Plain-tailed wrens coordinate with each other to sing duets by inhibiting motor circuits in the brain.
Image credit: Melissa J. Coleman.
Edited by Ho-kwang Mao, Carnegie Institution of Washington, Washington, DC, and approved October 11, 2013 (received for review June 10, 2013)
Significance
Carbon is an amazing material: it not only forms the chemical basis for all known life but also, because of its rich physics and chemistry, displays an array of structures: from the age-old graphite and diamond to more recent C60 fullerene, 1D nanotube, and 2D graphene. One of the unsolved issues in carbon science has been to find a 3D form of carbon that is metallic under ambient conditions. This paper addresses this important challenge. Using state-of-the-art theoretical calculations, we predict the existence of such a phase that is formed from interlocking hexagons and is dynamically, mechanically, and thermally stable. It is suggested that this new form of carbon may be synthesized chemically by using benzene or polyacenes molecules.
Abstract
Design and synthesis of 3D metallic carbon that is stable under ambient conditions has been a long-standing dream. We predict the existence of such phases, T6- and T14-carbon, consisting of interlocking hexagons. Their dynamic, mechanical, and thermal stabilities are confirmed by carrying out a variety of state-of-the-art theoretical calculations. Unlike the previously studied K4 and the simple cubic high pressure metallic phases, the structures predicted in this work are stable under ambient conditions. Equally important, they may be synthesized chemically by using benzene or polyacenes molecules.
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: qianwang2{at}pku.edu.cn.
Author contributions: Q.W. designed research; S.Z. performed research; Q.W. and P.J. analyzed data; and S.Z., Q.W., X.C., and P.J. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1311028110/-/DCSupplemental.
Three-dimensional metallic carbon
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