We have measured the complex dielectric constant of Ta${\mathrm{S}}_3$ and Nb${\mathrm{S}}_3$ at 9.8 GHz. In the charge-density-wave state the conductivity at this frequency is several orders of magnitude larger than the dc value. The dielectric constant is of the order of ${10}^5$ in both systems. Using the overdampedoscillator model, we calculate the temperature dependence of the crossover frequency as well as obtain estimates of the damping frequency and effective mass in Ta${\mathrm{S}}_3$.

• Received 15 July 1982

DOI:https://doi.org/10.1103/PhysRevB.28.910