Contribution to the thermodynamics of the isomorphous γ ⇆ α-transition in metallic cerium

Abstract

Using the method of the theory of thermodynamic stability and the form of the lines of the phase equilibrium of the isomorphous γ ⇆ α-transition in metallic cerium, the authors investigate the behavior of the basic thermodynamic characteristics of this transition in the two-phase region and in a neighborhood of the critical point. Attention is focused primarily on the little-studied adiabatic quantities (T/C_V, (−∂P/∂V)_S, (∂T/∂V)_S). It is shown that along the phase tie-lines these quantities do not depend on V and S; in the limit of the critical point all adiabatic quantities have nonzero minima, and all isodynamic quantities (T/Cp, (−∂P/∂V)_T, (∂T/∂V)_P) approach zero according to the same law. The obtained thermodynamic results are compared with existing experimental data and models which can be interpreted thermodynamically. It is concluded that critical phenomena in cerium correspond to critical behavior of the first type.