An equation of state applied to solid up to 1 TPa

Abstract

In this paper, an isothermal three-parameter equation of state (EOS) of solid is presented in the form V/V0 = f(P). The proposed EOS uses three parameters expressible in terms of B0, B´0 and B´´0, denoting bulk modulus and its first and second pressure derivatives at zero pressure. The new EOS is applied to the isotherms of ionic, metallic, quantum and rare-gas solid, with pressures ranging from zero to variable maximum pressures of up to 1 TPa ( = 10 Mbar). The fits are uniformly excellent, and equally excellent is the agreement of the fitted parameters B0 and B´0 with experimental values. Deviations between data points and fits are computed and compared with the successful EOSs of similar form from the literature, and the drastic superiority of our new model is demonstrated. Further, the proposed model is applied to the isotherms of metals at ultrahigh pressures, with B0 and B´0 constrained to experimental values. An inter-comparison of results obtained from different EOSs, including the universal formulations, shows that our new form yields a superior fit.