Synthesis, structural characterization and optical properties of new compounds: Centrosymmetric Ba2GaMQ5 (M=Sb,Bi; Q=Se,Te), Ba2InSbTe5 and noncentrosymmetric Ba2InSbSe5

The six compounds Ba2GaMQ5 (M=Sb,Bi; Q=Se,Te) and Ba2InSbQ5 (Q=Se,Te) have been synthesized for the first time. Ba2GaMQ5 (M=Sb,Bi; Q=Se,Te) and Ba2InSbTe5 crystallize in the centrosymmetric space group Pnma, while Ba2InSbSe5 belongs to the noncentrosymmetric polar space group Cmc21. The structures of the six new compounds contain infinite [MM'Q5]4−∞1 anionic chains built by MQ4 (M′=Ga,In) tetrahedra and heavily distorted M′Q6 (M′=Sb,Bi) octahedra. Ba2InSbSe5 possesses a band gap of 1.92(5) eV and exhibits a weak powder second harmonic generation signal using the 2090 nm laser as fundamental wavelength.

Ba2InSbSe5 contains infinite [InSbSe5]4−∞1 chains which are built by corner-shared InSe4 tetrahedra chains and edge-shared SbSe6 octahedra chains connected through edge sharing .Figure optionsDownload as PowerPoint slideHighlights
► Ba2GaMQ5 (M=Sb,Bi; Q=Se,Te) and Ba2InSbQ5 (Q=Se,Te) have been synthesized.
► The structures contain infinite [MM'Q5]4−∞1 (M′=Ga,In) anionic chains.
► The chains are built by distorted MQ6 (M=Sb,Bi) octahedra and M′Q4 (M′=Ga,In) tetrahedra.
► Ba2InSbSe5 exhibits a weak powder second harmonic generation signal.