Investigation of the Structure, Phase Transitions, Molecular Dynamics, and Ferroelasticity of Organic-inorganic Hybrid NH(CH)CdCl Crystals

Understanding the physical and chemical properties of the organic-inorganic hybrid NH(CH)CdCl is essential for its application. Considering its importance, a single crystal of NH(CH)CdCl was grown with an orthorhombic structure at 300 K. The phase transition temperatures were determined to be 345 (), 376 (), and 452 K () (phases IV, III, II, and I, respectively, starting from a low temperature). The partial decomposition temperature was 522 K (). Furthermore, the NMR chemical shifts of the H, C, and Cd atoms of the cation and anion varied with increasing temperature. Consequently, a significant change in the coordination geometry of Cl around Cd in CdCl and a change in the coordination geometry of H in NH was associated with changes in the N-H⋯Cl hydrogen bond near the phase transition temperature. The C activation energy obtained from the spin-lattice relaxation time was smaller than that of H , suggesting that energy transfer around C is easier. Additionally, a comparison of the twin domain walls measured optical polarizing microscopy and Sapriel's theory indicated that the crystal structure in phase III was more likely to be orthorhombic than hexagonal.