The effect of Ni content in metal solvent on diamond growth and N-related defects

In the experiment of synthesizing diamond crystals by temperature gradient method the catalyst is an essential condition, and exploring the effect of the catalyst on the growth of diamond crystals is crucial. In this paper, we use different Ni-content catalysts to study the synthesis of diamond crystals by using the domestic six-face top press and analyze the properties of the synthesized diamonds. The synthesis temperature was 1700 K. The synthesis pressure was 6.0 GPa. Among them, the results of Raman spectra showed that the content of Ni in the catalyst would change the crystallinity of diamond crystals; in the Fourier infrared spectra, the peaks of 1046 cm-1 and 1332 cm-1 (N+ ions), 1130 cm-1 and 1344 cm-1 appeared, which indicated that with the increase of Ni content in the catalyst, the crystallinity of the nitrogen in the diamonds would change. The results of photoluminescence spectroscopy show that the diamond synthesized by using Fe-containing catalyst will have the phonon boundary 692 nm and 694 nm structure of NV-color center, and the intensity of NV-basically matches the intensity of N+ ions, which further suggests that the charge in the NV-center is provided by the N-atoms, and the N-atoms lose their charge, and the N-atoms lose their charge. Atoms in the NV-color centers and the N atoms will turn into N+ ions after losing the charge; The Ni content in the catalyst has a considerable influence on the characteristics of diamond, which is validated by both the traditional average d-electron number model and the finite element simulation.