Title: THERMODYNAMICS AND DIELECTRIC ANOMALIES OF DMAAS AND DMAGaS CRYSTALS IN THE REGION OF PHASE TRANSITIONS (LANDAU THEORY APPROACH)
Author(s): I.V.Stasyuk, O.V.Velychko (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Str., 79011 Lviv, Ukraine), Z.Czapla, R.Czukwinski (Institute of Experimental Physics, University of Wroclaw, 9 M.Borna Sq., 50--204 Wroclaw, Poland)

A simple description of thermodynamics of DMAAS and DMAGaS ferroelectric crystals by means of Landau expansion is proposed. Conditions of occurrence of phase transitions are established and their temperatures are obtained. The influence of external hydrostatic pressure on phase transitions is described. The temperature behaviour of dielectric susceptibility components and their anomalies in the vicinity of phase transition points are investigated. The results obtained are compared with the experimental data.

Comments: Figs. 4, Refs. 18, Tabs. 0.