Linienprofilanalyse von Röntgen-Weitwinkelreflexen mittels Fourier-Transformation zur Bestimmung von Mikrospannungen und parakristallinen Störungen / Analysis of X-Ray Line Profiles for Microstrains and Paracrystalline Distortions by Fourier Transformation

1974 ◽  
Vol 29 (8) ◽  
pp. 1152-1158 ◽  
Keyword(s):  
Gaussian Distribution ◽  
Fourier Transformation ◽  
The Other ◽  
Line Profiles ◽  
Linear Polyethylene ◽  
X Ray ◽  
Other Hand ◽  
Distortion Analysis ◽  
Diffraction Patterns

Many synthetic and biopolymers are paracrystalline. The same holds for some catalysts, graphites and semiconductors. This can be proved directly by diffraction patterns, the integral widths being proportional to (sin ϑ)2 for the higher orders of reflection of the same net plane. To test this, three orders of reflections must be observable. Warren, on the other hand, has shown that microstrains with a Gaussian distribution can directly be calculated from the line profiles of only two reflections by Fourier-Transformation. His method is expanded here to other types of microstrains and to paracrystalline distortions by carefully taking into account a termination effect. Examples are given for turbostratic graphite, linear polyethylene and annealed polybutene I. They demonstrate how useful this method is for distortion analysis.

scholarly journals White Dwarf Masses and Accretion Rates of Recurrent Novae: an X-ray Perspective

2011 ◽  
Vol 7 (S281) ◽  
pp. 186-189
Author(s):  
Koji Mukai ◽  
Jennifer L. Sokoloski ◽  
Thomas Nelson ◽  
Gerardo J. M. Luna
Keyword(s):  
White Dwarf ◽  
Cataclysmic Variables ◽  
The Other ◽  
X Ray ◽  
Other Hand ◽  
Accretion Rates

AbstractWe present recent results of quiescent X-ray observations of recurrent novae (RNe) and related objects. Several RNe are luminous hard X-ray sources in quiescence, consistent with accretion onto a near Chandrasekhar mass white dwarf. Detection of similar hard X-ray emissions in old novae and other cataclysmic variables may lead to identification of additional RNe candidates. On the other hand, other RNe are found to be comparatively hard X-ray faint. We present several scenarios that may explain this dichotomy, which should be explored further.

Synthesis of ZrO2 Nanotubes by Anodization of Zr Foil

2015 ◽  
Vol 799-800 ◽  
pp. 125-129
Author(s):  
Mary Donnabelle L. Balela ◽  
April Alexa S. Lagarde ◽  
Stephen Jann A. Tamayo ◽  
Nikko S. Villareal ◽  
Ann Marielle Parreno
Keyword(s):  
Aqueous Solution ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Surface Preparation ◽  
The Other ◽  
Preparation Methods ◽  
X Ray ◽  
Anodization Time ◽  
Other Hand ◽  
Scanning Electron

Zirconia (ZrO2) nanotubes were synthesized by anodization of zirconium (Zr) foil in NH4Fand (NH4)2SO4 aqueous solution. Different surface preparation methods (electropolishing and etching) were applied on the Zr foil prior to anodizaton. In addition, the anodization time and NH4F concentration were varied. The structure and morphologies of the nanotubes and their crystallinity were confirmed using scanning electron microscope and x-ray diffractometer, respectively. ZrO2 nanotubes with large diameters and thick walls were formed at lower NH4F concentration and longer anodization time. On the other hand, smaller nanotubes with thinner walls were produced when the NH4F concentration was increased. The synthesized nanotubes were predominantly tetragonal ZrO2 with small amounts of monoclinic ZrO2.

Distribution of Calcium and Phosphate in Cells of the Enamel Organ in the Rat Lower Incisor

1987 ◽  
Vol 1 (2) ◽  
pp. 236-244 ◽  
Author(s):  
T. Kawamoto ◽  
M. Shimizu
Keyword(s):  
The Other ◽  
Whole Body ◽  
Enamel Organ ◽  
Maturation Stage ◽  
Lower Incisor ◽  
X Ray ◽  
Other Hand ◽  
Freeze Dried ◽  
Significant Difference ◽  
Cell Layers

