Observation of etch pits and defects in diamond single crystals prepared under high temperature–high pressure

As-grown diamond single crystals synthesized under high temperature–high pressure in the presence of FeNi catalyst were directly observed by scanning electron microscopy and transmission electron microscopy (TEM). Etch pits on the (1 1 1) surface of the diamond, which are generated by the screw dislocations meeting the diamond (1 1 1) surface at the points of emergence of dislocations, can be revealed by electrolytic etching and be used to study the motion of dislocations under the action of applied stress. Stacking-fault tetrahedral and stacking faults were investigated by moiré images. The stacking-fault tetrahedral and stacking faults may be derived from supersaturated vacancies generated during rapid cooling from high temperature to room temperature. Dislocation networks and an array of parallel dislocations were directly examined by TEM, which are related to the thermal stress caused by the inclusions in the diamond.