Lonsdaleite is faulted and twinned cubic diamond and does not exist as a discrete material
Description
Lonsdaleite, also called hexagonal diamond, has been widely used as a marker of asteroidal impacts. It is thought to play a central role during the graphite-to-diamond transformation, and calculations suggest that it possesses mechanical properties superior to diamond. However, despite extensive efforts, lonsdaleite has never been produced or described as a separate, pure material. Here we show that defects in cubic diamond provide an explanation for the characteristic d-spacings and reflections reported for lonsdaleite. Ultrahigh-resolution electron microscope images demonstrate that samples displaying features attributed to lonsdaleite consist of cubic diamond dominated by extensive {113} twins and {111} stacking faults. These defects give rise to nanometre-scale structural complexity. Our findings question the existence of lonsdaleite and point to the need for re-evaluating the interpretations of many lonsdaleite-related fundamental and applied studies.
Date Created
The date the item was original created (prior to any relationship with the ASU Digital Repositories.)
2014-11-01
Agent
- Author (aut): Nemeth, Peter
- Author (aut): Garvie, Laurence
- Author (aut): Aoki, Toshihiro
- Author (aut): Dubrovinskaia, Natalia
- Author (aut): Dubrovinsky, Leonid
- Author (aut): Buseck, Peter
- Contributor (ctb): Department of Chemistry and Biochemistry
- Contributor (ctb): College of Liberal Arts and Sciences
- Contributor (ctb): School of Earth and Space Exploration
- Contributor (ctb): Center for Meteorite Studies
- Contributor (ctb): Ira A. Fulton Schools of Engineering
- Contributor (ctb): LeRoy Eyring Center for Solid State Science
- Contributor (ctb): School of Molecular Sciences