Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China.
Inorg Chem. 2010 Oct 18;49(20):9212-6. doi: 10.1021/ic1006742.
The new compound BaGa(4)Se(7) has been synthesized for the first time. It crystallizes in the monoclinic space group Pc with a = 7.6252 (15) Å, b = 6.5114 (13) Å, c = 14.702 (4) Å, β = 121.24 (2)°, and Z = 2. In the structure, GaSe(4) tetrahedra share corners to form a three-dimensional framework with cavities occupied by Ba(2+) cations. The material is a wide-band gap semiconductor with the visible and IR optical absorption edges being 0.47 and 18.0 μm, respectively. BaGa(4)Se(7) melts congruently at 968 °C and exhibits a second harmonic generation response at 1 μm that is approximately 2-3 times that of the benchmark material AgGaS(2). A first-principles calculation of the electronic structure, linear and nonlinear optical properties of BaGa(4)Se(7) was performed. The calculated birefractive indexΔn = 0.08 at 1 μm and the major SHG tensor elements are: d(11) = 18.2 pm/V and d(13) = -20.6 pm/V. This new material is a very promising NLO crystal for practical application in the IR region.
首次合成了新化合物 BaGa(4)Se(7)。该晶体属于单斜晶系，空间群为 Pc，晶胞参数为：a = 7.6252 (15) Å, b = 6.5114 (13) Å, c = 14.702 (4) Å, β = 121.24 (2)°，Z = 2。在结构中，GaSe(4)四面体通过共享角形成一个三维框架，框架的空腔中填充着 Ba(2+)阳离子。该材料是一种宽带隙半导体，其可见光和红外光吸收边缘分别为 0.47 和 18.0 μm。BaGa(4)Se(7)在 968°C 下发生共熔，在 1 μm 处表现出二次谐波响应，大约是基准材料 AgGaS(2)的 2-3 倍。对 BaGa(4)Se(7)的电子结构、线性和非线性光学性质进行了第一性原理计算。计算得到的 1 μm 处的双折射指数Δn = 0.08，主要的二次谐波张量元素为：d(11) = 18.2 pm/V 和 d(13) = -20.6 pm/V。这种新材料是一种非常有前途的 NLO 晶体，有望在红外区域得到实际应用。
