Effects of the additive boron on diamond crystals synthesized in the system of Fe-based alloy and carbon at HPHT

Abstract

In this paper, the boron-doped diamond crystals were synthesized at high pressure and high temperature (HPHT) by adding amorphous boron to the system of carbon and Fe-based solvent/catalyst. The effects of the additive boron on the properties of the synthesized diamond crystals, especially, on the growth process and the morphology of diamonds, have been extensively studied. We found that the integrity of diamond crystals synthesized at optimal growth condition and the growth region of particular morphology changed with increasing of the content of additive boron. It is found that the growth region of {111} face becomes wider, and that of {100} face becomes narrower and almost disappears with the increasing boron concentrations. The surface morphology of boron-doped diamonds were detected with scanning electron microscope (SEM), and we found a great deal of defects on {111} face when the content of additive boron increased to 0.25 wt.%. The results of X-ray photoelectron spectroscopy (XPS) on the surface of diamond show that boron lies on the surface of diamonds and bonds with C and O, respectively. We proposed a model of bald-point to explain these experimental observations.