نتایج جستجو برای: powder diffraction
تعداد نتایج: 104031 فیلتر نتایج به سال:
The incommensurately modulated structure of K(3)In(PO(4))(2) has been solved and refined. The origin of the modulation relates to the ordering of K cations within the hexagonal close packing of the PO(4) anions. The driving forces for the modulation of the other cations are In-P and K-P interactions. The modulation of O atoms of rigid PO(4) units follows the cations in order to stabilize the In...
The crystal structures of Nd(0.7)Ti(0.9)Al(0.1)O3, taken to represent the ideal Nd(2/3)TiO3, have been elucidated from 4 to 1273 K using high-resolution neutron powder diffraction in combination with group-theoretical analysis. The room-temperature structure is monoclinic in C2/m, on a cell with a = 7.6764 (1), b = 7.6430 (1), c = 7.7114 (1) A, beta = 90.042 (2) degrees . Pertinent features are...
The charge-flipping algorithm (CFA) is a member of the diverse family of dual-space iterative phasing algorithms. These algorithms use alternating modifications in direct and reciprocal space to find a solution to the phase problem. The current state-of-the-art CFA is reviewed and it is put in the context of related dual-space algorithms with relevance for crystallography. The CFA has found app...
The title compound, C16H12N2, was investigated in a powder diffraction study and its structure refined utilizing the Rietveld Method. The mol-ecule has approximate C2 symmetry. The dihedral angle between the rings is 25.6 (7)°. The crystal packing is consolidated by weak C-H⋯C N hydrogen-bond-like contacts, which lead to the formation of a three-dimensional network. Further stabilization of the...
Databases dedicated to predicted inorganic crystal structures are emerging fast. Possible applications are listed, from identification through the powder diffraction pattern fingerprint, leading to crystal structure determination before estimation of the cell parameters of newly synthesized real compounds, to the prediction of interesting properties of still unknown materials, allowing chemical...
Upon guest CHCl3 release, the one-dimensional (1D) coordination polymer ·CHCl3 gives rise to a non-porous structure, , following a unit cell volume reduction of ca. 22%. Due to the considerable structural transformation, the single crystal does not maintain its integrity, and therefore the structure determination has been carried out by combining single crystal X-ray diffraction and ab initio X...
We describe a model-independent approach for the extraction of detailed lattice dynamics information from neutron powder diffraction data, based on a statistical analysis of atomistic configurations generated using reverse Monte Carlo structural refinement. Phonon dispersion curves for MgO extracted in this way are shown to reproduce many of the important features found in those determined inde...
The crystal structure of Fe(3)O(4) below the 122 K Verwey transition has been refined using high-resolution x-ray and neutron powder diffraction data. The refinements give direct evidence for charge ordering (CO) over four independent octahedral Fe sites, two with a charge of +2.4 and the other two of +2.6. CO schemes consistent with our model do not meet the widely accepted Anderson condition ...
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