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Published on: December 4, 2014
Synthesis, crystal structures and optical properties of noncentrosymmetric oxysulfides AeGeS2O (Ae = Sr, Ba)
Xian Zhang1, Yi Xiao, Ruiqi Wang
1Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Beijing 100094, P. R. China. zhangxian@qxslab.cn.
Abstract:
Two new oxysulfides, AeGeS2O (Ae = Sr, Ba), were successfully synthesized via the molten salt method. The two isostructural compounds crystallize in the noncentrosymmetric space group P212121. Their structures feature 1∞[GeS2O]2- one-dimensional helical chains which are built up by [GeS2O2]4- heteroanionic tetrahedra via corner sharing of O atoms. The two oxysulfides are typical semiconductors with wide bandgaps (SrGeS2O: 3.9 eV and BaGeS2O: 4.1 eV) that are perfectly consistent with the first-principles calculation results. They show typical band emissions under UV light excitation (SrGeS2O: 375 nm and BaGeS2O: 360 nm). In addition, SrGeS2O also possesses an orange-yellow light emission (572 nm). SrGeS2O and BaGeS2O exhibit moderate second harmonic generation (SHG) intensities of 0.4 × AgGaS2 and 0.5 × AgGaS2, respectively.
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