Expansão térmica de redes aleatórias de carbono

Abstract

In this work, a simulation routine of carbon random networks, with variable hybridization, oriented to calculate the coeÿcient of thermal expansion, is presented. The method uses an algorithm for the generation of carbon random networks in addition to the quasi-harmonic approximation that, associated with the interatomic potential AIREBO, were used for the simulation. Using this approach, a set of 33 structures, composed of 32 atoms, with variable sp, sp2, sp3 carbon contents were generated and the respective volumetric thermal expansion coeÿcients were determined in a temperature range from 0 to 500 K. The results obtained suggest that, for this number of atoms per supercell, the coeÿcient of thermal expansion does not depend only on the percentage of carbon hybridization and, in principle, this is attributed to the thermodynamic limit of the system not being reached. Finally, it was possible to identify, in specific cases of structures where the percentages of sp2 carbon were maintained, that aspects such as the amount of sp carbon have influence on the coeÿcient of thermal expansion.