Identification of planar defects in D0(19) phases using high-resolution transmission electron microscopy

An analysis based on crystal symmetry and high-resolution transmission elec tron microscopy (HRTEM) is presented as a general methodology to identify p lanar defects on the basal planes of D0(19) compounds. As a starting point, the possible (close-packing preserving) planar defects are classified in a ccordance with their visibility, and the magnitude of the displacement vect or on prismatic projections. Analysis of experimental HRTEM images, obtaine d under two different viewing conditions, followed by matching with simulat ed images, enables unambiguous identification to be made. The methodology i s applied to planar defects observed in D0(19) Co3W, which are identified a s pi rotations around [0001]. To the best of our knowledge these defects ha ve not been identified before in D0(19) phases.