A structurally stable crystalline carbon allotrope is predicted by means of the first-principles calculations. This allotrope can be derived by substituting each atom in diamond with a carbon tetrahedron, and possesses the same space group Fd^1 3m as diamond, which is thus coined as T- carbon. The calculations on geometrical, vibrational and electronic properties reveal that T-carbon, with a considerable structural stability and a much lower density 1.50 g/cm3, is a semiconductor with a direct band gap about 3.0 eV, and has a Vickers hardness 61.1 GPa lower than diamond but comparable with cubic boron nitride. Such a form of carbon, once obtained, would have wide applications in photocatalysis, adsoption, hydrogen storage and aerospace materials.
@article{arxiv.1105.0977,
title = {T-Carbon: A Novel Carbon Allotrope},
author = {Xian-Lei Sheng and Qing-Bo Yan and Fei Ye and Qing-Rong Zheng and Gang Su},
journal= {arXiv preprint arXiv:1105.0977},
year = {2015}
}