新型无机硼锗（硅）酸盐NLO晶体的设计合成

KBe2(BO3)F2（KBBF）是目前仅有的能够倍频实现深紫外激光输出的晶体，但它有层状晶体生长习性和合成过程中使用了毒性很大的氧化铍，这些缺点限制了其工业应用，探索其它性能优良、环境友好的深紫外NLO晶体仍是目前很迫切的任务。 在本项目中我们拟以锗或硅替代硼铍酸盐中的铍元素，利用水热或高温固相合成方法合成硼锗（硅）酸盐，将含孤对电子的阳离子如Pb2+、 Bi3+等引入到硼锗（硅）酸盐中进一步提高化合物的倍频系数，在上述硼锗（硅）酸盐中引入卤素阴离子增大化合物的带隙和NLO系数；通过大量的合成实验、性能测试及理论计算, 总结上述硼锗（硅）酸盐的NLO性能随合成条件、抗衡阳离子大小、卤素阴离子、不对称结构单元的排列与组装方式的调控规律; 设计合成1-2种性能优越的新型硼酸盐深紫外NLO晶体材料。

In the DUV, currently only KBe2BO3F2 (KBBF) is capable of lasing at 177.3 nm. However, KBBF suffers from two serious drawbacks：use of toxic BeO in the synthesis and layering growth habit for its single crystal, hence explorations of new environment friendly DUV NLO crystals remain an important and urgent task. In this project, we propose to replace the Be element in B-Ge-O systems by silicon or germanium. By using hydrothermal and solid state reactions at high temperatures, we will systematically explore various metal borosilicates and borogermanates; to introduce lone pair containing cations such as Bi3+ and Pb2+ into the above two types of compounds to enhance their SHG performance; and to introduce halide anions into these compounds to increase their band gaps and UV or DUV cutoff edges; to summarize the effects of synthetic conditions, the size of counter-cations, halide anions and the packing patterns of the asymmetric structural building units on the SHG properties of above borate materials through a great number of synthetic experiments, physical property measurements and theoretical calculations; to design and synthsize one or two new candidates of DUV borate NLO crystals for further studies and future applications.