Electronic and mechanical properties of C/Si phases with sp2 and sp3 hybridization: A first-principles study

A first-principles approach is utilized to systematically investigate the electronic and mechanical properties of SiC3/Si3C phases with sp2 and sp3 hybridization. In the SiC3 phases, electronic states around the Fermi level mainly originate from the C-2p orbitals, whereas in the case of Si3C phases, it is the C-2p and Si-3p orbitals. Cm-SiC3 and Cmc21-SiC3 show metallic properties arising from sp2-hybridized components. P4¯m2-Si3C exhibits good ductility and metallic properties due to the formation of conductive sublattices as a result of the distribution of valence electrons in three-dimensional C and Si frameworks. Furthermore, the semiconducting P4¯m2-SiC3 phase is a superhard material with a remarkable hardness of 47.14 GPa. In general, SiC3 phases exhibit higher brittleness due to sp3-hybridized C atoms while Si3C phases are more ductile.