Abstract: | Structure and Properties of Gd3I3C . The compound Gd3I3C is prepared by reaction of Gd, GdI3 and C (2:1:1 mole) at 1 250 K in sealed Ta tubes. It is obtained as bronze-coloured needles which are air and moisture sensitive. The structure of Gd3I3C contains twin chains of C centered Gd6 octahedra surrounded by I atoms capping all free edges like in the M6X12 cluster. The one-dimensional units are oriented along 010] and linked according to (GdGd1/3Gd2/2Gd2/3C)2IIII. Gd3I3C is metallic in the temperature range 300 K ≥ T ≥ 120 K, between 120 and 15 K the electrical resistance increases by 6 orders of magnitude. At high temperatures the susceptibility follows the Curie-Weiß law with a paramagnetic Curie temperature θ ≈ - 340 K. Two local maxima in the susceptibility at 100 K and 25 K indicate successive formation of antiferromagnetically ordered structures. |