Effect of Methylene Chain Length on the Thermodynamic Properties, Ferroelastic Properties, and Molecular Dynamics of the Perovskite-type Layer Crystal [NH(3)(CH(2))(n)NH(3)]MnCl(4) (n = 2, 3, and 4)

[Image: see text] The structures and phase transitions of [NH(3)(CH(2))(n)NH(3)]MnCl(4) (n = 2, 3, and 4) crystals were confirmed through X-ray diffraction and differential scanning calorimetry (DSC) experiments. Thermodynamic properties, ferroelastic properties, and molecular dynamics of three crystals were studied as a function of the number (n) of CH(2) groups in the alkylene chains. The loss in molecular weight due to a decrease in n marked the onset of the partial thermal decomposition. The thermal decomposition temperature, T(d), increased with increasing length of the CH(2) chain. While the ferroelastic twin domain walls for n = 2 and 4 were in the same direction at all temperatures, the domain walls for n = 3 were rotated by 45°, and the direction of extinction in phase II was rotated by 45° with respect to phases I and III. The (1)H and (13)C MAS NMR spectra of the three crystals were recorded as a function of temperature. With increasing length of the CH(2) chain, the (1)H spin relaxation time decreased, indicating that molecular motions were activated. These results provide insights into the thermodynamic properties and structural dynamics of the [NH(3)(CH(2))(n)NH(3)]MnCl(4) crystals and are expected to facilitate their potential applications.