The crystal structure of WAl12, MoAl12and (Mn, Cr)Al12

The crystal structure of WAllg.has been determined from powder samples.The unit cell is bodycentred cubic and a ----7.580 A. There are two WAll~ units per cell.The space group is T~-Im3.Two W atoms are placed in special positions 0, 0, 0, ~,1 :t2, '~ and 24 A1 atoms are in positions 24(g) with y ----0.184and z = 0.309.The calculated density is 3.88 g.cm.-a.MoAll~ and (Mn, Cr)All~ (the G phase) are isomorphous with WA119.a ----7.573i for MoAll~ and a = 7.507 /t, for (Mn, Cr)All~.