The latter is produced by physical vapor deposition, assisted by an oxygen plasma in the case of oxides. Fig. 2 gives an example of a Au bicrystal film oriented along different zone axes in the two grains. These methods have opened up a new range of experimental studies on the atomic-scale structure of GBs, which previously were limited to tilt GBs, using the axial illumination HREM technique. A structural defect is formed at the left hand side of the image. The viewing directions are indicated for each grain are indicated on the left.
Structural disorder is indicated in the atomic columns directly bordering the interface.
Propagation of the ledge on the right hand side provides a mechanism for GB migration.