Recent progress in the observation of dislocation distributions around nano-indentations by chemical etching was considered. This so-called nano-etching technique was used to determine the dislocation mechanisms which were associated with the pop-in phenomenon in MgO and LiF. Successive stages of highly controlled chemo-mechanical polishing had revealed that these dislocations were half-loops which lay in the classical slip systems of MgO or LiF. However, they did not extend on the surface in a classical rosette pattern, but remained concentrated around the impression. A mechanism of dislocation interactions, modified by the fact that the dislocations were suddenly nucleated in a small volume, was proposed to explain this specific distribution.

Pop-In Phenomenon in MgO and LiF - Observation of Dislocation Structures. Y.Gaillard, C.Tromas, J.Woirgard: Philosophical Magazine Letters, 2003, 83[9], 553-61