A computer program to analyze x‐ray diffraction films

1993 ◽  
Vol 64 (12) ◽  
pp. 3456-3461 ◽  
Author(s):  
Jeffrey H. Nguyen ◽  
Raymond Jeanloz
Keyword(s):  
Computer Program ◽  
X Ray Diffraction ◽  
X Ray

Separation of Broad Crystalline and Amorphous X-Ray Diffraction Peaks

1980 ◽  
Vol 24 ◽  
pp. 239-243
Author(s):  
O. W. Marks ◽  
D. K. Smith ◽  
M. D. Chris
Keyword(s):  
Computer Program ◽  
General Purpose ◽  
Polymer Mixtures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fitting Procedure ◽  
Computer Input ◽  
Overlapped Peaks ◽  
General Purpose Computer ◽  
Polymer Crystallinity

Separating overlapped peaks is a part of many x-ray diffraction analyses, for example, polymer crystallinity. Natta [1] defined a method for polypropylene in 1957. His method was computerized at the Hercules Research Center in 1960 with an automatic “curve follower” which punched paper tape for the computer. A later method deviated fTom Natta's method by approximating the amorphous curve with a fixed shape and a height chosen to best fit the diffraction data from 2θ = 7.5 through 10. degrees. Neither of these methods worked on “smectic” polymer samples, i.e., composed of very small crystallites. Also, a different computer program was used for each different polymer, so a general purpose computer program was developed using a peak profile method. This method has been used en polymer mixtures and copolymers of ethylene, propylene, and butene; and on cellulose, modified cellulose, and catalysts. The selection of a profile function is discussed in the next section. In later sections, the background, the fitting procedure, and computer input and output are discussed.

Standard X-Ray Diffraction Powder Patterns from the JCPDS Research Associateship

1986 ◽  
Vol 1 (2) ◽  
pp. 64-77 ◽  
Author(s):  
Howard F. McMurdie ◽  
Marlene C. Morris ◽  
Eloise H. Evans ◽  
Boris Paretzkin ◽  
Winnie Wong-Ng ◽  
...  
Keyword(s):  
Computer Program ◽  
Least Squares ◽  
Internal Consistency ◽  
Computer Programs ◽  
National Bureau ◽  
X Ray Diffraction ◽  
Internal Standards ◽  
X Ray ◽  
Cell Refinement ◽  
Computer Controlled

The following new or updated patterns are submitted by the JCPDS Research Associateship at the National Bureau of Standards. The patterns are a continuation of the series of standard X-ray diffraction powder patterns published previously in the NBS Circular 539, the NBS Monograph 25, and in this journal. The methods of producing these reference patterns are described in this journal, Vol. 1, No. 1, p. 40 (1986).The data for each phase apply to the specific sample described. A sample was mixed with 1 or 2 internal standards: silicon (SRM640a), silver, tungsten, or fluorophlogopite (SRM675). Expected 2-theta values for these standards are specified in the methods described (ibid.). Data from which the reported 2-theta values were determined, were measured with a computer controlled diffractometer. Computer programs were used to locate peak positions and calibrate the patterns as well as to perform variable indexing and least squares cell refinement. A check on the overall internal consistency of the data was also provided by a computer program.

Direct Printout X-Ray Pole Figures from Digital Computers

1968 ◽  
Vol 12 ◽  
pp. 391-403 ◽  
Author(s):  
Hung-Chi Chao
Keyword(s):  
Computer Program ◽  
Pole Figure ◽  
Sheet Metal ◽  
Digital Computer ◽  
Stereographic Projection ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pole Figures ◽  
Time Required ◽  
Digital Computers

AbstractThe texture of sheet metal Is best described, by means of pole figures, which are very expensive and time-consuming to prepare. About 8 to 12 hours of effort by a specially trained, and. highly skilled technician are needed to prepare each pole figure. Accordingly, pole figures are not used as extensively in research studies as they would, be if they could be obtained more easily.A method has been developed for automatically producing pole figures by printing results directly from a digital computer. This method does not require the use of additional plotting attachments and, is therefore less expensive and time consuming than other methods. With this method, any laboratory with access to a digital computer can produce pole figures automatically.X-ray diffraction intensities are recorded on punched tape or on punched cards and are fed into the digital computer. A computer program corrects X-ray data obtained, by either transmission or reflection X-ray techniques, maps the stereographic projection, and prints pole figures directly. The time required, to prepare an accurate pole figure is reduced from 8 to 12 hours to 20 minutes or less depending on the type of digital computer used.

