Crystal structures of CsFe 2S 3 and RbFe 2S 3: synthetic analogs of rasvumite KFe 2S 3
Abstract
The isostructural alkali thioferrate compounds CsFe 2S 3, RbFe 2S 3 and KFe 2S 3 have been synthesized by reacting Fe and S with their corresponding AFeS 2 ( A=K, Rb, Cs) precursors. The crystal structures of these and binary compounds of intermediate composition were determined by Rietveld analysis of laboratory powder X-ray diffraction patterns. All of the synthesized compounds adopt the space group Cmcm (#63), Z=4 with: a=9.5193(8) Å, b=11.5826(10) Å, c=5.4820(4) Å for CsFe 2S 3; a=9.2202(7) Å, b=11.2429(9) Å, c=5.4450(3) Å for RbFe 2S 3; and a=9.0415(13) Å, b=11.0298(17) Å, c=5.4177(6) Å for KFe 2S 3. These mixed valence alkali thioferrates show regular changes in cell dimensions, AS 10 ( A=K, Rb, Cs) polyhedron volumes, polyhedron distortion parameters, and calculated oxidation state of Fe with respect to increasing size of the alkali element cation. The calculated empirical oxidation state of iron varies from +2.618 (CsFe 2S 3), through +2.666 (RbFe 2S 3) to +2.77 (KFe 2S 3).
- Publication:
-
Journal of Solid State Chemistry France
- Pub Date:
- June 2004
- DOI:
- 10.1016/j.jssc.2004.01.007
- Bibcode:
- 2004JSSCh.177.1867M