Lithium magnesium thiophosphate, Li4-2xMgxP2S6, was synthesized, and its crystal structure and ionic conduction were investigated. The structure was CdI2 type, where two thirds of the Cd sites were occupied by Mg2+ and Li+ ions with an occupancy ratio of x/(2-x), and the residual Li+ ions reside in the van der Waals gap in the CdI2 structure. (P4+)2 paired-ions occupy the octahedral sites in the van der Waals gap as well as the remaining Cd sites with a statistical distribution. With the increase in the Mg composition, the occupancy for the former sites decreased. As a result, the vacancies were generated in the alternate Li layers, where Li+ ions become mobile.

Lithium Ion Conduction in Lithium Magnesium Thiophosphate. K.Takada, T.Inada, A.Kajiyama, H.Sasaki, S.Kondo, M.Watanabe, M.Kanda: Solid State Ionics, 2002, 147[1-2], 23-7