Study of the melting temperature baric dependence for Au, Pt, Nb

Abstract

In this work we present new analytical (i.e., without computer modeling) method for calculating the dependence of the melting temperature (Tm) on pressure (P) for a single-component crystal. The method is based on the paired four–parameter Mie–Lennard-Jones interatomic interaction potential, and the delocalized criterion of melting. This method was used to calculate the baric dependences of the melting temperature Tm(P) and its pressure derivative Tm′(P) for gold, platinum and niobium in the pressure range: P = 0–1000 GPa. It has been shown that the dependences calculated by this method for gold and platinum are in better agreement with experimental data than the dependences obtained by computer modeling methods: the molecular dynamics simulations and the ab initio Z-method calculations. For niobium, the calculated Tm(P) dependence turned out to be steeper, i.e. the Tm′(P) values turned out to be greater than the experimental data obtained in [D. Errandonea et al. Communications Materials 1, 1 (2020)]. It has been indicated that this deviation can be caused both by a decrease in the Lindemann parameter with an increase in pressure, and by the redistribution of electrons in the s-to-d orbitals during compression of transition metals with a bcc structure. Furthermore, the discrepancy may also be due to the highly-correlated chain-like self-diffusion, which is inherent in bcc metals before melting.