Synthesis and characterization of Er3SmQ6 (Q=S, Se) and Er1.12Sm0.88Se3

The interlanthanide compounds Er3SmS6, Er3SmSe6, and Er1.12Sm0.88Se3 have been synthesized from stoichiometric reactions of the elements in a KI salt flux at 1273, 1173, and 1123 K, respectively. Er3SmS6 and Er3SmSe6, which are isostructural and ordered, crystallize in space group P21/m in the ScEr3S6 structure type whereas Er1.12Sm0.88Se3, in which the Er and Sm atoms are disordered, crystallizes in space group Pnma in the U2S3 structure type. Er3SmS6 is a paramagnet with a μeff=11.25(1) μB/mol. From optical measurements a direct band gap of 2.0 eV for light perpendicular to the (100) crystal face of Er3SmSe6 is derived whereas for isostructural Er3SmS6 an optical transition at 2.2–2.4 eV and a broad absorption peak at lower energies are observed.