Electrical properties of K2ZnCl4 crystal pure and doped with Co2+ ions between 300 and 500 K

The dielectric constant epsilon and the electrical conductivity sigma were measured of crystalline plates cut perpendicular to the a-, b-, and c-axes from K2ZnCl4 (KZC) crystals, pure and doped with Co2+ ions, in the temperature range from 300 to 500 K. A pronounced broad peaks exists at the commensurate-incommensurate phase transition temperature (T-c1). A thermal hysteresis of about 10 K is observed for the transition during heating and cooling processes. The J-E characteristics along the crystallographic axes were measured below and above T-c1. Conductivity anomalies were observed at T-c1. The results of electrical conductivity temperature measurements were analyzed and the activation energies of conduction at different temperature regions have been evaluated. The mechanism of the electrical conduction of the various phases and the anomaly at the transition point was discussed.