Über neuere Polymetallate / Polyanions of Novel Structural Types

1973 ◽  
Vol 28 (7-8) ◽  
pp. 389-404 ◽  
Author(s):  
Joachim Fuchs
Keyword(s):  
Single Crystals ◽  
Vibrational Spectroscopy ◽  
Metal Salt ◽  
Organic Cations ◽  
Salt Solutions ◽  
X Ray ◽  
Structural Types ◽  
Insight Into ◽  
Complicated Mechanism

By the application of newer preparative methods and specific organic cations single crystals of polymetallates were obtained of till now unknown structural types. These are salts with polyanions W6O192-, W10O324-, [HW12O38(OH)2]5-, Mo6O192- and HV4O123-, furthermore para-tungstates A and B, as well as the compounds [N(CH)3)4]2 Μο8Ο25·5Η2Ο and [N(CH3)4]2Mo10 O31 · 7H2O. The structures of the anions W6O192- and W10O324- were elucidated by X-Ray analyses; the structure of the Μο6Ο192- was derived by vibrational spectroscopy. The knowledge of newer polyanion structures increasingly enables us to gain an insight into the complicated mechanism of oxyhydrate formation by acidification of metal salt solutions.

Scintillation of Un-doped ZnO Single Crystals

MRS Advances ◽  
2016 ◽  
Vol 1 (2) ◽  
pp. 121-126 ◽  
Author(s):  
A. M. Colosimo ◽  
Jianfeng Ji ◽  
P. S. Stepanov ◽  
L. A. Boatner ◽  
F. A. Selim
Keyword(s):  
Single Crystals ◽  
Photo Luminescence ◽  
Radiation Detectors ◽  
Scientific Instruments ◽  
Good Energy Resolution ◽  
X Ray ◽  
Good Energy ◽  
Anode Signal ◽  
Doped Zno ◽  
Insight Into

ABSTRACTScintillation properties are often studied by photo-luminescence (PL) and scintillation measurements. In this work, we combine X-ray-induced luminescence (XRIL) spectroscopy [Review of Scientific Instruments 83, 103112 (2012)] with PL and standard scintillation measurements to give insight into the scintillation properties of un-doped ZnO single crystals. XRIL revealed that ZnO luminescence proportionally increases with X-ray power and exhibits excellent linearity - indicating the possibility of developing radiation detectors with good energy resolution. By coupling ZnO crystals to fast photomultiplier tubes and monitoring the anode signal, rise times as fast as 0.9 ns were measured.

Controlling the Properties of Bulk Metal Oxides at a Molecular Level: Alkoxides Vs Carboxylates‐Alkoxides Routes

1994 ◽  
Vol 346 ◽  
Author(s):  
Liliane G. Hubert‐pfalzgraf ◽  
Stephane Daniele ◽  
Souad Boulmaaz ◽  
Renee Papiernik
Keyword(s):  
Light Scattering ◽  
Metal Oxides ◽  
Single Crystals ◽  
Molecular Level ◽  
Bulk Metal ◽  
X Ray ◽  
Material Data ◽  
Metal Derivatives ◽  
Ft Ir ◽  
Insight Into

ABSTRACTThe reactions between alkoxides and/or alkoxides and anhydrous acetates have been investigated for access to advanced multicomponent niobates or titanates and with the aim to get insight into relationships between the nature of the initial precursors ‐ single or mixed‐metal derivatives, ligands (OAc or OR, R = Et, iPr),…‐ and the properties of the final material. Data are based on a variety of techniques: FT‐IR, multinuclear NMR (1H, 13C, 207Pb, 113Cd), X‐ray investigations on single crystals. Powders have been analyzed by TGA, SEM‐EDX, light scattering and XRD.

Chemical modification of the bacterial wall to determine sites of metal deposition

1978 ◽  
Vol 36 (2) ◽  
pp. 350-351
Author(s):  
T. J. Beveridge
Keyword(s):  
Electron Scattering ◽  
Metal Salt ◽  
Metal Deposition ◽  
Suitable Model ◽  
X Ray Diffraction ◽  
Subtilis Cell ◽  
Thin Sections ◽  
X Ray ◽  
Section Data ◽  
Metal Impregnation

The Bacillus subtilis cell wall provides a protective sacculus about the vital constituents of the bacterium and consists of a collection of anionic hetero- and homopolymers which are mainly polysaccharidic. We recently demonstrated that unfixed walls were able to trap and retain substantial amounts of metal when suspended in aqueous metal salt solutions. These walls were briefly mixed with low concentration metal solutions (5mM for 10 min at 22°C), were well washed with deionized distilled water, and the quantity of metal uptake (atomic absorption and X-ray fluorescence), the type of staining response (electron scattering profile of thin-sections), and the crystallinity of the deposition product (X-ray diffraction of embedded specimens) determined.Since most biological material possesses little electron scattering ability electron microscopists have been forced to depend on heavy metal impregnation of the specimen before obtaining thin-section data. Our experience with these walls suggested that they may provide a suitable model system with which to study the sites of reaction for this metal deposition.

