scholarly journals Revealing inconsistencies in X-ray width methods for nanomaterials

Nanoscale ◽  
2019 ◽  
Vol 11 (46) ◽  
pp. 22456-22466 ◽  
Author(s):  
Cody Kunka ◽  
Brad L. Boyce ◽  
Stephen M. Foiles ◽  
Rémi Dingreville
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Multiple Generations ◽  
Scherrer Method

Since the landmark development of the Scherrer Method a century ago, multiple generations of width methods for X-ray diffraction originated to non-invasively and rapidly characterize the property-controlling sizes of nanomaterials.

Breakage Mechanism of Al2O3 Layer on Nano Al Powder by Magnetic Pulsed Dynamic Compaction

2004 ◽  
Vol 449-452 ◽  
pp. 801-804
Author(s):  
Geun Hee Lee ◽  
Chang Kyu Rhee ◽  
Wheung Whoe Kim ◽  
Victor Ivanov
Keyword(s):  
Compaction Pressure ◽  
Dynamic Compaction ◽  
Magnetic Pulse ◽  
X Ray Diffraction ◽  
Aluminum Powders ◽  
X Ray ◽  
Transmission Electron ◽  
Bulk Structure ◽  
Breakage Mechanism ◽  
Scherrer Method

Magnetic Pulse Compaction (MPC), as a dynamic compaction, can be possible to reach higher relative density of nano metallic compacts owing to sufficiently high pressure and adiabatic heating in very short duration of an order of µsec. The present work is concerned with the magnetic pulsed compaction of the nano-sized aluminum powders, which particle size was a range of 50 ~ 100 nm passivated in air. The compaction pressure was 1.5 GPa for 300 µsec in the temperature range from 20°C to 500°C. The grain size of compacts was maintained less than 50 nm, which was analyzed by X-ray diffraction (XRD) using Scherrer method. From the calculation of adiabatic heat and of pressure induced by thermal expansion, and the observation by transmission electron microscopy (TEM), it was found that Al2O3 could be broken and dispersed with a few nano-meter sizes in the Al matrix and that the ultra fine and uniform bulk structure was maintained up to 400°C of compaction temperature.e

Pure and La3+/Nd3+ Doped SrTiO3 Powders Obtained by Solid State Reaction and Microwave Assisted Hydrothermal Synthesis

2015 ◽  
Vol 820 ◽  
pp. 167-171
Author(s):  
André Silva Chaves ◽  
Olívia de Andrade Raponi ◽  
Maria Virginia Gelfuso ◽  
Daniel Thomazini
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Stoichiometric Ratio ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
X Ray ◽  
Sem Image ◽  
Microwave Assisted ◽  
Titanate Ceramic ◽  
Scherrer Method

Strontium titanate ceramic powders (SrTiO3), pure and doped with lanthanum (La3+) and neodymium (Nd3+), were synthesized by solid state reaction (SSR) and microwave assisted hydrothermal technique (MHT). For SSR, a mixture of SrCO3, TiO2, La2O3and Nd2O3oxides was performed in stoichiometric ratio, to produce SrTiO3(STO), Sr0.96La0.04TiO3(STO-04La), Sr0.96Nd0.04TiO3(STO - 04Nd) and Sr0.96La0.02Nd0.02TiO3(STO-02La02Nd), in a ball mill, for 3.5 h. This mixture was dried at 70°C for 24h. This powder was calcined at 1150°C for 2h in a conventional oven. For MHT synthesis, Ti (C4H9O)4, SrCO3, La2O3and Nd2O3precursors were solubilized in nitric acid (10M), in stoichiometric proportions to form STO , STO-04La, STO-04Nd and STO-02La02Nd. This solution was precipitated adding NH4OH (10M). Quota of 2g of precipitated powder was then dried in an air oven at 70°C for 24 hours, and then added to 40 ml of a KOH solution (10M). These suspensions were subjected to MHT for 1h, at 120°C. The ceramic powders obtained by the two routes were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The crystallite size was calculated by Scherrer method and from SEM image, linear intercept method for both the SSR and MHT powders was used to measure the particles size, which show the increase of particles size related to the cation substitution.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

Electron Microscopy of Human Gallstones

1971 ◽  
Vol 29 ◽  
pp. 296-297
Author(s):  
C. Wolpers ◽  
R. Blaschke
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Bile Pigment ◽  
X Ray Diffraction ◽  
Triclinic Crystal System ◽  
X Ray ◽  
Follow Up Study ◽  
Infra Red ◽  
Main Components

Scanning microscopy was used to study the surface of human gallstones and the surface of fractures. The specimens were obtained by operation, washed with water, dried at room temperature and shadowcasted with carbon and aluminum. Most of the specimens belong to patients from a series of X-ray follow-up study, examined during the last twenty years. So it was possible to evaluate approximately the age of these gallstones and to get information on the intensity of growing and solving.Cholesterol, a group of bile pigment substances and different salts of calcium, are the main components of human gallstones. By X-ray diffraction technique, infra-red spectroscopy and by chemical analysis it was demonstrated that all three components can be found in any gallstone. In the presence of water cholesterol crystallizes in pane-like plates of the triclinic crystal system.

