LOW-TEMPERATURE HEAT-CAPACITY OF ACRIDINIUM DITETRACYANOQUINODIMETHANIDE [ACRIDINIUM (TCNQ)2]

The heat capacity of a high-purity sample of acridinium dietetracyanoquinodimethanide [acridinium (TCNQ)2 or Ad(TCNQ)2] was measured at temperatures from 0.5-10 K in fields of 0, 10, 20, and 40 kOe. The results are shown to correspond very well, within the experimental accuracy, to a superposition of a T3 lattice contribution and a random-exchange antiferromagnetic Heisenberg-chain magnetic contribution. The Bulaevski theory parameters derived from these heat-capacity measurements without the use of any exogenous data are found to be α=0.75±0.01 and A=(1.69±0.04)×10-3 K-0.25. The Debye temperature is found to be 68.3±0.2 K. © 1979 The American Physical Society.