Temperature-pressure-volume equation of state of the B2 phase of sodium chloride

The temperature-pressure-volume (T-P-V) data of the B2 phase of sodium chloride (NaCl) were measured at high temperatures between 1023 and 1973 K, and high pressures between 22.9 and 26.3 GPa, using synchrotron powder x-ray diffraction experiments with a Kawai-type multianvil high pressure apparatus. The Mie-Gruneisen-type thermal pressure analysis was made to obtain the high temperature and high pressure T-P-V equation of state (EOS) of the B2 phase based on the present measured T-P-V data together with the 300 K volume compression data previously reported using diamond-anvil-cell experiments. Some molecular dynamics calculations using a breathing shell model interionic potential, recently developed for the NaCl system, were also carried out to investigate the behavior of thermal pressure of the B2 phase at high temperatures and high pressures. The resulting T-P-V EOS agrees very well with recently measured volume compression data at 1000 K. Here we present the T-P-V EOS of the B2 phase up to 3000 K and more than 150 GPa, as a reliable pressure standard at high temperatures and high pressures. (C) 2008 American Institute of Physics.