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Humidity Controlled Diffractometry and its Applications

Published online by Cambridge University Press:  06 March 2019

Radko A. Kühnel  and
Sjerry J. van der Gaast
Radko A. Kühnel
Affiliation:
International Institute for Aerospace Survey and Earth Sciences (ITC), 2628 EB, Delft, The Netherlands
Sjerry J. van der Gaast
Affiliation:
Netherlands Institute for Sea Research (NIOZ), 1790 AB, Den Burg, Texel, The Netherlands
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Abstract

Humidity sensitive mineral phases change their structure when humidity varies resulting in X-ray pattern changes in intensity, position, and shape of lines. These structural changes in hydrous minerals are induced by dehydration and rehydration, which can lead to phase transformations or to steady depletion which may result in a total structure collapse. By means of X-ray diffraction with a special attachment, such reactions can be followed. The controlled relative humidity is provided in situ, in a closed cell, by a flow of moistened helium gas which is flushed through the cell during the XRD analysis. Humidity diffractometry allows studies of reaction rates of dehydration-rehydration reactions and their reversibilities, as well as effects of additives and impurities on these reactions. Potential applications in basic research and in industry are demonstrated using montmorilionite, ettringites, sodium carbonates and calcium sulfates.

Type
VIII. High-Temperature and Non-Ambient Applications of XRD
Information
Advances in X-Ray Analysis , Volume 36: Forty-First Annual Conference on Applications of X-ray Analysis, August 3-7, 1992 , 1992 , pp. 439 - 449
Copyright
Copyright © International Centre for Diffraction Data 1992

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