BI5.6NI5I - A PARTLY OXIDIZED INTERMETALL IC PHASE WITH CHANNEL STRUCTURE

Bi5,6Ni5I was prepared from the elements by chemical vapour deposition . Single-crystal investigations (space group I2/m, a = 1852.1(3), b = 418.45(6), c = 1373.8(3)pm, beta = 90.42(2)degrees, V=1064.7(3).10(6)p m(3)) revealed parallel double-walled channels of nickel and bismuth a toms. The central pseudo 5 axis of each channel is occupied by 6/5 dis ordered bismuth atoms per lattice translation along [010]. Double rows of iodine atoms fill the distorted hexagonal arrangement of the chann els. Bi5,6Ni5I,I is stabilized by metallic bonding in the framework me tal atoms and additional heteropolar interactions between bismuth and iodine atoms as well as between bismuth and nickel atoms. Bi5,6Ni5I sh ows metallic conductivity and ferromagnetic ordering below 17 K.