71Ga NMR in chalcogenide and chalco-halide glasses

Chalcogenide and chalco-halide glasses containing gallium have been studied through 71Ga solid state nuclear magnetic resonance (NMR). An unusual line shape of the 71Ga NMR spectra has been observed for the first time. This line shape was ascribed to the preferential local symmetry existing around gallium atoms in these glasses which are characterized by the covalent character of their chemical bonds. Then, the local environment of gallium in Ga2S3-GeS2-CsCl glasses was studied by 71Ga NMR as a function of the ionic cesium chloride CsCl concentration. In this system, CsCl directly interacts with Ga by forming anionic complexes, modifying its environment. The Czjzek's electric field gradient distribution and its recent extension have been successfully applied to reconstruct the experimental 71Ga NMR spectra. These results highlight the evolution of local surroundings of Ga atoms in the glass network as a function of the CsCl concentration.