Dielectric properties of NH2 (CH3)(2)AL(SO4)(2)center dot 6H(2)O crystals at low temperatures

The dielectric permittivity epsilon' and dielectric loss tg delta of NH2(CH3)(2)AL(SO4)(2) center dot 6H(2)O (DMAAS) crystals were measured in the low-temperature range at different frequencies of the measuring electric field. The existence of a transition to the ferroelectric phase (T-C = 152 K) was confirmed. in addition, anomalies of both dielectric parameters, characteristic of the phase transition were also observed at T-1 = 107 K (on heating) and T-2 = 75 K. It has been found that DMAAS crystals possess a considerable dispersion of e' and tg delta in the temperature range of the ferroelectric phase.