新型锑硫属卤素混合阴离子化合物的探索合成、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. 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 Sb3+ with stereochemically active lone pair. SbQx （Q = Chalcogenidesis; x = 3, 4, 5,6） also an asymmetric coordination sphere as a consequence of stereochemically active lone pair electrons of antimony . However, the number of NLO-active antimony chalcohalides is still rare. Guided by the idea of asymmetric assembly of NLO-active anion unit modified by the counterions and anions, we focus on the M/Sb/Q/X [M = alkali(earth) cations, Rare earth cations and the combination of two cations; Q = Chalcogenides; X = halides] systems in search of new NCS compounds. An interesting structural feature of these compounds is that a highly electronegative halides tends to form strong ionic bonds with a highly electropositive one (e.g., alkali(earth), Rare earth metal), which is helpful for increasing the band gap and laser damage threshold， whereas a less electronegative chalcogenides tends to form stable covalent bonds with a less electropositive one (e.g., p-block Sb), which is helpful for generating a large NLO response, thus we could combine the advantages of chalcogenides (large NLO response) with those of halides (large band gap and laser damage threshold) into one 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。. 三价锑的孤电子对效应可能诱导非心晶体结构的产生，目前具有 NLO 活性锑硫属卤素混合阴离子化合物的研究还很薄弱，本项目在锑硫属卤素化合物中引入碱（土）金属，稀土离子或其中两者的混合阳离子，通过调节阴阳离子的半径、组合进一步调控具有活性孤电子对的三价锑 NLO 活性单元的不对称组装得到非心结构化合物，由于卤素和硫属元素混合阴离子与正电性阳离子和非线性功能元素 Sb 分别以离子键和共价键作用，可以将卤化物的优点（高带隙, 高激光损伤阈）和硫属化物的优点（高非线性响应）相结合，通过粉末倍频测试，进一步筛选具有应用前景的新型红外非线性光学晶体。

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。. 三价锑的孤电子对效应可能诱导非心晶体结构的产生，目前具有 NLO 活性锑硫属卤素混合阴离子化合物的研究还很薄弱，本项目在锑硫属卤素化合物中引入碱（土）金属，稀土离子或其中两者的混合阳离子，通过调节阴阳离子的半径、组合进一步调控具有活性孤电子对的三价锑 NLO 活性单元的不对称组装得到 6 例非中心对称结构化合物，初步进行了光学性质研究，遗憾的是没有检测到明显的倍频信号，可能是由于结晶质量不好导致。该项目丰富锑硫属卤素混合阴离子化合物结构化学的同时，也为非中心对称化合物的合成提供了新的借鉴。