Transport studies on mechanochemically synthesized amorphous AgI–Ag2 O–CrO3 superionic system

Abstract

Mechanochemical synthesis, a relatively new technique in the field of solid state ionics, has been successfully used to obtain highly conducting amorphous materials of composition x AgI(100−x)[0.5Ag2O+0.5CrO3] for x=50, 60 and 70. The ionic conductivity of ball-milled amorphous samples is found to be ∼10−2 Ω−1cm−1 at room temperature which is ∼3 orders of magnitude higher than that of AgI and comparable with superionic glass of the same compositions. The amorphous samples are thermally stable upto ∼100 °C. On annealing the samples at ∼110 °C there is precipitation of AgI and Ag2O nanocrystallites of size ∼10 nm. For all the samples the ionic transport number is found to be near unity. The galvanic cells of the type Ag|a-SIC|I2+C, fabricated using mechanically milled materials as electrolyte, are thermodynamically stable. The electrical, structural, electrolytic and thermal properties are very much close to those of AgI–Ag2O–CrO3 and AgI–Ag2CrO4 superionic glasses investigated earlier.