Crystallization of diamond with different nitrogen concentrations was carried out with a FeNiCo-C system at pressure of 6.5 GPa.As the nitrogen concentration in diamond increased,the color of the synthesized diamond c...Crystallization of diamond with different nitrogen concentrations was carried out with a FeNiCo-C system at pressure of 6.5 GPa.As the nitrogen concentration in diamond increased,the color of the synthesized diamond crystals changed from colorless to yellow and finally to atrovirens(a dark green).All the Raman peaks for the obtained crystals were located at about 1330 cm^(-1)and contained only the sp^(3)hybrid diamond phase.Based on Fourier transform infrared results,the nitrogen concentration of the colorless diamond was<1 ppm and absorption peaks corresponding to nitrogen impurities were not detected.However,the C-center nitrogen concentration of the atrovirens diamond reached 1030 ppm and the value of A-center nitrogen was approximately 180 ppm with a characteristic absorption peak at 1282 cm^(-1).Furthermore,neither the NV^(0)nor the NV^(-)optical color center existed in diamond crystal with nitrogen impurities of less than 1 ppm by photoluminescence measurement.However,Ni-related centers located at 695 nm and 793.6 nm were observed in colorless diamond.The NE8 color center at 793.6 nm has more potential for application than the common NV centers.NV^(0)and NV^(-)optical color centers coexist in diamond without any additives in the synthesis system.Importantly,only the NV^(-)color center was noticed in diamond with a higher nitrogen concentration,which maximized optimization of the NV^(-)/NV^(0)ratio in the diamond structure.This study has provided a new way to prepare diamond containing only NV^(-)optical color centers.展开更多
Thermal-electricaJ-fluid coupled finite element analyses are performed in the model of the growth cell in a high-pressure and high-temperature （HPHT） cubic apparatus in which the large diamond crystal can be grown b...Thermal-electricaJ-fluid coupled finite element analyses are performed in the model of the growth cell in a high-pressure and high-temperature （HPHT） cubic apparatus in which the large diamond crystal can be grown by using Ni-based solvent with temperature gradient method （TGM）. The convection in the Ni-based solvent with different thicknesses at 1700-1800 K is simulated by finite element method （FEM）. The experiments of diamond crystal growth are also carried out by using Ni-based solvent at 5.7GPa and 1700-1800K in a China-type cubic high pressure apparatus （CHPA）. The simulation results show that the Rayleigh number in the solvent is enhanced obviously with the increasing solvent thickness. Good quality diamond single crystal cannot be grown if the Rayleigh number in the solvent is too high.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12064038 and 52072113)the Natural Science Foundation of Guizhou Province Science and Technology Agency(Grant Nos.ZK[2021]019 and ZK[2021]031)+1 种基金the Outstanding Young Science and Technology Talents of Guizhou Pronice,China(Grant No.[2019]5673)the Open Project of Inner Mongolia Key Lab of High-pressure Phase Functional Materials(Grant No.cfxygy202004)。
文摘Crystallization of diamond with different nitrogen concentrations was carried out with a FeNiCo-C system at pressure of 6.5 GPa.As the nitrogen concentration in diamond increased,the color of the synthesized diamond crystals changed from colorless to yellow and finally to atrovirens(a dark green).All the Raman peaks for the obtained crystals were located at about 1330 cm^(-1)and contained only the sp^(3)hybrid diamond phase.Based on Fourier transform infrared results,the nitrogen concentration of the colorless diamond was<1 ppm and absorption peaks corresponding to nitrogen impurities were not detected.However,the C-center nitrogen concentration of the atrovirens diamond reached 1030 ppm and the value of A-center nitrogen was approximately 180 ppm with a characteristic absorption peak at 1282 cm^(-1).Furthermore,neither the NV^(0)nor the NV^(-)optical color center existed in diamond crystal with nitrogen impurities of less than 1 ppm by photoluminescence measurement.However,Ni-related centers located at 695 nm and 793.6 nm were observed in colorless diamond.The NE8 color center at 793.6 nm has more potential for application than the common NV centers.NV^(0)and NV^(-)optical color centers coexist in diamond without any additives in the synthesis system.Importantly,only the NV^(-)color center was noticed in diamond with a higher nitrogen concentration,which maximized optimization of the NV^(-)/NV^(0)ratio in the diamond structure.This study has provided a new way to prepare diamond containing only NV^(-)optical color centers.
基金Supported by the National Natural Science Foundation of China under Grant Nos 50572032 and 50731006.
文摘Thermal-electricaJ-fluid coupled finite element analyses are performed in the model of the growth cell in a high-pressure and high-temperature （HPHT） cubic apparatus in which the large diamond crystal can be grown by using Ni-based solvent with temperature gradient method （TGM）. The convection in the Ni-based solvent with different thicknesses at 1700-1800 K is simulated by finite element method （FEM）. The experiments of diamond crystal growth are also carried out by using Ni-based solvent at 5.7GPa and 1700-1800K in a China-type cubic high pressure apparatus （CHPA）. The simulation results show that the Rayleigh number in the solvent is enhanced obviously with the increasing solvent thickness. Good quality diamond single crystal cannot be grown if the Rayleigh number in the solvent is too high.
