摘要
Conventional wisdom says that nonpolar structures do not favorably produce strong second-harmonic generation(SHG)responses since the polarization in their microscopic functional groups are counteracted.Herein,we report the first nonlinear optical thiosulfate,Na_(10)Cd(NO_(3))_(4)(SO_(3)S)_(4),which crystallizes in a nonpolar space group of P−4.However,this thiosulfate exhibits a strong SHG response of about 4.2 times that of the benchmark KH2PO4,which is larger than those of polar sulfates.According to first-principles calculations and a flexible dipole model,the SHG enhancement is mainly ascribed to the larger flexibility of the S=S bond in the SO_(3)S tetrahedra in comparison with the S–O bond in the SO4 tetrahedra.These findings indicate that constructing flexible bonds is an effective strategy to design highperformance nonlinear optical materials regardless of polarity.
基金
supported by the National Natural Science Foundation of China(nos.21833010,61975207,21921001,21971238,51872297,and 51890864)
the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(no.ZDBS-LY-SLH024)
the Strategic Priority Research Program of the Chinese Academy of Sciences(nos.XDB20010200 and XDB20000000)
Fujian Institute of Innovation(no.FJCXY18010201)in Chinese Academy of Sciences,the National Key Research and Development Program of China(no.2019YFA0210400)
Key Laboratory of Functional Crystals and Laser Tech-nology,TIPC,CAS(no.FCLT 202003)
as well as Key Laboratory of New Processing Technology for Nonferrous Metal&Materials,Ministry of Education/Guangxi Key Laboratory of Optical and Electronic Materials and Devices(no.20KF-11).
