Synthesizing fully sp 3 -bonded non-crystalline carbon remains a long-standing challenge due to the intrinsic instability of the sp 3 bond at ambient pressure. Recently, paracrystalline diamond, a new-form sp 3 -bonded non-crystalline carbon consisting of sub-nanometer-sized paracrystallites, has been synthesized from face-centered cubic C 60 at 30 GPa, which has attracted attention due to its unique structural features and excellent physical properties. However, the ultrahigh synthesis pressure of paracrystalline diamond poses an obstacle to its large-scale production and applications. In this study, paracrystalline diamond is synthesized at an exceptionally low pressure (16 GPa) via inducing uniaxiality at high-pressure and high-temperature conditions, thereby breaking through the temperature-pressure phase diagram of C 60 . By combining structural characteristics and advanced molecular dynamics simulation, the remarkable reduction of synthesis pressure is attributed to the fact that the symmetry of the C 60 cage is broken due to the uniaxiality, which further allows the C 60 cage to collapse at much lower pressures. This work reveals the critical role of uniaxiality in the reduced-pressure synthesis of paracrystalline diamond, which may provide a potent methodological strategy for the development of novel low-cost high-pressure materials.
As an emerging ultrathin semiconductor material, Bi 2 O 2 Se has shown outstanding performance in fields of electronics, optoelectronics and ultrafast optics. High performance Bi 2 O 2 Se nanosheets were desperately needed for further foundational research and practical applications. However, their synthesis has not yet been completely developed. In this paper, high quality Bi 2 O 2 Se nanosheets were efficiently obtained by sdjusting synthesis pressure. The uniform nucleation of Bi 2 O 2 Se nanosheets on substrates was achieved, put forward the nucleation mechanism of Bi 2 O 2 Se nanosheets. The near-infrared (NIR) optoelectronic properties of multilayer Bi 2 O 2 Se nanosheets were systematically investigated. Photodetectors were constructed based on Bi 2 O 2 Se nanosheets of different thicknesses and the near-infrared (NIR) photoelectric properties of Bi 2 O 2 Se-based photodetectors with the highest responsivity were systematically investigated. The multilayer Bi 2 O 2 Se nanosheets exhibit sensitive responsivity to the NIR, including high responsivity (∼825 A/W), high external quantum efficiency (∼1.25 × 10 5 %) and high detectivity (6 × 10 10 Jones). These results suggest that devices based on multilayer Bi 2 O 2 Se nanosheets may have great potential for future applications in ultrafast, high-sensitivity NIR optoelectronic devices.
危险品化学品经营许可证（带存储）