Triple junctions and elastic stability of polycrystalline silicon - art. no. 045302

We studied the atomic structure of a multiple-twin triple junction in silic on, formed by the convergence of two (111) and one (221) symmetric-tilt gra in boundaries. Molecular-dynamics simulations with the Stillinger-Weber pot ential and constant-traction border conditions were performed on several tr iple junction configurations, obtained by different combinations of the thr ee grain boundaries. All the configurations have a positive excess line ene rgy, a measurable volume contraction and display regions of opposite, tensi le, and compressive, residual stress. We propose that triple junctions comp rising twin boundaries could have the largest possible values of line tensi on and residual stress and discuss their role in the elastic stability of p olycrystalline Si.