Formation and ionic conductivity of Li2S–GeS2–Ga2S3 glasses and thin films

Li2S–GeS2–Ga2S3 glasses and thin films were prepared and their conductivities were compared. Bulk glasses were melted in Si-coated silica tubes. The glass-forming region was observed at cation ratios of 0 or 40–70% Li and less than 50% Ga. Thin films with a wider composition range were formed by RF sputtering. Conductivities were almost identical in bulk glasses and films of similar composition and increased along with increasing Li2S content. Conductivity and glass transition temperature (Tg) increased slightly with addition of a moderate amount of Ga2S3. These results are due to the mixed-former effect.