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The variance and other measures of line broadening in powder diffractometry. II. Determination of particle size
Author(s) -
Langford J. I.
Publication year - 1968
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889868005182
Subject(s) - particle size , maxima , particle size distribution , grain size , materials science , diffraction , nickel , powder diffraction , particle (ecology) , line (geometry) , sample size determination , crystal (programming language) , analytical chemistry (journal) , crystallography , mineralogy , optics , chemistry , statistics , mathematics , physics , chromatography , geometry , metallurgy , programming language , art history , performance art , art , oceanography , computer science , geology
The procedure for interpreting broadened diffraction maxima in terms of particle size is illustrated by means of two samples of nickel powder. The average size of the particles in submicron nickel is determined from a comparison of various measures of breadth of broadened profiles with the breadths of `standard' lines. Information about the shape of the particles and an indication of the distribution of size are also obtained. The size from X‐ray methods (about 200 Å) is in close agreement with the value obtained from electron micrographs of the powder, indicating that the grains observed in the latter are mainly single crystals. The limitations of this technique are discussed for cases in which diffraction broadening is not appreciable. An advantage of the variance as a measure of breadth is that it provides a direct method of investigating crystal imperfections. Data from a sample of carbonyl nickel powder, with an average grain size of 5.5 μm, are used to illustrate this method. The mean particle size is 650 Å, indicating that each grain consists of several coherently diffracting regions, or 'particles' as determined by X‐ray methods.