X-ray diffraction from partially disordered layer structures: General case

Clay Minerals ◽  
1980 ◽  
Vol 15 (4) ◽  
pp. 393-398 ◽  
Author(s):  
B. K. Ray ◽  
A. K. De ◽  
S. Bhattacherjee
Keyword(s):  
General Expression ◽  
X Ray Diffraction ◽  
X Ray ◽  
Partially Ordered ◽  
Layer Structures ◽  
Disordered Layer

AbstractA general expression for diffracted intensities from partially ordered layer structures with a ‘mistake’ has been calculated. The ‘mistake’ consists of a shift of a layer parallel to adjacent layers by any arbitrary fraction b/q along the b axis, q being any integer. The expression is free from any simplifying approximations.

The crystal structure of gersdorffite (III), a distorted and disordered pyrite structure

1968 ◽  
Vol 36 (283) ◽  
pp. 940-947 ◽  
Author(s):  
P. Bayliss ◽  
N. C. Stephenson
Keyword(s):  
Crystal Structure ◽  
Metal Atom ◽  
Diffraction Data ◽  
Three Dimensional ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Partially Ordered ◽  
The Ideal

SummaryThe crystal structure of gersdorffite (III) has been examined with three-dimensional Weissenberg X-ray diffraction data. The unit cell is isometric with a 5·6849 ± 0·0003 Å, space group PI, and four formula units per cell. This structure has the sulphur and arsenic atoms equally distributed over the non-metal atom sites of pyrite. All atoms show significant random displacements from the ideal pyrite positions to produce triclinic symmetry, which serves to distinguish this mineral from a disordered cubic gersdorffite (II) and a partially ordered cubic gersdorffite (I). Factors responsible for the atomic distortions are discussed.

X-ray microdiffraction study of the half-V-shaped switching liquid crystal

2004 ◽  
Vol 19 (1) ◽  
pp. 53-55 ◽  
Author(s):  
Kazuhiro Takada ◽  
Takashi Noma ◽  
Takeshi Togano ◽  
Taihei Mukaide ◽  
Atsuo Iida
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Formation Process ◽  
Ferroelectric Liquid Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transient Layer ◽  
Smectic C ◽  
Layer Structures ◽  
Temperature Controlled

Local layer structures and their formation process in a half-V-shaped switching ferroelectric liquid crystal (HV-FLC) were investigated by means of synchrotron X-ray microdiffraction. The HV-FLC is a FLC that has a cholesteric–chiral smectic C (Ch–SmC*) phase transition sequences. X-ray microdiffraction measurements revealed that the SmC* phase in the HV-FLC was composed of asymmetric chevron and inclined-bookshelf structures. In addition, temperature-controlled X-ray diffraction measurements showed that the transient layer structures appeared during the Ch to SmC* phase transition.

Free-standing Smectic LC Elastomer Films

2001 ◽  
Vol 709 ◽  
Author(s):  
C. Tolksdorf ◽  
R. Zentel ◽  
R. Köhler ◽  
U. Dietrich ◽  
M. Lösche ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
Liquid Crystalline ◽  
Film Plane ◽  
X Ray Diffraction ◽  
Free Standing ◽  
Layer Spacing ◽  
X Ray ◽  
Precursor Polymer ◽  
Layer Structures ◽  
Freely Suspended

ABSTRACTWe probe the mesophase transitions and layer structures in thin ordered smectic liquid crystalline elastomer films by means of x-ray diffraction and optical microscopy. Oriented elastomer films of submicrometer thickness are produced by crosslinking freely suspended smectic polymer films. After crosslinking, the mesomorphism is similar to that of the precursor polymer. Smectic layers align parallel to the film plane. The layer spacing increases with temperature in the SmC* phase while it decays above the SmC*-SmA transition.

Synthesis, Structure and Properties of Lanthanide-Organic Frameworks with Imidazolylmethylisophthalate Ligands

2013 ◽  
Vol 68 (11) ◽  
pp. 1233-1238
Author(s):  
Xiao-Chun Cheng ◽  
Xiao-Hong Zhu
Keyword(s):  
Isophthalic Acid ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Metal Centers ◽  
Lanthanide Oxide ◽  
X Ray ◽  
Silver Perchlorate ◽  
Carboxylate Groups ◽  
Layer Structures ◽  
Elemental Analyses

Three new lanthanide-organic frameworks {[Ln(L)(OClO3)(H2O)]·0.5H2O}n [Ln=Sm (1), Eu (2), Er (3)] have been prepared by hydrothermal reactions of the corresponding lanthanide oxide (Ln2O3), silver perchlorate (AgClO4) and 5-(imidazol-1-ylmethyl)isophthalic acid. The complexes have been characterized by single-crystal and powder X-ray diffraction, IR spectroscopy, and elemental analyses. In 1-3, the metal centers are eight-coordinated to show polyhedral coordination geometries with an LnO8 donor set. The imidazolyl groups are free of coordination, and the perchlorate and carboxylate groups bridge the Ln3+ cations leading to the formation of wave-like layer structures containing metal-chains. The fluorescence properties of complex 2 were investigated.

