A Computer Technique for X-Ray Diffraction Curve Fitting/Peak Decomposition

2015 ◽  
pp. 51-101 ◽  
Author(s):  
R. C. Jones
Keyword(s):  
Curve Fitting ◽  
X Ray Diffraction ◽  
Computer Technique ◽  
Diffraction Curve ◽  
X Ray ◽  
Peak Decomposition

An Estimation of Hardness of Hardened Steels by X-Ray Diffraction Using a Gaussian Curve-Fitting Method

1984 ◽  
Vol 12 (1) ◽  
pp. 13 ◽  
Author(s):  
R Horstman ◽  
KA Peters ◽  
RL Meltzer ◽  
MB Vieth ◽  
M Kurita ◽  
...  
Keyword(s):  
Curve Fitting ◽  
X Ray Diffraction ◽  
Hardened Steels ◽  
X Ray ◽  
Gaussian Curve ◽  
Fitting Method ◽  
Curve Fitting Method

Digital Filtering and Shape Identification in the Analysis of WAXD Patterns of Semicrystalline Polymers

2013 ◽  
Vol 203-204 ◽  
pp. 189-192 ◽  
Author(s):  
Małgorzata Rabiej
Keyword(s):  
Numerical Differentiation ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Amorphous Halo ◽  
Shape Identification ◽  
Diffraction Curve ◽  
X Ray ◽  
The Degree Of Crystallinity ◽  
Quick Determination

Most frequently, the degree of crystallinity of polymers is determined using Wide Angle X-ray Diffraction (WAXD) technique. The method consists in the resolution of WAXD diffraction curve of a polymer into individual crystalline peaks and amorphous halo. This work presents a procedure, which was elaborated to help in a quick determination of the angular positions of crystalline peaks present in the diffraction curve of investigated polymer. The positions of peaks are determined using numerical differentiation. Using these data the computer program WAXSFIT identifies investigated polymer and prepares a set of starting parameters which are used in the calculations of the degree of crystallinity.

Study on X-Ray Integral Diffraction Intensity of GaAs Photocathode

2013 ◽  
Vol 631-632 ◽  
pp. 209-215
Author(s):  
Feng Shi ◽  
Ben Kang Chang ◽  
Hong Chang Cheng ◽  
Xiao Bing Xu
Keyword(s):  
High Vacuum ◽  
Image Intensifier ◽  
Electron Source ◽  
Ultra High Vacuum ◽  
Transmission Mode ◽  
Crystal Quality ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
Diffraction Curve ◽  
X Ray

In order to precisely predict the sensitivity of Ф18 mm transmission-mode GaAs photocathode, a concept of integral diffraction intensity is proposed based on X-ray diffraction principle after analyzing the predecessors′ limitations of testing the micro-area of such photocathode and GaAs photocathode of image intensifier tube is plane electron source in this paper. The integral diffraction intensity on the entire photocathode surface was obtained by multi-points detection in the effective area of the photocathode with integral method. The crystal quality of entire photocathode surface will be taken with the integral diffraction intensity. According to the principle, X-ray diffraction testing for 4 samples of GaAs photocathode modules was executed with high-resolution four-wafer X-ray Diffractometer whose test spot size is 4 mm×5 mm. The diffraction curves were obtained and the integral diffraction intensity was calculated. Subsequently the 4 photocathode modules was activation processed with Cs-O in ultra-high vacuum system simultaneity the photocurrent of photocathode modules was measured. Comparing the variation of diffraction curve with integral diffraction vs photocathode photocurrent curve, they show that the greater the integral diffraction intensity of is, the more photocurrent is in the photocathode module. The variation relation curve between X-ray integral diffraction intensity and photocurrent in the photocathode was fitted with least square method. The curve, which accords with logarithm curve and whose fitting degree is 0.878, was achieved. Since photocathode sensitivity is direct proportion to photocathode photocurrent. The above results prove that A Practicality Φ18mm photocathode of image intensifier tube is plane electron source, GaAs photocathode sensitivity and other photoelectric performance lies on entire photocathode surface crystal quality, the photocathode module integrality reflected by the integral diffraction intensity plays crucial role of GaAs photocathode sensitivity. So integral sensitivity of Ф18 mm transmission-mode GaAs photocathode can be precisely predicted with X-ray integral diffraction intensity, some feasible ideas for further research of GaAs photocathode was obtained in this paper.

