Ab initio calculations of the band structure, total and partial densities of states and the spatial distribution of the electron charge density of crystalline Na2GeS3 are performed in the framework of density function...Ab initio calculations of the band structure, total and partial densities of states and the spatial distribution of the electron charge density of crystalline Na2GeS3 are performed in the framework of density functional theory in the local density approximation for an exchange-correlation potential. According to the calculation results, sodium thiogermanate is a direct-gap crystal with the top of the valence band and the bottom of the conduction band at the point of the Brillouin zone. The calculated band gap is Eg= 2.51 eV. The nature of the components of the electronic states in different subbands of the valence band is determined. The calculated total density of states in the valence band of the crystal is compared with the known experimental X-ray photoelectron spectrum of Na2GeS3 glass. Based on the maps of the electron density distribution, the nature of the chemical bonds and high mobility of Na+ ions in Na2GeS3 crystal is analyzed.展开更多
Two new thiohalides Pb_(3)GeS_(4)Br_(2) and Pb_(3.5)GeS_(4)Br_(3) have been synthesized by introducing Pb^(2+)into the thiogermanate system.The compounds crystallize in centrosymmetric P2_(1)/c(Pb_(3)GeS_(4)Br_(2))and...Two new thiohalides Pb_(3)GeS_(4)Br_(2) and Pb_(3.5)GeS_(4)Br_(3) have been synthesized by introducing Pb^(2+)into the thiogermanate system.The compounds crystallize in centrosymmetric P2_(1)/c(Pb_(3)GeS_(4)Br_(2))and noncentrosymmetric P63(Pb_(3.5)GeS_(4)Br_(3))space groups,respectively.To the best of our knowledge,Pb_(3)GeS_(4)Br_(2) and Pb_(3.5)GeS_(4)Br_(3) are the first Pb-containing thiogermanate halides,and the latter is the first phase-matching IR nonlinear optical material in the thiogermanate halide system.Due to the presence of Pb^(2+)with stereochemically active lone pair electrons,Pb_(3)GeS_(4)Br_(2) exhibits a strong optical anisotropy with a birefringence of 0.131@1064 nm,while Pb_(3.5)GeS_(4)Br_(3) shows a large second-harmonic generation response(0.8×AgGaS_(2))and high laser-induced damage threshold(3.0×AgGaS_(2)).These results enrich the structural and chemical diversity of chalcohalides.展开更多
文摘Ab initio calculations of the band structure, total and partial densities of states and the spatial distribution of the electron charge density of crystalline Na2GeS3 are performed in the framework of density functional theory in the local density approximation for an exchange-correlation potential. According to the calculation results, sodium thiogermanate is a direct-gap crystal with the top of the valence band and the bottom of the conduction band at the point of the Brillouin zone. The calculated band gap is Eg= 2.51 eV. The nature of the components of the electronic states in different subbands of the valence band is determined. The calculated total density of states in the valence band of the crystal is compared with the known experimental X-ray photoelectron spectrum of Na2GeS3 glass. Based on the maps of the electron density distribution, the nature of the chemical bonds and high mobility of Na+ ions in Na2GeS3 crystal is analyzed.
基金supported by the National Natural Science Foundation of China(61835014 and 51972336)the Xinjiang Tianshan Talent Program(2022TSYCTD0005)the Scientific Foundation of Binzhou Medical University(No.50012304488).
文摘Two new thiohalides Pb_(3)GeS_(4)Br_(2) and Pb_(3.5)GeS_(4)Br_(3) have been synthesized by introducing Pb^(2+)into the thiogermanate system.The compounds crystallize in centrosymmetric P2_(1)/c(Pb_(3)GeS_(4)Br_(2))and noncentrosymmetric P63(Pb_(3.5)GeS_(4)Br_(3))space groups,respectively.To the best of our knowledge,Pb_(3)GeS_(4)Br_(2) and Pb_(3.5)GeS_(4)Br_(3) are the first Pb-containing thiogermanate halides,and the latter is the first phase-matching IR nonlinear optical material in the thiogermanate halide system.Due to the presence of Pb^(2+)with stereochemically active lone pair electrons,Pb_(3)GeS_(4)Br_(2) exhibits a strong optical anisotropy with a birefringence of 0.131@1064 nm,while Pb_(3.5)GeS_(4)Br_(3) shows a large second-harmonic generation response(0.8×AgGaS_(2))and high laser-induced damage threshold(3.0×AgGaS_(2)).These results enrich the structural and chemical diversity of chalcohalides.
