Abstract
Three new compounds, Cs2Bi2ZnS5, Cs 2Bi2CdS5, and Cs2Bi 2MnS5, have been synthesized from the respective elements and a reactive flux Cs2S3 at 973K. The compounds are isostructural and crystallize in a new structure type in space group Pnma of the orthorhombic system with four formula units in cells of dimensions at 153K of a=15.763(3), b=4.0965(9), c=18.197(4)Å, V=1175.0(4)Å3 for Cs2Bi2ZnS5; a=15.817(2), b=4.1782(6), c=18.473(3) Å, V=1220.8(3) Å3 for Cs2Bi 2CdS5; and a=15.830(2), b=4.1515(5), c=18.372(2)Å, V=1207.4(2)Å3 for Cs2Bi2MnS5. The structure is composed of two-dimensional ∞ 2[Bi2MS52-] (M=Zn, Cd, Mn) layers that stack perpendicular to the [100] axis and are separated by Cs+ cations. The layers consist of edge-sharing ∞ 1[Bi2S66-] and ∞1[MS34-] chains built from BiS6 octahedral and MS4 tetrahedral units. Two crystallographically unique Cs atoms are coordinated to S atoms in octahedral and monocapped trigonal prismatic environments. The structure of Cs 2Bi2MS5, is related to that of Na 2ZrCu2S4 and those of the AMM′Q 3 materials (A=alkali metal, M=rare-earth or Group 4 element, M′= Group 11 or 12 element, Q=chalcogen). First-principles theoretical calculations indicate that Cs2Bi2ZnS5 and Cs2Bi2CdS5 are semiconductors with indirect band gaps of 1.85 and 1.75eV, respectively. The experimental band gap for Cs2Bi2CdS5 is ≃1.7eV, as derived from its optical absorption spectrum.
Original language | English (US) |
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Pages (from-to) | 334-341 |
Number of pages | 8 |
Journal | Journal of Solid State Chemistry |
Volume | 174 |
Issue number | 2 |
DOIs | |
State | Published - Sep 2003 |
Funding
This research was supported by NSF Grant DMR00-96676. Use was made of the Central Facilities supported by the MRSEC program of the National Science Foundation (DMR00-76097) at the Materials Research Center of Northwestern University. We thank Kwasi Mitchell for his assistance.
Keywords
- Band gap
- Cesium bismuth metal sulfides
- Crystal structure
- Synthesis
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry