Double-icosahedral Li clusters in a new binary compound Ba(19)Li(44): a reinvestigation of the Ba-Li phase diagram

The binary Ba-Li system was reinvestigated for compositions with less than 80 at. % Li. A new compound, Ba(19)Li(44), stable up to 126 degrees C, was found and structurally characterized. According to single-crystal X-ray diffraction data, the compound crystallizes in a new structure type with a tetragonal unit cell, space group I42d, a = 16.3911(5) Angstrom, c = 32.712(1) Angstrom, Z = 4, and V = 8788.7(5) Angstrom(3). It can be described as a complicated variant of the chalcopyrite structure. Typical for Li-rich phases, Ba(19)Li(44) contains icosahedron-based polytetrahedral clusters.