title: Experimental versus expected halide-ion size differences; structural changes in three series of isotypic bismuth chalcogenide halides.
abstract: Experimentally determined halide-ion size differences are compared with expected size differences in the three series of isotypic bismuth chalcogenide halide compounds, KBi(6)O(9)X (X = Cl, Br and I), BiOX (X = F, Cl, Br and I) and BiSX (X = Cl, Br and I). The strong deviations observed can be assigned to steric strain caused by the heterogeneity of the bond-valence pattern and (for BiOX) to anion-anion repulsion and a change in the connectivity scheme. Some special features of the BiOF structure and the question of "isotypism" within the BiOX series are briefly discussed. Structural changes within the BiSX series are analysed.
authors.affiliation: Kristallographisches Institut der Universität Freiburg, Hermann-Herder-Strasse 5, D-79104 Freiburg, Germany. egbert.keller@krist.uni-freiburg.de
authors.forename: Egbert
authors.initials: E
authors.lastname: Keller
authors.forename: Volker
authors.initials: V
authors.lastname: Krämer