A novel family of layered bismuth compounds I. The crystal structures of Pb0.6Bi1.4Cs0.6O2Cl2 and Pb0.6Bi3.4Cs0.6O4Cl4

Twenty new multinary bismuth oxide halogenides have been prepared and chara cterized by means of X-ray powder diffraction. In their structures, fluorit e-related layers are separated by CsCl-related metal-halogen sheets. Four c ompounds are isostructural to Ca3Bi5CsO8Cl6 which has an intergrowth struct ure between a Sillen XI phase and a novel structural element ("Y2"). Anothe r four compounds crystallize in a novel structure type which is an intergro wth between the X2 Sillen phase and the Y2 element. The remaining 12 compou nds adopt the Y2 structure which is also a new structure type. In the forme r two families, Bi3+ can be substituted only by pb(2+); in the latter famil y, Bi3+ can also be substituted by Na+ and Ba2+. The crystal structure of P b0.6Bi3.4Cs0.6Cl4 (intergrowth X2Y2 structure) has been solved from single crystal data, and the structure of Pb0.6Bi1.4CS0.6O2Cl2 (Y2 structure) has been solved from powder data. Crystal chemical relationships to Sillen phas es are discussed, (C) 1999 Academic Press.