Structure and properties of lithium thio-boro-germanate glasses

Abstract Structural studies of the ternary xLi2S + (1 − x)[0.5B2S3 + 0.5GeS2] glasses using IR, Raman, and 11B NMR show that the Li2S is not shared proportionately between the GeS2 and B2S3 sub-networks of the glass. The IR spectra indicate that the B2S3 glass network is under-doped in comparison to the corresponding composition in the xLi2S + (1 − x)B2S3 binary system. Additionally, the Raman spectra show that the GeS2 glass network is over-modified. Surprisingly, however, the 11Boron static NMR gives evidence that ∼80% of the boron atoms are in tetrahedral coordinated. A super macro tetrahedron, B10S18−6 is proposed as one of the structures in these glasses in which can account for the apparent low fraction of Li2S present in the B2S3 sub-network while at the same time enabling the high fraction of tetrahedral borons in the glass.