New superhard carbon phases between graphite and diamond |
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| Authors: | Chaoyu He Lizhong Sun Chunxiao Zhang Xiangyang Peng Kaiwang Zhang Jianxin Zhong |
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| Affiliation: | 1. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China;2. Geophysical Laboratory, Carnegie Institution of Washington, WA, D.C. 20015, USA;1. College of Physical Science and Technology, Sichuan University, Chengdu 610064, China;2. School of Physics and Engineering, Henan University of Science and Technology, Luoyang 471003, China;3. National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang, China |
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| Abstract: | Two new carbon allotropes (H-carbon and S-carbon) are proposed, as possible candidates for the intermediate superhard phases between graphite and diamond obtained in the process of cold compressing graphite, based on the results of first-principles calculations. Both H-carbon and S-carbon are more stable than previously proposed M-carbon and W-carbon and their bulk modulus are comparable to that of diamond. H-carbon is an indirect-band-gap semiconductor with a gap of 4.459 eV and S-carbon is a direct-band-gap semiconductor with a gap of 4.343 eV. The transition pressure from cold compressing graphite is 10.08 GPa and 5.93 GPa for H-carbon and S-carbon, respectively, which is in consistent with the recent experimental report. |
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