A structural study of Ag-rich Ag-As-S glasses

Thermal behavior, density, infrared absorption and X-ray photoelectron spectroscopy of AgxAs60-xS40 bulk glasses (35 less than or equal to alpha less than or equal to 47.5) have been investigated to obtain structural information on glasses that exhibit photoinduced surface deposition (PSD) of Ag. The compositional trends in the range of 40 less than or equal to x less than or equal to 47.5, where the PSD effect is observed, were very different from those in the range of 35 less than or equal to x less than or equal to 40. The trends in the range of 40 less than or equal to x less than or equal to 47.5 can be explained by assuming the existence of excess Ag+ ions in the glasses. The excess Ag+ ions, which contribute to the PSD, may lie between isolated AsS3 pyramids and bind loosely with surrounding S atoms.