Structural Behavior of Li2B10H10

On the basis of X-ray and neutron powder diffraction, first-principles calculations, and neutron vibrational spectroscopy, Li 2 B 10 H 10 was found to exhibit atypical hexagonal symmetry to best stabilize the ionic packing of the relatively small Li + cations and large ellipsoidal B 10 H 10 2– anions. Moreover, differential scanning calorimetry and neutron-elastic-scattering fixed-window scans suggested that Li 2 B 10 H 10, similar to its polyhedral cousin Li 2 B 12 H 12, undergoes an order–disorder phase transition near 640 K. These results provide valuable structural information pertinent to understanding the potential role that Li 2 B 10 H 10 plays during LiBH 4 dehydrogenation–rehydrogenation as well as its prospects as a superionic Li + cation conductor.