On the nature of the γ-α phase transition in cerium

In 1964 Davis and Adams established that the large increase of the thermal expansion and compressibility in the critical region of the gamma- to alpha-Ce phase transition occurs predominantly in the alpha phase. This provides strong evidence that a tricritical point is realized in Ce. This also means that the aforementioned transition is not isomorphic and that alpha-Ce should have a distorted fee structure. A careful examination of Jayaraman's data (1965) shows that a second-order transition line continues beyond the tricritical point to the vicinity of a triple point on the melting curve. The phase boundary with the tricritical point and the minimum of the melting curve are reconstructed within the framework of Landau theory. (C) 1998 American Institute of Physics.