两个含镧硫化物的结构及红外非线性光学性质

Structures and Infrared Nonlinear Optical Properties of Two La-Containing Chalcogenides

通过高温固相反应得到了两个新的四元稀土硫化物,La_3MgGaS_7(1)和La_6MgSn_2S_(14)(2)。化合物1和2都结晶于六方晶系手性空间群P63且异质同构,其三维晶体结构可描述为:化合物中的MgS_6八面体通过共面形成一条以沿63轴对称的一维链,其周围被三重轴对称的MS4(M=Ga,Sn)四面体包围,MgS_6一维链和MS4四面体通过S-La键连接而形成三维结构。化合物2的二阶非线性信号在入射光波长为1910nm时为AgGaS_2(AGS)的0.2倍。第一性计算表明,化合物1和2的光吸收主要是由电子从S-3p轨道跃迁至La-6s轨道引起。

Two quaternary chalcogenides compounds La3MgGaS7 （ high-temperature solid-state reaction for the first time. Compounds 1） 1 and La6MgSn2S14 （2） were synthesized by and 2 were isostructural and belonged to the chiral space group P63, in the structure of them the MgS6 octahedra chains face-shared around the 63 axis, and the MgS6 octahedra chains were surrounded by isolated GaS4 （SnS4 ） tetrahedra with 3-fold symmetry. These MgS6 chains and isolated GaS4 （SnS4 ） tetrahedra are connected into a 3-dimensional framework by La-S bonds. Compound 2 exhibit the second harmonic generation （SHG） signals of 0.2 times that of AgGaS2 （AGS） under 1910 nm. Theoretical calculation indicates that the optical absorptions of 1 and 2 are mainly due to the charge transfer from S-3p states to La-6s states.