Elastic stiffness constants, C _ijs, of single crystal of NaCl B1 phase have been determined at pressure up to 20 GPa using inelastic x-ray scattering to measure elastic wave velocities and x-ray diffraction to measure densities in the same experimental setup. The Voigt-Reuss-Hill average velocities calculated from the present C_ijs are in good agreement with previous ultrasonic measurements of polycrystalline samples. Absolute pressures based on the present elastic constants and densities are proposed. In order to fit our results an equation of state with at least three parameters (an addition to a reference volume), such as the fourth-order form of Birch–Murnaghan equation or the higher order form of Vinet equation, is required, as fewer parameters do not reproduce the observed pressure dependence of the volume and bulk modulus.

在相同的实验设置中，使用非弹性X射线散射测量弹性波速度和X射线衍射测量密度，在高达20 GPa的压力下测定了NaCl B1相单晶的弹性刚度常数C _ij s。根据当前C _ij s计算出的Voigt-Reuss-Hill平均速度与先前对多晶样品进行的超声测量非常吻合。提出了基于当前弹性常数和密度的绝对压力。为了拟合结果，需要具有至少三个参数的状态方程（除了参考体积之外），例如Birch–Murnaghan方程的四阶形式或Vinet方程的高阶形式，因为数量较少参数不能再现观察到的体积和体积模量的压力依赖性。