The A 2M 4U 6Q 17 compounds Rb 2Pd 4U 6S 17, Rb 2Pd 4U 6Se 17, Rb 2Pt 4U 6Se 17, Cs 2Pd 4U 6S 17, Cs 2Pd 4U 6Se 17, and Cs 2Pt 4U 6Se 17 were synthesized by the high-temperature solid-state reactions of U, M, and Q in a flux of ACl or Rb 2S 3. These isostructural compounds crystallize in a new structure type, with two formula units in the tetragonal space group P4/mnc. This structure consists of a network of square-planar MQ 4, monocapped trigonal-prismatic UQ 7, and square-antiprismatic UQ 8 polyhedra with A atoms in the voids. Rb 2Pd 4U 6S 17 is a typical semiconductor, as deduced from electrical resistivity measurements. Magnetic susceptibility and specific heat measurements on single crystals of Rb 2Pd 4U 6S 17 show a phase transition at 13 K, the result either of antiferromagnetic ordering or of a structural phase transition. Periodic spin-polarized band structure calculations were performed on Rb 2Pd 4U 6S 17 with the use of the first principles DFT program VASP. Magnetic calculations included spin-orbit coupling. With U f-f correlations taken into account within the GGA+U formalism in calculating partial densities of states, the compound is predicted to be a narrow-band semiconductor with the smallest indirect and direct band gaps being 0.79 and 0.91 eV, respectively.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry