Deltoidal icositetrahedron faceting on α-Fe crystals found on the surface of the Moon

K. M. Knowles and H. K. D. H. Bhadeshia

Abstract

Crystallographic analysis of scanning electron microscopy images of small μm-sized single crystals of b.c.c. iron found on the surface of the Moon shows that the deltoidal icositetrahedron faceting behaviour clearly seen is best describable as being from planes of the {229}_α; form. While possibly unexpected given the lack of any report of such faceting in terrestrial and meteoritic b.c.c. iron single crystals, this deltoidal icositetrahedron faceting behaviour can be rationalised straightforwardly in terms of the local chemical conditions which will have been experienced by these crystals while growing from the vapour in the part of the lunar environment from which these samples were obtained.

Journal of Crystal Growth 617(2023) 127257.

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Here is an interesting citation of our paper, where it is appreciated that in general, crystals will tend to have factes that are low-index planes, except when they form in odd conditions such as on the moon: Zimmerman J, Rabkin E. Sculpturing metal nanoparticles by controlled massive deformation. Scripta Materialia. 252 (2024) 116248. Very small crystals were deformed between parallel platens to produce facets corresponding to planes with unusual crystallographic indices. The argument is that there are "unlimited possibilities for obtaining novel functional properties" at these artificial, high-energy facets.

5th edition published 2024

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October 8th, 2024