Peculiarities of Dielectric Relaxation in DMAAS Ferroelectric Crystals

This paper presents the results of investigations of the dielectric properties of NH$\text{}_{2}$(CH$\text{}_{3}$)$\text{}_{2}$Al(SO$\text{}_{4}$)$\text{}_{2}$×6H$\text{}_{2}$O crystals performed in a wide frequency range. In particular, the temperature and frequency dependences of the dielectric permittivity were measured in the region of ferroelectric phase at different rates of temperature change. The thermal dipole relaxation with a critical slowing-down at T$\text{}_{c1}$ was observed at comparatively low frequencies of measuring field. The relaxation connected with the domain freezing takes place at still lower frequencies (below 100 kHz) and was found to be strongly dependent on the rate of the temperature change. It was shown that deuteration results in a noticeable change of the parameters characterising this process including the temperature of domain wall freezing.