scholarly journals Characterization of Nanophase Materials by X-Ray Diffraction and Computer Simulation

1989 ◽  
Vol 153 ◽  
Author(s):  
J. A. Eastman ◽  
L. J. Thompson
Keyword(s):  
Computer Simulation ◽  
Grain Boundary ◽  
Interplanar Spacing ◽  
Structural Parameters ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nanophase Materials ◽  
Boundary Width ◽  
Model Structures

AbstractX-ray diffraction experiments on nanophase Pd have been performed with the primary goal of determining the nature of grain boundary structures in nanophase materials. A kinematical diffraction analysis has been developed to interpret x-ray θ-2θ data by comparing actual scans with scans produced by computer simulation. This simulation program has been used to explore the effects on diffracted intensity of a variety of microstructural and grain boundary structural parameters such as void concentration, grain size, grain boundary width, and changes in interplanar spacing and density in grain boundary regions. It has been found that a reasonable match to experimental data is produced by at least two model structures; in one, the material contains randomly positioned voids or vacancies, while in the other, the interplanar spacings in grain boundary regions are varied with respect to the spacings found in the grain interiors.

Preparation and Characterization of Quaternary TiZrMnFe Gettering Compound

2013 ◽  
Vol 834-836 ◽  
pp. 350-355
Author(s):  
Shu Qiu Wang ◽  
Fan Hao Zeng ◽  
Jiang Feng Song ◽  
Xiao Fen Tan ◽  
Lin Wei Li
Keyword(s):  
Electron Microscopy ◽  
Interplanar Spacing ◽  
Nuclear Industry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Arc Melting ◽  
Transmission Electron ◽  
Ti Content ◽  
Scanning Electron

The quaternary TixZr1-xMnFe gettering alloys (x =0, 0.1, 0.2, 0.3 and 0.4) were synthesized successfully by arc melting and their phase structures along with microstructures had been investigated by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). It showed that the addition of Ti did not change the phase structure of ZrMnFe of C14 laves phase. XRD results showed that Ti successfully replaced part of the Zr and the decrease of interplanar spacing had a linear relationship with the increase of Ti content. The success of this trial preparation provides reference for nuclear industry gettering materials.

scholarly journals Characterization of Ni-Cd Nanostructured System Obtained by Chemical Reduction of Salts

2016 ◽  
Vol 17 (4) ◽  
pp. 275 ◽  
Author(s):  
V.M. Pugachev ◽  
Yu.A. Zaharov ◽  
A.S. Valnyukova ◽  
V.G. Dodonov
Keyword(s):  
Chemical Reduction ◽  
Structural Parameters ◽  
Reduction Process ◽  
Metal Powders ◽  
X Ray Diffraction ◽  
X Ray ◽  
Initial Stage ◽  
Fcc Lattice ◽  
High Alkalinity

<p>The process of obtaining of highly dispersed metal powders of Ni-Cd system by reduction of their salts by hydrazine in aqueous medium at high alkalinity was investigated. The possibility of production metal powders containing up to 50 mol% of cadmium is established and conditions for their synthesis are optimized. Phase composition, structural parameters, dispersity of solid products during the reduction process were studied by X-ray diffraction (XRD) and SAXS. The formation of metal solid solutions with FCC lattice contradicts to the known phase diagram for Ni-Cd and may be explained by increasing the energy of the particles in the nanostate. The formation of intermetallide NiCd<sub>5</sub> in the studied compositions area is caused by sequential character of reduction process; as a result the metal product on the initial stage of reduction is significantly enriched with cadmium.</p>

scholarly journals Synthesis and characterization of Ag-chalcogenide nanoparticles for possible applications in photovoltaics

2018 ◽  
Vol 36 (3) ◽  
pp. 375-380 ◽  
Author(s):  
Subhash Chand ◽  
Pankaj Sharma
Keyword(s):  
Crystallite Size ◽  
Structural Parameters ◽  
Blue Shift ◽  
Optical Characterization ◽  
Molar Ratio ◽  
Synthesis And Characterization ◽  
Capping Agent ◽  
X Ray Diffraction ◽  
X Ray

