Crystal structure and magnetic properties of the diuranium tritelluride U2Te3

Single crystals of U₂Te₃ were obtained by solid state reaction between the elements in stoichiometric proportions mixed with a small quantity of cesium chloride. U₂Te₃ crystallizes in the orthorhombic system, space group Pnma (n^o 62), with unit cell parameters a = 12.175(2)Å, b = 4.370(1)Å, c = 11.828(2)Å, and Z = 4. The structure was determined from single crystal X-ray diffraction data and refined to final residual factors R(F) = 0.030 and Rω(F) = 0.035 for 32 variable parameters and a unique data set of 1100 diffraction intensities [I > 3σ(I)]. The U atoms are located on two 4c non equivalent crystallographic positions. U(1) has a 7-fold coordination of Te atoms with a coordination polyhedron deriving from an octahedron in which one apex is split into two positions, and U(2) has a monocapped trigonal prismatic coordination. U₂Te₃ exhibits rather complex magnetic behaviour, with an onset of ferromagnetic order at T ∼ 110 K and spin reorientation below 105 K.