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Abstract: A new series of transition-metal rare-earth chalcogenides, Ln 3FeGaQ7 (Ln=Nd, Sm, Gd, Dy, Q=S; Ln=Nd, Gd, Dy, Q=Se), have been synthesized by solid state reactions. They are isostructural and crystallize in the space group P63. They adopt a three-dimensional framework composed of LnQ7 monocapped trigonal prisms with the interesting [FeS3]4− chains and isolated GaQ4 tetrahedra lying in two sets of channels in the framework. Magnetic susceptibility measurements on Ln 3FeGaQ7 (Ln=Gd, Dy; Q=S, Se) indicate that they are paramagnetic and obey the Curie–Weiss law. Based on the diffuse reflectance spectra, Ln 3FeGaQ7 (Ln=Gd, Dy; Q=S, Se) should have band gaps smaller than 0.5eV. Electronic conductivity measurement on Dy3FeGaSe7 demonstrates semiconducting behavior with σ 300=0.124S/cm. The first-principles calculations were also performed to study the electronic structures of these compounds. [Copyright &y& Elsevier]

The new title compound is synthesized by solid state reaction of BaSe, In2Se3, Yb, and Se in the molar ratio 4:1:2:3 (1173 K, 72 h). [ABSTRACT FROM AUTHOR]