Three tetragonal superhard sp3 carbon allotropes. (January 2021)

• Record Type: Journal Article
• Authors: Zhou, Yalan; Chen, Xiang; Liu, Song-Li; Gan, Li-Hua
• Is Part Of: Solid state communications. Volume 323(2021)
• Publication Date: 2021-01
• Subjects: Carbon phase -- Stability -- Hardness -- Anisotropy -- Debye temperature -- Thermal conductibility; Solid state chemistry -- Periodicals; Solid state physics -- Periodicals; Chimie de l'état solide -- Périodiques; Physique de l'état solide -- Périodiques; 530.41
• DOI: 10.1016/j.ssc.2020.114095
• Languages: English
• ISSNs: 0038-1098

Abstract

Abstract: Four tetragonal anisotropic superhard carbon phases, T-C8, T-C12, T-C20 and T-C28 were generated by RG 2 program, T-C8 has been reported and named bct-Carbon. The calculated relative enthalpy, elastic constants and phonon dispersion spectra show that these structures are stable. Their lattice failure modes are mainly tensile. Thermodynamic stability, thermal performance and hardness are all in the order T-C20 >T-C8 >T-C12 >T-C28, which is contrary to the proportion of the four membered ring in the corresponding structure, suggesting that strained four-membered ring is detrimental to the stability and mechanical properties of carbon phases. Among them, T-C20 with hardness of 90.8 GPa is more stable than bct-Carbon and graphite under 20 GPa, suggesting that it is likely to be transformed by cold compressed graphite. Highlights: Four tetragonal anisotropic superhard carbon phases are proved to be stable. Stability, thermal properties and hardness follow this order T-C20 > T-C8 > T-C12 > T-C28. T-C20 with high hardness and stability may be synthesized via cold compressed graphite.