Structural, electronic and mechanical properties of all-sp<sup>2</sup> carbon allotropes with density lower than graphene
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Volume
159
Pagination
512 - 526
Publisher
DOI
10.1016/j.carbon.2019.12.024
Journal
Carbon
ISSN
0008-6223
Metadata
Show full item recordAbstract
© 2019 Elsevier Ltd In this work we propose a few novel energetically and dynamically stable all-sp2 carbon-based architectures with low density obtained by augmenting planar three-coordinated uniform tessellations. Using geometrical packing arguments, we show that such arrangements satisfy the locally–jammed packing condition and represent some of the least dense structures of all-sp2 bonded carbon allotropes that could ever be synthesised. We fully characterize from first principles these new architectures, by assessing i) the electronic properties, such as the band structure and the density of states; ii) the dynamical characteristics, such as the phonon dispersion; and iii) the mechanical properties, such as the elastic constants and the stress–strain relationships. We compare our findings with already synthesised carbon-based materials, in particular graphene, and we find that in the lowest–density structures the mechanical rigidity is considerably depleted, while other specific mechanical characteristics, such as toughness and strength, are comparable to the relevant specific values of graphene. Furthermore, a flat band at the Fermi level emerges in the electronic band structure of the augmented geometries, which is a feature similarly appearing in Kagome lattices.