Investigation of the Effect of Ionic Transport Properties on Phase Transition in a [CdHgI4:xAgI] Type Mixed Composite System

An experimental investigations concerning the preparation and characterization of the superionic composite system [CdHgI4:xAgI], (x=0.2, 0.4, and 0.6 mol. wt. %), have been undertaken with a view to evaluate the ionic transport properties of the mixed composite system, and to identify the phase transition. Powder samples of various compositions containing x mol. wt. %AgI were synthesized by solid state reactions, where [CdHgI4] system was used as host. Samples were analyzed using powder X-ray diffraction, thermal gravimetric analysis (TGA) techniques. These studies have revealed the formation of new substance having phase transition temperature similar to that of AgI. Detailed electrical conductivity measurement carried out at frequencies of 100 Hz, 120 Hz, 1 kHz, and 10 kHz in the temperature range 150-250 °C by a Gen Rad 1659 RLC Digibridge, have identified the best conducting composition namely 4 mol. wt. %, exhibiting an electrical conductivity of 1.88×10-1 Scm-2K at 543 K and an activation energy of 1.66 eV for Ag+ ion migration within the solid host. Activation energies for the system in eV both for the pretransition and post-transition phase transformations are reported .