TERNARY ALUMINIDES LNT(2)AL(10) (LN=Y, LA-ND, SM, GD-LU AND T=FE, RU,OS) WITH YBFE2AL10 TYPE-STRUCTURE AND MAGNETIC-PROPERTIES OF THE IRON-CONTAINING SERIES

Of the title compounds 25 have been prepared for the first time. They crystallize with the orthorhombic YbFe2Al10 type structure (Cmcm. Z = 4), which was refined from single-crystal X-ray data of SmFe2Al10 [a = 898.9(2), b = 1018.6(2), c = 904.3(2) pm, R = 0.043 for 823 structure factors and 19 variable parameters] and LaOs2Al10 [a = 920.5(6), b = 1027.4(5), c = 916.9(6) pm, R = 0.047 for 1475 F values and 21 variabi es]. Two aluminium sites of LaOs2Al10 show significant deviations from the ideal occupancies, resulting in the exact composition LaOs2Al9.74 (2). The magnetic properties of the iron-containing compounds have bee n determined with a SQUID magnetometer in the temperature range 2-300 K with magnetic flux densities up to 5.5 T. YFe2Al10 and LaFe2Al10 are Pauli-paramagnetic, indicating that the iron atoms in these isotypic compounds do not carry magnetic moments. The behaviour of the other ir on-containing compounds is dominated by the magnetic properties of the rare-earth components. CeFe2Al10 and YbFe2Al10 show mixed-valent beha viour. This can also be concluded from the cell volumes for CeRu2Al10 and YbRu2Al10. SmFe2Al10 is Van Vleck paramagnetic, and the others fol low the Curie-Weiss law with magnetic ordering temperatures of < 20 K. The magnetic properties of these compounds were further investigated by magnetization measurements at 2 K.