Actinide complexes of the calixarenes. Part 1. Syntheses and crystal structures of bis(homo-oxa)-p-tert-butylcalix[4]arene and its uranyl ion complex

1991 ◽  
pp. 979 ◽  
Author(s):  
Jack M. Harrowfield ◽  
Mark I. Ogden ◽  
Allan H. White
Keyword(s):  
Crystal Structures ◽  
Uranyl Ion

Crystal Structures of Uranyl Ion Complexes of Tetrahydroxy[3.1.3.1]metacyclophane (Homocalix[4]arene)

2003 ◽  
Vol 15 (5) ◽  
pp. 359-365 ◽  
Author(s):  
Pierre Thuéry ◽  
Jeong Tae Gil ◽  
Takehiko Yamato
Keyword(s):  
Crystal Structures ◽  
Uranyl Ion

Causes of uranyl ion nonlinearity in crystal structures

2013 ◽  
Vol 55 (2) ◽  
pp. 137-146 ◽  
Author(s):  
V. N. Serezhkin ◽  
M. O. Karasev ◽  
L. B. Serezhkina
Keyword(s):  
Crystal Structures ◽  
Uranyl Ion

Crystal Structure of Uranyl Carboxylates

2005 ◽  
Vol 893 ◽  
Author(s):  
Paul Giesting ◽  
Peter Burns ◽  
Nathan Porter
Keyword(s):  
Crystal Structures ◽  
Structural Information ◽  
Structural Features ◽  
Uranyl Ion ◽  
Chemical System ◽  
Hydrothermal Conditions ◽  
Uranyl Compounds ◽  
Hexavalent Uranium ◽  
Similar Work ◽  
Organic Complexes

AbstractUranyl-organic complexation in geologic fluids can have a profound impact upon uranium solubility and transport. Studies of uranyl organometallic crystal structures provide a basis for understanding complexation of the uranyl ion in solution.The crystal structures of several novel uranyl oxalates, synthesized under mild hydrothermal conditions, have been determined. These structures demonstrate new features little seen or not previously known in this chemical system, in particular polymerization into infinite sheets and direct linkage of uranyl polyhedra. Further work on the chemistry of this and other systems of hexavalent uranium and low molecular weight carboxylic acids, especially formic acid, is likely to turn up new insights.Although a hierarchical scheme exists for classifying inorganic uranyl compounds [1], no similar work has been done for organic compounds. Such a hierarchy would have practical benefits, in particular making structural information more accessible and understandable to workers studying related problems such as the environmental transport of hexavalent uranium as dissolved organic complexes. We offer a simple scheme that classifies uranyl oxalate structures by analyzing the long-range structural features and the coordination environments of uranyl ions, which leads to a structural symbol that can be used to easily identify uranyl oxalates with common structural features. This system is equally applicable to other carboxylate complexes with the uranyl ion, and could be extended to apply to any organic complex of the uranyl ion.

Pollutant Identification by Selected Area Electron Diffraction

1974 ◽  
Vol 32 ◽  
pp. 532-533
Author(s):  
R. E. Ferrell ◽  
G. G. Paulson ◽  
C. W. Walker
Keyword(s):  
Thermal Treatment ◽  
Electron Diffraction ◽  
Sample Preparation ◽  
Crystal Structures ◽  
Water Samples ◽  
Environmental Samples ◽  
Short Review ◽  
Selected Area Electron Diffraction ◽  
Multiple Component

Selected area electron diffraction (SAD) has been used successfully to determine crystal structures, identify traces of minerals in rocks, and characterize the phases formed during thermal treatment of micron-sized particles. There is an increased interest in the method because it has the potential capability of identifying micron-sized pollutants in air and water samples. This paper is a short review of the theory behind SAD and a discussion of the sample preparation employed for the analysis of multiple component environmental samples.

The Imaging of Crystal Structures and Crystal Defects

1978 ◽  
Vol 36 (3) ◽  
pp. 207-217
Author(s):  
J.M. Cowley
Keyword(s):  
Electron Microscope ◽  
Crystal Structures ◽  
Phase Contrast ◽  
Crystal Defects ◽  
Atom Density ◽  
Lack Of Information ◽  
Spatial Frequencies

The problem of "understandinq" electron microscope imaqes becomes more acute as the resolution is improved. The naive interpretation of an imaqe as representinq the projection of an atom density becomes less and less appropriate. We are increasinqly forced to face the complexities of coherent imaqinq of what are essentially phase objects. Most electron microscopists are now aware that, for very thin weakly scatterinq objects such as thin unstained bioloqical specimens, hiqh resolution imaqes are best obtained near the optimum defocus, as prescribed by Scherzer, where the phase contrast imaqe qives a qood representation of the projected potential, apart from a lack of information on the lower spatial frequencies. But phase contrast imaqinq is never simple except in idealized limitinq cases.

Transmission electron microscope studies in special ceramics

1978 ◽  
Vol 36 (1) ◽  
pp. 268-269
Author(s):  
A. Zangvil ◽  
L.J. Gauckler ◽  
G. Schneider ◽  
M. Rühle
Keyword(s):  
Phase Diagrams ◽  
Crystal Structures ◽  
Thin Foil ◽  
Limited Extent ◽  
Complex Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Lattice Resolution

The use of high temperature special ceramics which are usually complex materials based on oxides, nitrides, carbides and borides of silicon and aluminum, is critically dependent on their thermomechanical and other physical properties. The investigations of the phase diagrams, crystal structures and microstructural features are essential for better understanding of the macro-properties. Phase diagrams and crystal structures have been studied mainly by X-ray diffraction (XRD). Transmission electron microscopy (TEM) has contributed to this field to a very limited extent; it has been used more extensively in the study of microstructure, phase transformations and lattice defects. Often only TEM can give solutions to numerous problems in the above fields, since the various phases exist in extremely fine grains and subgrain structures; single crystals of appreciable size are often not available. Examples with some of our experimental results from two multicomponent systems are presented here. The standard ion thinning technique was used for the preparation of thin foil samples, which were then investigated with JEOL 200A and Siemens ELMISKOP 102 (for the lattice resolution work) electron microscopes.

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