Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology , Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190 , P. R. China.
University of Chinese Academy of Sciences , Beijing 100049 , P. R. China.
Inorg Chem. 2018 Aug 6;57(15):9446-9452. doi: 10.1021/acs.inorgchem.8b01437. Epub 2018 Jul 13.
KZnGeS belonging to the noncentrosymmetric space group P2 of the monoclinic system was discovered via a solid-state method. It possesses two-dimensional [ZnGeS] layers, with alkali-metal cations K located between the layers. On the basis of UV-vis-near-IR diffuse-reflectance spectrometry, the band gap of KZnGeS is 3.36(2) eV. According to powder second-harmonic-generation (SHG) measurements, the SHG response of KZnGeS is about 0.9 times that of AgGaS at the particle size range of 20-41 μm. Experimental results demonstrate that KZnGeS keeps a good balance between a large band gap (3.36 eV) and a moderate SHG response. Moreover, according to the differential scanning calorimetry measurements, KZnGeS melts congruently at around 1023 K and recrystallizes at about 963 K. Therefore, it is possible to obtain bulk single crystals via the Bridgman-Stockbarger method. The first-principles calculations indicate that the optical properties of KZnGeS are dominantly determined by the [GeS] tetrahedra as well as a small contribution from the [ZnS] tetrahedra.
KZnGeS 属于四方晶系的非中心对称空间群 P2。它具有二维的[ZnGeS]层，层间有碱金属阳离子 K。根据紫外-可见-近红外漫反射光谱，KZnGeS 的带隙为 3.36(2) eV。根据粉末二次谐波产生(SHG)测量，KZnGeS 的 SHG 响应在 20-41 μm 的粒径范围内约为 AgGaS 的 0.9 倍。实验结果表明，KZnGeS 在大带隙（3.36 eV）和适度的 SHG 响应之间保持了良好的平衡。此外，根据差示扫描量热法测量，KZnGeS 在约 1023 K 处完全熔化，并在约 963 K 处再结晶。因此，可以通过 Bridgman-Stockbarger 方法获得块状单晶。第一性原理计算表明，KZnGeS 的光学性质主要由[GeS]四面体决定，同时也有少量来自[ZnS]四面体的贡献。
