Some novel fast ionic solids in the mixed system were made to prepare [0.7(Ag₂CdI₄):0.3(AgI_x:CuI_(1-x))] where x = 0.2, 0.4, 0.6 and 0.8 mol. wt. % respectively by solid state reaction and quenching them at particular temperature. Powdered samples of different compositions containing x mol. wt. % of (AgI_x:CuI_(1-x)) were synthesized by solid state reactions, using [Ag₂CdI₄] ternary halides as host. Powder specimens of these compositions were analyzed using differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), Fourier transmission infrared spectra (FTIR) and x-ray powder diffraction (XRD) techniques. In host system, Ag and Cu substitution appears to stabilize the high-temperature, hexagonal structure to temperature well in excess of 445 K, associated correspondingly with the melting of the (Ag⁺:Cu⁺) sublattice and with the storage of iodide/or cadmium sublattices.

Keywords: Fast-Ion Conductor; X- Ray Diffraction; Thermal Analysis; Doping;