Structure Studies of Graded Amorphous Carbon Obtained by Liquid Carbon Quenching

A new method for obtaining graded amorphous carbon using quenching of a graphite melt on a diamond substrate is proposed. Using molecular dynamics modeling of liquid carbon quenching on a cold diamond substrate, it is shown that the amorphous carbon obtained in the experiment is a material with a strongly gradient structure and properties along the depth of the sample. This is due to the quenching rate decrease with the distance from the substrate in the range of 10 14 –10 12 K/s. In this case, the density of amorphous carbon varies from 1.50 to 1.93 g/cm 3 . The spatial change in the structural characteristics of the obtained amorphous carbon was studied: the distribution of carbon atoms according to the degree of chemical bond hybridization ( sp 1 -, sp 2 -, sp 3 -), the radial distribution function, the angular distribution function, and a statistical analysis of carbon rings were carried out. It is shown that at a pressure in liquid of 1 GPa, the carbon structure within the quenched zone changes from a highly porous structure with a large number of sp 1 chains of carbon atoms near the substrate to an amorphous graphene structure at the periphery.