Chemical characteristics of Dy-S bonds in Ge-As-S glass

From Dy L-3-edge extended X-ray absorption fine structure spectroscopic analysis of Dy-doped Ge-As-S glass, we verified that both the coordination number and Dy-S distance are decreased in this representative chalcogenide glass compared to those in the Dy2S3 crystalline counterpart. The strong covalent nature inherent in chemical bonds between the constituent atoms of Ge-As-S glass would be responsible for the enhanced covalency of the Dy-S bonds, which would then be sensitively related to the optical characteristics of the 4f <-> 4f transitions of Dy3+ as well as the low rare-earth solubility exhibited by the Ge-As-S glass. (C) 2007 Elsevier B.V. All rights reserved.