EQUATION OF STATE AND INTERNALLY CONSISTENT THERMODYNAMIC FUNCTIONS OF MINERALS

Abstract

We present a modified equation of state for solid phases based on the method of potentials of Zharkov and Kalinin (1968). The potential part of the Helmholtz free energy was expressed in a logarithmic form (Poirier and Tarantola, 1998), and a three-parameter modification of the Bose-Einstein model (Kut'in and Pyadushkin, 1998) was used instead of the Debye energy. This allowed us to approximate with high accuracy the experimental measurements of heat capacity, enthalpy, volume, and adiabatic bulk modulus between 10-15 K and the melting temperature at zero pressure and volume data in the region of its experimental determination using a single equation of state. Taking sodium chloride as an example, it was shown that the proposed thermal equation of state allowed us to evaluate self-consistent thermodynamic functions from experimental measurements, as well as to calculate these functions in a wide range of T, P, and V.