The distribution of calcium and phosphate in the cells of the enamel organ of the rat lower incisors was investigated by autoradiography and energy-dispersive x-ray spectrometry (EDS). Radioactive calcium or phosphate was injected i.p. into seven-day-old rats of the Wistar strain. The animals were frozen 0.5, 1, and 10 min after injection, and embedded in 5% carboxymethyl cellulose. Sagittal sections of 10 μm thickness were made in which the lower incisor was included as a part of the whole-body section. For autoradiography, the sections were freeze-dried and placed in contact with dry thin films prepared from autoradiographic emulsion. For EDS, sections were mounted on carbon stubs, freeze-dried, coated with carbon, and examined by EDS in a SEM. 45Ca and 32P autoradiograms showed that the radioactivity was located over the papillary layer cells adjacent to the secretory stage ameloblasts and was much higher here than in the ameloblastic layer. On the other hand, there was no significant difference between the amount of radioactivity of these two cell layers in the maturation stage, although higher radioactivity was detectable in the maturation stage enamel than in the secretory stage enamel. Pronounced Ka x-ray peaks were obtained for P, S, Cl, and K originating from the cells of the papillary and ameloblastic layers in the secretory stage, but only very low peaks were obtained for Ca. On the other hand, in addition to these elements, remarkably high Ca and Fe peaks could be detected in the ameloblastic layer of the maturation stage.

scholarly journals Year-scale Morphological Variation of the X-ray Crab Nebula

2004 ◽  
Vol 218 ◽  
pp. 181-184 ◽  
Author(s):  
Koji Mori ◽  
David N. Burrows ◽  
George G. Pavlov ◽  
J. Jeff Hester ◽  
Shinpei Shibata ◽  
...  
Keyword(s):  
Morphological Variation ◽  
Crab Nebula ◽  
The Other ◽  
X Ray ◽  
Morphological Variations ◽  
Other Hand ◽  
Pulsar Wind ◽  
Circular Structures ◽  
The Crab Nebula

We present year-scale morphological variations of the Crab Nebula revealed by the Chandra X-ray Observatory. Observations have been performed about every 1.7 years over the three years from launch. The variations are clearly recognized at two sites: the torus and the southern jet. The torus, which had been steadily expanding until 1.7 years ago, now appears to have shrunk in the latest observation. Additionally, the circular structures seen to the northeast of the torus have decayed into several arcs. On the other hand, the southern jet shows the growth of its overall kinked-structure. We discuss the nature of these variations in terms of the pulsar wind nebula mechanism.

Configuration of Quadrivalent Atoms

1929 ◽  
Vol 25 (2) ◽  
pp. 219-221
Author(s):  
T. M. Lowry
Keyword(s):  
The Other ◽  
Tetrahedral Configuration ◽  
X Ray ◽  
Metallic Atom ◽  
Other Hand ◽  
Function Change ◽  
The One ◽  
Image Position ◽  
Octahedral Configuration ◽  
As If

Two alternative views have been expressed in regard to the configuration of quadrivalent atoms. On the one hand le Bel and van't Hoff assigned to quadrivalent carbon a tetrahedral configuration, which has since been confirmed by the X-ray analysis of the diamond. On the other hand, Werner in 1893 adopted an octahedral configuration for radicals of the type MA6, e.g. inand then suggested that “the molecules [MA4]X2 are incomplete molecules [MA6]X2. The radicals [MA4] result from the octahedrally-conceived radicals [MA6] by loss of two groups A, but with no function-change of the acid residue…. They behave as if the bivalent metallic atom in the centre of the octahedron could no longer bind all six of the groups A and lost two of them leaving behind the fragment [MA4]” (p. 303).

X-Ray Diffractometry of Polymers by a Transmission Method

1964 ◽  
Vol 8 ◽  
pp. 151-161
Author(s):  
Zigmond W. Wilchinsky
Keyword(s):  
The Other ◽  
Reflection Method ◽  
Transmission Method ◽  
X Ray ◽  
Intensity Measurements ◽  
Other Hand ◽  
Line Asymmetry ◽  
Line Positions

AbstractThe practicability of using a symmetrical transmission method for accurate measurement of line positions and intensities for polymer samples was investigated. In comparison with the conventional symmetrical reflection method, the transmission method has some inherent advantages in the measurement of line positions. Very little extraneous line asymmetry is introduced by transmission, and errors due to sample misalignment can usually be corrected empirically. On the other hand, the reflection method introduces noticeable line asymmetry and a shift of the center of intensity toward smaller 2θ. Also, errors due to sample misalignment may be difficult to correct. Intensity measurements can usually be made with about the same accuracy by either method. However, the transmission method is less sensitive to misalignment errors, especially at the lower diffraction angles.

