Yao, Jiyong Mei, Dajiang Bai, Lei Lin, Zheshuai Yin, Wenlong Fu, Peizhen Wu, Yicheng BaGa<sub>4</sub>Se<sub>7</sub>: A New Congruent-Melting IR Nonlinear Optical Material The new compound BaGa<sub>4</sub>Se<sub>7</sub> has been synthesized for the first time. It crystallizes in the monoclinic space group <i>Pc</i> with <i>a =</i> 7.6252 (15) Å, <i>b =</i> 6.5114 (13) Å, <i>c =</i> 14.702 (4) Å, β = 121.24 (2)°, and <i>Z</i> = 2. In the structure, GaSe<sub>4</sub> tetrahedra share corners to form a three-dimensional framework with cavities occupied by Ba<sup>2+</sup> 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<sub>4</sub>Se<sub>7</sub> 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<sub>2</sub>. A first-principles calculation of the electronic structure, linear and nonlinear optical properties of BaGa<sub>4</sub>Se<sub>7</sub> was performed. The calculated birefractive indexΔ<i>n</i> = 0.08 at 1 μm and the major SHG tensor elements are: d<sub>11</sub> = 18.2 pm/V and d<sub>13</sub> = −20.6 pm/V. This new material is a very promising NLO crystal for practical application in the IR region. birefractive index Δn;18.0 μ m;1 μ m;NLO;benchmark material AgGaS 2.;space group Pc;BaGa 4Se;SHG tensor elements;compound BaGa 4Se;pm;IR;GaSe 4 tetrahedra share corners 2010-10-18
    https://acs.figshare.com/articles/dataset/BaGa_sub_4_sub_Se_sub_7_sub_A_New_Congruent_Melting_IR_Nonlinear_Optical_Material/2720773
10.1021/ic1006742.s001