Observation of a new phase in the Li-B system.

The simple compounds of boron and light elements have attracted interest since the unexpected discovery of high temperature phonon-coupled superconductivity (SC) in MgB$_{2}$. The numerous theoretical works show that the Li-B system has electronic features similar to those in MgB$_{2}$ and compounds in the system are expected to be superconducting. In fact, there were early reports of Li-B compounds. Although the small Li-size suggests a rich phase-diagram, the previous investigations discovered only one stable compound over a broad initial stoichiometry. The extreme reactivity and hydrolyses of Li in air may be partially responsible for this. We were able to synthesize a new Li-B pure phase that belongs to hexagonal symmetry through a new synthesis procedure. We report on the structural, magnetic, and electron energy loss spectra (EELS) analyses of this compound. Despite the similarity with the electronic structure of MgB$_{2}$, the Li-B system has not yet shown the existence of SC.