Open AccessEffect of Methylene Chain Length on the Thermodynamic Properties, Ferroelastic Properties, and Molecular Dynamics of the Perovskite-type Layer Crystal [NH3(CH2)nNH3]MnCl4 (n = 2, 3, and 4)
Author(s) -
Seon Ju Lee,
Moon Young Choi,
Ae Ran Lim
Publication year - 2021
Publication title -
acs omega
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.779
H-Index - 40
ISSN - 2470-1343
DOI - 10.1021/acsomega.1c01782
Subject(s) - differential scanning calorimetry , molecular dynamics , relaxation (psychology) , phase (matter) , crystallography , crystal (programming language) , methylene , chemistry , diffraction , perovskite (structure) , thermal decomposition , phase transition , materials science , thermodynamics , computational chemistry , organic chemistry , physics , psychology , social psychology , computer science , optics , programming language
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.