It had previously been observed in Monte Carlo simulations (Mori et al., 2007) that an intrinsic stacking fault shrank through glide of a Shockley partial dislocation terminating its lower end in a hard-sphere crystal under gravity coherently grown in <001>. This was the answer to a long-standing question as to why the stacking disorder in colloidal crystals reduced under gravity (Zhu et al., 1997). Here, an elastic energy calculation was presented. In addition to the self-energy of the partial dislocation (Mori et al., 2009), the cross-coupling term between the elastic field due to gravity and that due to a Shockley partial dislocation was calculated. The cross-term was an increasing function of the linear dimension over which the elastic field expanded; showing that a driving force arose for a partial dislocation moving towards the upper boundary of a grain.

Interplay between Elastic Fields due to Gravity and a Partial Dislocation for a Hard-Sphere Crystal Coherently Grown under Gravity: Driving Force for Defect Disappearance. A.Mori, Y.Suzuki: Molecular Physics, 2010, 108[13], 1731-8