ANOMALOUS DIELECTRIC BEHAVIOR OF NH2(CH3)(2)AL(SO4)(2)CENTER-DOT-6H(2)O CRYSTALS IN THE FERROELECTRIC PHASE

The temperature- and frequency-dependent dielectric susceptibility par allel to the ferroelectric axis of NH2(CH3)(2)Al(SO4)(2).6H(2)O crysta ls was studied in the ferroelectric phase. The dispersion correspondin g to a critical slowing down of the thermal dipole relaxation was obse rved in the vicinity of T-c in the frequency range 1-10 MHz. Besides, a dispersion which is related to the dipole reversal within the domain walls was found at lower frequencies. The latter is much more pronoun ced in the deuterated sample and is thought to be connected with the d ynamics of hydrogen bonds.