Li-Filled, B-Substituted Carbon Clathrates

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• 作者：Tao Zeng ; Roald Hoffmann ; Reinhard Nesper ; N. W. Ashcroft ; Timothy A. Strobel ; Davide M. Proserpio
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：October 7, 2015
• 年：2015
• 卷：137
• 期：39
• 页码：12639-12652
• 全文大小：826K
• ISSN：1520-5126

文摘

Inside the cages of hypothetical carbon clathrates there is precious little room, even for the smallest atoms, such as Li鈥攗nless it is the Li⁺ ion that is inserted, in which case a compensating negative charge should be distributed over the carbon cage. The hypothesis explored in this paper is that Li insertion can be achieved with appropriate B substitution within the framework. The resulting structures of 2Li@C₁₀B₂ (Clathrate VII), 8Li@C₃₈B₈ (Clathrate I), 7Li@C₃₃B₇ (Clathrate IV), 6Li@C₂₈B₆ (Clathrate H), and 6Li@C₂₈B₆ (Clathrate II) are definitely stabilized in theoretical calculations, especially under elevated pressure, as judged by enthalpy criteria and bond length metrics. Different strategies for B substitution (symmetry reduction, following the parent charge distribution, and substitution on the most weakened bonds, relieving stress on bond angles) are explored. Two possible competing channels for Li doping鈥揃 substitution, formation of LiBC and C-vacancies, are investigated.