Structural, Thermal, and Electrical Behavior of Cu-Substituted KPbI3 Ternary Compound

Abstract

Series of ion conducting system (KI)_4 – x‒(CuI)_x‒PbI₂, x = 0.0‒0.4, have been prepared by solid state reaction method and studied by powder X-ray diffraction, DTA techniques and conductivity measurements. Room temperature XRD reveals the presence of the orthorhombic KPbI₃ as the major component in the sample. The X-ray diffraction analysis also confirms the presence of both KI and CuPbI₃ in the samples. DTA of x = 0.0 composition shows an endothermic peak at 349°C attributed to the melting of the compound. AC impedance spectroscopy revealed that the contribution of grain is strong over the grain boundary. The addition of CuI content results in the increase of electrical conductivity of the samples. The maximum ionic conductivity σ = 6.33 × 10^–1 S cm^–1 was shown by x = 0.3 composition at 633 K with lowest activation energy of ~0.11eV in the temperature range of 298‒633 K.