Fixed points for pressure calibration above 100 kbars related to semiconductor-metal transitions

Pressures assigned to the semiconductor-metal transitions in ZnTe, ZnS, GaAs, and GaP have been determined by detecting the electrical resistance change of the semiconductors while the lattice parameter of standard material NaCl was simultaneously measured with x-ray diffraction techniques. A pressure vessel of the split-octahedron type and various pressure-transmitting media have been employed. Pressures were estimated according to the equation of state for NaCl proposed by Decker. The transition pressures, 1296 kbars for ZnTe, 1557 kbars for ZnS, 1888 kbars for GaAs, and 25310 kbars for GaP, constitute fixed points for pressure calibration above 100 kbars at room temperature.