Strength and equation of state of NaCl from radial x-ray diffraction

Abstract

The strength and equation of state of NaCl were determined under nonhydrostatic compression up to 27 GPa using an energy-dispersive radial x-ray diffraction technique in a diamond-anvil cell using the lattice strain theory. Together with estimation of the high-pressure shear modulus, it is suggested that NaCl could support a maximum differential stress of 0.980 GPa at 22.6 GPa under uniaxial compression. The differential stress rapidly drops at 27.2 GPa due to the phase transition from B1 phase to B2 phase for NaCl. The hydrostatic compression data of B1 phase yield a bulk modulus K0 = 25.6(8) GPa and its pressure derivative K0′ = 5.16(20) using Pt pressure scale. In addition, a comparative study of the observed pressures from Pt scale and ruby-fluorescence scale shows that the ruby-fluorescence pressures may reflect the lower stress state under nonhydrostatic compression compared with hydrostatic compression.