High Resolution Replication of Organoclay Surfaces

1982 ◽  
Vol 40 ◽  
pp. 576-577
Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys
Keyword(s):  
Clay Mineral ◽  
Organic Molecule ◽  
Organic Molecules ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Naturally Occurring ◽  
Silicate Layers ◽  
Mineral Identification

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.

Electron Microscopy of Shock Loaded Polycrystalline Beryllium

1974 ◽  
Vol 32 ◽  
pp. 506-507 ◽  
Author(s):  
J. M. Galbraith ◽  
L. E. Murr ◽  
A. L. Stevens
Keyword(s):  
Electron Microscopy ◽  
Wave Propagation ◽  
Structural Change ◽  
Single Crystal ◽  
Diffraction Pattern ◽  
Shock Loading ◽  
Slip Systems ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
X Ray

Uniaxial compression tests and hydrostatic tests at pressures up to 27 kbars have been performed to determine operating slip systems in single crystal and polycrystal1ine beryllium. A recent study has been made of wave propagation in single crystal beryllium by shock loading to selectively activate various slip systems, and this has been followed by a study of wave propagation and spallation in textured, polycrystal1ine beryllium. An alteration in the X-ray diffraction pattern has been noted after shock loading, but this alteration has not yet been correlated with any structural change occurring during shock loading of polycrystal1ine beryllium.This study is being conducted in an effort to characterize the effects of shock loading on textured, polycrystal1ine beryllium. Samples were fabricated from a billet of Kawecki-Berylco hot pressed HP-10 beryllium.

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.

Polygonal profiles of ferritin molecules

1983 ◽  
Vol 41 ◽  
pp. 600-601
Author(s):  
William H. Massover
Keyword(s):  
Axial Ratio ◽  
X Ray Diffraction ◽  
Rhombic Dodecahedron ◽  
Apparent Contradiction ◽  
Iron Storage ◽  
X Ray ◽  
Hexagonal Shape ◽  
Axes Of Symmetry ◽  
Apparent Conflict ◽  
Iron Storage Protein

The molecular structure of the iron-storage protein, ferritin, is becoming known in ever finer detail. The 24 apoferritin subunits (MW ca. 20,000) have a 2:1 axial ratio and are polymerized with 4:3:2 symmetry to form an outer shell surrounding a variable amount of microcrystalline iron, Recent x-ray diffraction results indicate that the projected outline of the native molecule has a quasi-hexagonal shape when viewed down the 3-fold axes of symmetry, and a quasi-square shape when looking down the 4-fold axes. To date, no electron microscope study has reported observing anything other than circular profiles, which would indicate that ferritin is strictly spherical. The apparent conflict between the "hollow sphere" of electron microscopy (E.M.) and the "truncated rhombic dodecahedron" of x-ray diffraction could reflect the poorer effective resolution of E.M. coming from radiation damage, staining, drying, etc. The present study investigates the detailed shape of individual ferritin molecules in order to search for the predicted aspherical profiles and to interpret the nature of this apparent contradiction.

Cytomembrane Preservation in Tissue Dehydrated Only With Glutaraldehyde and Epon 812 Resin

1973 ◽  
Vol 31 ◽  
pp. 320-321
Author(s):  
Daniel C. Pease
Keyword(s):  
Diffraction Pattern ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Unpublished Study ◽  
X Ray ◽  
Sectioned Material

A previous study demonstrated that tissue could be successfully infiltrated with 50% glutaraldehyde, and then subsequently polymerized with urea to create an embedment which retained cytomembrane lipids in sectioned material. As a result, the 180-190 Å periodicity characteristic of fresh, mammalian myelin was preserved in sections, as was a brilliant birefringence, and the capacity to bind OsO4 vapor in the hydrophobic bilayers. An associated (unpublished) study, carried out in co-operation with Drs. C.K. Akers and D.F. Parsons, demonstrated that the high concentration of glutaraldehyde (and urea) did not significantly alter the X-ray diffraction pattern of aldehyde-fixed, myelin. Thus, by itself, 50% glutaraldehyde has little effect upon cytomembrane systems and can be used with confidence for the first stages of dehydration.

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