High-Pressure Synthesis and Characterization of Cr-Doped Large Single-Crystal Diamonds

Diamond crystals doped with chromium were produced at 1400 °C and 5.8 GPa. The effect of Cr on the crystal morphology, nitrogen impurity content, and surface defects of diamonds grown on {111} and {100} planes has been studied in detail. The entry of the Cr impurity lattice in the Fe64Ni36–Cr–C and Fe64Ni36–Cr–Ti–C systems has also been analyzed. The results show that the addition of the proper amount of Cr in the FeNi–Cr–C system increases the growth rate of crystals. When Cr exists in the system, the N content decreases, and the crystallinity of the crystal increases. For the Fe64Ni36–Cr–Ti–C system, Cr is more easily doped into the synthesized crystals in terms of chromium–carbon and chromium–oxygen bonds, showing two valence states of Cr (VI) and Cr (III).