Rational structural design and modification based on known compounds is an effective strategy to explore new nonlinear optical(NLO)materials.Here,three new rare-earth(RE)oxythiogermanates Eu_(18)Ge_(9)O_(5)S_(31)(1),C...Rational structural design and modification based on known compounds is an effective strategy to explore new nonlinear optical(NLO)materials.Here,three new rare-earth(RE)oxythiogermanates Eu_(18)Ge_(9)O_(5)S_(31)(1),Ca_(3.32)Eu_(14.68)Ge_(9)O_(5)S_(31)(2)and Ba_(3)Eu_(15)Ge_(9)O_(5)S_(31)(3)were obtained by the novel cation and anion co-partial substitution strategy from the parentβ-Eu2GeS4(0),which induces centrosymmetric to noncentrosymmetric(NCS)structural transformation and NLO activities.They crystallize with a pseudo-zero dimensional structure in the chiral R3 space group,featuring almost linearly arranged isolated GeS_(4)and GeOS_(3)tetrahedra.Their optical band gaps were determined to be 2.18,2.23 and 2.24 eV,respectively.1 and 2 show balanced NLO properties with moderate second-harmonic generation(SHG)responses(0.5 and 0.6×AGS)and high laser-induced damage thresholds(LIDTs)(3.3×AGS).Moreover,theoretical calculations show that their NLO properties are determined by the synergistic effect of GeS_(4)and GeOS_(3)tetrahedra.This work enriches the chemistry of rarely studied RE oxychalcogenides and provides a fresh route for designing NCS structures targeting diverse applications.展开更多
基金the financial support from the National Natural Science Foundation of China(22071212 and 22371246)the Natural Science Foundation of Yunnan Province(202401AS070120).
文摘Rational structural design and modification based on known compounds is an effective strategy to explore new nonlinear optical(NLO)materials.Here,three new rare-earth(RE)oxythiogermanates Eu_(18)Ge_(9)O_(5)S_(31)(1),Ca_(3.32)Eu_(14.68)Ge_(9)O_(5)S_(31)(2)and Ba_(3)Eu_(15)Ge_(9)O_(5)S_(31)(3)were obtained by the novel cation and anion co-partial substitution strategy from the parentβ-Eu2GeS4(0),which induces centrosymmetric to noncentrosymmetric(NCS)structural transformation and NLO activities.They crystallize with a pseudo-zero dimensional structure in the chiral R3 space group,featuring almost linearly arranged isolated GeS_(4)and GeOS_(3)tetrahedra.Their optical band gaps were determined to be 2.18,2.23 and 2.24 eV,respectively.1 and 2 show balanced NLO properties with moderate second-harmonic generation(SHG)responses(0.5 and 0.6×AGS)and high laser-induced damage thresholds(LIDTs)(3.3×AGS).Moreover,theoretical calculations show that their NLO properties are determined by the synergistic effect of GeS_(4)and GeOS_(3)tetrahedra.This work enriches the chemistry of rarely studied RE oxychalcogenides and provides a fresh route for designing NCS structures targeting diverse applications.
