Study of the ferroelastic phase transition in the tetraethylammonium compound [N(C2H5)4]2ZnBr4 by magic-angle spinning and static NMR

The ferroelastic phase transition of tetraethylammonium compound [N(C2H5)(4)](2)ZnBr4 at the phase transition temperature (T-C) = 283 K was characterized by magic-angle spinning (MAS) and static nuclear magnetic resonance (NMR), and confirmed by optical polarizing spectroscopy. The structural geometry near TC was studied in terms of the chemical shifts and the spin-lattice relaxation times T-1 rho in the rotating frame for H-1 MAS NMR and C-13 cross-polarization (CP)/MAS NMR. The two inequivalent ethyl groups were distinguishable in the C-13 NMR spectrum, and the T-1 rho. results indicate that they undergo tumbling motion above T-C in a coupled manner. From the N-14 NMR results, the two nitrogen nuclei in the N(C2H5)(4)(+) ions were distinguishable above T-C, and the splitting in the spectra below T-C was related to the ferroelastic domains with different orientations. (c) 2016 Author(s).