EXAFS STUDY OF AG-AS-SE AND AG-AS-S IONIC CONDUCTOR GLASSES

The local structure of glasses that belong to the (Ag2Se)x(AsSe)1-x (L1 line), (Ag2S)x(As2S3)1-x (L2 line) and (Ag2Se)x(As2Se3)1-x (L3 line) have been studied using X ray absorption spectroscopy (XAS). The arsenic atoms are three coordinated for all glassy compositions. However, for L2 and L3 line glasses we observed an evolution of the Debye-Waller factor around these atoms, whereas this parameter is constant for L1 line glasses. This is explained by the existence of As-As homopolar bonds in L1 line glasses that block the structure. The same behaviour is observed for the surroundings of the silver atoms . The vitreous transition temperature and the electrical characteristics are reported and analyzed relatively to the structural results.