Predicting experimentally stable allotropes: Instability of penta-graphene.

Ewels, Christopher P; Rocquefelte, Xavier; Kroto, Harold W; Rayson, Mark J; Briddon, Patrick R; Heggie, Malcolm I · Proc Natl Acad Sci U S A · 2015

basic_science · Level V

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Abstract

In recent years, a plethora of theoretical carbon allotropes have been proposed, none of which has been experimentally isolated. We discuss here criteria that should be met for a new phase to be potentially experimentally viable. We take as examples Haeckelites, 2D networks of sp(2)-carbon-containing pentagons and heptagons, and "penta-graphene," consisting of a layer of pentagons constructed from a mixture of sp(2)- and sp(3)-coordinated carbon atoms. In 2D projection appearing as the "Cairo pattern," penta-graphene is elegant and aesthetically pleasing. However, we dispute the author's claims of its potential stability and experimental relevance.