新型锑硫属化合物的探索合成、结构及二阶非线性光学性能研究

NLO materials have received increased demands in the laser technology, such as SHG, OPA and OPO. Most metal oxides NLO crystals have proven superior in the UV to near-IR region. However, in the Middle and Far IR region,the typical IR benchmark materials: AgGaS2 and ZnGeP2 have drawbacks, such as a low laser damage threshold and the two-photon absorption. Chalcogenide semiconductors possess higher SHG coefficients owing to the highly polarizable M-S (Se) bonds and wider transmission window in the IR region. Therefore, the search for new chalcogenides with excellent IR NLO performance is of broad interest and great challenge in NLO material science.. The common strategy to predesign a NCS compound is to involve asymmetric building units in the crystal structure, such as d0 transition metal cations (Ti4+, Nb5+, W6+ etc.) susceptible to second-order Jahn-Teller distortion or p cations with stereochemically active lone pair electrons (Se4+, Te4+, As3+ etc). SbQx is also an asymmetric coordination sphere as a consequence of stereochemically active lone pair electrons of antimony . However, the number of NLO-active antimony chaldogenides is still rare. Guided by the idea of asymmetric assembly of NLO-active anion unit modified by the counterions, we focus on the A/M/Sb/Q [A = Rare earth or alkali(earth) metal; M = triel,tetrel, and d0 transition metal cations (Ti4+, Nb5+, W6+ etc.) susceptible to second-order Jahn-Teller distortion; Q = Chalcogenides] systems in search of new potential candidates with the excellent IR NLO performance.

非线性光学（NLO）晶体材料主要应用于激光的频率转换，参量放大和振荡。现有的NLO材料大多适用于紫外到近红外范围，但在中(远)红外波段性能优良的却很少，因而探索新型中(远)红外NLO材料是当前非线性光学材料研究的难点和热点，由于硫属化合物良好的红外透过性，因而是新型红外NLO材料开发的焦点。.研究表明，三价锑的孤电子对效应可能诱导非心晶体结构的产生，相应化合物有望具有NLO性质，目前这方面的研究还很薄弱，本项目对于A/M/Sb/Q [A = 稀土或碱（土）金属；M = 过渡或主族金属；Q = 硫族] 四元体系开展固体化学研究，旨在通过稀土或碱（土）金属阳离子调控四面体构型的主族金属和姜泰勒畸变的高价态d0过渡金属离子和三价锑活性孤电子对等 NLO 活性单元的不对称组装得到非心结构硫属化合物，进行二阶非线性光学性能研究，进一步筛选发现具有应用前景的新型红外非线性光学晶体材料。

非线性光学（NLO）晶体材料主要应用于激光的频率转换，参量放大和振荡。现有的NLO材料大多适用于紫外到近红外范围，但在中(远)红外波段性能优良的却很少，因而探索新型中(远)红外NLO材料是当前非线性光学材料研究的难点和热点，由于硫属化合物良好的红外透过性，因而是新型红外NLO材料开发的焦点。. 研究表明，三价锑的孤电子对效应可能诱导非心晶体结构的产生，相应化合物有望具有NLO性质，目前这方面的研究还很薄弱，本项目对于A/M/Sb/Q [A = 稀土或碱（土）金属；M = 过渡或主族金属；Q = 硫族] 四元体系开展固体化学研究，旨在通过稀土或碱（土）金属阳离子调控四面体构型的主族金属和姜泰勒畸变的高价态d0过渡金属离子和三价锑活性孤电子对等 NLO 活性单元的不对称组装得到非心结构硫属化合物，进行二阶非线性光学性能研究，进一步筛选发现具有应用前景的新型红外非线性光学晶体材料。. 合成了La8Sb2S15，La6Si2Sb0.66S14，La6Si2Sb0.66Se14 和 Ba3KSb4S9Cl 等多种新颖结构多元金属锑硫属化合物，进一步进行了相关光学性能表征。其中，化合物 La8Sb2S15 的粉末倍频效应达到商用红外非线性光学材料 AgGaS2 的 1.2 倍，长度表象方法的理论计算结果基本与实验观察一致。 其透过范围宽（0.60-25.00 μm），光学能隙 2.30 eV ， 与 AgGaS2 (2.73 eV) 接近，表明具有相当的激光损伤阈值，热稳定性高达 663 °C， 因而，在红外波段具有潜在应用前景。