An EXAFS structural approach of the lanthanum-gallium-sulfur glasses

• Published in: Journal of non-crystalline solids 1989-07, Vol.110 (1), p.89-100
• Main Authors: Benazeth, S, Tuilier, M.H, Loireau-Lozac'h, A.M, Dexpert, H, Lagarde, P, Flahaut, J
• Format: Article
• Language: English
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Chemical industry and chemicals; Exact sciences and technology; Glasses; Structure, analysis, properties
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/0022-3093(89)90186-5

Three La: Ga:S glassy compositions spanning the range of the vitreous region, have been investigated by EXAFS (gallium K-edge, lanthanum LIII edge). As a first result, the gallium is found tetracoordinated for any composition and the GaS 4 polyhedra are the glassy former units (average GaS distances = 2.27 A ̊ ). The lanthanum modifying cation has the same mean surrounding as in the crystalline state, but with more dispersed LaS distances (average LaS surrounding = seven first neighbours, situated from 2.91 to 2.93 Å). However disordered, this environment is well defined. A structural model is then proposed as a covalent network of GaS 4 tetrahedra, intercalated by the essentially ionic LaS channels. This model is close to the modified random network usually presented for the oxide glasses.