Représentation topologique (p, T) du trimorphisme du ferrocène : métastabilité intrinsèque de la phase triclinique

Abstract
Structural and thermodynamic data reported in literature about the three crystalline phases of ferrocene are used to build up a topological representation of its (p,T) phase diagram. Two phases (orthorhombic and monoclinic) exhibit stable phase regions whose temperature ranges increase with increasing pressure. The triclinic phase is found to be metastable whichever temperature and pressure. In the (p,T) diagram, it is not associated with any state of lowest energy although it transforms into the monoclinic phase according to a transition which is reversible. It is shown that this occurs in the phase region where the orthorhombic phase is the stable phase.