Ln3FeGaQ7: A new series of transition-metal rare-earth chalcogenides

•New compounds, Ln3FeGaQ7 (Ln=Nd, Sm, Gd, Dy, Q=S, Se), were synthesized.•They are isostructural and crystallize in the noncentrosymmetric space group P63.•They adopt a three-dimensional framework built by LnQ7 monocapped trigonal prisms.•Ln3FeGaQ7 (Ln=Gd, Dy; Q=S, Se) are paramagnetic and obey the Curie–Weiss law.•Electronic conductivity of Dy3FeGaSe7 shows semiconducting behavior.

A new series of transition-metal rare-earth chalcogenides, Ln3FeGaQ7 (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 ∞1[FeS3]4− chains and isolated GaQ4 tetrahedra lying in two sets of channels in the framework. Magnetic susceptibility measurements on Ln3FeGaQ7 (Ln=Gd, Dy; Q=S, Se) indicate that they are paramagnetic and obey the Curie–Weiss law. Based on the diffuse reflectance spectra, Ln3FeGaQ7 (Ln=Gd, Dy; Q=S, Se) should have band gaps smaller than 0.5 eV. Electronic conductivity measurement on Dy3FeGaSe7 demonstrates semiconducting behavior with σ300=0.124 S/cm. The first-principles calculations were also performed to study the electronic structures of these compounds.

Graphical abstractLn3FeGaQ7 adopt a three-dimensional framework composed of LnQ7 monocapped trigonal prisms with interesting ∞1[FeS3]4− chains and isolated GaQ4 tetrahedra lying in two sets of channels in the framework.Figure optionsDownload full-size imageDownload as PowerPoint slide