INVESTIGATION OF ANTIMONY LOCAL ENVIRONMENT IN SOME Sb2S3-As2S3-Sb2Te3 GLASSES BY MOSSBAUER SPECTROSCOPY

Some glasses with Sb2Te3 constant concentrations at 0, 20 and 40 mol% in Sb2S3-As2S3-Sb2Te3 system have been studied by means of Sb-121 Mossbauer spectroscopy. Mossbauer parameters such as the isomer shift (delta), the quadrupolar interaction (Delta) and the linewidth (Gamma) have been used to investigate the local environment of 121 antimony concerning its oxidation state, its coordination, the nature of the chemical bonding in the polyhedron coordination and the stereochemical activity of the non-bonded pair called E. The interpretation of the results has indicated that the negative values of isomer shift (delta) are characteristic of pyramidal environments (SbS3E) in all studied cases. The increase in delta as the function of As2S3 content has been attributed to an increasing of Sb-S covalency bonds in SbS3E pyramidal units. The length of Sb-S bonds decreased and became short. The increasing of Delta in the cases of Sb2S3-As2S3 system and 20 mol% Sb2Te3 section in Sb2S3-As2S3-Sb2Te3 system has indicated an increase in the stereochemical activity of antimony atom's lone pair. The decrease in Delta for glasses of 40 mol% Sb2Te3 section has induced a decreasing of the stereochemical activity of the lone pair and the covalency of Sb-S bonds in these suggested case.