ROOM-TEMPERATURE SYNTHESIS STUDY OF HIGHLY DISORDERED A-NI2P2S6

The metathesis reaction in aqueous media between Ni2+ and (P2S6)4- ions, leading after drying to the Ni2P2S6 phase, was followed by in situ X-ray absorption. This reaction proceeds regularly to the final sulfide phase. The complexes formed in water during the reaction as deduced from the EXAFS study correspond to single sheet crystallites with a diameter of approximately 0.5 nm and a composition close to (H or Li)1.6Ni2(P2S6)1.4. After drying, this phase does present a local structure corresponding to crystallized Ni2P2S6 and a transmission electron microscopy study confirms the occurrence of these crystallites, scattered within an amorphous matrix. The temperature dependence of the magnetic susceptibility has been measured from 5 to 310 K. The magnetic behavior, which shows magnetic ordering of only the crystalline portion of the phase, is well explained by the structure of the end-product a-NiPS3.