Compressibility of Solids and Liquids at High Pressures

Abstract

An equation for compressibility (identical in form to the Tait equation) derived previously from the virial theorem and the Fermi—Thomas atomic model is modified on the assumption that one of its parameters (αβ0) is reciprocally related to the internal pressure when the cohesive energy density is assumed to be an essential part of the internal pressure. Pressure—volume data for about fifty homonuclear solids, two alloy systems, twenty ionic compounds, and five secondary bonded liquids are analyzed and the model found to fit with surprising accuracy when due consideration is given to pressure-induced phase or polymorphic changes and thermodynamic ``holes'' (most important near, and above, the melting point) that may contribute appreciably to specific volume. Data from static and shock methods of compression are considered and the differences noted. The model is apparently applicable to the compression of homonuclear solids and liquids, if indeed not all condensed materials in general.

Equation of State and Entropy Theory Approach to Thermodynamic Scaling in Polymeric Glass-Forming Liquids

“…If we apply a new pressure to the material, we can obtain the alternative form for condensed polymer materials upon rearrangement of the ME While it is natural to adopt P = 0 as a reference condition, as implicit in eq , we may just as well expand B in a Taylor series about any reference pressure P o , defining a different reference state. Cook and Rogers later derived the ME by a different route and their work is of interest for understanding the relation between γ M κ T,o and the material cohesive energy density and internal pressure. The work of Cook and Rogers also well illustrates that deviations from the ME arise near phase transitions, such as crystal melting and insulating–conducting or magnetic phase transitions, which should come as no surprise since such transitions can lead to sharp changes in the volume or cohesive energy density.…”

“…Cook and Rogers later derived the ME by a different route and their work is of interest for understanding the relation between γ M κ T,o and the material cohesive energy density and internal pressure. The work of Cook and Rogers also well illustrates that deviations from the ME arise near phase transitions, such as crystal melting and insulating–conducting or magnetic phase transitions, which should come as no surprise since such transitions can lead to sharp changes in the volume or cohesive energy density. “Kinks” in the EOS near thermodynamic transitions have independent interests in relation to the existence of such transitions in GF liquids, which we briefly consider below.…”

Calculation of seismic source mechanisms

“…Griineisen constant y and enthalpy of vapo An analysis of compressibility data of metals and alloys used by Cook & Rogers (1963) has been applied to rocks by Rogers (1964). This procedure, besides affording insight into the compression process and phase changes, leads directly to values of y and the vaporization enthalpy.…”