ON THE NATURE OF THE GAMMA-ALPHA PHASE-TRANSITION IN CERIUM

In 1964 Davis and Adams established that the large increase of the the rmal 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 i n Ce. This also means that the aforementioned transition is not isomor phic and that alpha-Ce should have a distorted fee structure. A carefu l examination of Jayaraman's data (1965) shows that a second-order tra nsition line continues beyond the tricritical point to the vicinity of a triple point on the melting curve. The phase boundary with the tric ritical point and the minimum of the melting curve are reconstructed w ithin the framework of Landau theory. (C) 1998 American Institute of P hysics.