The structural, mechanical and electronic properties of novel superhard carbon allotropes: ab initio study

ABSTRACT The structural, mechanical and electronic properties of carbon allotropes were systematically investigated by the first-principles calculations in this study, and the origin of high hardness of carbon allotropes was analyzed. We studied the mechanical properties, including the elastic moduli, Poisson’s ratio and Vickers hardness, of six novel carbon allotropes and compared with two known superhard carbon phases (diamond and lonsdaleite). It was found that six novel carbon allotropes exhibit the potential to be superhard materials. Besides, the band structures and electronic density of states of these carbon allotropes were calculated as well, and the superhard properties of the six novel carbon allotypes were preliminarily revealed. Finally, the tiling approach was adopted to analyze the origin of high hardness of six novel carbon allotropes from the perspective of structure.