title: SnGa2GeS6: synthesis, structure, linear and nonlinear optical properties.
abstract: A new sulfide, SnGa2GeS6, has been synthesized, which represents the first member in the quaternary Sn/M/M'/Q (M = Ga, In; M' = Si, Ge; Q = S, Se, Te) system. It adopts a new structure type in the non-centrosymmetric space group Fdd2. In the structure, Sn(2+) is coordinated to a distorted square-pyramid of five S atoms, demonstrating the stereochemical activity of the lone electron pair, while the Ge atom and Ga atom are both tetrahedrally coordinated to four S atoms. The SnS5 square-pyramids and the MS4 (M = Ga, Ge) tetrahedra are connected to each other via corner and edge-sharing to generate a three-dimensional framework. The compound exhibits a powder second harmonic generation signal at 2 μm whose strength is about one-fourth that of the benchmark material AgGaS2, which may be explained in view of the macroscopic arrangement of the SnS5 square-pyramids and the MS4 tetrahedra. Moreover, based on UV-vis-NIR spectroscopy measurements and the electronic structure calculations, SnGa2GeS6 has two optical transitions at about 1.12 eV and 2.04 eV respectively.
authors: Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
authors: Zuohong
authors: Z
authors: Lin
authors: Chao
authors: C
authors: Li
authors: Lei
authors: L
authors: Kang
authors: Zheshuai
authors: Z
authors: Lin
authors: Jiyong
authors: J
authors: Yao
authors: Yicheng
authors: Y
authors: Wu