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DF: Fachverband Dielektrische Festkörper

DF 12: Poster II

DF 12.11: Poster

Mittwoch, 25. März 2009, 09:30–12:30, P5

A model of ferroelectricity in thiourea — •Izabela Sliwa¹ and Wojciech Wanarski² — ¹Institute of Molecular Physics, Polish Academy of Sciences, Poznan, Poland — ²Faculty of Physics, Adam Mickiewicz University, Poznan, Poland

We propose a new mechanism of the phenomenon of ferroelectricity in the molecular crystal of thiourea (SC(NH₂)₂). The mechanism is based on a model of interaction between two electric dipoles in molecules. The dipoles are assumed to be not ideal points, but they have a finite length. Besides, they can reorient mutually. The reorientation is determined by the crystal structure specified by experimental structural research. On the basis of this theory, a formula for the potential energy of the interaction of the pair of two non-point dipoles as a function of the angle of reorientation is derived and discussed. The formula is applied within the limit of the molecular field approximation (MFA). We discovered different possible mechanisms of formation of the resultant dipole moments of pairs of molecules which are related to different phases of thiourea monocrystal.