Isomorphous replacement in electron diffraction of wet crystals of rat hemoglobin

1983 ◽  
Vol 41 ◽  
pp. 446-447
Author(s):  
William F. Tivol ◽  
Murray Vernon King ◽  
D. F. Parsons
Keyword(s):  
Electron Diffraction ◽  
Heavy Atom ◽  
Isomorphous Substitution ◽  
X Ray Diffraction ◽  
Salt Solutions ◽  
X Ray ◽  
Isomorphous Replacement ◽  
Structure Factors ◽  
Diffraction Structure ◽  
The Mean

Feasibility of isomorphous substitution in electron diffraction is supported by a calculation of the mean alteration of the electron-diffraction structure factors for hemoglobin crystals caused by substituting two mercury atoms per molecule, following Green, Ingram & Perutz, but with allowance for the proportionality of f to Z3/4 for electron diffraction. This yields a mean net change in F of 12.5%, as contrasted with 22.8% for x-ray diffraction.Use of the hydration chamber in electron diffraction opens prospects for examining many proteins that yield only very thin crystals not suitable for x-ray diffraction. Examination in the wet state avoids treatments that could cause translocation of the heavy-atom labels or distortion of the crystal. Combined with low-fluence techniques, it enables study of the protein in a state as close to native as possible.We have undertaken a study of crystals of rat hemoglobin by electron diffraction in the wet state. Rat hemoglobin offers a certain advantage for hydration-chamber work over other hemoglobins in that it can be crystallized from distilled water instead of salt solutions.

Bulk standards for low-temperature biological x-ray microanalysis

1984 ◽  
Vol 42 ◽  
pp. 282-283
Author(s):  
P. Echlin ◽  
M. McKoon ◽  
E.S. Taylor ◽  
C.E. Thomas ◽  
K.L. Maloney ◽  
...  
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Analytical Method ◽  
Salt Solutions ◽  
Absolute Concentration ◽  
Cooling Process ◽  
X Ray ◽  
The Absolute ◽  
Analytical Procedures ◽  
Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

Zone-axis ALCHEMI for the rapid assessment of site occupancies in garnets

1986 ◽  
Vol 44 ◽  
pp. 706-707
Author(s):  
M.T. Otten ◽  
P.R. Buseck
Keyword(s):  
Single Crystals ◽  
Rapid Assessment ◽  
Site Occupancy ◽  
Zone Axis ◽  
Synthetic Compounds ◽  
X Ray ◽  
Large Group ◽  
Crystallographic Planes

ALCHEMI (Atom Location by CHannelling-Enhanced Microanalysis) is a TEM technique for determining site occupancies in single crystals. The method uses the channelling of incident electrons along specific crystallographic planes. This channelling results in enhanced x-ray emission from the atoms on those planes, thereby providing the required site-occupancy information. ALCHEMI has been applied with success to spinel, olivine and feldspar. For the garnets, which form a large group of important minerals and synthetic compounds, the channelling effect is weaker, and significant results are more difficult to obtain. It was found, however, that the channelling effect is pronounced for low-index zone-axis orientations, yielding a method for assessing site occupancies that is rapid and easy to perform.

Quantitative Analysis Of X-Ray Images From Geological Materials

1990 ◽  
Vol 48 (2) ◽  
pp. 244-245
Author(s):  
J. M. Paque ◽  
R. Browning ◽  
P. L. King ◽  
P. Pianetta
Keyword(s):  
Quantitative Analysis ◽  
Bulk Composition ◽  
Principal Component ◽  
Analytical Description ◽  
Bulk Sample ◽  
Geological Samples ◽  
X Ray ◽  
Software And Hardware ◽  
And Storage ◽  
Insight Into

Geological samples typically contain many minerals (phases) with multiple element compositions. A complete analytical description should give the number of phases present, the volume occupied by each phase in the bulk sample, the average and range of composition of each phase, and the bulk composition of the sample. A practical approach to providing such a complete description is from quantitative analysis of multi-elemental x-ray images.With the advances in recent years in the speed and storage capabilities of laboratory computers, large quantities of data can be efficiently manipulated. Commercial software and hardware presently available allow simultaneous collection of multiple x-ray images from a sample (up to 16 for the Kevex Delta system). Thus, high resolution x-ray images of the majority of the detectable elements in a sample can be collected. The use of statistical techniques, including principal component analysis (PCA), can provide insight into mineral phase composition and the distribution of minerals within a sample.

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