NMR studies of phase transition in ammonium hydrogen bischloroacetate, NH4H(CH2ClCOOO)2

Proton second moment (M2) and spin-lattice relaxation time (T1) of Ammonium Hydrogen Bischloroacetate (ABCA) have been measured in the range 77-350 K. A value of 6.5 G2 has been observed for the second moment at room temperature, which is typical of NH4+ reorientation and also a second moment transition in the range 170-145 K indicates the freezing of NH4+ motion. The NMR signal disappears dicontinuously at 128 K. Proton spin-lattice relaxation time (T1) Vs temperature, yielded only one sharp miniumum of 1.9 msec which is again typical of NH4+ reorientation. A slope change at 250 K is also observed, prbably due to CH2 motion. Further, the FID signal disappears at 128 K. Thus the Tc appears to be 128 K (of two reported values 120 K and 128 K). Activation energies have been calculated and the mechanism of the phase transition is discussed.

[1]  G. Soda,et al.  Ferroelectric Phase Transition in Ammonium Hydrogen Bis(Chloroacetate). V. Nuclear Magnetic Resonance of NH4H(CH2ClCOO)2 and ND4D(CH2ClCOO)2 , 1981 .

[2]  R. K. Shenoy,et al.  A solid state pulsed NMR spectrometer , 1980 .

[3]  H. E. Petch,et al.  Nuclear magnetic resonance study of ionic motions in ammonium bifluoride , 1979 .

[4]  J Ramakrishna,et al.  A simple and inexpensive two channel boxcar integrator , 1979 .

[5]  Y. Furukawa,et al.  Molecular motion in ammonium hydrogendifluoride studied by pulsed NMR. , 1979 .

[6]  S. Ganguli,et al.  Order-disorder type of transition in ferroelectric NH4H(ClCH2COO)2 crystal , 1979 .

[7]  H. Chihara,et al.  Ferroelectric Phase Transition in Ammonium Hydrogen Bis (Chloroacetate). IV. Heat Capacity of NH 4 H(ClCH 2 COO) 2 and ND 4 D(ClCH 2 COO) 2 , 1976 .

[8]  H. Chihara,et al.  Ferroelectric Phase Transition in Ammonium Hydrogen Bis (Chloroacetate). III. Chlorine-35 Quadrupole Relaxation , 1974 .

[9]  H. Chihara,et al.  Raman and Infrared Studies of the Ferroelectric Transition in NH4H(CICH2COO)2 and ND4D(CICH2COO)2 , 1974 .

[10]  G. Soda,et al.  Note on the Theory of Nuclear Spin Relaxation Exact Formulae in the Weak Collision Limit , 1974 .

[11]  H. Chihara,et al.  Ferroelectric Phase Transition in Ammonium Hydrogen Bis (Chloroacetate) I. Nuclear Quadrupole Resonance in NH4H(ClCH2COO)2 and ND4D(ClCH2COO)2 , 1973 .

[12]  M. Ichikawa.  The crystal structure and phase transition of ammonium hydrogen bis-chloroacetate. II. The crystal structure of the ferroelectric phase , 1972 .

[13]  E. R. Andrew,et al.  Nuclear Magnetic Resonance , 1955 .

[14]  E. R. Andrew.  NUCLEAR MAGNETIC RESONANCE MODULATION CORRECTION , 1953 .

[15]  H. S. Gutowsky,et al.  Structural Investigations by Means of Nuclear Magnetism. II. Hindered Rotation in Solids , 1950 .

[16]  E. Purcell,et al.  Relaxation Effects in Nuclear Magnetic Resonance Absorption , 1948 .