Dependence of nitrogen concentration in type Ib diamonds on synthesis temperature

Type Ib diamonds were grown by the temperature gradient method (TGM) at 5.5 GPa and 1500–1560 K in a china-type cubic anvil high pressure apparatus using Ni70Mn25Co5 alloy as solvent/catalyst. The concentration of nitrogen (C N) in type Ib diamonds synthesized at different synthesis temperatures was measured by a Fourier transform infrared (FTIR) spectrometer. The dependence of C N in diamond on synthesis temperature was studied. For the type Ib diamonds synthesized using Ni70Mn25Co5 as catalyst, its C N decreases along with the increase of synthesis temperature. Supported by the National Natural Science Foundation of China (Grant Nos. 50572032, 50731006)