Cao Xue-Li, Hu Chun-Li, Kong Fang, Mao Jiang-Gao
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences , Fuzhou 350002, People's Republic of China.
Inorg Chem. 2015 Nov 16;54(22):10978-84. doi: 10.1021/acs.inorgchem.5b02074. Epub 2015 Oct 29.
Standard high-temperature solid-state reactions of NaCl, Nb2O5, and SeO2 resulted in two new sodium selenites containing a second-order Jahn-Teller (SOJT) distorted Nb(5+) cation, namely, Na2Nb4O7(SeO3)4 (P1̅; 1) and NaNbO(SeO3)2 (Cmc21; 2). Compound 1 exhibits an unusual 3D Nb4O7(SeO3)4 anionic network composed of 2D Nb4O11(SeO3)2 layers which are further bridged by additional SeO3(2-) anions via corner sharing; the 2D Nb4O11(SeO3)2 layer is formed by unusual quadruple Nb4O17 niobium oxide chains of corner-sharing NbO6 octahedra being further interconnected by selenite anions via Nb-O-Se bridges. The polar compound 2 features a 1D NbO(SeO3)2 anionic chain in which two neighboring Nb(5+) cations are bridged by one oxo and two selenite anions. The alignments of the polarizations from the NbO6 octahedra in 2 led to a strong SHG response of ∼7.8 × KDP (∼360 × α-SiO2), which is the largest among all phases found in metal-Nb(5+)-Se(4+)/metal-Nb(5+)-Te(4+)-O systems. Furthermore, the material is also type I phase matchable. The above experimental results are consistent with those based on DFT theoretical calculations. Thermal stabilities and optical properties for both compounds are also reported.
NaCl、Nb₂O₅和SeO₂的标准高温固态反应生成了两种新的亚硒酸钠，它们含有二阶 Jahn-Teller（SOJT）畸变的Nb(5+)阳离子，即Na₂Nb₄O₇(SeO₃)₄（P1̅；1）和NaNbO(SeO₃)₂（Cmc21；2）。化合物1呈现出一种不寻常的三维Nb₄O₇(SeO₃)₄阴离子网络，它由二维Nb₄O₁₁(SeO₃)₂层组成，这些层通过额外的SeO₃(2-)阴离子通过角共享进一步桥连；二维Nb₄O₁₁(SeO₃)₂层由不寻常的四重Nb₄O₁₇氧化铌链形成，角共享的NbO₆八面体通过Nb-O-Se桥与亚硒酸根阴离子进一步相互连接。极性化合物2具有一维NbO(SeO₃)₂阴离子链，其中两个相邻的Nb(5+)阳离子由一个氧和两个亚硒酸根阴离子桥连。2中NbO₆八面体的极化排列导致了约7.8×KDP（约360×α-SiO₂）的强SHG响应，这是在金属-Nb(5+)-Se(4+)/金属-Nb(5+)-Te(4+)-O体系中发现的所有相中最大的。此外，该材料也是I型相位匹配的。上述实验结果与基于DFT理论计算的结果一致。还报道了两种化合物的热稳定性和光学性质。
