An investigation was made of Bi doping in the bulk, and in a Σ = 13 tilt grain boundary, by using ab initio density functional theory calculations. A negative segregation energy was obtained; thus suggesting that Bi accumulated in the grain boundary. The Bi atoms caused considerable atomic displacements in the grain boundary, increasing the local Bi-O bond-length and attracting an O-atom on the opposite side of the structural unit in the grain boundary. The results suggested the formation of a Bi–rich phase in the grain boundary. The Bi atoms acted as donors, and conduction electrons were quasi-localized in the grain boundary region.

Electronic Structure of a Bi-Doped Σ = 13 Tilt Grain Boundary in ZnO. Carlsson, J.M., Domingos, H.S., Hellsing, B., Bristowe, P.D.: Interface Science, 2001, 9[3-4], 143-8