Molecular Dynamics Simulations on the Tensile Failure of Crystalline CoSb3 Along Different Orientations

As an intermediate-temperature thermoelectric material, CoSb3 attracts broad attention. To promote the understanding of its deformation mechanism and mechanical failure under tension, we performed molecular dynamics simulations for single-crystalline CoSb3 bulk in this work. The first step was to assess the reliability of this methodology. Since the lattice structure of CoSb3 is not isotropic, the uniaxial tension was sequentially implemented along the five typical crystal orientations ([100], [110], [210], [111], and [211]). The stress–strain responses demonstrate the nonlinear elasticity and brittleness of CoSb3, but remarkable differences in vital mechanical parameters for different tensile orientations. To trace the origin of the brittle failure, the data for the bond length variations were obtained during the tensile process of each orientation, and they show dissimilar patterns. Through careful observations of atomic snapshots, we also discovered that different tensile orientations can result in different fracture patterns of CoSb3. The intrinsic mechanical behavior of crystalline CoSb3, revealed in this work, is expected to provide useful information for the realistic application of nanostructure skutterudites.