Universal features of the equation of state of solids

TLDR

The equation of state can be determined from zero‑pressure volume, isothermal compression, and its pressure derivative, assuming no phase transitions. The universal function is derived from experimental compression data of measured isotherms across many solids. The authors find a universal equation of state for all solid classes and propose a new method to analyze isotherms and extrapolate high‑pressure data from low‑pressure measurements.

Abstract

A study of the energetics of solids leads to the conclusion that the equation of state for all classes of solids in compression can be expressed in terms of a universal function. The form of this universal function is determined by sealing experimental compression data for measured isotherms of a wide variety of solids. The equation of state is thus known (in the absence of phase transitions), if zero-pressure volume and isothermal compression and its pressure derivative are known. The discovery described by the authors has two immediate consequences: first, despite the well known differences in the microscopic energetics of the various classes of solids, there is a single equation of state for all classes in compression; and second, a new method is provided for analysing measured isotherms and extrapolating high-pressure data from low-pressure (e.g. acoustic) data.