Phase Transitions and Ionic Motions Including Self-Diffusion in Solid Trimethylammonium Tetrafluoroborate Studied by 1H and 19F NMR

Abstract 1H and 19F NMR of (CH3)3NHBF4 were measured in the three solid phases. In Phase I existing above 453 K, the cations and anions were found to perform rapid self-diffusion as well as isotropic reorientation. In Phase II (384 ≤ T/K ≤ 453), the onset of self-diffusion of the anions and the isotropic reorientation of the cations was observed. In Phase III stable below 384 K, C3 reorientations of the CH3 groups and the whole cation, and the anionic isotropic reorientation were detected.