Characteristics of some inclusions contained in synthetic diamond single crystals

Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have been successfully used to investigate microstructures of synthetic diamond single crystals grown from the Fe–Ni–C system under high temperature and high pressure. Several types of inclusions incorporated into the diamond during the process of diamond growth were identified. Both the chemical composition and structure of the inclusions in diamond were successfully determined. It was found that the inclusions trapped in the diamond consisted of f.c.c. (FeNi)23C6, orthorhombic FeSi2, f.c.c. silicon carbide and amorphous graphite.