New Quaternary Bismuth Sulfides: Syntheses, Structures, and Band Structures of AMBiS4 (A = Rb, Cs; M = Si, Ge)
详细信息 查看全文
- 作者：Jiyong Yao ; Bin Deng ; Donald E. Ellis ; and James A. Ibers
- 刊名：Inorganic Chemistry
- 出版年：2002
- 出版时间：December 30, 2002
- 年：2002
- 卷：41
- 期：26
- 页码：7094 - 7099
- 全文大小：264K
- 年卷期：v.41,no.26(December 30, 2002)
- ISSN：1520-510X
文摘
Four new compounds, RbSiBiS4, RbGeBiS4, CsSiBiS4, and CsGeBiS4, have been synthesized by means of thereactive flux method. The isostructural compounds RbSiBiS4, RbGeBiS4, and CsGeBiS4 crystallize in space groupP21/c of the monoclinic system with four formula units in cells of dimensions at 153 K of a = 6.4714(4) Å, b =6.7999(4) Å, c = 17.9058(11) Å, and 
= 108.856(1)
for RbSiBiS4, a = 6.5864(4) Å, b = 6.8559(4) Å, c =17.9810(12) Å, and = 109.075(1) for RbGeBiS4, and a = 6.5474(4) Å, b = 6.9282(4) Å, c = 18.8875(11) Å,and = 110.173(1) for CsGeBiS4. CsSiBiS4 crystallizes in a different structure type in space group P21/c of themonoclinic system with four formula units in a cell of dimensions at 153 K of a = 9.3351(7) Å, b = 6.9313(5) Å,c = 12.8115(10) Å, and = 109.096(1). The two structure types are closely related and consist of 
[MBiS4-](M = Si, Ge) layers separated by bicapped trigonal-prismatically coordinated alkali-metal atoms. In each, the Matom is coordinated to a tetrahedron of four S atoms and the Bi atom is coordinated to seven S atoms comprisingfive close S atoms at the corners of a square pyramid with Bi near the center of the basal plane and the sixth andseventh S atoms further away to complete a distorted monocapped trigonal prism. The optical band gaps of 2.23eV for RbGeBiS4 and 2.28 eV for CsGeBiS4 were deduced from their diffuse reflectance spectra. From a bandstructure calculation, the optical absorption for RbGeBiS4 originates from the 
[GeBiS4-] layer. The Ge 4p orbitals,Bi 6p orbitals, and S 3p orbitals are highly hybridized.
= 108.856(1) for RbSiBiS4, a = 6.5864(4) Å, b = 6.8559(4) Å, c =17.9810(12) Å, and = 109.075(1) for RbGeBiS4, and a = 6.5474(4) Å, b = 6.9282(4) Å, c = 18.8875(11) Å,and = 110.173(1) for CsGeBiS4. CsSiBiS4 crystallizes in a different structure type in space group P21/c of themonoclinic system with four formula units in a cell of dimensions at 153 K of a = 9.3351(7) Å, b = 6.9313(5) Å,c = 12.8115(10) Å, and = 109.096(1). The two structure types are closely related and consist of [MBiS4-](M = Si, Ge) layers separated by bicapped trigonal-prismatically coordinated alkali-metal atoms. In each, the Matom is coordinated to a tetrahedron of four S atoms and the Bi atom is coordinated to seven S atoms comprisingfive close S atoms at the corners of a square pyramid with Bi near the center of the basal plane and the sixth andseventh S atoms further away to complete a distorted monocapped trigonal prism. The optical band gaps of 2.23eV for RbGeBiS4 and 2.28 eV for CsGeBiS4 were deduced from their diffuse reflectance spectra. From a bandstructure calculation, the optical absorption for RbGeBiS4 originates from the [GeBiS4-] layer. The Ge 4p orbitals,Bi 6p orbitals, and S 3p orbitals are highly hybridized.