高压下碱卤晶体的三参量等温状态方程

An Isothermal Three-Parameter Equation of State Applied to Alkali Halide Crystals under High Pressures

由等温体积弹性模量的定义及其与压强关系的假设出发，导出了一个新的适用于高压下碱卤晶体的三参量等温状态方程。计算了室温下NaCl晶体在0～30GPa压强范围内、CsCl晶体在0～40GPa压强范围内的相对体积以及NaCl晶体在0-30GPa压强范围内的等温体积弹性模量，计算结果与实验值一致。对等温体积弹性模量及其对压强的一阶、二阶导数与压强的关系进行了讨论，指出压强趋于无穷大时的等温体积弹性模量是常数。

From the definition of isothermal bulk modulus and an assumption of its relationship with the pressure,an isothermal three-parameter equation of state has been proposed, which is found to be applicable at high pressure. The proposed equation of state has been used to compute the pressure-volume behavior of NaCl crystal in the pressure range 0-30 GPa and CsCl crystal in the pressure range 0-40 GPa. The isothermal bulk modulus in the pressure range 0-30 GPa of NaCl crystal were also calculated. The results are in very good agreement with the experimental data. The pressure dependence of the isothermal bulk modulus BT and its first- and second-order pressure derivative are discussed, and the bulk modulus increases continuously with the increasing pressure and has a finite value as p→∞ .