Structure, phase transitions and molecular dynamics in ferroelastic crystal pyrrolidinium hexachloroantimonate(V), [C4H 8NH2][SbCl6]
Jakubas R.1, Bednarska-Bolek B.1, Zaleski J.2, Medycki W.3, Hołderna-Natkaniec K.4, Zieliński P.5, Gała̧zka M.5
- 1Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wrocław, Poland
- 2Institute of Chemistry, University of Opole, Oleska 48, 45-951 Opole, Poland
- 3Institute of Molecular Physics, PAS, Smoluchowskiego 17, 60-179 Poznań, Poland
- 4Institute of Physics, UAM, Umultowska 85, 61-614 Poznań, Poland
- 5H. Niewodniczanski Inst. Nucl. Phys., PAN, 31-342 Kraków, Poland
Solid State Sciences, 7 (4), pp.381-390, 2005
DOI:: 10.1016/j.solidstatesciences.2005.01.010
Abstract:
The crystal structure of the pyrrolidinium hexachloroantimonate(V), [C 4H8NH2][SbCl6], abbreviated PCA, has been determined by means of X-ray diffraction at 300 and 340 K. The space groups are monoclinic P21/n (phase III) and orthorhombic Pmnb (phase II), respectively. The crystal undergoes two structural phase transitions: first-order type at 356/329 K (heating/cooling) from phase (I) to (II) and second-order type at 323 K from phase (II) to (III). Dielectric studies suggest the plastic crystals behaviour above 356 K (phase I). Proton spin-lattice relaxation time (T1) and second moment (M2) of polycrystalline [C 4H8NH2][SbCl6] have been determined at 77-370 K, at 90 and 25 MHz. Temperature dependence of the M2 indicates that the continuous increase in the freedom of rotational motion of the pyrrolidinium cations takes place over the phase (III). The ferroelastic domain structure of [C4H8NH2][SbCl6] is observed over the phase (III). Mechanisms of phase transitions in PCA are discussed. © 2005 Elsevier SAS. All rights reserved.
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