Phenomenological theory of phase diagrams. The case of Landau’s potentials with
The South Russia State Polytechnic University,
132 Prosveshhenija st., 346428
Received in final form: 26 December 2013
Published online: 5 February 2014
Phase diagrams of the crystals undergoing phase transitions induced by irreducible representations with the symmetry group have been constructed within the phenomenological theory of the second-order phase transitions. The equations of state of all phases induced by symmetry have been received, and the general conditions of their thermodynamic stability have been formulated. For the fourth-order expansion of thermodynamic potential in terms of the order parameter components, exhaustive results have been obtained: equations of phases stability boundaries and all possible types of phase diagrams have been found analytically. For the eighth-order expansion of the potential the variety of phase diagrams has been analyzed using computer calculations. For the first time the possibility of existence of phase diagrams described by this potential and containing one or several triple points, three-phase and four-phase regions is shown. Examples of the crystals undergoing phase transitions with considered symmetry of the order parameter have been given.
Key words: Solid State and Materials
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2014