A Fortran computer program to collect X-ray diffraction data on macromolecules

1977 ◽  
Vol 10 (3) ◽  
pp. 206-208
Author(s):  
R. L. Girling ◽  
M. K. Wood ◽  
E. E. Abola
Keyword(s):  
Computer Program ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray

Standard Data for the Identification of Phases By X-Ray Diffraction

1973 ◽  
Vol 17 ◽  
pp. 20-31
Author(s):  
Howard F. McMurdie
Keyword(s):  
Computer Program ◽  
Single Crystal ◽  
Powder Diffraction ◽  
Unit Cell ◽  
National Bureau ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
X Ray ◽  
Standard Data

AbstractThe identification of crystalline phases by x-ray diffraction, either by powder or single crystal techniques requires a dependable body of reference data. It is not only necessary to have data on each phase which are accurate and complete, it also is desirable to have data on as wide a range of compounds as possible, and to have the data organized in such a manner as to be readily usable. The outstanding compilations which approach these goals are the Powder Diffraction File and Crystal Data.The Powder Diffraction File, published by the Joint Committee on Powder Diffraction Standards has data covering about 22,500 phases, both organic and inorganic. These data are of various degrees of accuracy as is indicated by symbols. The File is continuously being improved by the addition of evaluated data from the general literature and by data produced by supporting projects, the principal one being the Joint Committee Associateship at the National Bureau of Standards.To be noted in the File with a star, and to be truly considered standard data a powder pattern must be complete in the sense of including all reflections above the minimum “d” spacing covered, both weak lines and those with large “d” spacings. Since the best test of a pattern is its own internal consistency, the reflections must all have hkl's assigned and must show a good agreement between the spacings observed and those calculated from a refined cell, and they must be consistent with the known space group. This agreement can be best obtained by the use of an internal standard and a computer program. The intensities should be measured by a method which minimizes the effect of crystal orientation.The PDF is provided with search procedure manuals arranged on a scheme of the strongest lines to help in locating data matching that from an unknovm. A computer program for rapid searching is available. A recent development is the inclusion of a “reference intensity” to aid in estimating the quantitative analysis of mixtures.Crystal Data is a compilation now in the third edition made at the National Bureau of Standards and published by the Joint Committee on Powder Diffraction Standards. It contains data on the unit cell parameters of over 24,000 phases. These data are arranged by crystal system and axial ratios to simplify identification of phases from unit cell data obtained from Single crystal cameras.Both of these large compilations are also important reference sources for crystallographic information giving structural information and literature references.

Computer Program for Deconvoluting Powder Diffraction Spectra

1987 ◽  
Vol 2 (3) ◽  
pp. 137-145 ◽  
Author(s):  
K. E. Wiedemann ◽  
J. Unnam ◽  
R. K. Clark
Keyword(s):  
Computer Program ◽  
Least Squares ◽  
Powder Diffraction ◽  
Sum Of Squares ◽  
X Ray Diffraction ◽  
X Ray ◽  
Deconvoluted Spectrum ◽  
Reconstructed Spectrum ◽  
Spectra Deconvolution

AbstractA program is presented that removes broadening from X-ray diffraction spectra. An instrumental spectrum can be used to describe empirically the broadening to be removed, or a Gaussian, Cauchy, or Pearson-VII distribution can be used to analytically describe it. In either case, singlet or doublet forms can be generated. The program returns the deconvoluted spectrum, the reconstructed spectrum, and a sum-of-squares difference between the original and reconstructed spectra. Deconvolution is accomplished using a combination of least-squares, background, and smoothing criteria that minimizes the effect of random counting errors.

Standard X-Ray Diffraction Powder Patterns from the JCPDS Research Associateship

1986 ◽  
Vol 1 (4) ◽  
pp. 334-345 ◽  
Author(s):  
Howard F. McMurdie ◽  
Marlene C. Morris ◽  
Eloise H. Evans ◽  
Boris Paretzkin ◽  
Winnie Wong-Ng ◽  
...  
Keyword(s):  
Computer Program ◽  
Least Squares ◽  
Internal Consistency ◽  
Computer Programs ◽  
National Bureau ◽  
X Ray Diffraction ◽  
Internal Standards ◽  
X Ray ◽  
Cell Refinement ◽  
Computer Controlled

The following new or updated patterns are submitted by the JCPDS Research Associateship at the National Bureau of Standards. The patterns are a continuation of the series of standard X-ray diffraction powder patterns published previously in the NBS Circular 539, the NBS Monograph 25, and in this journal. The methods of producing these reference patterns are described in this journal, Vol. 1, No. 1, p. 40 (1986).The data for each phase apply to the specific sample described. A sample was mixed with one or two internal standards: silicon (SRM640a), silver, tungsten, or fluorophlogopite (SRM675). Expected 2-theta values for these standards are specified in the methods described (ibid.). Data, from which the reported 2-theta values were determined, were measured with a computer controlled diffractometer. Computer programs were used to locate peak positions and calibrate the patterns as well as to perform variable indexing and least squares cell refinement. A check on the overall internal consistency of the data was also provided by a computer program.

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