Direct measurements of electrical resistivity and caloric equation of state have been performed for fluid tungsten in order to establish the relation between the liquid-vapor and the metal-to-nonmetal transition caused by thermal expansion. The measurements have been done with accuracy better than $\pm 10\%$ using mainly the experimental technique developed in our previous works. To estimate the systematic uncertainty of the measurements a supplementary technique has been developed which allows the thermal expansion of tungsten in the experiments to be measured directly. We demonstrate that fluid tungsten remains in a two-phase state at pressures of about one order of magnitude higher than the critical pressure of the liquid-vapor transition expected from theoretical estimates. Such behavior is very similar to that observed earlier in fluid iron [Korobenko and Rakhel, Phys. Rev. B 85, 014208 (2012)].

• Received 3 May 2013

DOI:https://doi.org/10.1103/PhysRevB.88.134203