%0 journal article %@ 0360-3199 %A Pistidda, C., Napolitano, E., Pottmaier, D., Dornheim, M., Klassen, T., Baricco, M., Enzo, S. %D 2013 %J International Journal of Hydrogen Energy %N 25 %P 10479-10484 %R doi:10.1016/j.ijhydene.2013.06.025 %T Structural study of a new B-rich phase obtained by partial hydrogenation of 2NaH + MgB2 %U https://doi.org/10.1016/j.ijhydene.2013.06.025 25 %X The structure of an unknown crystalline phase observed during the hydrogen absorption reaction of the powder mixtures 2NaH + MgB2 at high pressure has been studied by ab-initio structure determination from powder diffraction. The sequence of un-overlapped peaks extracted from the X-ray powder diffraction pattern could be indexed with a primitive cubic cell with lattice parameter a = 7.319 Å. The diffraction patterns of the peaks are matched with the Pa-3 space group. The stoichiometry of the hydrogen absorption reaction suggests the presence of a high-boron content phase in the compound under investigation. Assuming this phase to be composed only by boron atoms and therefore having a density similar to that found for boron polymorphs, the solution with a space group of Pa-3 leads to reasonable B–B interatomic distances.