Effect of FeS doping on large diamond synthesis in FeNi–C system

Abstract

The large single-crystal diamond with FeS doping along the (111) face is synthesized from the FeNi-C system by the temperature gradient method (TGM) under high-pressure and high-temperature (HPHT). The effects of different FeS additive content on the shape, color, and quality of diamond are investigated. It is found that the (111) face of diamond is dominated and the (100) face of diamond disappears gradually with the increase of the FeS content. At the same time, the color of the diamond crystal changes from light yellow to gray-green and even gray-yellow. The stripes and pits corrosion on the diamond surface are observed to turn worse. The effects of FeS doping on the shape and surface morphology of diamond crystal are explained by the number of hang bonds in different surfaces of diamond. It can be shown from the test results of the Fourier transform infrared (FTIR) spectrum that there exists an S element in the obtained diamond. The N element content values in different additive amounts of diamond are calculated. The XPS spectrum results demonstrate that our obtained diamond contains S elements that exist in S-C and S-C-O forms in a diamond lattice. This work contributes to the further understanding and research of FeS-doped large single-crystal diamond characterization.

Synthesis and Characteristics of Type Ib Diamond Doped with NiS as an Additive

“…Furthermore, the C 1𝑠 and S 2𝑝 spectra of diamond doped with FeS has the same signal peak as those of diamond doped with NiS. [19] It can be seen that S is incorporated into the diamond and exists in diamond in the forms of C-S, S-O and C-S-O bonds. Meanwhile, S exists in the same state of bond in diamond with sulfide (FeS/NiS) as a dopant.…”

“…We find that the effect of NiS doping on diamond growth is different from that of FeS doping on diamond. [19] By increasing the addition amount of FeS, the inclusions in the obtained diamond increase and crystal quality decreases under HPHT. However, synthesis of diamond is unaffected when the amount of FeS is increased.…”

“…On the other hand, the N-peak of diamond doped with FeS is not significant in the infrared spectrum and 𝐶 N is small in diamond. [19] Therefore, it is indicated that NiS as a dopant has an important influence on the increase of 𝐶 N in the synthesized diamond. 3.…”

“…However, the amount of the incorporated S into the diamond was very small. [18] In our previous study, we [19] successfully synthesized diamond doped with FeS additive, using the (111) plane as a growth surface. We also analyzed and evaluated the existence, form and effective amount of S in the synthetic diamond.…”

Regulation mechanism of catalyst structure on diamond crystal morphology under HPHT process*

“…[1][2][3][4][5][6][7][8][9][10] High temperature and high pressure (HPHT) process based on temperature gradient method (TGM) is an effective way to obtain high-quality large single-crystal diamond. [11][12][13][14][15][16][17][18][19][20][21][22][23][24] For the HPHT preparation, the temperature gradient in molten catalyst is the main driving force for the growth of diamond, while the natural convection in the catalyst caused by the temperature gradient can effectively transport carbon atoms to the seed diamond surface. [20,23] Therefore, the temperature gradient and natural convection flow in the catalyst are significant factors that determine the crystal quality, morphology, and growth rate of the synthetic diamond.…”