Time relaxation of dielectric constant in the commensurate phase of TlGaSe2

The results of measurements of the time dependences of the dielectric constant of TlGaSe2 in the commensurate ferroelectric phase are presented. From the result of the observation of the decay of ε at different stabilized temperatures below the commensurate phase transition temperature after cooling from the incommensurate phase, the presence of two different characteristic relaxation time constants with the same temperature behaviour has been revealed. This peculiarity is considered as a result of a coexistence of two polar sublattices in the temperature range below 110 K. According to these results, the previously reported dielectric anomaly at about 103 K is considered as a final lock-in phase transition accompanied by the forming of the antiferroelectric state in TlGaSe2.