Superdense carbon allotropes

Superdense carbon allotropes are proposed configurations of carbon atoms that result in a stable material with a higher density than diamond.

Contents

Three structures

Various configurations were simulated at various temperatures and pressures. This resulted in three structures that appear to be stable enough to have the potential for fabrication. These are termed hP3, tI12 and tP12. However these are not as hard as diamonds, but nearly as dense. They exceed the density of diamond by 3.2 per cent. These are the densest carbon allotropes yet achieved. In addition to other attributes, this characteristic means a higher index of refraction and stronger dispersion of light.[1][2][3]

Band gaps

The three structures have band gaps, but each has a dissimilar bandgap compared to the other. During ambient conditions, tP12 (phase) has the widest band gap of any carbon allotrope at 7.3 eV. It is an insulator. hP3 has a band gap of 3.0 eV, and is a semiconductor. [1] [2][3]

Carbon tetrahedra

These new materials would have structures based on carbon tetrahedra, and represent the densest of such structures. On the opposite end of the density spectrum is a recently theorized tetrahedral structure called T-carbon. This is obtained by replacing carbon atoms in diamond with carbon tetrahedra. In contrast to superdense allotropes, T-carbon would have very low density and hardness[4][5].

References

  1. ^ a b Zhu, Qiang; Oganov, Artem; Salvadó, Miguel; Pertierra, Pilar; Lyakhov, Andriy (2011). "Denser than diamond: Ab initio search for superdense carbon allotropes". Physical Review B 83 (19). Bibcode 2011PhRvB..83s3410Z. doi:10.1103/PhysRevB.83.193410. 
  2. ^ a b Campbell, MacGregor (June 8, 2011). "New super-dense forms of carbon outshine diamond" (Online magazine article). New Scientist. http://www.newscientist.com/article/dn20551-new-superdense-forms-of-carbon-outshine-diamond.html. Retrieved 2011-06-10. 
  3. ^ a b "Researchers predict material 'denser than diamond'" (Online magazine article). Phys.Org. June 8, 2011. http://www.physorg.com/news/2011-06-material-denser-diamond.html. Retrieved 2011-06-10. 
  4. ^ Sheng, Xian-Lei; Yan, Qing-Bo; Ye, Fei; Zheng, Qing-Rong; Su, Gang (2011). "T-Carbon: A Novel Carbon Allotrope". Physical Review Letters 106 (15). Bibcode 2011PhRvL.106o5703S. doi:10.1103/PhysRevLett.106.155703. 
  5. ^ "New carbon allotrope could have a variety of applications" (Online magazine article). Phys.Org. April 22, 2011. http://www.physorg.com/news/2011-04-carbon-allotrope-variety-applications.html. Retrieved 2011-06-10.