Two novel carbon allotropes with exceptional properties as superhard materials

Abstract

Scientific researchers are always working to study carbon allotropes, which are considered significant objectives. In this study, we identified two novel high-pressure carbon materials, named C14-c and C14-p, respectively, both of which demonstrate excellent performance across several physical parameters. At the same time, we proved their stability in dynamics and mechanics by calculating their phonon spectrum and elastic constants, and determined some of their physical attributes using formula calculations. Ultimately, we conducted research and performed calculations on the pertinent physical characteristics of the structure. As a result, we reached the conclusion that the band gap at 0 pressure for both structures is 3.75 eV and 3.89 eV, respectively, indicating that they are both insulators. Their enthalpy values are somewhat greater than that of diamond, but lower than the enthalpy values of the majority of known carbon allotropes. With a hardness of 81 GPa, these materials outperform many carbon structures and are considered typical superhard materials, but they do not quite approach the hardness of diamond. Their Young's modulus is anisotropic, but is isotropic on certain crystallographic planes. The thermal conductivity at room temperature is 1.725 W/cmK−1 and 1.730 W/cmK−1, respectively, both of which greater than that of diamond, illustrating that they have promising characteristics as semiconductor materials under certain high-pressure conditions.