The characteristics of diamond crystallized from carbonyl nickel powders at high pressure and high temperature conditions

In this paper, diamond crystallization from carbonyl nickel powders is investigated in detailed by temperature gradient growth (TGG) at high pressure (6.0–6.5 GPa) and high temperature (1350–1430 °C) conditions. We find that the synthesis condition for diamond crystallization is higher than that of the conventional Fe–Ni catalyst medium. The morphology of the diamond synthesized from carbonyl nickel powders tends to an irregular shape. Furthermore, Fourier transform infrared (FTIR) measurements indicate that nitrogen atoms simultaneously exist in the synthesized diamond in the forms of A-centers and C-centers. We hope that our paper can provide valuable information and clues to study the incorporation of nitrogen impurity into natural diamond structure.

► Diamond crystallization from carbonyl nickel powders is achieved at HPHT conditions.
► Nitrogen concentration of the obtained diamond is up to 1035 ppm.
► A-center nitrogen content increases with total nitrogen value increase in diamond.