Abstract
The research has focused on candidates for application in various fields on the organic-inorganic hybrid perovskite-type [N-(C(2)H(5))(4)](2)CoCl(4). Here, [N-(C(2)H(5))(4)](2)CoCl(4) single crystals were grown, and their phase transition temperature (T (C)) was about 228 K. Single-crystal X-ray diffraction performed at 300 K revealed that the crystals possess a tetragonal structure belonging to the P4(2)/nmc space group, and their thermal behavior was subsequently analyzed. To investigate the influence of N-(C(2)H(5))(4) cations near T (C), temperature dependences of the resonance frequency and chemical shifts in the (1)H, (13)C, and (14)N NMR spectra were analyzed. The abrupt change in the (1)H NMR resonance frequencies near T (C), in contrast to the variations observed in the (13)C and (14)N chemical shifts, is suggested to be closely related to the change in the Cl ligand of the CoCl(4) group nearest to the terminal methyl group. Furthermore, the activation energies for the molecular motions determined from the (1)H spin-lattice relaxation time in phases I and II were 4.16 and 1.08 kJ/mol, respectively. It can be inferred that CH(2) and CH(3) groups move more freely in phase II, in contrast to phase I, where the [N-(C(2)H(5))(4)](+) cation displays mostly unified overall motion. We compared the results for [N-(C(2)H(5))(4)](2)CoCl(4) obtained in this study and [N-(C(2)H(5))(4)](2) BCl(4) (B=Cu and Zn) obtained by our previous group. The fundamental mechanism of the phase transition in the [N-(C(2)H(5))(4)](2)CoCl(4) crystal of the A (2) BX (4) type indicates that this material may be effectively utilized in diverse application areas.