Electrical investigations in the normal and incommensurate phases of [N(CH3)4]2ZnCl4 single crystals

The dielectric permittivity (epsilon) of TMA-ZC single crystals was measured along the mean crystallographic axes a, b and c, in a temperature range from 273 to 340 K. The epsilon-T relationship exhibited peak values at T-i = 296 K and T-c1 = 279 K for the three axes. These peaks are attributed to the contribution of discommensurations. The d.c. and a.c. electrical conductivity showed anomalous variation at the same transition temperatures, with a remarkable change in the value of the activation energy around the transition temperatures. The j-E characteristic indicates different types of electrical conduction. The mechanism of the phase transition and the electrical process were discussed on the basis of Shottky and Frenkel conduction mechanisms. (C) 2002 Elsevier Science Ltd. All rights reserved.