Short and medium range order in Ga-Ge-S glasses: An X-ray absorption spectroscopy study at room and low temperatures

Glasses belonging to the Ga2S3-GeS2 line are studied at room temperature and at 7 K by XAFS spectroscopy at Ga and Ge K-edges, The results show that the addition of Ga2S3 to the GeS2 glass former leads to the formation of tetrahedral units of GaS4, linked to the GeS4 tetrahedra. Mainly low temperature measurements of the Ge K-edge allow an analysis of the short and medium range order. As the Ga content increases a substitution takes place of corner-sharing linkages with edge-sharing linkages of (Ge/Ga)S-4 tetrahedral units. (C) 1996 Academic Press, Inc.