Abstract
Cu2HgI4 powder was prepared at room temperature using the reactive chemical solutions process. The structure of the prepared powder was identified by X-ray diffraction. The dc electrical conductivity, sigma(dc), studied in the temperature range 303-370 K shows a drastic change around 340 K, which is attributed to a phase transition from a first-order phase to a fast ion-conducting one. The frequency dispersion curves of the conductivity, sigma(ac)(omega), capacitance, C-x, real and imaginary parts of the dielectric constants, epsilon', epsilon '', and loss-factor, tan delta have been investigated in the frequency range 10(2)-10(5) Hz and temperature range 303-354 K. A characteristic hopping frequency, omega(p), was found to be involved in the conduction mechanism, above which the conductivity obeys the universal power-law behaviour. The variation of capacitance with frequency was explained according to the Goswami and Goswami model. The frequency dependence of the loss tangent, tan delta, shows a relaxation peak which shifts towards higher frequency with increasing temperature., indicating a characteristic feature of the Debye-type relaxation. The imaginary part of the dielectric constant, epsilon '', varies inversely with frequency. The maximum barrier height, W-m, has been calculated at different temperatures and was used to calculate the theoretical value of the material optical band gap, E-g.