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.