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High-pressure synthesis of a novel form of endohedral Li diamond from Li graphite intercalation compound |
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| Authors: | H Hirai K Wanme A Ikeda |
| Institution: | a Institute of Geoscience, University of Tsukuba, 1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan b Graduate School of Science and Engineering, Chuo University, 1-13-27, Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan c Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan d Graduate School of Engineering, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan |
| Abstract: | A novel form of hexagonal diamond containing Li atoms in the open rooms surrounded by sp3-bonded carbon atoms was successfully synthesized from a Li graphite intercalation compound under high pressure, as had been predicted by theoretical studies. High-pressure experiments with LiC6 were performed in the pressure range from 0.1 MPa to 43 GPa using a diamond-anvil cell. In situ X-ray diffractometry and optical microscopy revealed that LiC6 was transformed to a hexagonal-diamond form without losing Li atoms. The c-axis of the hexagonal-diamond form was considerably longer than that of the hexagonal diamond transformed from pure graphite, which was consistent with the predicted structure of the endohedral Li diamond. The observed high-pressure form exhibited a golden metallic gloss, which was also consistent with the calculated metallic band structure. |
| Keywords: | C High pressure C X-ray diffraction D Phase transitions |
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