The Thermodynamics of Melting for Alkali Metals

Abstract

In spite of the fact that there is no general theory of melting, the status of this phenomenon for simple substances of the argontype is clear enough. Real and “machine” experiments indicate the prevailing role of the short-range repulsive interactions in the crystallization of rare gases [1,2]. These results indicate the important conclusions concerning the melting thermodynamics of rare-gas systems at very high pressures. In particular, since with increasing density the contribution of the repulsive interaction to the free energy and pressure of the rare-gas system will also increase, we can insist that the following asymptotic relations take place at rare-gas melting:

$$\left. {\begin{array}{*{20}{c}} {\Delta S/R \to Const} \\ {\Delta V/{{V}_{s}} \to Const} \\ {{{P}_{m}} \to \alpha \;T_{m}^{c}} \\ \end{array} } \right\}P \to \infty$$

(1)

The relations in (1) lead immediately to the derivations of the unlimited increase of the melting temperature on compression and of the impossibility of a critical point on the melting curve.

Invited paper.