REACTION AND DIFFUSION IN SILVER-ARSENIC CHALCOGENIDE GLASS SYSTEMS

The diffusion of Ag from the metal or Ag2Se in amorphous As2S3 and As2Se3 at 175°C is accompanied by the reduction of As from a valence of 3+ to 2+ or 2+ to 1 + to maintain charge neutrality in the glass. Only Ag+ diffuses at this temperature; all other ions are essentially immobile. An amorphous reaction‐product phase is formed in the diffusion zone with a composition range of 28.6 to 44.4 at % Ag. The lower limit corresponds to all As cations of 2+ valence (equivalent to amorphous Ag2As2S3); the upper limit, the maximum solubility of Ag in these glasses, corresponds to all As cations of 1 + valence (equivalent to amorphous Ag1As2S3). The diffusivity of Ag in these glasses at 175°C for concentrations of 10 to 35 at.% Ag is Sulfide 4× 10−14 exp[(+0.23±0.01)(at.% Ag)]cm2/s Selenide 2′ 10−11 exp[(+0.14±0.01)(at.% Ag)]cm2/s Copyright © 1979, Wiley Blackwell. All rights reserved