Temperature effects on the universal equation of state of solids.

Recently 1t has been argued based on theoretical calculations and experimental data that there 1s a universal form for the equation of state of sol Ids. This observation was restricted to the range of temperatures and pressures such that there are no phase transitions. The use of this universal relation to estimate pressure-volume relations (I.e., Isotherms) required three Input parameters at each fixed temperature. In this paper we show that o for many solids the Input data needed to predict high temperature thermodynamlcal properties can be dramatically reduced. In particular, only four numbers are needed: (1) the zero pressure (P = 0) Isothermal bulk modulus; (2) Its P = 0 pressure derivative; (3) the P = 0 volume; and (4) the P = 0 thermal expansion; all evaluated at a single (reference) temperature. Explicit predictions are made for the high temperature Isotherms, the thermal expansion as a function of temperature, and the temperature variation of the 00 I *V1s1t1ng scientist from Laboratolre de Technologic des Surfaces, Ecole Centrale de Lyon, B.P. 163, 69131 Ecully Cedex, France. Isothermal bulk modulus and Its pressure derivative. These predictions are tested using experimental data for three representative sol Ids: gold, sodium chloride and xenon. Good agreement between theory and experiment 1s found.