通过聚阳离子取代策略实现压缩黄铜矿型硒化物[Rb3BaCl][In_(8)Se_(14)]以获得优异的非线性光学性能

单价Ag+或Li+引入到类金刚石结构的MQ22-(M=Ga,In;Q=S,Se)阴离子基团中能合成出良好的二阶非线性光学(NLO)晶体材料.然而,这些晶体分别面临着较低的抗激光损伤阈值(LIDT)或二氧化硅易被腐蚀等缺点,严重限制了其在高功率激光应用中的实用性.在本研究中,基于类金刚石结构的ZnSe,我们采用[Se_(4)Zn_(13)]Se_(2)4→[ClRb_(3)Ba]Se_(24)非常规的聚阳离子取代策略,设计并合成了一种新型的盐包硫属化合物[Rb_(3)BaCl][In_(8)Se_(14)](1).化合物1属于压缩黄铜矿型硒化物并保持了与AgInSe_(2)相同的晶体对称性(I-42d空间群).值得注意的是,由于InSe_(4)四面体结构单元的平行排列,化合物1具有相位匹配的强二次谐波(SHG)响应(2.0倍于AgGaS_(2)@2.90μm).此外,聚阳离子[Rb_(3)BaCl]^(4+)的引入促进了光学带隙(2.02 eV)的增强,有效地避免了对2.09μm激光的双光子吸收;同时结合较低的热膨胀系数,使得化合物1表现出高的LIDT(3.2倍于AgGaS2@2.09μm).本研究验证了在类金刚石结构中进行聚阳离子取代的可行性,并成功获得了性能优异的中远红外NLO材料.

The centrosymmetric to non-centrosymmetric transformation induced by alkaline-earth cations producing infrared nonlinear optical AeMn_(6)Ga_(6)S_(16)(Ae=Ca,Sr)

Non-centrosymmetric(NCS)structure is an indispensable prerequisite for second-order nonlinear optical(NLO)material.Currently,the mainstream approach for designing new NCS structures still relies on chemical substitution,necessitating an urgent infusion of fresh ideas.In this work,two isomorphic sulfides AeMn_(6)Ga_(6)S_(16)(Ae=Ca,1;Sr,2)are afforded by modifying the skeleton of centrosymmetric(CS)Mn_(2)Ga_(2)S_(5) via introducing strong electropositive alkaline-earth cations.Concretely,the incorporation of Ca^(2+)/Sr^(2+)cations allows the elementary[MnGaS_(9)]_(∞)chains to reconfigure into bumpy[MnS_(6)]-[GaS_(4)]layers in a new engagement manner,thus enabling the conversion from CS to NCS structure.Such modifications cause not only strong second-harmonic generation(SHG)responses(~1.5×benchmark AgGaS_(2)@1,700 nm),but also significantly feasible bandgaps(2.60-2.64 e V)compared to the sulfide Mn_(2)Ga_(2)S_(5)(1.36 e V),which ultimately facilitate ultrahigh laser-induced damage thresholds(4.4-6.6×AgGaS_(2)@1,064 nm for compounds 1 and 2).The present study offers an ingenious approach for the transformation of CS to NCS structure.

三元AGa_(5)S_(8)(A=K,Rb,Cs):通过“一替多取代”策略制备的红外非线性光学材料

目前,商用的红外非线性光学晶体材料,如具有类金刚石结构的硫属化合物AgGaQ_(2)(Q=S,Se),具有强的非线性光学系数.然而,相对较低的抗激光损伤阈值制约了其在高能激光领域的应用.以类金刚石结构的闪锌矿ZnS为模板,我们通过“一替多取代”策略,即[SZn_(4)^(6+)+5Zn^(2+)■A^(+)+5Ga^(3+)](A=K、Rb和Cs),采用固相合成方法,获得了三元晶体AGa_(5)S_(8)(A=K、Rb和Cs).极性结构的AGa_(5)S_(8)保持了类金刚石阴离子骨架框架,非线性光学功能基元GaS4四面体以平行排列的方式堆积,使其具有高的相位匹配倍频强度(1.1–1.2×AgGaS_(2));另外,含有高正电性A+阳离子使其表现出3.10–3.37 eV的宽带隙,进而提高抗激光损伤阈值(9.3–12.4×AgGaS_(2)).晶体AGa_(5)S_(8)(A=K、Rb和Cs)是第一个具有大倍频响应(≥1.0×AgGaS_(2))和宽带隙(≥3.0 eV)的三元含碱金属的硫属化合物,满足了优秀红外非线性光学材料的严格要求.此外,“一替多取代”策略在类金刚石结构演变中具有重要意义,并为获得新非线性光学材料提供了良好的机遇.