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

Abstract

AbstractOrganic–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)5NH3]CdCl4 crystal were confirmed by X-ray diffraction and differential scanning calorimetry. From the nuclear magnetic resonance results, the crystallographic configurations of 1H, 13C, and 14N in the cation changed at temperatures close to TC1 (336 K), whereas that of 113Cd in the anion shows significant changes at temperatures close to TC1 and TC2 (417 K). The activation energy, Ea, values for 1H and 13C obtained from the spin–lattice relaxation time, T1ρ, below and above TC1 were evaluated, where the Ea value for 13C 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···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.