Molecular Motion in Solid Tetramethylammonium Tetrafluoroborate

Abstract

AbstractMeasurements of 11B and 1H NMR relaxation times, differential scanning calorimetry and thermomechanical analysis, carried out on polycrystalline (CH3)4 NBF4 from room temperature to about 100 K, have permitted to discuss the crystal dynamics of this salt and to analyze the nature of the phase transition occurring at ≈ 150 K. Moreover, by means of an evaluation of the 11B quadrupole coupling constant, information about the position of the F atoms has been obtained. An explanation of the NMR data in terms of an order-disorder phase transition involving the F- ions is given.