Analysis of thermal expansivity of NaCl at high pressures and high temperatures
We have developed a method for determining thermal expansivity of NaCl at simultaneously elevated pressures and temperatures. The Anderson formula for the temperature dependence of thermal expansivity has been used along different isobars at selected pressures. We have used the relationship between the Anderson-Grüneisen parameter and the volume dependence of thermal expansivity. Results are obtained for thermal expansivity of NaCl at high pressures and high temperatures. It is found that the thermal expansivity decreases very fast with the increasing pressure and becomes independent of temperature at high pressures. The thermal expansion is small, but non-zero, at pressure of 30 GPa. The results are consistent with the theory which predicts that thermal expansion goes to zero at volume approaching zero.
Keywords: Thermal expansivity, Anderson-Grüneisen parameter, Equation of state, NaCl.