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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.
Physical Review Letters
|April 7, 2010
Summary
A new crystalline sp3 carbon phase, bct C4, is dynamically stable and transparent. It is more stable than graphite above 18.6 GPa and may explain experimental observations of carbon under pressure.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Computational Chemistry
Background:
- Recent molecular dynamics simulations revealed a new sp3 carbon allotrope, bct C4, under high pressure conditions.
- Understanding the properties of novel carbon phases is crucial for materials science and high-pressure physics.
Purpose of the Study:
- To investigate the electronic, vibrational, and structural properties of the newly discovered bct C4 carbon phase using first-principles calculations.
- To determine the stability and potential applications of bct C4 in relation to known carbon allotropes.
Main Methods:
- First-principles calculations were employed to simulate and analyze the properties of bct C4.
- Density Functional Theory (DFT) was used to compute electronic, vibrational, and structural characteristics.
Main Results:
- The bct C4 phase exhibits dynamic stability at zero pressure and is transparent.
- It demonstrates greater stability than graphite at pressures exceeding 18.6 GPa.
- The structural characteristics of bct C4 are intermediate between graphite and hexagonal diamond.
Conclusions:
- The bct C4 phase is an accessible form of sp3 carbon along the graphite-to-hexagonal diamond transformation pathway.
- The coexistence of bct C4 with M carbon can elucidate the X-ray diffraction patterns observed in transparent, hard carbon phases formed by cold compression of graphite.
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