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A Study of the Unusual Line Structure in Powder Patterns of Pyrolytically Deposited Boron Compounds and Other Materials

Published online by Cambridge University Press:  06 March 2019

Robert L. Prickett ,
R. L. Hough  and
Duane Earley
Robert L. Prickett
Affiliation:
Air Force Materials Laboratory Wright-Patterson AFB, Ohio
R. L. Hough
Affiliation:
Hough Laboratories Springfield, Ohio
Duane Earley
Affiliation:
University of Dayton Dayton, Ohio
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Abstract

A prolonged study has been roade of the unusual X-ray powder patterns generated by certain pyrolytically formed boron compounds, consisting of two to four moderately broad diffraction lines in the 1-4 Å range. These broad lines are unexpectedly made to disappear by a singie sharp blow with a hammer on the specimen in a Plattner diamond mortar, the disappearance being accompanied by the spontaneous generation of the standard diffraction lines expected for normally crystalline materials. The same diffraction pattern changes also may be brought about by regular grinding methods, fracture, or thermal annealing. Transmission electron diffraction yields results identical with those obtained by X-ray. Orientation studies demonstrate that the phenomenon is not orientation dependent. Controlled fracture has been applied in an attempt to develop a hypothesis. It appears from the constancy of the width and position of the diffraction lines among samples that the phenomenon being studied has a definite potential energy, well located somewhere between amorphous and crystalline states. Demonstration of this phenomenon of line broadening has been obtained with boron, boron carbide, and in part with silicon, carbide. These materials have been formed by various methods: pyrolytic decomposition of carborane, low pressure electrical discharge in diborane, chemical reaction between boron halide and hydrogen.

Type
Research Article
Information
Advances in X-Ray Analysis , Volume 10: Fifteenth Annual Conference on Applications of X-ray Analysis, August 10-12, 1966 , 1966 , pp. 221 - 233
Copyright
Copyright © International Centre for Diffraction Data 1966

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