Investigation of the structure, phase transitions, molecular dynamics, and ferroelasticity of organic-inorganic hybrid NH(CH3)3CdCl3 crystals.

Abstract

Understanding the physical and chemical properties of the organic-inorganic hybrid NH(CH3)3CdCl3 is essential for its application. Considering its importance, a single crystal of NH(CH3)3CdCl3 was grown with an orthorhombic structure at 300 K. The phase transition temperatures were determined to be 345 (TC3), 376 (TC2), and 452 K (TC1) (phases IV, III, II, and I, respectively, starting from a low temperature). The partial decomposition temperature was 522 K (Td). Furthermore, the NMR chemical shifts of the 1H, 13C, and 113Cd atoms of the cation and anion varied with increasing temperature. Consequently, a significant change in the coordination geometry of Cl around Cd in CdCl6 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 13C activation energy Ea obtained from the spin-lattice relaxation time was smaller than that of 1H Ea, suggesting that energy transfer around 13C is easier. Additionally, a comparison of the twin domain walls measured via optical polarizing microscopy and Sapriel's theory indicated that the crystal structure in phase III was more likely to be orthorhombic than hexagonal.