Ionic transport in sodium phosphate glasses doped with chlorides of Co, Cd and Ag

Abstract

Several samples of sodium phosphate glasses doped with different concentrations of chlorides of cadmium and cobalt along with samples of undoped sodium phosphate glass have been prepared. Sodium phosphate glasses doped with varying amounts of AgCl have also been prepared to see the role of Ag⁺ ion in modifying the conductivity of sodium phosphate glass. These glasses have been characterized by elemental analysis, X-ray diffraction, IR spectra, differential scanning calorimetry, transference number measurements and electrical conductivity studies. All the glasses are found to be essentially ionic conductors. The undoped sodium phosphate glass has low σ value in comparison to the doped ones. The values of ionic conductivity in Na₂O‑P₂O₅‑CdCl₂ and Na₂O-P₂O₅-CoCl₂ glasses are maximum for 1% CdCl₂ and 5% CoCl₂ doped ones respectively. However, in the case of Na₂O-P₂O₅-AgCl glass the σ values go on increasing with the increasing concentrations of the dopant AgCl and the following sequence is observed.

σ (-CdCl₂) < σ(-CoCl₂) < σ (-AgCl)

These results have been explained on the basis of changes in the structure of sodium phosphate glass matrix by the addition of different dopant cations, viz; Cd²⁺, Co²⁺and Ag⁺.