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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 new quaternary rare earth sulfides, La_3MgGaS_7 (1) and La_6MgSn_2S_ (14) (2), were obtained by high temperature solid state reaction. Compounds 1 and 2 both crystallize in the hexagonal chiral space group P63 and are isomorphic. The three-dimensional crystal structure can be described as follows: the MgS_6 octahedron in the compound forms a one-dimensional chain symmetrically along the 63 axis through coplanar formation, Its periphery is surrounded by a triple axisymmetric MS4 (M = Ga, Sn) tetrahedron. The one-dimensional chains of MgS_6 and MS4 are connected by S-La bonds to form a three-dimensional structure. The second order nonlinear signal of compound 2 is 0.2 times of that of AgGaS_2 (AGS) when the wavelength of incident light is 1910nm. First-order calculations show that the light absorption of compounds 1 and 2 is mainly caused by the transition of electrons from the S-3p orbitals to the La-6s orbitals.