Identification of Different Crystalline Forms of Diatrizoic Acid

1978 ◽  
Vol 61 (1) ◽  
pp. 72-75
Author(s):  
Victor A Folen ◽  
George Schwartzman ◽  
Millard Maienthal ◽  
Wilson L Brannon
Keyword(s):  
Weight Loss ◽  
The Other ◽  
Reference Standard ◽  
Thermal Gravimetric ◽  
X Ray Diffraction ◽  
X Ray ◽  
No Weight Loss ◽  
Diffraction Patterns ◽  
Crystalline Forms ◽  
Reference Samples

Abstract Standard reference samples of diatrizoic acid gave 2 different infrared (IR) spectra, x-ray diffraction patterns, and differential thermal and thermal gravimetric curves. One form, the anhydrous acid, shows no weight loss when heated to 170°C. The other form, the dihydrate, loses 5.36% of its weight when heated from 86 to 144°C. The anhydrous diatrizoic acid is the preferred reference standard, because it has an IR spectrum and x-ray diffraction pattern suitable for identification purposes.

scholarly journals Identification of two allotwins of mica polytypes in reciprocal space through the minimal rhombus unit

2000 ◽  
Vol 56 (4) ◽  
pp. 639-647 ◽  
Author(s):  
Massimo Nespolo ◽  
Giovanni Ferraris ◽  
Hiroshi Takeda
Keyword(s):  
Reciprocal Lattice ◽  
Reciprocal Space ◽  
The Other ◽  
Relative Rotation ◽  
Asymmetric Unit ◽  
X Ray ◽  
Long Period ◽  
Diffraction Patterns

The X-ray investigation (precession method) of the Ruiz Peak oxybiotite, which is well known for the occurrence of a large number of polytypes and twins, revealed two complex diffraction patterns, which cannot be identified as long-period polytypes. These patterns are analysed in terms of the minimal rhombus, a geometrical asymmetric unit in reciprocal space which permits the decomposition of the composite reciprocal lattice of a twin or allotwin into the reciprocal lattices of the individuals. Both the recorded patterns correspond to a 1M–2M 1 allotwin: the relative rotation between the individuals is 120° in one case and 60° in the other. The geometrical criteria for evaluating the presence of twinning or allotwinning are analysed through these two natural examples.

X-Ray Diffraction of Iron Containing Samples: The Importance of a Suitable Configuration

2017 ◽  
Vol 262 ◽  
pp. 545-548 ◽  
Author(s):  
Yvonne M. Mos ◽  
Arnold C. Vermeulen ◽  
Cees N.J. Buisman ◽  
Jan Weijma
Keyword(s):  
Radiation Source ◽  
The Other ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
High Quality ◽  
Crystalline Phases ◽  
X Ray ◽  
Other Hand ◽  
Cobalt Radiation

X-ray diffraction (XRD) is a commonly used technology to identify crystalline phases. However, care must be taken with the combination of XRD configuration and sample. Copper (most commonly used radiation source) is a poor match with iron containing materials due to induced fluorescence. Magnetite and maghemite are analysed in different configurations using copper or cobalt radiation. Results show the effects of fluorescence repressing measures and the superiority of diffractograms obtained with cobalt radiation. Diffractograms obtained with copper radiation make incontestable phase identification often impossible. Cobalt radiation on the other hand yields high quality diffractograms, making phase identification straightforward.

Powder X-Ray Data for Synthetic Anhydrous Sodium Zirconium Silicates

1987 ◽  
Vol 2 (3) ◽  
pp. 176-179 ◽  
Author(s):  
G. Wilson ◽  
F. P. Glasser
Keyword(s):  
Solid State ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Solid State Reaction ◽  
The Other ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
X Ray ◽  
Sodium Zirconium ◽  
Diffraction Patterns

AbstractA systematic survey of phase formation in the Na2O-ZrO2-SiO2 system has revealed inconsistencies in the number and identity of ternary phases, and of their X-ray powder data. The phases Na2ZrSiO5, Na4Zr2Si3O12, Na2ZrSi2O7 and Na2ZrSi4O11 were prepared by solid-state reaction and their experimental X-ray diffraction patterns measured. Calculated X-ray diffraction patterns were generated by computer, using published crystallographic data, and critically compared with the experimentally observed values. The unit-cell constants were redefined to a greater accuracy than the presently accepted values published in the Powder Diffraction File. Only Na4Zr2Si3O12 produced an X-ray diffraction pattern which agreed with that previously published; those from the other phases were significantly different in both the intensities and positions of the reflections. Data for synthetic Na2ZrSi4O11 identical to the mineral vlasovite are reported.

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