Skip to Main Content
Book Chapter

Appendix: Tables for the determination of d in Å from 2θ° for the Kᾱ and radiations of copper, cobalt and iron

By
G. Brown
G. Brown
Soils and Plant Nutrition Department,
Rothamsted Experimental Station, Harpenden,
Hertfordshire AL5 254, England
Search for other works by this author on:
Published:
January 01, 1980

Abstract

POWDER diffraction patterns are almost always reported and compared in terms of the interplanar spacings, d, represented by the intensity maxima. In practice, d is obtained from the diffraction angle, θ, which is half the angle between the incident and diffracted rays, by means of the Bragg relationship

 
formula

where λ is the wavelength of the radiation. The relation between these d-spacings and lattice spacings is discussed in Chapter 5, Section 3.7. Symmetrical reflection powder diffractometers are the instruments most widely used for examining clays by X-ray diffraction and they are usually calibrated in terms of 2θ rather than θ. To convert observed values of 2θ to d spacings it is convenient to have available solutions of the Bragg equation for radiations that are commonly used over the angular range normally encountered.

A number of compilations already exist in graphical or tabular form but these are either unnecessarily elaborate or too limited to be convenient for day-to-day use in studies of clays and related materials. Reflections with d spacings less than 1 Å are usually weak or absent in diffraction patterns of clays and when present they are of little value for identification. Because of structural defects and small crystal size, reflections from clays are usually broader than those obtained from materials such as quartz or feldspars and as a result the 1, 2 doublet is rarely resolved. By contrast, corresponding to the stronger reflections, weak reflections arising from radiation are not uncommon, especially if, as sugggested (Chapter 5, Section 3.2), thin β-filters are used.

You do not currently have access to this article.

Figures & Tables

Contents

Mineralogical Society Monograph

Crystal Structures of Clay Minerals and their X-Ray Identification

G. W. Brindley
G. W. Brindley
Department of Geosciences, and Materials Research Laboratory,
The Pennsylvania State University, University Park,
Pennsylvania 16802, U.S.A.
Search for other works by this author on:
G. Brown
G. Brown
Soils and Plant Nutrition Department,
Rothamsted Experimental Station, Harpenden,
Hertfordshire AL5 254, England
Search for other works by this author on:
Mineralogical Society of Great Britain and Ireland
Volume
5
ISBN electronic:
9780903056373
Publication date:
January 01, 1980

GeoRef

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal