title: Various ferroic orderings of triclinic tetrachloro-metallate dihydrate crystals.
abstract: In the triclinic crystals Rb(2)MnCl(4)·2H(2)O, Cs(2)MnCl(4)·2H(2)O and Cs(2)CaCl(4)·2H(2)O the ferroelastic domain structure has been observed for temperatures from 100 K to the dehydration point. On heating at a few degrees before the dehydration point the structure has been found to reorganize. On heating in Rb(2)MnCl(4)·2H(2)O and Cs(2)MnCl(4)·2H(2)O (but not in Cs(2)CaCl(4)·2H(2)O) a dielectric anomaly typical of a weak ferroelectric phase transition has been noted. The low-frequency dielectric dispersion in the low-temperature phase is attributed to the oscillations of the domain walls. The activation energy of this motion is 73 and 67 kJ mol(-1) in Rb(2)MnCl(4)·2H(2)O and Cs(2)MnCl(4)·2H(2)O, respectively. In the phase transition region the complex permittivity has been found to show oscillations as a function of temperature.
authors.affiliation: Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland.
authors.forename: Z
authors.initials: Z
authors.lastname: Tylczyński
authors.forename: M
authors.initials: M
authors.lastname: Członkowska
authors.forename: M
authors.initials: M
authors.lastname: Laniecki