Phagraphene

Phagraphene (/fæˈɡræfiːn/) is a proposed graphene allotrope composed of 5-6-7 carbon rings. Phagraphene was proposed in 2015 based on systematic evolutionary structure searching.^[1] Theoretical calculations showed that phagraphene is not only dynamically and thermally stable, but also has distorted Dirac cones. The direction-dependent cones are robust against external strain with tuneable Fermi velocities.^[1]

Higher-energy allotropes named Haeckelite contained penta- hexa- and hepta-carbon rings. Three types (rectangular, oblique and hexagonal) were proposed as early as 2000.^[2] These metastable allotropes have a trivial intrinsic metallic behavior.

Phagraphene is predicted to have a potential energy of 193.2 kcal/mol.^[3] The bond order is 1.33, the same as for graphene.^[3]

PHA/graphene

An unrelated material called PHA/graphene is a polyhydroxyalkanoate graphene composite.