Growth and Characterization of Pbse and Pbl-Sn1 Se Layers on Si (100)

1997 ◽  
Vol 487 ◽  
Author(s):  
H. K. Sachar ◽  
I. Chao ◽  
X. M. Fang ◽  
P. J. McCann
Keyword(s):  
Buffer Layer ◽  
Molecular Beam ◽  
Layer Structure ◽  
Good Growth ◽  
X Ray Diffraction ◽  
Growth Solution ◽  
X Ray ◽  
Layer Structures ◽  
Surface Morphologies

AbstractCrack-free layers of PbSe were grown on Si (100) by a combination of liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE) techniques. The PbSe layer was grown by LPE on Si (100) using a MBE-grown PbSe/BaF2/CaF2 buffer layer structure. Pb1−xSnxSe layers with tin contents in the liquid growth solution equal to 3%, 5%, 6%, 7%, and 10%, respectively, were also grown by LPE on Si (100) substrates using similar buffer layer structures. The LPE-grown PbSe and Pb1−xSnxSe layers were characterized by optical Nomarski microscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Optical Nomarski characterization of the layers revealed their excellent surface morphologies and good growth solution wipe-offs. FTIR transmission experiments showed that the absorption edge of the Pb1−xSnxSe layers shifted to lower energies with increasing tin contents. The PbSe epilayers were also lifted-off from the Si substrate by dissolving the MBE-grown BaF2 buffer layer. SEM micrographs of the cleaved edges revealed that the lifted-off layers formed structures suitable for laser fabrication.

X-ray Diffraction Study of Chalcopyrite ZnSnP2 Epitaxial Layers

1999 ◽  
Vol 583 ◽  
Author(s):  
S. Francoeur ◽  
G. A. Seryogin ◽  
S. A. Nikishin ◽  
H. Temkin
Keyword(s):  
Order Parameter ◽  
Growth Conditions ◽  
Cation Sublattice ◽  
Crystallographic Structure ◽  
Epitaxial Layers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Partially Ordered ◽  
Interesting Candidate

AbstractWe apply the technique of x-ray diffraction to the determination of the crystallographic structure and the quantitative measurement of the order parameter of ZnSnP2 epitaxial layers. In bulk, ZnSnP2 it is possible to obtain highly ordered distribution of Zn and Sn atoms in the cation sublattice, but epitaxial growth often produces partially ordered layers. The ordered and disordered phases correspond to the chalcopyrite and sphalerite structures and their respective band gaps are 1.66 and 1.24 eV. Since ZnSnP2 is almost lattice-matched to GaAs. it is interesting candidate for optoelectronic applications.Samples used in this work were grown by gas source molecular beam epitaxy on GaAs substrates. Slight variations in growth conditions could be induced to produce partially ordered and disordered structures. Chalcopyrite ordering is determined by the observation of several characteristic reflections identifying the lower symmetry of this structure. For example, reflections from (101), (217) and (611) planes, strictly forbidden for sphalerite, were measured. The quantitative determination of the order parameter could be made by comparing intensities of a carefully chosen set of measured and calculated reflections. We show that while kinematic approximation can be used to model weak superstructure reflections, in the calculation of the strong, low-angle, fundamental reflections used for intensity normalization it is necessary to take into account extinction effects. Order parameters varying from 0 to 30% were obtained.

A new ZnII coordination polymer based on 4-(pyridin-4-yl)benzoic and formic acids: in-situ synthesis, crystal structure and luminescence properties

2018 ◽  
Vol 74 (10) ◽  
pp. 1133-1137 ◽  
Author(s):  
Fuming Luo ◽  
Guodong Tang ◽  
Jinfang Zhang
Keyword(s):  
Three Dimensional ◽  
Luminescence Properties ◽  
Supramolecular Framework ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Structural Units ◽  
X Ray ◽  
Layer Structures ◽  
State Luminescence

The title compound, poly[(μ2-formato-κ3 O,O′:O)[μ2-4-(pyridin-4-yl)benzoato-κ3 N:O,O′]zinc(II)], [Zn(C12H8NO2)(HCOO)] n , has been synthesized in situ and characterized by thermogravimetric analysis (TGA) and single-crystal and powder X-ray diffraction analyses. The polymer contains two independent structural units in the asymmetric unit. These are constructed from Zn2+ ions, 4-(pyridin-4-yl)benzoate (4-pbc) bridges and in-situ-generated formate ligands, forming two similar two-dimensional (2D) layer structures. These similar 2D layers are arranged alternately and are linked with each other by dense C—H...O hydrogen bonds to generate a three-dimensional (3D) supramolecular framework. The crystal is pseudomerohedrally twinned about [201]. Compared with free 4-Hpbc, the polymer exhibits a red shift and significantly enhanced solid-state luminescence properties.

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