Three-dimensional tetrahexcarbon: Stability and properties

Although cyclobutene consisting of 4-membered rings of C atoms is highly unstable, one-and twodimensional (1D, 2D) carbon allotropes, called tetrahexcarbon (th-C) consisting of 4-and 6 membered rings, have been reported recently, which shows novel properties with prominent applications in nano-electronics, optoelectronics, and nano-mechanics. Going beyond the studies of 1D and 2D tetrahexcarbon, in this study we propose a 3D-tetrahexcarbon structure (3D th-C12), which shows dynamical, mechanical, and thermal stability. Different from the mixed sp(2)-sp(3) features in 1D and 2D tetrahexcarbon structures, all the C atoms are 4-coordinated in the 3D tetrahexcarbon. Moreover, different from the metallic and highly ductile 2D tetrahexcarbon sheet, the 3D tetrahexcarbon is brittle with high hardness, and it is semiconducting with an indirect bandgap of 3.92 eV at HSE06 level, exhibiting anisotropic elasticity, good optical absorption in visible and UV regions, strong phonon inelastic scattering. This study expands the tetrahexcarbon family with additional new features. (C) 2022 Elsevier Ltd. All rights reserved.