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.

scholarly journals A prototype handheld X-ray diffraction instrument

2018 ◽  
Vol 51 (6) ◽  
pp. 1571-1585 ◽  
Author(s):  
Graeme Hansford
Keyword(s):  
Sample Preparation ◽  
Mineralogical Composition ◽  
General Purpose ◽  
Performance Criteria ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fine Grained ◽  
Back Reflection ◽  
Promising Area ◽  
Sample Position

A conceptual design for a handheld X-ray diffraction (HHXRD) instrument is proposed. Central to the design is the application of energy-dispersive XRD (EDXRD) in a back-reflection geometry. This technique brings unique advantages which enable a handheld instrument format, most notably, insensitivity to sample morphology and to the precise sample position relative to the instrument. For fine-grained samples, including many geological specimens and the majority of common alloys, these characteristics negate sample preparation requirements. A prototype HHXRD device has been developed by minor modification of a handheld X-ray fluorescence instrument, and the performance of the prototype has been tested with samples relevant to mining/quarrying and with an extensive range of metal samples. It is shown, for example, that the mineralogical composition of iron-ore samples can be approximately quantified. In metals analysis, identification and quantification of the major phases have been demonstrated, along with extraction of lattice parameters. Texture analysis is also possible and a simple example for a phosphor bronze sample is presented. Instrument formats other than handheld are possible and online process control in metals production is a promising area. The prototype instrument requires extended measurement times but it is argued that a purpose-designed instrument can achieve data-acquisition times below one minute. HHXRD based on back-reflection EDXRD is limited by the low resolution of diffraction peaks and interference by overlapping fluorescence peaks and, for these reasons, cannot serve as a general-purpose XRD tool. However, the advantages ofin situ, nondestructive and rapid measurement, tolerance of irregular surfaces, and no sample preparation requirement in many cases are potentially transformative. For targeted applications in which the analysis meets commercially relevant performance criteria, HHXRD could become the method of choice through sheer speed and convenience.

A profile-fitting procedure for analysis of broadened X-ray diffraction peaks. I. Methodology. Erratum

1989 ◽  
Vol 22 (2) ◽  
pp. 184-184 ◽  
Author(s):  
S. Enzo ◽  
G. Fagherazzi ◽  
A. Benedetti ◽  
S. Polizzi
Keyword(s):  
X Ray Diffraction ◽  
Correct Equation ◽  
X Ray ◽  
Fitting Procedure ◽  
Profile Fitting ◽  
Diffraction Peaks

Equation (18) of the paper by Enzo, Fagherazzi, Benedetti & Polizzi [J. Appl. Cryst. (1988). 21, 536–542] is in error. The correct equation is: A(2θ) = exp [−a|(2θ − 2θ 0)/cot 2θ 0|].

A General Purpose Computer Program for the Dynamic Simulation of Vehicle-Guideway Interactions

AIAA Journal ◽  
1973 ◽  
Vol 11 (3) ◽  
pp. 278-282 ◽  
Author(s):  
GEORGE DAILEY ◽  
WILLIAM C. CAYWOOD ◽  
JAMES S. O'CONNOR
Keyword(s):  
Computer Program ◽  
Dynamic Simulation ◽  
General Purpose ◽  
General Purpose Computer ◽  
Purpose Computer

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.

NEPCOMP: The Navy Engine Performance Program

1974 ◽  
Author(s):  
S. R. Shapiro ◽  
M. J. Caddy
Keyword(s):  
Computer Program ◽  
Engine Performance ◽  
General Purpose ◽  
Modular Approach ◽  
Computational Tool ◽  
Air Breathing ◽  
Design Point ◽  
General Purpose Computer ◽  
Performance Analyses ◽  
Purpose Computer

A general purpose computer program is described which permits rapid design point and off-design performance analyses of air breathing engines. The modular approach used in building the over-all program allows analysis of many engine configurations including multi-stream, multi-nozzle, augmented engines, shaft engines and ramjets. The program may be operated with or without component maps. The result is a computational tool that can be used to perform independent analyses of an engine manufacturer’s product as well as provide engine performance data for use in engine-airframe design and integration studies.

A profile-fitting procedure for analysis of broadened X-ray diffraction peaks. I. Methodology

1988 ◽  
Vol 21 (5) ◽  
pp. 536-542 ◽  
Author(s):  
S. Enzo ◽  
G. Fagherazzi ◽  
A. Benedetti ◽  
S. Polizzi
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Fitting Procedure ◽  
Profile Fitting ◽  
Diffraction Peaks

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
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