Metallization of Cu₃N Semiconductor under High Pressure

Using the four-probe method, we investigate the electrical conductivity of Cu₃N under high pressure with the diamond anvil cell. Cu₃N is a semiconductor at ambient pressure showing a band gap about 1eV. With the application of quasi-hydrostatic pressures, its resistance decreases dramatically over five orders of magnitude from ambient to 9GPa. The compound became a metal at pressure about 5.5GPa, which is in well agreement with the recent first principle calculation.