1. Different effect of NiMnCo or FeNiCo on the growth of type-IIa large diamonds with Ti/Cu as nitrogen getter.
- Author
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Shang-Sheng Li, He Zhang, Tai-Chao Su, Qiang Hu, Mei-Hua Hu, Chun-Sheng Gong, Hon-An Ma, Xiao-Peng Jia, Yong Li, and Hong-Yu Xiao
- Subjects
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DIAMONDS , *CATALYSTS , *TEMPERATURE lapse rate , *ATMOSPHERIC temperature , *NICKEL-manganese alloys - Abstract
In order to synthesize high-quality type-IIa large diamond, the selection of catalyst is very important, in addition to the nitrogen getter. In this paper, type-IIa large diamonds are grown under high pressure and high temperature (HPHT) by using the temperature gradient method (TGM), with adopting Ti/Cu as the nitrogen getter in Ni70Mn25Co5 (abbreviated as NiMnCo) or Fe55Ni29Co16 (abbreviated FeNiCo) catalyst. The values of nitrogen concentration (Nc) in both synthesized high-quality diamonds are less than 1 ppm, when Ti/Cu (1.6 wt%) is added in the FeNiCo or Ti/Cu (1.8 wt%) is added in the NiMnCo. The difference in solubility of nitrogen between both catalysts at HPHT is the basic reason for the different effect of Ti/Cu on eliminating nitrogen. The nitrogen-removal efficiency of Ti/Cu in the NiMnCo catalyst is less than in the FeNiCo catalyst. Additionally, a high-quality type-IIa large diamond size of 5.0 mm is obtained by reducing the growth rate and keeping the nitrogen concentration of the diamond to be less than 1 ppm, when Ti/Cu (1.6 wt%) is added in the FeNiCo catalyst. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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