Structure, mechanical and filtration properties of graphyne compounds of the self-intercalated type

Abstract

We performed a study of the structure and properties of hybrid carbon compounds based on graphyne layers with a self-intercalated type of crystal lattice using ab initio calculations. It is found that only compounds based on α -graphyne-1 and β 1-graphyne-2 can have an ordered crystal structure. Calculations have shown that the most stable α -type phase is tetragonal ( I/ 4 mcm ) self-intercalated α -graphyne-1 with a density of 1.28 g/cm 3 , a bulk modulus of 31 GPa, a Young’s modulus from 3 to 107 GPa, which is characterized by a minimum negative linear compressibility of − 11.7 TPa − 1 along the [001] axis. This makes it a promising material for use in pressure sensors.  Additionally, the I/ 4 mcm phase can be used as a selective filter for hydrogen molecules, the permeability of which can be increased by uniaxial compression or stretching per- pendicular to [001]. The studied nanostructured phases can be unambiguously identified from the calculated powder X-ray diffraction patterns.