Phase Transitions in Dimethylammonium Tetrafluoroborate and Molecular Motions in Its Ionic Plastic Phase Studied by 1H and 19F NMR, Thermal Measurements, and X-Ray Powder Diffraction Techniques

摘要: Three solid phases of (CH3)2NH2BF4 were found between 200 K and the melting point (375 K) by differential thermal analysis, scanning calorimetry, 1H 19FNMR measurements. The highest-temperature phase obtainable above 283.5 was shown to be an ionic plastic phase, where cations as well anions perform rapid translational self-diffusion isotropic reorientation about their center gravity. crystal in this revealed form a CsCl-type cubic structure with α = 5.35 A at ca. 290 powder X-ray diffraction. two transitions, from lowest-temperature intermediate one highest temperature successively occur nearly same ± 0.5 K. could clearly observed undercooled state.