SELF-CONSISTENT PRESSURE SCALES BASED ON THE EQUATIONS OF STATE FOR RUBY, DIAMOND, MgO, B2–NaCl AS WELL AS Au, Pt, AND OTHER METALS TO 4 Mbar AND 3000 K
Based on the modified formalism, we calculated the equation of state for diamond, MgO, Ag, Al, Au, Cu, Mo, Nb, Pt, Ta, and W by simultaneous optimization of the data of shock-wave experiments and ultrasonic, X-ray diffraction, dilatometric, and thermochemical measurements in the temperature range from ~100 K to the melting points and pressures of up to several megabars, depending on the material. The obtained room-temperature isotherms were adjusted with a shift of the R1 luminiscence line of ruby, which was measured simultaneously with the unit cell parameters of metals in the helium and argon pressure media. The new ruby pressure scale is expressed as P(GPa) = 1870 Δλ/λ0(1 + 6 Δλ/λ0). It can be used for correction of room-pressure isotherms of metals, diamond, and periclase. New simultaneous measurements of the volumes of Au, Pt, MgO, and B2–NaCl were used for an interrelated test of the obtained equations of state and calculation of the room-pressure isotherm of B2–NaCl. The constructed equations of state for nine metals, diamond, periclase, and B2–NaCl can be considered self-consistent and consistent with the ruby scale and are close to a thermodynamic equilibrium. The calculated PVT relations can be used as self-consistent pressure scales in the study of the PVT properties of minerals using diamond anvil cell in a wide range of temperatures and pressures.