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The nature and origin of interstellar diamond
D F Blake1, F Freund, K F Krishnan
1NASA Ames Research Center, Moffett Field, California 94035, USA.
Nature
|April 14, 1988
Summary
Microscopic diamond found in meteorites shows properties conflicting with expectations. New data suggest this may be due to surface atoms on the extremely fine-grained diamond material.
Area of Science:
- Cosmochemistry
- Materials Science
- Mineralogy
Background:
- Microscopic diamond has been identified in carbonaceous chondrite meteorites.
- Certain properties of this meteorite diamond (C delta component) appear anomalous.
- These anomalies necessitate further investigation into the diamond's nature and origin.
Purpose of the Study:
- To analyze the microscopic diamond from meteorites using high spatial resolution techniques.
- To reconcile the observed properties of meteorite diamond with theoretical expectations.
- To investigate the formation mechanisms of microscopic diamond in extraterrestrial environments.
Main Methods:
- High spatial resolution analytical techniques were employed.
- Characterization of the C delta diamond component from meteorites.
- Analysis of surface and interfacial atomic contributions to material properties.
Main Results:
- The C delta diamond is an extremely fine-grained (0.5-10 nm) single-phase material.
- Surface and interfacial carbon atoms, up to 25% of the total, contribute an 'amorphous' character to spectral data.
- Observed properties can be explained by the fine-grained nature and surface effects.
Conclusions:
- The 'amorphous' spectral character is attributed to surface/interfacial atoms in fine-grained diamond.
- Findings support the hypothesis of high-pressure interstellar formation from amorphous carbon and graphite.
- Low-pressure formation mechanisms for meteorite diamond remain a possibility.
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