Molecular dynamics simulation study of mechanical properties of 3C-SiC with extended defects

TL;DR

This study uses molecular dynamics simulations to quantify how extended defects like dislocations affect the elastic properties of 3C-SiC, showing a measurable decrease in stiffness with increasing defect density.

Contribution

It provides the first detailed quantification of how extended defect concentrations alter the elastic constants and moduli of 3C-SiC using two different interatomic potentials.

Findings

Elastic stiffness decreases by up to 6% with increased defect density.

Triple dislocation complexes cause smaller changes in elastic properties.

Both Vashishta and ABOP potentials show consistent trends in stiffness reduction.

Abstract

In this study, large-scale molecular dynamics simulations with the Vashishta potential and the analytic bond-order potential (ABOP) were performed to investigate the effect of extended defects on the elastic properties of cubic silicon carbide (3C-SiC). Specifically, we focused on systems containing Shockley partial dislocations terminating stacking faults, along with double and triple dislocation complexes. The changes in the independent elastic stiffness constants C11, C12 and C44 upon varying the mentioned extended defects concentrations were quantified. Using the values of these constants, the effective bulk, shear, and Young's moduli were calculated for different defect types and concentrations. The moduli were calculated along particular crystallographic directions aligned with the mentioned defect configurations as well as evaluated using Voigt-Reuss-Hill averaging to provide overall orientation-independent characterization of the defect-altered lattice. The obtained results reveal a general trend of diminishing the material's stiffness with increasing densities of Shockley partial dislocations and dislocation complexes. Depending on the defect configuration, the average elastic moduli decrease by up to approximately 6 % with the Vashishta potential and up to about 4 % using the analytic bond-order potential. At this, triple dislocation complexes induce smaller perturbations. These findings demonstrate that extended defect networks can measurably modify the elastic response of 3C-SiC and should be considered in further scientific research and practical applications of this material.