X-ray, thermal and vibrational studies of two structural phases transition in hexylenediammonium pentachlorobismuthate (III) [NH3(CH2)6NH3]BiCl5

► X-ray analysis: the crystal shows 2 phase transitions: α (223K) ↔ β (308K) ↔γ (373K). ► A paraelastic-ferroelastic transition may be occurred between γ and β phases. ► DSC analysis: α ↔ β and β ↔ γ are of first-order and weak first-order type, respectively. ► Raman spectra: anionic and cationic motions contribute to phase transition mechanisms. ► Order-disorder type of α ↔ γ transition is due to changes in dynamical state of cations.