Novel superhard semiconductor carbon allotrope Pcc2 C24 under pressure: First-principles calculation

Abstract

Carbon allotropes have been used in microelectronic devices and optoelectronic devices due to their excellent mechanical properties and tunable electronic properties. Adopting density functional theory (DFT), we propose a new carbon allotrope Pcc2 C₂₄. Pcc2 C₂₄ can maintains dynamic and mechanical stability under ambient and high pressure, and its thermal stability at room temperature has also been confirmed. The increase of pressure has little effect on the relative enthalpy, which further illustrates the excellent stability of the new carbon. Mechanical properties and electronic bands at 0–100 GPa are also analyzed in detail. Elastic constants, elastic modulus and mechanical anisotropy all increase under pressure induction, and Pcc2 C₂₄ can maintains superhard properties. In addition to its excellent stability and superhard properties, the new material is also a wide band gap semiconductor. Pcc2 C₂₄ has an indirect band gap of 3.39 eV, which is obtained by HSE06 functional, and the band gap decreases with the increase of pressure. This newly proposed carbon allotrope as a superhard semiconductor may have development potential in the field of microelectronic devices and semiconductor devices operating under high pressure.