多基团协同作用构建具有强倍频效应的硼酸盐非线性光学材料——Pb_2B_5O_9I

The Cooperation of Multiple Groups Produces Strong SHG in a Borate NLO Material——Pb_2B_5O_9I

本研究将具有孤对电子效应的Pb2+阳离子和弱电负性的I-阴离子同时引入五硼酸框架结构,构建出一种相匹配、强倍频效应的非线性光学晶体材料Pb2B5O9I。该材料在近紫外至中红外波段具有良好的透光性,其粉末倍频效应达到商用非线性光学基准材料KDP的13.5倍,是目前报道的硼酸盐体系中的最强值。基于密度泛函理论对其电子结构及截止能相关倍频系数的计算分析表明,该材料强倍频效应源自Pb2+的孤对电子、I-阴离子及多种硼氧基团的协同作用。此研究将为不断提高硼酸盐材料的倍频效应及拓宽其透光波段开辟新的材料设计思路。

The combination of lone-pair effects on Pb2＋ cations and small electronegativity of I-anions into the pentaborate framework generates a phase-matchable material,Pb2B5O9I,with the largest powder SHG response among borates,about 13.5 times that of the commercially used benchmark NLO material KDP（KH2PO4）,and transparency over the near-UV to middle-IR region.DFT calculations on electronic structure and cutoff-energy-dependent SHG coefficients confirm that the strong SHG activity originates mainly from the cooperation of Pb2＋ lone pairs,I-anions and B-O groups.