Abstract
The ionic conductivity and phase transition temperature of binary and doped binary system [(AgI)(x)-(PbI2)1-x, x = 2/3] were investigated by electrical conductivity, DSC and X-ray diffraction techniques. The conductivity of binary sample was gradually increased and followed by an abrupt jump during 400-420 K. It indicates a superionic phase and evidence of a compound f.c.c-AgxPb1-xI2-x, x = 2/3 (Ag2PbI4). Substitution of cations (K+ and Cu+) modified the conductivity in pre- and post-transition regions of binary systems. These results provide further insight into complexities of phase transition, thus help arriving at a mechanism governing the ionic transport/mobility. The slow variation accompanied by a gradation in dielectric constant was attributed to the free ions that build up space-charge and restructuring of lattice. The activation energy of K+-doped system is found to be lower than that of Cu+\-doped system in post-transition region.