Ba7AgGa5S15:一种新型混合金属硫化物的非线性光学性能研究  

Ba7AgGa5S15:Study on the Nonlinear Optical Properties of aNew Metal-Mixed Sulfide

作　　者：周嘉政 楚羽 李俊杰 艾力江·阿卜杜如苏力 蒋相站 黄以能 潘世烈[2] ZHOU Jiazheng;CHU Yu;LI Junjie;AILIJIANG Abudurusuli;JIANG Xiangzhan;HUANG Yineng;PAN Shilie(Yili Normal University,Yili 835000,China;Xinjiang Technical Institute of Physics&Chemistry,CAS,Urumqi 830011,China)

机构地区：[1]伊犁师范大学,伊犁835000 [2]中国科学院新疆理化技术研究所,乌鲁木齐830011

出　　处：《人工晶体学报》2020年第8期1509-1516,共8页Journal of Synthetic Crystals

基　　金：国家自然科学基金(91622107,51425206)。

摘　　要：采用高温熔融-自发结晶法成功获得一种新型混合金属硫化物Ba7AgGa5S15。该化合物结晶于非中心对称的P 31 c空间群(No.159),晶胞参数为a=0.96453(10)nm,c=1.8059(4)nm,Z=2。其结构是由[Ga4S10]T2超四面体与[AgS 4]四面体共顶点连结形成的含有18元环孔道的三维网状框架,孤立的[Ga(2)S 4]四面体填充在孔道中,Ba^2+填充在该三维框架结构的空隙当中。第一性原理计算研究了该化合物的电子结构、态密度、双折射率、二阶非线性光学系数,以及倍频密度。结果表明,该化合物具有大的光学带隙(3.76 eV),其带隙主要由S 3p,Ba 5d和Ga4s轨道决定;其d 33方向上的倍频系数约为AgGaS2的0.4倍,主要倍频贡献来源于[AgS 4]和[GaS 4]四面体。该研究表明在Ag-Ga-S体系中引入Ba^2+,形成的Ba7AgGa5S15表现出比AgGaS2更宽的带隙,有利于产生高的激光损伤阈值(LDT)。A new metal-mixed chalcogenide Ba7AgGa5S15 was successfully synthesized by high temperature flux spontaneously crystallization method.The compound crystallizes in the asymmetric space group P 31 c(No.159)with the cell parameters of a=0.96453(10)nm,c=1.8059(4)nm and Z=2.The structure of Ba7AgGa5S15 is regarded as an 18-member tunnel-contained three-dimensional(3D)framework formed by the[Ga 4S 10]T2 supertetrahedra and the[AgS 4]tetrahedra by sharing vertexes.Isolated[Ga(2)S 4]tetrahedra locate inside the tunnels and the Ba^2+cations insert in the space of the framework.The optical properties of the title compound were systematically studied based on first-principles calculations,which includes the electronic structure,density of states,birefringence,the second order nonlinear optical(NLO)coefficients and the second-harmonic generation(SHG)density.The results show that Ba7AgGa5S15 has a direct band gap of 3.76 eV,which is mainly determined by the S 3p,Ba 5d and Ga4s orbitals.The NLO coefficient in the d 33 direction is^0.4 times that of AgGaS2(AGS),and the main contribution of SHG is from[AgS 4]and[GaS 4]tetrahedrons.This work indicates that introducing alkali earth metal Ba^2+into the Ag-Ga-S system could effectively enlarge the band gap of the formed Ba7AgGa5S15 compared with classical AGS compound,which is helpful in producing higher laser damage threshold(LDT).

关 键 词：硫属化合物 非线性光学材料 晶体结构 带隙 第一性原理 Ba7AgGa5S15 

分 类 号：O734[理学—晶体学]