Dynamics of a glycine molecule in a new ferroelectric glycine phosphite studied by proton NMR

The second moments of the proton magnetic resonance lines and relaxation times in the laboratory frame T-1, in polycrystalline glycinum phosphite (NH(3)(+)CH(2)COOJ)(H2PO3-) were measured. The proton spin-lattice relaxation measurements reveal one minimum due to the C-3 reorientations of the amino groups of glycinum cations. Analysis of the relaxation data yields the activation energy barrier of 28.7 kJ mol(-1). Second moment measurements confirm the phase transition at T-c = 224 K known from different studies. The molecular mechanism of the order-disorder phase transition is discussed. (C) 1998 Published by Elsevier Science Ltd.