Hybrid dense carbon allotropes from crystal chemistry and first principles: 'glitter' C6, 'isoglitter' C8 and 'metaglitter' C8

Oppositely to diamond which is built of corner sharing C4 tetrahedra with C(sp3), the presence of mixed carbon hybridization (sp2 and sp3) in three carbon allotropes derived from so-called 'glitter' has been shown through DFT-based quantum calculations to produce stable systems sharing some properties of diamond with regard to hardness, thermodynamics and electronic properties. The three carbon allotropes, 'glitter' (C6), 'isoglitter' (C8), and 'metaglitter' (C8) were found to be dynamically stable and characterized by large bulk and shear moduli and very high hardness. A metallic behavior arising from trigonal C(sp2) forming pairs, is observed for 'glitter' and 'isoglitter', while 'metaglitter' is closer to diamond due to the semi-conducting behavior. The novel carbon allotropes are proposed as an opportunity for materials science with potential for applications as superabrasives and in electronic devices.