Synthesis and characterization of a single diamond crystal with a high nitrogen concentration.

In this paper, we explore diamond synthesis with a series of experiments using an Fe-Ni catalyst and a P3N5 additive in the temperature range of 1250-1550 0C and the pressure range of 5.0-6.3 GPa. We also investigate the influence of nitrogen on diamond crystallization. Our results show that the synthesis conditions (temperature and pressure) increase with the amount of P3N5 additive increasing. The nitrogen impurity can significantly influence the diamond morphology. The diamonds stably grow into strip and lamellar shapes in the nitrogen-rich environment. The Fourier-transform infrared spectrum shows that the nitrogen concentration increases rapidly with the content of P3N5 additive increasing. By spectrum analysis, we find that with the increase of the nitrogen concentration, the Ib-type nitrogen atoms can aggregate in the A-centre form. The highest A-centre nitrogen concentration is approximately 840 ppm. [ABSTRACT FROM AUTHOR]