Abstract
The title compound, di(strontium/lead) hexa-aluminate, is a member of the solid solution series (Sr2-x Pb x )Al6O11. It contains two statistically occupied M (2+) (M = Sr, Pb) sites [both with site symmetries ..m; Sr:Pb occupancy ratios = 0.756 (2):0.244 (2) and 0.8968 (19):0.1032 (19)] that are located in the voids of an aluminate framework. The M (2+) sites are surrounded by six and seven O atoms, respectively, if a cut-off M-O distance of 3 Å is chosen, resulting in considerably distorted MO x polyhedra. The aluminate framework consists of three AlO6 octa-hedra (two with point-group symmetries ..2/m and one with ..2) sharing edges to form partially filled layers extending parallel to (100) and located at x = 0, 0.5. Adjacent AlO6 layers are linked by a network made up from two crystallographically different AlO4 tetra-hedra by sharing corners.