含孤对电子金属阳离子的硫卤化物红外非线性光学晶体材料的探索

非线性光学（NLO）晶体材料在实现波长连续可调激光中发挥着不可替代的作用。目前，商用红外NLO材料（如AgGaS2、AgGaSe2、ZnGeP2等）具有红外透过范围宽、NLO系数大等优点，但同时存在激光损伤阈值低的缺点，难于满足大功率激光发展的要求，探索兼具大NLO系数及高激光损伤阈值的新NLO晶体材料成为关键。调研发现，含孤对电子金属阳离子的硫属化合物具有大的NLO系数，在硫属化合物中引入离子性强的卤族元素形成硫卤化物，可增大化合物的带隙，有望保持大NLO系数的同时，实现高激光损伤阈值。基于以上研究思路，本项目以含孤对电子金属阳离子的硫卤化物为研究体系，发展可控制备的新方法，设计合成系列化合物，筛选出1-2个具有潜在应用价值的中远红外NLO晶体材料，并结合量化计算揭示组成、结构与NLO性能的构效关系。预期发表高质量SCI论文4-7篇，申请发明专利2-4件。

Nonlinear optical (NLO) crystals materials play a crucial role in modulating laser wavelength continuously. The commercial NLO materials used in the IR region such as AgGaS2, AgGaSe2, and ZnGeP2 feature broad optical transparency and high NLO coefficients. However, they suffer from relatively low laser induced damage thresholds (LIDTs), which limiting their high-power applications. Therefore, it is urgent to study on IR-NLO materials with large NLO coefficients and high LIDT. In previous theory and experimental studies, we found that chalcogenides including stereoactive lone-pair cation exhibit large NLO coefficients. It is well accepted that enlarging band gap could help to increase LIDT. Introducing highly electronegative halide anions into chalcogenides lead to forming chalcohalides, which could exhibit both large NLO coefficients and large band gap for high LIDTs. Based on above ideas, we focus on the chalcohalides including stereoactive lone-pair cation exploring. In the project, new synthesis methods would be developed; series of chalcohalides would be found; the relationship between structure and properties for various compounds would be studied. Moreover, 1-2 promising IR-NLO materials, 4-7 SCI papers, 2-4 patents for new invention would be achieved.