Room temperature synthesis study of highly disordered a-Ni 2P 2S 6

Abstract

The metathesis reaction in aqueous media between Ni 2+ and (P 2S 6) 4− ions, leading after drying to the Ni 2P 2S 6 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 ∼0.5 nm and a composition close to (H or Li) 1.6Ni 2(P 2S 6) 1.4. After drying, this phase does present a local structure corresponding to crystallized Ni 2P 2S 6 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-NiPS 3.