High resolution solid state NMR studies of ionically conductive Li2S-SiS2-Li2O-P2O5 oxysulphide glasses

Glass structure of oxysulphide glasses of composition (1-y) [xLi(2)S. (100- x)SiS2].y[xLi(2)O.(100-x)P2O5] (50 less than or equal to x less than or equ al to 65; y=0.05, 0.20) was systematically investigated using Si-29 and P-3 1 MAS-NMR measurements by changing x, the total lithium ion concentration, and also by changing y, the amount of oxide Li2O-P2O5 added to the sulphide Li2S-SiS2. fn the case of changing x with a constant y=0.05 the amounts of SiOnS4-n (n=1,2,3) tetrahedral units were maximised and those of SiS4 tetr ahedral units were minimised in the glass with x=55. PS4 and POS3 tetrahedr al units were mainly present in the range 50 less than or equal to x less t han or equal to 58. However; the amounts of PO2S2, PO3S and PO4 tetrahedral units increased with an increase of x in the range 60 less than or equal t o x less than or equal to 65. In the case of changing y with a constant x=6 0 the fraction of SiS4, PS4 and POS3 units decreased with an increase of y from 0.05 to 0.20.