Investigations of point defect and interface in cg-N under high-pressure

The properties of cg-N with point defects and an interface are investigated based on the first-principles method. Our results show that at 0 GPa, the stability of cavities depends on their size. A smaller cavity has higher stability than the larger case. The decomposition of N2 molecules mainly occurs on the (110) surface of the cavity. However, the decomposition process will be suppressed by applying high-pressure. For the interface constructed by (110) surfaces, N2 molecules will be released at low pressure, and polymerization of N2 molecules with surfaces is triggered by loading pressures of 80–100 Gpa, giving rise to a stable polymerized interface, which is also stable after decreasing the pressure to 0 GPa. The results indicate that the existence of polymeric nitrogen networks can enhance the polymerization of N2 molecules at low-temperature.