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A Comparison of Methods for Reducing Preferred Orientation

Published online by Cambridge University Press:  06 March 2019

L. D. Calvert
Affiliation:
Chemistry Division, National Research Council of Canada, Ottawa, K1A0R9, CANADA
A. F. Sirianni
Affiliation:
Chemistry Division, National Research Council of Canada, Ottawa, K1A0R9, CANADA
G. J. Gainsford
Affiliation:
Chemistry Division, National Research Council of Canada, Ottawa, K1A0R9, CANADA
C. R. Hubbard
Affiliation:
Center for Materials Science, National Bureau of Standards, Washington, D.C, 20234
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Extract

Preferred orientations in powder diffraction specimens can cause large errors in measured intensities. An extreme case is shown in Figure 1, Smith and Barrett (1979) reviewed the various methods which have been proposed for reducing this effect. Subsequently, two methods which are used commercially for aggregating finely divided solids have been proposed for preparing powder diffraction specimens (Smith, Snyder, and Brownell, 1979; Calvert and Sirianni, 1980). In one of these, spray drying, a finely divided solid is suspended in a liquid together with small quantities of a deflocculent and a binder. This mixture is pulled by venturi action through a nozzle into a heated chamber. The spherically shaped aggregates dry before falling to a collection surface. The apparatus is fairly large (3 X 3 X 4 ft. at NBS), and operating parameters must be carefully chosen.

Type
III. Quantitative XRD Analysis
Copyright
Copyright © International Centre for Diffraction Data 1982

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Footnotes

*

Permanent address: D.S.I.R., Petone, New Zealand.

Contribution of the National Bureau of Standards; not subject to copyright.

References

Calvert, L. D. and Sirianni, A. F., 1980, J. Appl. Cryst., 13:462.Google Scholar
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Smith, D. K. and Barrett, C. S., 1979, Adv. X-Ray. Analy., 22:1.Google Scholar
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