Structural change accompanying crystallization in the lithium ion conductive Li2S-SiS2-Li3PO4 oxysulfide glasses

The structural change of the (100 - x) (0.6Li(2)S . 0.4SiS(2)). xLi(3)PO(4) 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 SiOnS4-n (n = 1, 2, 3) and POnS4-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 S2- 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.