It was pointed out that a range of stable solid solutions with the -LISICON type structure formed in the Li4-2xGe1-xSxO4 system, at x-values of between 0.08 and 0.42. This phase exhibited a high Li ion conductivity, with a maximum value (in the bulk) of about 1.85 x 10-5S/cm for x = 0.20 at 27C. The net pellet conductivity for this composition was about 1.0 x 10-5S/cm at 27C; increasing to about 0.04S/cm at 300C. Conductivity Arrhenius plots for various compositions in the -solid solution range exhibited a markedly non-linear behavior at temperatures above about 300C. The activation energies below this temperature ranged from 0.50 to 0.60eV. The  solid solutions were structurally related to orthorhombic -Li3PO4, and contained interstitial Li+ ions for x = 0.20; with a = 0.6253, b = 1.0828, and c = 0.5114nm at room temperature.

M.A.K.L.Dissanayake, R.P.Gunawardane, A.R.West, G.K.R.Senadeera, P.W.S.K.Bandaranayake, M.A.Careem: Solid State Ionics, 1993, 62[3-4], 217-23