Study on structural geometry and dynamic property of [NH3(CH2)5NH3]CdCl4 crystal at phases I, II, and III

Organic-inorganic hybrid perovskites can potentially be used in electrochemical devices, such as batteries and fuel cells. In this study, the structure and phase transition temperatures of the organic-inorganic material [NH3(CH2)(5)NH3]CdCl4 crystal were confirmed by X-ray diffraction and differential scanning calorimetry. From the nuclear magnetic resonance results, the crystallographic configurations of H-1, C-13, and N-14 in the cation changed at temperatures close to T-C1 (336 K), whereas that of Cd-113 in the anion shows significant changes at temperatures close to T-C1 and T-C2 (417 K). The activation energy, E-a, values for H-1 and C-13 obtained from the spin-lattice relaxation time, T-1 rho, below and above T-C1 were evaluated, where the E-a value for C-13 was more flexible at low temperatures than at high temperatures. In addition, the effect on molecular motion was effective at high temperatures. The phase transition at 336 K was associated with the change in the N-H center dot center dot center dot Cl bond due to the change in the coordination geometry of Cl around Cd in the CdCl6 anion. On the other hand, the phase transition at 417 K was related to the ferroelastic phase transition attributed to the twin domains.