https://doi.org/10.1140/epjb/e2014-40962-2
Regular Article
Phenomenological theory of phase diagrams. The case of Landau’s
potentials with 
The South Russia State Polytechnic University,
132 Prosveshhenija st., 346428
Novocherkassk, Rostov
Region, Russia
a
e-mail: forever_young@inbox.ru
Received:
28
October
2013
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
