A series of BaAl2−xSixH2−x (0.4 < x < 1.6) hydrides with compositions and structures in between BaSi2 and BaAl2H2

By substituting Si− with (Al-H)− in trigonal BaSi2, a series of hydrides has been synthesized with compositions BaAl2−xSixH2−x (0.4 < x < 1.6). DFT calculations show that the end compositions BaSi2 and BaAl2H2 are conductors whereas the intermediate BaAlSiH is a semiconductor. The cell parameters for the trigonal cell vary linearly as a function of the Si−/(Al-H)− substitution in this MgB2 related structure type, opening up the possibility of continuously tunable electric properties.