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).
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
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)
出处
《人工晶体学报》
EI
CAS
北大核心
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)。
