Low-density superhard materials: Computational study of Li-inserted B-substituted closo-carboranes LiBC<inf>11</inf>and Li<inf>2</inf>B<inf>2</inf>C<inf>10</inf>

Feng, X and Zhang, X and Liu, H and Qu, X and Redfern, S. A. T. and Tse, JS and Li, Q (2016) Low-density superhard materials: Computational study of Li-inserted B-substituted closo-carboranes LiBC<inf>11</inf>and Li<inf>2</inf>B<inf>2</inf>C<inf>10</inf>. RSC Advances, 6. pp. 52695-52699. ISSN 2046-2069 DOI https://doi.org/10.1039/C6RA10177A

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Abstract

Insertion of Li atoms into a B-substituted carbon cage produces two superhard compounds with relatively low density: LiBC 11 and Li 2 B 2 C 10 . For each structure, phonon frequencies across the whole Brillouin zone are positive, indicating dynamic stability. Electronic structure calculations indicate that they are semiconductors under ambient conditions. Estimates of the Vickers hardness, based on a semi-empirical model, highlight the incompressible nature of these two compounds. We then performed calculations on the ideal strengths of these two structures to confirm the hardness and investigate origins of the mechanical properties. Strikingly, both LiBC 11 and Li 2 B 2 C 10 can be classed as superhard materials, with hardness values of 49 GPa and 41 GPa, respectively. The current results shed light on the properties of new superhard carbon cage structures more generally.

Item Type: Article
Uncontrolled Keywords: 2016AREP;
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
Journal or Publication Title: RSC Advances
Volume: 6
Page Range: pp. 52695-52699
Identification Number: https://doi.org/10.1039/C6RA10177A
Depositing User: Sarah Humbert
Date Deposited: 06 Apr 2018 16:58
Last Modified: 06 Apr 2018 16:58
URI: http://eprints.esc.cam.ac.uk/id/eprint/4087

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