Abstract: Transmisson electron microscopy (TEM) has been used to investigate the microstructures and analyze the defects in synthetic diamond prepared under high temperature-high pressure in the presence of FeNi alloy catalyst.It was found that there exist prismatic dislocations,stacking faults,array of dislocations and dislocation network.The formation mechanism of these defects was studied.Results show that defects in the diamond were closely related to high temperature-high pressure synthesis process and originated mainly from excess amount of saturated vacancies and internal stress generated by micro-inclusions.

Key words: Transmisson electron microscopy (TEM) has been used to investigate the microstructures and analyze the defects in synthetic diamond prepared under high temperature-high pressure in the presence of FeNi alloy catalyst.It was found that there exist prismatic dislocations,stacking faults,array of dislocations and dislocation network.The formation mechanism of these defects was studied.Results show that defects in the diamond were closely related to high temperature-high pressure synthesis process and originated mainly from excess amount of saturated vacancies and internal stress generated by micro-inclusions.