La_(4)Ge_(3)S_(12)was structurally characterized in 1974 without any optical or nonlinear optical properties reported.Herein we report that the acentric crystal structure of La_(4)Ge_(3)S_(12)has been confirmed by sin...La_(4)Ge_(3)S_(12)was structurally characterized in 1974 without any optical or nonlinear optical properties reported.Herein we report that the acentric crystal structure of La_(4)Ge_(3)S_(12)has been confirmed by singlecrystal X-ray diffraction.The nonlinear optical properties test revealed its phase-matchable behavior with a good balance between the second harmonic generation(SHG)response and laser damage threshold(LDT).Theory calculations predicted that the optical properties of La_(4)Ge_(3)S_(12)are dominantly contributed by sulfur atoms.Band gap engineering was applied to tune the optical properties of La_(4)Ge_(3)S_(12)by replacing S with Se,which resulted in five new compounds:La_(4)Ge_(3)Se_(2)S_(10),La_(4)Ge_(3)Se_(4)S_(8),La_(4)Ge_(3)Se_(6)S_(6),La_(4)Ge_(3)Se_(8)S_(4),and La_(4)Ge3Se10S2.High quality mm-sized crystals of La_(4)Ge_(3)Se_(x)S_(12−x)(x=0,2,4,6,8,10)were grown by a hightemperature vapor transport reaction followed by salt flux growth methods.All La_(4)Ge_(3)Se_(x)S_(12−x)(x=0,2,4,6,8,10)compounds are isostructural and crystallize in the noncentrosymmetric rhombohedral space group R3c(no.161)with unit cell volumes of 2639.2Å^(3),2698.6Å^(3),2745.3Å^(3),2792.6Å^(3),2845.3Å^(3),and 2912.1Å^(3),for x=0,2,4,6,8,and 10,respectively.La_(4)Ge_(3)S_(12)shows a band gap of 3.1(1)eV,and the incorporation of Se to the system suppresses the band gap of the compound La_(4)Ge_(3)Se_(10)S_(2) to 1.9(1)eV.The incorporation of Se significantly shifts the nonlinear optical properties of La_(4)Ge_(3)S_(12),with an example of the SHG response of La_(4)Ge_(3)Se_(4)S_(8)being four times higher than La_(4)Ge_(3)S_(12).The optical and nonlinear optical properties of La_(4)Ge_(3)Se_(x)S_(12−x)(x=0,2,4,6,8,10)compounds are reported.展开更多
基金supported by start-up funds from Wichita State University.
文摘La_(4)Ge_(3)S_(12)was structurally characterized in 1974 without any optical or nonlinear optical properties reported.Herein we report that the acentric crystal structure of La_(4)Ge_(3)S_(12)has been confirmed by singlecrystal X-ray diffraction.The nonlinear optical properties test revealed its phase-matchable behavior with a good balance between the second harmonic generation(SHG)response and laser damage threshold(LDT).Theory calculations predicted that the optical properties of La_(4)Ge_(3)S_(12)are dominantly contributed by sulfur atoms.Band gap engineering was applied to tune the optical properties of La_(4)Ge_(3)S_(12)by replacing S with Se,which resulted in five new compounds:La_(4)Ge_(3)Se_(2)S_(10),La_(4)Ge_(3)Se_(4)S_(8),La_(4)Ge_(3)Se_(6)S_(6),La_(4)Ge_(3)Se_(8)S_(4),and La_(4)Ge3Se10S2.High quality mm-sized crystals of La_(4)Ge_(3)Se_(x)S_(12−x)(x=0,2,4,6,8,10)were grown by a hightemperature vapor transport reaction followed by salt flux growth methods.All La_(4)Ge_(3)Se_(x)S_(12−x)(x=0,2,4,6,8,10)compounds are isostructural and crystallize in the noncentrosymmetric rhombohedral space group R3c(no.161)with unit cell volumes of 2639.2Å^(3),2698.6Å^(3),2745.3Å^(3),2792.6Å^(3),2845.3Å^(3),and 2912.1Å^(3),for x=0,2,4,6,8,and 10,respectively.La_(4)Ge_(3)S_(12)shows a band gap of 3.1(1)eV,and the incorporation of Se to the system suppresses the band gap of the compound La_(4)Ge_(3)Se_(10)S_(2) to 1.9(1)eV.The incorporation of Se significantly shifts the nonlinear optical properties of La_(4)Ge_(3)S_(12),with an example of the SHG response of La_(4)Ge_(3)Se_(4)S_(8)being four times higher than La_(4)Ge_(3)S_(12).The optical and nonlinear optical properties of La_(4)Ge_(3)Se_(x)S_(12−x)(x=0,2,4,6,8,10)compounds are reported.
