Oxygen under High Pressure. Temperature Dependence of Electrical Resistance.

Abstract

We have measured electrical resistance of oxygen under high pressures up to 120 GPa and at temperatures down to 45 mK. With increasing pressure, the resistivity of oxygen was found to decrease rapidly and reached 0. 3 ohm x cm at 95 ± 5 GPa that was still comparable to that of semiconductor. We present measurements of the temperature dependence of electrical resistance of oxygen to observe the metallic behavior in the temperature dependence. The temperature dependence of resistance clearly changes its slope of dR/dT at around 90 GPa. The critical pressure is in agreement with previous reports for the metallization. We found an abrupt drop of resistance which may indicate superconducting transition of metallic oxygen at pressures above 98 GPa with T_c∼0. 6 K. This is confirmed by the magnetic field dependence of the resistance drop.