在乙二胺溶剂体系中,180℃条件下合成了两种化合物[M(en)_3]_2[Sn_2Se_4S_2](1)和[Co(en)3]2[Sn_2Se_4S_2](2)。通过X-射线单晶衍射、SEM、IR、TGA和UV-Vis等手段对其进行了表征。X-射线单晶衍射结果表明化合物1和2是类质同晶,均为正交...在乙二胺溶剂体系中,180℃条件下合成了两种化合物[M(en)_3]_2[Sn_2Se_4S_2](1)和[Co(en)3]2[Sn_2Se_4S_2](2)。通过X-射线单晶衍射、SEM、IR、TGA和UV-Vis等手段对其进行了表征。X-射线单晶衍射结果表明化合物1和2是类质同晶,均为正交晶系,并属于Pbca空间群,结构中均含有Sn和两种硫属元素S、Se组成的二聚体阴离子[Sn2Se4S2]2-。两种晶体的晶胞参数分别为:化合物1,a=1.6020(8)nm,b=1.1842(6)nm,c=1.9658(10)nm,Z=8;化合物2,a=1.5491(5)nm,b=1.1688(4)nm,c=1.18666(6)nm,Z=8。紫外-可见漫反射光谱研究结果表明,化合物1和2的禁带宽度分别为1.54 e V和1.64 e V,均有半导体性能。展开更多
Two new quaternary sulfides,KSmSiS4(1) and KYbSiS4(2),have been synthesized by high-temperature solid-state reaction.Single-crystal X-ray diffraction analyses indicate that both compounds crystallize in the space grou...Two new quaternary sulfides,KSmSiS4(1) and KYbSiS4(2),have been synthesized by high-temperature solid-state reaction.Single-crystal X-ray diffraction analyses indicate that both compounds crystallize in the space group P21/m,and the crystal data are as follows:a = 6.426(11),b = 6.582(11),c = 8.602(15) ,β = 107.90(13)°,Z = 2,V = 346.2(10) 3,Dc = 3.317 g/cm3,F(000) = 318,μ(MoKα) = 10.334 mm-1,the final R = 0.0559 and wR = 0.1370 for 1;and a = 6.3244(10),b = 6.5552(10),c = 8.5701(15) ,β = 108.001(13)°,Z = 2,V = 337.91(9) 3,Dc = 3.621 g/cm3,F(000) = 334,μ(MoKα) = 15.737 mm-1,the final R = 0.0422 and wR = 0.0960 for 2.The KLnSiS4(Ln = Sm,Yb) structure consists of corrugated ∞2 [LnSiS4]-layers which are formed by edge-sharing LnS8 bicapped trigonal prisms and SiS4 tetrahedra.The K+ cations are located in the cavities defined by S2-anions between the ∞2 [LnSiS4]-layers.Band-gap analyses show that compounds 1 and 2 are semiconductors with optical band-gaps of 2.40 and 2.34 eV,respectively.展开更多
The compound Ni2Ta2Te4 is obtained by heating the elements at 1000℃ in evacuated silica tube. Mr=989.70, orthorhombic system,space group Pma2,a = 7.914(1),b= 6.2372(5),c=7.2362(6)A,V = 357.2(1)A3, Z = 2, DC = 9.201 g...The compound Ni2Ta2Te4 is obtained by heating the elements at 1000℃ in evacuated silica tube. Mr=989.70, orthorhombic system,space group Pma2,a = 7.914(1),b= 6.2372(5),c=7.2362(6)A,V = 357.2(1)A3, Z = 2, DC = 9.201 g/ca3,λ(MoKα)=0.7093A,μ= 537.90Cm-1.F(000)=820. Final R=0.083 and Rw=0.103 for 889 reflections.This compound is iso-structural to Ni2Nb2Te4,with two-dimensional(2D) network structure. In each cluster unit,two Ni and two Ta atons form a rhombic plane with four Ni-Ta bonds (average 2.655 A) and one Ni-Ni bond (2.512 A) without Ta-Ta interac-action. The distorted tetrahedral coordination of each metal atons is completed by four Te atoms.The average distances are 2.792A for bonds Ta-Te and 2.556 A for bonds Ni-Te.展开更多
The temperature dependence of lattice constants is studied by using first-principles calculations to determine the effects of in-plane stiffness and charge transfer on the thermal expansions of monolayer semiconductin...The temperature dependence of lattice constants is studied by using first-principles calculations to determine the effects of in-plane stiffness and charge transfer on the thermal expansions of monolayer semiconducting transition metal dichalcogenides.Unlike the corresponding bulk material,our simulations show that monolayer MX_2(M = Mo and W;X = S,Se,and Te) exhibits a negative thermal expansion at low temperatures,induced by the bending modes.The transition from contraction to expansion at higher temperatures is observed.Interestingly,the thermal expansion can be tailored regularly by alteration of the M or X atom.Detailed analysis shows that the positive thermal expansion coefficient is determined mainly by the in-plane stiffness,which can be expressed by a simple relationship.Essentially the regularity of this change can be attributed to the difference in charge transfer between the different elements.These findings should be applicable to other two-dimensional systems.展开更多