AbstractBottom-up technique has been used to synthesize Ag-chalcogenide nanoparticles. This work reports on the synthesis of Ag2Se by varying the molar ratio of capping agent and pH of the solution. The synthesized nanoparticles have been characterized in terms of structural parameters using X-ray diffraction. By this technique, various parameters such as crystallite size, dislocation density and strain of the nanoparticles were calculated. The crystallite size decreased with the increase in pH of the solution. The optical characterization was carried out by UV-Vis-NIR spectrophotometer. With the decrease in the crystallite size, a blue shift in the absorption peak of the nanoparticles was observed. These properties are suitable for energy harvesting with the help of photovoltaics.

scholarly journals Structural investigations of the α12Si–Ge superstructure

2015 ◽  
Vol 48 (1) ◽  
pp. 262-268 ◽  
Author(s):  
Tanja Etzelstorfer ◽  
Mohammad Reza Ahmadpor Monazam ◽  
Stefano Cecchi ◽  
Dominik Kriegner ◽  
Daniel Chrastina ◽  
...  
Keyword(s):  
Structural Parameters ◽  
X Ray Diffraction ◽  
Structural Investigations ◽  
X Ray ◽  
Direct Bandgap ◽  
Superlattice Structure ◽  
Band Structure Calculations ◽  
Nominal Structure ◽  
Structure Calculations

This article reports the X-ray diffraction-based structural characterization of the α12multilayer structure SiGe2Si2Ge2SiGe12[d'Avezac, Luo, Chanier & Zunger (2012).Phys. Rev. Lett.108, 027401], which is predicted to form a direct bandgap material. In particular, structural parameters of the superlattice such as thickness and composition as well as interface properties, are obtained. Moreover, it is found that Ge subsequently segregates into layers. These findings are used as input parameters for band structure calculations. It is shown that the direct bandgap properties depend very sensitively on deviations from the nominal structure, and only almost perfect structures can actually yield a direct bandgap. Photoluminescence emission possibly stemming from the superlattice structure is observed.

On The Study Of Grain Boundary Segregation Using X-Ray Diffraction And Computer Simulation

1991 ◽  
Vol 238 ◽  
Author(s):  
C. A. Counterman ◽  
I. Majid ◽  
P. D. Bristowe ◽  
R. W. Balluffi
Keyword(s):  
Computer Simulation ◽  
Grain Boundary ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Boundary Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Boundary Structure ◽  
Structure Factors ◽  
Diffraction Effects

ABSTRACTThe possibility of studying grain boundary segregation using X-ray diffraction is explored by performing a computer simulation of the diffraction effects expected from the segregation of solute atoms to grain boundaries in two gold alloy systems, i.e. Au-Ag and Au-Ni. Using atomistic Monte-Carlo and molecular statics methods, equilibrium boundary structures are determined and analyzed by computing the grain boundary structure factors. Various changes in both relative and absolute grain boundary structure factors are found which can be directly related to structural and compositional changes due to segregation. In addition, systematic diffraction effects are found as a function of boundary misorientation. The experimental conditions required for verifying these predictions are discussed.

ON THE CHARACTERIZATION OF METALLIC SUPERLATTICE STRUCTURES BY X-RAY DIFFRACTION

1999 ◽  
Vol 13 (19) ◽  
pp. 663-669
Author(s):  
MING XU ◽  
WENXUE YU ◽  
GUANGMING LUO ◽  
CHUNLING CHAI ◽  
TONG ZHAO ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Microstructural Characterization ◽  
High Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Superlattice Structures ◽  
Characterization Procedure ◽  
Subsidiary Maxima ◽  
Superlattice Period

To solve the problem on the microstructural characterization of metallic superlattices, taking the NiFe/Cu superlattices as example, we show that the structures of metallic superlattices can be characterized exactly by combining low-angle X-ray diffraction with high-angle X-ray diffraction. First, we determine exactly the total film thickness by a straightforward and precise method based on a modified Bragg law from the subsidiary maxima around the low-angle X-ray diffraction peak. Then, by combining with the simulation of high-angle X-ray diffraction, we obtain the structural parameters such as the superlattice period, the sublayer and buffer thickness. This characterization procedure is also applicable to other types of metallic superlattices.

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.

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.

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