Vibrational study of the structural phase transitions in a new ferroelastic (C5H10NH2)SbCl6 crystal by infrared and Raman spectroscopies

Infrared spectra of (C5H10NH2)SbCl6 in the region of the internal vibrations of the piperidinium cations (3500-400 cm(-1)) and Raman spectra in the region of internal vibrations of the SbCl6- anions (400-100 cm(-1)), around the phase transitions at T-c3 = 294 K, T-c2 = 310 K and T-c1 = 369 K, are presented and discussed. A detailed analysis has been performed for the bands assigned to the stretching and deformation vibrations of the NH2+ and CH2 groups. It has been shown that the hydrogen bonds play an important role in the mechanism of the phase transitions and influence the dynamics of either cations or anions in different phases of (C5H10NH2)SbCl6.