Defects of diamond single crystal grown under high temperature and high pressure

The diamond single crystal, synthesized with Fe–Ni–C–B system of catalyst under high temperature and high pressure, had been observed by field emission scanning electron microscope and transmission electron microscope. The presence of a cellular structure suggested that the diamond grew from melted catalyst solution and there existed a zone of component supercooling zone in front of the solid–liquid interface. The main impurities in the diamond crystal was (FeNi)23C6. The triangle screw pit revealed on the (111) plane was generated by the screw dislocation meeting the diamond (111) plane at the points of emergence of dislocations. A narrow twin plane was formed between the two (111) plane. •High pressure, high temperature synthesis of diamond single crystal.•Fe–Ni–C–B used as catalyst, graphite as carbon source.•The main impurity in the diamond crystal was (FeNi)23C6.•Surface defects arose from screw dislocations and stacking faults.