Yang Shuoxing, Wu Hongping, Hu Zhanggui, Wang Jiyang, Wu Yicheng, Yu Hongwei
Tianjin Key Laboratory of Functional Crystal Materials, Institute of Functional Crystal, College of Materials Science and Engineering, Tianjin University of Technology, Tianjin, 300384, China.
Small. 2024 Jan;20(3):e2306459. doi: 10.1002/smll.202306459. Epub 2023 Sep 7.
Nonlinear optical (NLO) crystals are indispensable for the solid-state lasers for their ability to expand wavelength spectral to the regions where the directing lasing is difficult or even impossible, yet the rational design of a high-performance NLO crystal remains a great challenge owing to the severe structural and properties' requirements. Herein, a new noncentrosymmetric (NCS) and polar gallium iodate, LiGa(IO ) , with a novel 2D anionic layer, is successfully designed and synthesized by the aliovalent substitution strategy based on classic α-LiIO . The 2D [Ga(IO ) ] layer in LiGa(IO ) is built from the GaO octahedra and highly polarizable units IO . Compared with its parent compound, the partial replacement of A-site Li cation with main group Ga cation facilitates LiGa(IO ) to possess excellent NLO properties, including the large second-harmonic generation (SHG) response (14 × KH PO (KDP) @ 1064 nm), wide bandgap (4.25 eV), large birefringence (0.23 @ 1064 nm), and wide optical transparency from UV to mid-IR. These reveal that LiGa(IO ) will be a promising NLO crystal.
非线性光学（NLO）晶体对于固态激光器而言不可或缺，因为它们能够将波长光谱扩展到难以甚至无法直接产生激光的区域。然而，由于对结构和性能有严格要求，高性能NLO晶体的合理设计仍然是一个巨大挑战。在此，基于经典的α-LiIO₃，通过异价取代策略成功设计并合成了一种具有新型二维阴离子层的新型非中心对称（NCS）极性碘酸镓LiGa(IO₃)₂。LiGa(IO₃)₂中的二维[Ga(IO₃)₆]层由GaO₆八面体和高极化性的IO₃⁻单元构成。与其母体化合物相比，主族Ga阳离子对A位Li阳离子的部分取代使LiGa(IO₃)₂具有优异的NLO性能，包括大的二次谐波产生（SHG）响应（在1064nm处为14×KH₂PO₄（KDP））、宽带隙（4.25eV）、大双折射（在1064nm处为0.23）以及从紫外到中红外的宽光学透明性。这些表明LiGa(IO₃)₂将是一种有前景的NLO晶体。
