Unusual faceting on α-iron crystals found on the Moon

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} 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.
Κ. Μ. Knowles and H. K. D. H. Bhadeshia
Journal of Crystal Growth 617 (2023) 127257
www.phase-trans.msm.cam.ac.uk/2023/moon.html

[@bhadeshia123]

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.

[@deepak.dinkar]

We need more such discussions in the near future. Thank you very much for making this discussion online. It is highly influential and inspiring too. This is how two intellectuals interact and deliver meaningful substances to society. One of the very rare kinds of conversation. Immensely thankful to you, Sir. -Deepak Dinkar

[@bhadeshia123]

Thank you for the kind words. The paper itself can be downloaded from www.phase-trans.msm.cam.ac.uk/2023/moon.html

[@deepak.dinkar]

@@bhadeshia123 Thank you very much for your kind reply and providing the link to download this important article. Downloaded it. Will reach you out at 310A if find any difficulty to understand it. Thank you, Sir.

[@bhadeshia123]

@@deepak.dinkar Either that, or by email would be fine, Deepak.

[@bhadeshia123]

@@deepak.dinkar No problem.

[@ARPAN-HawaiianGUITAR]

An elegant discussion

[@bhadeshia123]

Thank you, glad you like it. The paper can be downloaded from www.phase-trans.msm.cam.ac.uk/2023/moon.html