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BaGa4Se7: A New Congruent-Melting IR Nonlinear Optical Material

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posted on 2010-10-18, 00:00 authored by Jiyong Yao, Dajiang Mei, Lei Bai, Zheshuai Lin, Wenlong Yin, Peizhen Fu, Yicheng Wu
The new compound BaGa4Se7 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, GaSe4 tetrahedra share corners to form a three-dimensional framework with cavities occupied by Ba2+ 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. BaGa4Se7 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 AgGaS2. A first-principles calculation of the electronic structure, linear and nonlinear optical properties of BaGa4Se7 was performed. The calculated birefractive indexΔn = 0.08 at 1 μm and the major SHG tensor elements are: d11 = 18.2 pm/V and d13 = −20.6 pm/V. This new material is a very promising NLO crystal for practical application in the IR region.

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