On the contrast of dislocations in the transmission electron microscope when g·b = 0

Abstract

Gandais, Hihi, Willaime and Epelboin (1982, Phil. Mag. A, 45, 387) proposed that when g·b = 0, the residual contrast of a dislocation in an isotropic crystal will always be stationary two–sided. Here, we show that stationary two–sided images occur for g·b = 0 only when the crystal is thick enough. In thin crystals which are either isotropic or anisotropic, dislocations may exhibit moving one-sided images even though g·b = 0.