Structure, stability and stress properties of amorphous and nanostructured carbon films

TL;DR

This paper investigates the structural and mechanical properties of amorphous and nanostructured carbon films using simulations, revealing linear relationships between density and sp^3 fraction, and stability conditions for diamond inclusions.

Contribution

It provides new insights into the stability, stress, and hardness of amorphous and nanocomposite carbon films through computational modeling.

Findings

sp^3 fraction varies linearly with density

Bulk moduli follow a power-law with density

Diamond inclusions are stable only in dense matrices

Abstract

Structural and mechanical properties of amorphous and nanocomposite carbon are investigated using tight-binding molecular dynamics and Monte Carlo simulations. In the case of amorphous carbon, we show that the variation of sp^3 fraction as a function of density is linear over the whole range of possible densities, and that the bulk moduli follow closely the power-law variation suggested by Thorpe. We also review earlier work pertained to the intrinsic stress state of tetrahedral amorphous carbon. In the case of nanocomposites, we show that the diamond inclusions are stable only in dense amorphous tetrahedral matrices. Their hardness is considerably higher than that of pure amorphous carbon films. Fully relaxed diamond nanocomposites possess zero average intrinsic stress.