Structural Change Accompanying Crystallization in the Lithium Ion Conductive Li₂S-SiS₂-Li₃PO₄ Oxysulfide Glasses

Abstract

The structural change of the (100-x) (0.6Li₂S⋅0.4SiS₂)⋅xLi₃PO₄ oxysulfide glasses during crystallization was analyzed by means of solid-state nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS). The unique tetrahedral units of SiO_nS_4-n (n=1, 2, 3) and PO_nS_4-n (n=1, 2, 3) present in the glass samples vanished and the SiS₄, SiO₄, PS₄ and PO₄ units increased with proceeding of the crystallization process. Nonbridging sulfur and oxygen atoms decreased while bridging oxygens and S^2- increased with proceeding of the crystallization process. Large structural difference between the glass and the corresponding crystallized sample explained the high stability against crystallization found in the oxysulfide glass with the composition of x=5.