Preparation and Conduction Mechanism of Superionic Conducting Glasses in the Systems Aal-Ag₂Ch-P₂Ch₅ (Ch =O. S. Se)

Abstract

Superionic conducting glasses in the systems Aal-Ag₂Ch-P₂Ch₅ (Ch =O. S. Se) were prepared and their properties such as glass transition temperatures, ionic conductivities, electronic conductivities and ion transport numbers were measured. The effect of the replacement of anions, O, S and Se, on these properties and the conduction mechanism were discussed.
The glass-forming region was the widest in the sulfide system; in oxide and selenid e systems the region was smaller and similar each other in the area in the composition triangles. The glass transition temperatures ranged from 50 to 230°C and increased in the order of oxide, sulfide and selenide glasses, provided that the glasses contained the same amounts of Aal-Ag₂Ch-P₂Ch₅. The composition dependence of glass transition temperatures sugge sted the presence of partial covalency between Ag+ and nonbridging anions Ch^-. The conducitivity as high as 10^-2 S·cm^-1 at room temperatare was obtained in each system. The measurement of ion transport numbers revealed that all the glasses obtained were nearly 100% Ag⁺ ion conductors. The electron conductivity was less by 5 to 7 orders of magnitude than the total conductivity. The diffusion path model was concluded to be a more reasonable mechanism of conduction than the random site or the weak electrolyte model.