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Extinction Bend Contours in Electron Microscopy of Clay-Size Mica-Vermiculites

Published online by Cambridge University Press:  01 July 2024

M. Gal  and
C. I. Rich
M. Gal*
Affiliation:
Agronomy Department, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, U.S.A.
C. I. Rich
Affiliation:
Agronomy Department, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, U.S.A.
*
†Present address: Department of Soil Science, Faculty of Agriculture, the Hebrew University of Jerusalem, Rehovot, Israel
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Abstract

Extinction bend contours, observed in Cs-treated mica-vermiculites by transmission electron microscopy, give information on the morphology and crystal orientation and continuity in individual particles of clay size. Interlayer Cs apparently stretches that part of the silicate sheet in closest proximity and when exchange by Cs is incomplete, warping of the particle occurs. Warping favors the appearance of bend contours in transmission electron microscopic images of the particles. These contours terminate at crystal boundaries within a particle. A specimen tilting stage is useful in bringing the contours into view and in “exploring” individual particles.

Résumé

Résumé

Les contours d’extinction déformés observés en microscopie électronique par transmission dans les micas-vermiculites traités au Cs donnent une information sur la morphologie et l’orientation des cristaux, et sur la continuité des particules individuelles de la taille de l’argile. Apparemment, le Cs interfeuillet distend la partie de la couche silicatée qui est dans son voisinage immédiat et lorsque l’échange par Cs est incomplet, on observe un gauchissement de la particule. Ce gauchissement favorise l’apparition de contours déformés dans les images des particules obtenues en microscopie électronique par transmission. Ces contours s’établissent aux zones limites des cristaux à l’intérieur d’une particule. Un dispositif d’orientation de l’échantillon se révèle utile pour bien observer ces contours et pour “explorer” les particules individuelles.

Kurzreferat

Kurzreferat

Die durch das Elektronen-Durchstrahlungsmikroskop beobachteten Extinktions-Biegungskonturen in Cs-behandelten Glimmer-Vermiculiten geben Auskunft über die Morphologie und Kristallorientierung und -kontinuität in Einzelteilchen von Tongrösse. Es scheint, dass zwischenschichtiges Cs den am nächsten liegenden Teil der Silikattafel am meisten streckt, und wenn der Austausch durch Cs unvollständig ist, so tritt Werfung des Teilchens auf. Die Werfung begünstigt das Erscheinen von Biegungskonturen ind Bildern des Teilchens im Elektronen-Durchstrahlungsmikroskop. Diese Konturen enden an den Kristallgrenzen innerhalb eines Teilchens. Ein kippbarer Präparathalter ist dazu geeignet die Konturen ins Blickfeld zu bringen und Einzelteilchen zu “erforschen”.

Резюме

Резюме

Обнаруженная при помощи электронного микроскопа экстинкция контуров изгиба в слюдяных вермикулитах, обработанных Cs, дает сведения о морфологии и ориентации кристаллов и о неразрывности индивидуальных чатиц глины. Межслоевой Cs, очевидно, растягивает самую близкую к нему часть силикатной пластинки, и если обмен с Cs неполный, то происходит искривление частицы. Искривление способствует появлению контура изгиба на изображениях частиц под электронным микроскопом. Эти контуры заканчиваются на границах кристалла в пределах частицы. Для введения контуров в поле зрения при изучении отдельных частиц, рекомендуется наклонить образец.

Type
Research Article
Information
Clays and Clay Minerals , Volume 20 , Issue 4 , August 1972 , pp. 207 - 210
Copyright
Copyright © Clay Minerals Society 1972

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Footnotes

*

Support for this work by a grant (GA-18053) from the National Science Foundation is gratefully acknowledged.

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