Contrast from stacking faults and partial dislocations in the field-ion microscope

Abstract The effects of partial dislocations and stacking faults intersecting the surface of a field-ion tip are predicted from the geometrical properties of the defects. The surface configuration is related to the contrast expected in field-ion micrographs. The displacements producing partial dislocations and stacking faults lead to ‘steps’ and ‘kinks’ on the tip surface which give contrast in field-ion micrographs. Parameters are defined which conveniently and generally describe the contrast to be expected from dissociated total dislocations and faulted loops. Examples of faulted loops in iridium are discussed in terms of this theory.