Experimental electrical resistivity of liquid carbon in the temperature range from 4800 to ∼20,000 K

Specimens of high density pyrolytic graphite (2.2 g/cm3) were placed inside thick-walled sapphire tubes and heated over several microseconds by an electric current of 68 kA. The electrical resistivity of the liquid carbon was measured in a constant volume heating process. The transition of liquid carbon from semi-metal properties (resistivity decreasing with increase of input energy) to metal-like behavior (resistivity increasing with increase of input energy) was obtained at a high input energy (25-75 kJ/g) and at a high, but not measured, pressure. The transition temperature, T, was roughly estimated through the CV value (heat capacity under constant volume). The relationship between the density and the transition temperature is as follows: for 1.88 g/cm3 density, the transition temperature T = 6300 K, for 1.76 g/cm3, T = 10,100 K, and for 1.1 g/cm3, T = 13,500 K. The estimated temperature at the maximum input energy (75 kJ/g) for liquid metal-like carbon (just before the destruction of the sapphire tube) is 23,000 K, with a corresponding measured electrical resistivity of 3000 μΩ cm.