitional phenomena in this crystallographic superspace reveal competing short-range-ordering phenomena within the high-symmetry phase. Very high-resolution diffraction data show that critical scattering appears at inequivalent points within the four-dimensional Brillouin zone, although the first phase transition at T-c1 near 158 K implies the condensation at only one of those points. The resulting superspace group remains of dimension 4. Two other phase transitions are reported at T-c2 = 152.8(4) K and T-c3 = 109(4) K in n-octadecane/urea-d(4). The two low-symmetry phases that arise are described by rank-5 superspace groups.

【 授权许可】

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