Effect of additive boron on type-Ib gem diamond single crystals synthesized under HPHT

The boron-doped type-Ib gem diamond crystals were synthesized successfully by adding amorphous boron into a system of graphite and Kovar catalyst under high pressure and high temperature (HPHT). The effect of additive boron on type-Ib gem diamond was extensively studied including the growth characteristic, morphology and nitrogen concentration. The synthesized boron-doped type-Ib gem diamond crystals were characterized by optical microscope (OM), scanning electron microscope (SEM) and infrared spectrometer (IR). The results show that the growth region of the {111} face becomes wide, whereas the growth region of the {100} face becomes narrow and nearly disappears as increasing additive boron in the sample. The crystal will be opaque and imperfect, and the concentration of nitrogen will be decreased when the boron atoms are incorporated into gem diamond lattice. These techniques are very important and will be widely applied.