UNIVERSAL COMPRESSIBILITY BEHAVIOR OF DENSE PHASES

We recently proposed an isothermal equation of state that was successfully applied to study the high-pressure behavior of molecular liquids. In this work we extend its applicability to liquid metals, polymers, molten salts, and solids. The possibility of considering this equation as an alternative to long-standing equations such as those of Tait and Birch-Murnaghan is emphasized. This suggestion is firmly supported by comparisons with experimental data up to pressures of several GPa. A new physical interpretation of the pressure coefficient of the Tait equation BT is given. It can be identified to the divergence pressure along a pseudospinodal curve. We also compare the performance of our equation with the most successful equations of state used to represent isothermal data of solids, with excellent results. Our equation can be applied to systems with phase transitions. An interesting observation is that it seems that the different pseudospinodal curves obtained for the different phases can be put together into the same curve except for characteristic jumps occurring at the phase transitions. © 1995 The American Physical Society.