Abstract
The ionic conduction properties of undoped and doped Tl4HgI6 were investigated using electrical conductivity, dielectrics, differential scanning calorimetry, and X-ray diffraction techniques. The heavy Tl+-ions diffusion was activated at high temperature, whereas low conductivity at. the lower temperature suggested electronic contribution in undoped Tl4HgI6. The partial replacement of heavy Tl+ ion by suitable cations (Ag+ and Cu+) enhanced the conductivity by several orders of magnitude, whereas diminution in conductivity results with increasing dopants' concentration in Tl4HgI6. These results can be interpreted in terms of a lattice contraction and vacancy-vacancy interaction (leading to the cluster formation), respectively. The dielectric values of undoped Tl4HgI6 system gradually increasing with temperature, followed by a sharp change, were observed around 385 K and can be explained on the basis of increasing number of space charge polarization and ions jump orientation effects. The activation energy of undoped and doped Tl4HgI6 systems were calculated, and it was found that ionic conductivity activation energy for 5 mol% of cation dopants is much lower than that of undoped one, and also 10 mol% doped Tl4HgI6 systems.