Electrical conductivity of AgI–CdI2–KI and AgI–CuI–KI ionic conducting systems

Samples of general formulae (AgI)4−2x(CdI2)xKI and (AgI)4−x(CuI)xKI, x = 0–0.4, have been prepared and studied by conductivity measurements, powder X-ray diffraction and DSC techniques. Room temperature XRD reveals the presence of the orthorhombic K2AgI3 as the major component in the system. DSC traces show endothermic peaks in the temperature range of 309–330 K, depending on the sample composition. These are attributed to the solid state reaction between AgI and K2AgI3 to form the cubic KAg4I5. Impedance spectra show the prominence of electrode – electrolyte interface effect which is explained in terms of the high rate of ion migration. Ionic conductivity enhances with the increase of Cd2+ content, while Cu+ contained samples show a decrease in conductivity with increasing Cu+ ratio though the ionic conductivity remains higher than that of the pure one.