A Series of Mixed-Metal Germanium Iodates as Second-Order Nonlinear Optical Materials
A Series of Mixed-Metal Germanium Iodates as Second-Order Nonlinear Optical Materials
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一系列混合金属碘酸锗二阶非线性光学材料
DOI：
10.1021/acs.chemmater.8b00630
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发表时间：
2018-04-10
影响因子：
8.6
通讯作者：
Mao, Jiang-Gao
中科院分区：
文献类型：
--
作者：
Mao, Fei-Fei;Hu, Chun-Li;Mao, Jiang-Gao
在A/Ae-Ge ~（4+）-IO_3三元金属碘酸盐体系中引入GeO_6八面体，得到了一系列新化合物A（2）Ge（IO_3）（6）（A = Li，Na，Rb，Cs）和巴格（IO_3）（6）（H_2 O）。这五种新化合物的结构都是由GeO_6八面体与六个IO_3基团连接组成的零维[Ge（IO_3）（6）]（2-）阴离子，碱金属或碱土金属阳离子作为这些阴离子之间的间隔物，维持电荷平衡。有趣的是，同分异构体Li_2Ge（IO_3）（6）和Na_2Ge（IO_3）（6）是非中心对称的（NCS），而同构的Rb_2Ge（IO_3）（6）和Cs_2Ge（IO_3）（6）是中心对称的。巴格（IO 3）（6）（H2O）是首次报道的NCS碱土锗碘酸盐。粉末二次谐波产生（SHG）测量表明，Li 2Ge（IO 3）（6）、Na 2Ge（IO 3）（6）和巴格（IO 3）（6）（H2O）晶体是相位匹配的，并且显示出非常大的SHG信号，在1064 nm辐射下分别是KH 2 PO 4的大约32、15和12倍，以及KTiOPO 4的2、0.8和0.8倍，分别在2.05 mm激光照射下。该化合物具有较高的热稳定性和激光损伤阈值，在可见光和红外波段具有潜在的非线性光学（NLO）材料应用前景。测量的光学性能，热分析，和理论计算的SHG起源已被执行。我们的研究表明，将非二阶Jahn-Teller畸变的MO 6八面体引入到金属碘酸盐体系中也可以得到良好的混合金属碘酸盐非线性光学材料。
A series of new compounds in the A/Ae-Ge4+-IO3 system, namely, A(2)Ge(IO3 )(6) (A = Li, Na, Rb, or Cs) and BaGe(IO3)(6)(H2O), have been obtained by introducing GeO6 octahedra into a ternary metal iodate system. The structures of all five new compounds feature a zero-dimensional [Ge(IO3)(6)](2-) anion composed of a GeO6 octahedron connecting with six IO3 groups, the alkali or alkali-earth cations acting as spacers between these anions and maintaining charge balance. Interestingly, the isomeric Li2Ge(IO3)(6) and Na2Ge(IO3)(6) are noncentrosymmetric (NCS), whereas the isostructural Rb2Ge(IO3) 6 and Cs2Ge(IO3)(6) are centrosymmetric. BaGe(IO3)(6) (H2O) is the first NCS alkali-earth germanium iodate reported. Powder second-harmonic generation (SHG) measurements show that Li2Ge(IO3)(6) , Na2Ge(IO3)(6) , and BaGe(IO3)(6) (H2O) crystals are phase-matchable and display very large SHG signals that are approximately 32, 15, and 12 times that of KH2PO4 , respectively, under 1064 nm radiation and 2, 0.8, and 0.8 times that of KTiOPO4 , respectively, under 2.05 mm laser radiation. The compounds show high thermal stability and a large laser damage threshold, indicating their potential applications as nonlinear optical (NLO) materials in visible and infrared spectral regions. Measurement of optical properties, thermal analysis, and theoretical calculations of the SHG origin have been performed. Our studies indicate that introducing non-second-order Jahn-Teller-distortive MO6 octahedra into metal iodate systems can also lead to good mixed-metal iodate NLO materials.