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Updated: Jun 14, 2026

Fabrication of 3D Carbon Microelectromechanical Systems (C-MEMS)
Published on: June 17, 2017
Body-centered tetragonal C4: a viable sp3 carbon allotrope
Koichiro Umemoto1, Renata M Wentzcovitch, Susumu Saito
1Department of Geology and Geophysics, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA.
Abstract:
We have investigated by first principles the electronic, vibrational, and structural properties of bct C4, a new form of crystalline sp{3} carbon recently found in molecular dynamics simulations of carbon nanotubes under pressure. This phase is transparent, dynamically stable at zero pressure, and more stable than graphite beyond 18.6 GPa. Coexistence of bct C4 with M carbon can explain better the x-ray diffraction pattern of a transparent and hard phase of carbon produced by the cold compression of graphite. Its structure appears to be intermediate between that of graphite and hexagonal diamond. These facts suggest that bct C4 is an accessible form of sp{3} carbon along the graphite-to-hexagonal diamond transformation path.
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