Quantitative X-Ray Diffraction Measurements by Fast Scanning, HR-111

Quantitative X-Ray Diffraction Measurements by Fast Scanning, HR-111. Transportation, Department of


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Two goals were pursued in this research: first, to evaluate statistically some effects of sample preparation and instrument geometry on reproducibility of X-ray diffraction intensity data; and second, to develop a procedure for finding minimum peak and background counting times for a desired level of accuracy. The ratio of calcite to dolomite in limestones was determined in trials. Ultra-fine wet grinding of the limestone in porcelain impact type ball mill gave most consistent X-ray results, but caused considerable line broadening, and peaks were best measured on an area count basis. Sample spinning reduced variance about one third, and a coarse beam-medium detector slit arrangement was found to be best. An equation is developed relating coefficient of variation of a count ratio to peak and background counts. By use of the equation or graphs the minimum coefficient of variation is predicted from one fast scan, and the number and optimum arrangement of additional counting periods to reduce variation to a desired limit may be obtained. The calculated coefficient is the maximum which may be attributed to the counting statistic but does not include experimental deviations.

Item Type: Departmental Report
Keywords: Calcites, Data analysis, Data collection, Diffraction, Dolomite, Equations, Information processing, Limestone, Quantitative analysis, X ray analysis, Fast scanning
Subjects: Transportation
Transportation > Materials
Transportation > Research
Transportation > Data and Information Technology
ID Code: 17275
Deposited By: Iowa DOT Library
Deposited On: 30 Jun 2014 12:36
Last Modified: 29 Jan 2015 21:10
URI: https://publications.iowa.gov/id/eprint/17275