Disconnection Enhances the Second Harmonic Generation Response: Synthesis and Characterization of Ba23Ga8Sb2S38

An unusual zero-dimensional quaternary sulfide, Ba23Ga8Sb2S38, that crystallizes in the noncentrosymmetric polar space group Cmc21 was discovered by solid-state reaction of an elemental mixture. The involvement of a second building unit consisting of SbS3 pyramid and constituting 20% of the structure helped to realize the disconnection of the asymmetric GaS4 tetrahedra. Such a disconnection leads to the strongest powder second harmonic generation intensity in the IR region among sulfides to date, ∼22 times that of commercial AgGaS2 at an incident laser wavelength of 2.05 μm with the same particle size of 46–74 μm.通过单质混合物的固相反应，研究者发现了一种罕见的零维四元硫化物Ba₂₃Ga₈Sb₂S₃₈，该化合物结晶于非中心对称极性空间群Cmc2₁。由SbS₃三角锥构成的第二种结构基元（占整体结构的20%）的引入，促成了不对称GaS₄四面体的解离。该解离效应使得此化合物在迄今已报道的硫化物中，展现出最强的红外区粉末二次谐波产生（second harmonic generation）强度；在入射激光波长为2.05μm、测试样品粒径与商用AgGaS₂同为46–74μm的条件下，其信号强度约为后者的22倍。