Incommensurately modulated structure in natural melilites
نویسندگان
چکیده
منابع مشابه
Europium-IV: an incommensurately modulated crystal structure in the lanthanides.
High-resolution x-ray powder-diffraction experiments were performed on europium metal at high pressure up to 50 GPa. At variance with previous reports, the hcp phase of Eu was observed to be stable not only to 18 GPa, but to 31.5 GPa. At 31.5(5) GPa, europium transforms to a phase (Eu-IV) with an incommensurately modulated monoclinic crystal structure with superspace group C2/c(q(1)0q(3))00. Th...
متن کاملThe aperiodic nature of incommensurately modulated structures
The discovery of aperiodic crystals is perhaps one of the most important event which has changed our vision on crystalline architectures since the discovery of diffraction hundred years ago. It was the merit of a dutch crystallographer, P.M. de Wolff, to interpret their diffraction pattern as a three dimensional projection of a higher dimensional reciprocal lattice, idea which led directly to t...
متن کاملTransition from the incommensurately modulated structure to the lock-in phase in Co-åkermanite.
The adaptation of the incommensurate structure modulation in Ca(2)CoSi(2)O(7) (dicalcium cobalt disilicate) single crystals to decreasing temperature has been examined using in situ high-resolution transmission electron microscopy and electron diffraction. The transition from the incommensurate to the commensurate lock-in phase of Co-åkermanite exhibits a pronounced hysteresis of a highly strai...
متن کاملGetting more out of an incommensurately modulated structure: the example of K5Yb(MoO4)4.
A method based on the superspace approach is presented with the aim of generating a family of modular structures from a single incommensurately modulated structure. This approach based on the variation of the modulation vector q is applied to the generation of the K5Yb(MoO4)4, potassium ytterbium tetramolybdate, family of modular structures. The beta coefficient of the modulation vector q = bet...
متن کاملThe role of silver on the stabilization of the incommensurately modulated structure in calaverite, AuTe2
Structural investigations of several minerals belonging to the calaverite group with composition Au1–xAgxTe2 (x = 0.00, 0.02, 0.05, 0.09, 0.19, and 0.33) indicate that Ag is randomly distributed on the Au sites. This suppresses the valence fluctuation of Au and, therefore, the structure modulations. The results are compared with the previously published incommensurately modulated structure of c...
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ژورنال
عنوان ژورنال: Acta Crystallographica Section A Foundations of Crystallography
سال: 2005
ISSN: 0108-7673
DOI: 10.1107/s0108767305098971