Structural characterisation of CsCl incorporation in Ga2S3–La2S3 glasses

Abstract We report X-ray absorption spectroscopy study of (80− x )Ga 2 S 3 –20La 2 S 3 – x CsCl glasses, with x =0–40. The addition of CsCl to Ga 2 S 3 –La 2 S 3 glasses increases their thermal stability making them suitable a host-matrix for luminescent rare earth ions. The gallium-based network is composed of almost regular tetrahedra of sulfur atoms connected by corners. The average local lanthanum site is a distorted polyhedron of sulfur atoms at a distance of 2.96±0.01 A, with a coordination number close to 7. There is no alteration in the local environment of these elements in the doped glasses with respect to the undoped one detected in the X-ray absorption spectra. The chlorine and cesium sites, as observed in the X-ray absorption spectra, are similar to that in CsCl. These experimental observations are compatible with a model in which these elements are incorporated in network ionic vacancies in the form of CsCl n units.