文摘在乙二胺溶剂体系中,180℃条件下合成了两种化合物[M(en)_3]_2[Sn_2Se_4S_2](1)和[Co(en)3]2[Sn_2Se_4S_2](2)。通过X-射线单晶衍射、SEM、IR、TGA和UV-Vis等手段对其进行了表征。X-射线单晶衍射结果表明化合物1和2是类质同晶,均为正交晶系,并属于Pbca空间群,结构中均含有Sn和两种硫属元素S、Se组成的二聚体阴离子[Sn2Se4S2]2-。两种晶体的晶胞参数分别为:化合物1,a=1.6020(8)nm,b=1.1842(6)nm,c=1.9658(10)nm,Z=8;化合物2,a=1.5491(5)nm,b=1.1688(4)nm,c=1.18666(6)nm,Z=8。紫外-可见漫反射光谱研究结果表明,化合物1和2的禁带宽度分别为1.54 e V和1.64 e V,均有半导体性能。
基金supported by the Fundamental Research Funds for the Central Universities (WK2060140023, WK2060140022, CX3430000001 and WK2060140024)the Major/Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology (2016FXZY003)the National Natural Science Foundation of China (GG2060140085 and CX2310000097)
基金supported by the NNSFC (20521101)NSF for Distinguished Young Scientist of China (20425104)+1 种基金NSF of Fujian Province (2007J0173)the Fund of Fujian Key Laboratory of Nanomaterials (2006L2005)
文摘Two new quaternary sulfides,KSmSiS4(1) and KYbSiS4(2),have been synthesized by high-temperature solid-state reaction.Single-crystal X-ray diffraction analyses indicate that both compounds crystallize in the space group P21/m,and the crystal data are as follows:a = 6.426(11),b = 6.582(11),c = 8.602(15) ,β = 107.90(13)°,Z = 2,V = 346.2(10) 3,Dc = 3.317 g/cm3,F(000) = 318,μ(MoKα) = 10.334 mm-1,the final R = 0.0559 and wR = 0.1370 for 1;and a = 6.3244(10),b = 6.5552(10),c = 8.5701(15) ,β = 108.001(13)°,Z = 2,V = 337.91(9) 3,Dc = 3.621 g/cm3,F(000) = 334,μ(MoKα) = 15.737 mm-1,the final R = 0.0422 and wR = 0.0960 for 2.The KLnSiS4(Ln = Sm,Yb) structure consists of corrugated ∞2 [LnSiS4]-layers which are formed by edge-sharing LnS8 bicapped trigonal prisms and SiS4 tetrahedra.The K+ cations are located in the cavities defined by S2-anions between the ∞2 [LnSiS4]-layers.Band-gap analyses show that compounds 1 and 2 are semiconductors with optical band-gaps of 2.40 and 2.34 eV,respectively.
文摘The compound Ni2Ta2Te4 is obtained by heating the elements at 1000℃ in evacuated silica tube. Mr=989.70, orthorhombic system,space group Pma2,a = 7.914(1),b= 6.2372(5),c=7.2362(6)A,V = 357.2(1)A3, Z = 2, DC = 9.201 g/ca3,λ(MoKα)=0.7093A,μ= 537.90Cm-1.F(000)=820. Final R=0.083 and Rw=0.103 for 889 reflections.This compound is iso-structural to Ni2Nb2Te4,with two-dimensional(2D) network structure. In each cluster unit,two Ni and two Ta atons form a rhombic plane with four Ni-Ta bonds (average 2.655 A) and one Ni-Ni bond (2.512 A) without Ta-Ta interac-action. The distorted tetrahedral coordination of each metal atons is completed by four Te atoms.The average distances are 2.792A for bonds Ta-Te and 2.556 A for bonds Ni-Te.
基金supported by the National Natural Science Foundation of China(Grant Nos.11274280 and 11104254)the National Basic Research Program of China(Grant No.2012CB921300)
文摘The temperature dependence of lattice constants is studied by using first-principles calculations to determine the effects of in-plane stiffness and charge transfer on the thermal expansions of monolayer semiconducting transition metal dichalcogenides.Unlike the corresponding bulk material,our simulations show that monolayer MX_2(M = Mo and W;X = S,Se,and Te) exhibits a negative thermal expansion at low temperatures,induced by the bending modes.The transition from contraction to expansion at higher temperatures is observed.Interestingly,the thermal expansion can be tailored regularly by alteration of the M or X atom.Detailed analysis shows that the positive thermal expansion coefficient is determined mainly by the in-plane stiffness,which can be expressed by a simple relationship.Essentially the regularity of this change can be attributed to the difference in charge transfer between the different elements.These findings should be applicable to other two-dimensional systems.
