Chaoite
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Chaoite is a mineral described as an allotrope of carbon whose existence is disputed. It was discovered in shock-fused graphite gneiss from the Ries crater in Bavaria. It has been described as slightly harder than graphite, with a reflection colour of grey to white. From its electron diffraction pattern, the mineral has been considered to have a carbyne structure. A later report has called this identification, and the very existence of carbyne phases, into question, arguing that the new reflections in the diffraction pattern are due to clay impurities.
[edit] Ceraphite
It has been claimed that an identical form can be prepared from graphite by sublimation at 2700-3000 K or by irradiating it with a laser in high vacuum. This substance has been termed ceraphite.
A review cautions that "in spite of these seemingly definitive reports … several other groups have tried unsuccessfully to reproduce these experiments. Independent confirmatory work is obviously needed … and at the present time white graphite appears to be the carbon analog of polywater" - in other words unlikely, even fantastic claims were made that were not supported by the available data.
[edit] Sources
- ↑ A. El Goresy, G. Donnay, Science 1968, 161, 363.
- ↑ A.G. Whittaker, P.L. Kintner, Science 1969, 165, 589.
- ↑ P.P.K. Smith, P.R. Buseck, Science 1982, 216, 984.
- ↑ C. Nakayama, M. Okawa, H. Nagashima, Carbon 1977, 15, 434; D.J. Johnson, D. Crawford, C. Oates, 1971, 10th Carbon Conf, Bethlehem, PA, FC-18.
- ↑ D.W. McKee, Annu. Rev. Mater. Sci. 1973, 3, 195.
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