Dielectric Relaxation in the Incommensurate Phase of {N(CH3)4}2 ZnCl4

The complex dielectric constant of {N(CH 3 ) 4 } 2 ZnCl 4 crystal has been measured in the incommensurate phase in the frequency range from 30 kHz to 10 MHz. It has been found that the dielectric dispersion occurring along the ferroelectric a -axis is of the Debye-type with a single relaxation time in the incommensurate temperature range except the close vicinity of the commensurate-incommensurate phase transition point T c . In the incommensurate phase, the relaxation time increases nearly in inverse proportion to ( T - T c ) and reaches to the value of about 1.2×10 -7 sec at just above T c .