A Hydride Route to Alkali Metal Borides: A Case Study of Lithium Nickel Borides.

Ternary lithium nickel borides LiNi3B1.8 and Li2.8Ni16B8 have been synthesized by using reactive LiH as a precursor. This synthetic route allows for the better mixing of the precursor powders, thus facilitating fast preparation of the alkali metal containing ternary borides. This method is suitable for "fast screening" of multicomponent systems comprised of elements with drastically different reactivities. Crystal structures of the compounds LiNi3B1.8 and Li2.8Ni16B8 were reinvestigated by combination of X-ray single crystal/synchrotron powder diffraction data, solid state 7Li and 11B NMR, and scanning transmission electron microscopy which allow determination of fine structural details including split position of Ni sites and ordering of B vacancies. Field dependent and temperature dependent magnetization measurements are consistent with spin glass behavior for both samples.