Possible effects of irrigation with wastewater on the clay mineralogy of some Australian clayey soils: laboratory study

Soil Research ◽  
2016 ◽  
Vol 54 (7) ◽  
pp. 857 ◽  
Author(s):  
Serhiy Marchuk ◽  
Jock Churchman ◽  
Pichu Rengasamy
Keyword(s):  
Chemical Composition ◽  
Chemical Properties ◽  
Clay Mineralogy ◽  
Clayey Soils ◽  
X Ray Diffraction ◽  
X Ray ◽  
Physico Chemical ◽  
Soil Clays ◽  
Diffraction Patterns ◽  
Peak Decomposition

Potassium is common in a wide variety of wastewaters and in some wastewaters is present at several hundred to several thousand mg L–1. Potassium is taken up by expandable clays leading to its fixation and illitisation of smectitic and vermiculitic layers. Hence the addition of wastewaters to soils may lead to mineralogical changes in the soils that affect their physico-chemical properties. Winery wastewater was equilibrated with clay-rich soils from Southern Australia. X-ray diffraction patterns and chemical composition of clays extracted from untreated and treated soils were determined. In three of the four soils, shifts in peak positions occurred towards more illitic components along with increases in K and sometimes also Mg and Na contents of soil clays. Peak decomposition showed trends towards the formation of interstratifications of illite with smectite at the expense of smectite and an alteration of poorly crystallised illite into its more well-ordered forms. The results show that illitisation may occur as a result of the addition of K-rich wastewaters to clayey soils.

Identification of Cacao Peels Potential as a Basic of Electrodes Environmental Friendly Supercapacitors

2020 ◽  
Vol 846 ◽  
pp. 274-281 ◽  
Author(s):  
Yuli Yetri ◽  
Mursida ◽  
Dahyunir Dahlan ◽  
Erman Taer ◽  
Agustino ◽  
...  
Keyword(s):  
Chemical Activation ◽  
Sem Analysis ◽  
Basic Material ◽  
Carbon Electrodes ◽  
Physical Activation ◽  
Activation Process ◽  
X Ray Diffraction ◽  
Diffraction Curve ◽  
X Ray ◽  
A Value

Identification of the potential of cacao peel as the basic material of environmentally friendly supercapacitor electrodes had been identified. This identification was carried out through analysis of specific dimensions, densities, and capacitances. Activated carbon electrodes were made by a combination of chemical and physics activation methods. The technique of preparing carbon electrodes started from pre-carbonization, milling, chemical activation, pellet making, carbonization, and completed it with physics activation. In addition, the chemical activation applied 0.3 M KOH activator, whereas the physical activation used CO2 gas at a temperature of 700°C. The physical properties were tested by density and X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dipersive X-Ray (EDX). While the electrochemical properties were tested using the Ciclic Voltammetric (CV) method. The results showed that the mass, diameter, thickness, and density of the electrode decreased after passing the carbonization-activation process. A value of 2θ in the range of 23,569o for the reflection fields 002 and 44,781o for the reflection field 100 was obtained in the XRD measurements . The X-ray diffraction curve pointed out that the surface area of C 0,3 M sample was sizeable with the Lc value and lattice distance d002 around 20,01669 Å and 3,771705 Å. SEM analysis indicated the presence of pores between particles spread almost evenly on the surface of the sample, with an irregular and elongated shape. EDX testing showed carbon element of 87.05% while atomic percentage of 91.02%, and correspondently, electrochemical test showed the value of specific capacitance obtained at a concentration of 0.3 M was 90.2 F/gr with a density of 0.850gr/cm3. From the results of the tests obtained, it was shown that cacao peels was very potential to be used as electrodes for supercapacitors.

Application of immune and genetic algorithms to the identification of a polymer based on its X-ray diffraction curve

2013 ◽  
Vol 46 (4) ◽  
pp. 1136-1144 ◽  
Author(s):  
Małgorzata Rabiej
Keyword(s):  
Artificial Intelligence ◽  
Genetic Algorithm ◽  
Hybrid Algorithm ◽  
Optimization Methods ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Diffraction Curve ◽  
Amorphous Component ◽  
X Ray ◽  
Polymer Crystallinity

This paper describes how a combination of two methods of artificial intelligence, an immune algorithm and a genetic algorithm, can be used to recognize a polymer by the shape of its X-ray diffraction curve. To this end, the hybrid algorithm uses a database which contains theoretical functions describing wide-angle X-ray diffraction curves of different polymers. These curves are compared by the algorithm with the experimental diffraction curve and the most similar are chosen. Such theoretical curves are kept in the immunological memory, and their parameters can be set as the starting ones in the optimization methods used for decomposition of the experimental curve into crystalline peaks and amorphous component. Using this algorithm, the preparation of the starting parameters is much easier and faster. Decomposition is the most important step in polymer crystallinity determination.

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.

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