Penta-silicon carbide: A theoretical investigation.

Two newly designed penta-silicon carbides, namely p-SiC 10 and p-Si 4 C 7 , are proposed in this work with the aid of density functional theory (DFT) simulations. Their structural stabilities are verified from energetic, lattice dynamic, and mechanical aspects. These systems possess low mass densities owing to the big interior spaces inherited from the host (i.e., pentadiamond), and relatively high mechanical strengths. The substitutions of the s p 3 carbon atoms by silicon in pentadiamond results in the narrowing of the energy band gaps from 3.78 eV to 3.18 eV and 2.81 eV in p-SiC 10 and p-Si 4 C 7 lattices at HSE06 level, respectively. Moreover, the band gap changes from indirect in pentadiamond into quasi-direct in p-SiC 10. These advantages make p-SiC 10 and p-Si 4 C 7 materials be promising candidates in semiconductor industry and aerospace field. [Display omitted] • Two new silicon carbides are proposed by Si-substitutions in pentadiamond. • The band gaps are 3.18 eV and 2.81 eV in the designed penta-silicon carbides. • The quasi-direct band gap in p-Si4C7 benefits the carrier separation. • The low densities and high strengths imply their applications with weight advantage. [ABSTRACT FROM AUTHOR]