Regensburg 2010 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 16: Phase Transitions
DF 16.1: Hauptvortrag
Donnerstag, 25. März 2010, 14:00–14:40, H11
Succesive phase transitions in (Gua)4SO4Cl2 crystal - dielectric, pyroelectric, dilatometric and optical studies — •Zbigniew Czapla1,2, Artur Rokosa1, Slawomir Dacko1, and Boguslaw Kosturek1 — 1Institute of Experimental Physics, University of Wrocław, pl M. Borna 9, 50-204 Wrocław, Poland — 2Department of Physics, Opole Unoversity of Technology, Ozimska 75, 45-271 Opole, Poland
Te studies of dielectric and pyroelectric properties along the ferroelectric a - axis, optical observation along the b-axis and dilatometric measurements along the a-, b- and c- axes for of (Gua)4SO4Cl2 crystal were performed in the temperature range 330-380 K covering the phase transitions region at various heating/cooling rates regime. Presented studies on heating run at the rate 0.01 K/min showed the successive phase transitions at T2 = 353 K and T1 = 357.5 K with the symmetry changes according to the scheme: orthorhombic(III) - orthorhombic(II) - tetragonal (I) and on cooling: tetragonal (I) - orthorhombic (II). The dielectric, pyroelectric, dilatometric and optical studies allowed to conclude that the phase transition III-II at T2 is characterized by slow kinetics. The studies of permittivity and dimensions changes of the samples which were kept at constant temperature inside of phase II during 180 min gave some detailed information about kinetics of III-II phase transition. The time changes of permittivity and dimensions were describe using Avrami model.