Synthesis, crystal structure, resistivity, magnetic, and theoretical study of ScUS₃

Single crystals of ScUS₃ were synthesized in high yield in a single step at 1173 K. ScUS₃ crystallizes in the FeUS₃ structure type in the space group D^2h₁₇-Cmcm of the orthorhombic system with four formula units in a cell of dimensions a = 3.7500(8) Angstroms, b = 12.110(2) Angstroms, and c = 9.180(2) Angstroms. Its structure consists of edge- and corner-sharing ScS₆ octahedra that form two-dimensional layers. U atoms between layers are connected to eight S atoms in a bi-capped trigonal-prismatic fashion. ScUS₃ can be easily charge-balanced as Sc³⁺U³⁺(S^2-)₃ as there are no S-S single bonds present in the crystal structure. High temperature-dependent resistivity measurements on a single crystal of ScUS₃ show semiconducting behavior with an activation energy of 0.09(1) eV. A magnetic study on powdered single crystals of ScUS₃ reveals an antiferromagnetic transition at 198 K followed by a ferromagnetic transition at 75 K. The weak ferromagnetic behavior at low temperature may originate from canted antiferromagnetic spins. A density functional theory (DFT) calculation predicts ScUS₃ to be ferromagnetic and either a very poor metal or a semiconductor with a very small gap. (authors)