Structural Behavior of Li2B10H10

On the basis of X-ray and neutron powder diffraction, first-principles calculations, and neutron vibrational spectroscopy, Li2B10H10 was found to exhibit atypical hexagonal symmetry to best stabilize the ionic packing of the relatively small Li+ cations and large ellipsoidal B10H102– anions. Moreover, differential scanning calorimetry and neutron-elastic-scattering fixed-window scans suggested that Li2B10H10, similar to its polyhedral cousin Li2B12H12, undergoes an order–disorder phase transition near 640 K. These results provide valuable structural information pertinent to understanding the potential role that Li2B10H10 plays during LiBH4 dehydrogenation–rehydrogenation as well as its prospects as a superionic Li+ cation conductor.