Published online by Cambridge University Press: 26 February 2011
In a polycrystal of silicon, dissociated grain boundaries with orientations close to either the ∑=3{111}, ∑=3{112}, ∑=9{122} and ∑=27{255} coincident site lattices (CSL) were observed both optically and in the transmission electron microscope (TEM). Macroscopically ∑=3{111} and ∑=27{255} appeared stable whereas ∑=9{122} dissociated frequently into two ∑=3{111} boundaries. TEM observations revealed ∑=27{255} to dissociate into one or more triangular grains in several regions. These grains consisted of a ∑=3{111}, a ∑=9{122} and a ∑=9{111}/{115} boundary. The latter ∑=9 boundary dissociated further to form twin triangular grains. The driving forces for various dissociations are discussed.