Mechanochemically synthesized Ag 2S–Sb 2S 3 amorphous fast ionic conductors

Abstract

The mechanochemical synthesis of (Ag 2S) x –(Sb 2S 3) 1− x amorphous fast ion conductors (a-FICs) and their structural, thermal and electrical characterizations are investigated. It is found that after ∼10 h of ball-milling, the composition 0.85Ag 2S–Sb 2S 3 becomes amorphous and attains a conductivity of ∼6 × 10 −3 Ω −1 cm −1 at 25 °C which is three times greater than that of the analogous melt-quenched glass. These a-FICs are found to be predominantly ionic in nature and stable under battery conditions. By examining conductivity ( σ) versus composition ( x), it is concluded that the sharp rise in the conductivity with the dopant Ag 2S content is largely due to a significant increase in the mobility ( μ) of Ag + ions. These results imply that the role of salts (such as Ag 2S) is not so much to provide free (Ag +) ions for conduction but to modify the glass structure in a manner that favours fast ion transport. It is believed that these findings will guide the development of various models to relate ion transport with glass structure.