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 Cmc 21. The structures of the six new compounds contain infinite View the MathML source[MMʹQ5]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.