PHASE-TRANSITION IN THE TCNQ COMPLEX SALT FORMED FROM THE CATION (METHYL-1-N-ETHYL BENZIMIDAZOLIUM)+

During cooling, the electrical conductivity measured in crystalline needles of (Me 1—NEt Bz)+ · (TCNQ) 2− undergoes a discontinuity from which it drops by a factor which can be as large as 300. The temperature at which the discontinuity occurs, of the order of 250 K, varies from needle to needle. If the needle is then re‐heated, its conductivity increases quite regularly and continuously, and after thermal cycling the starting value is practically recovered. The discontinuity is never observed with larger specimens of the same material, produced by re‐crystallisation. In this case it is then replaced by a steep but continuous conductivity anomaly. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA