Ternary aluminides LnT2Al10 (Ln=Y, La–Nd, Sm, Gd–Lu andT=Fe, Ru, Os) with YbFe2Al10 type structure and magneticproperties of the iron-containing series

Abstract

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 variables]. Two aluminium sites of LaOs₂Al₁₀ show significant deviations from the ideal occupancies, resulting in the exact composition LaOs₂Al_9.74(2) . The magnetic properties of the iron-containing compounds have been 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 iron-containing compounds is dominated by the magnetic properties of the rare-earth components. CeFe₂Al₁₀ and YbFe₂Al₁₀ show mixed-valent behaviour. This can also be concluded from the cell volumes for CeRu₂Al₁₀ and YbRu₂Al₁₀ . SmFe₂Al₁₀ is Van Vleck paramagnetic, and the others follow 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.