Synthesis and structure of a new oxycarbonate, Sr5Mn4CO3O10, closely related to the perovskite structure

A new strontium manganese oxycarbonate Sr5Mn4CO3O10, related to the perovskite structure, was synthesised, using solid state reaction. The mean structure of this compound was solved by X-ray diffraction and electron microscopy in the P4/m space group. The cell parameters are related to the perovskite cell alpha(p) by the relation alpha = alpha(p)*root 5 = 8.795 Angstrom and c = alpha(p) = 3.785 Angstrom. This original phase can be deduced from the stoichiometric perovskite SrMnO3, by removing one [MnO5]infinity row of MnO6 octahedra out of five, in an ordered way; this leads to the framework Mn4O10, built up from corner-sharing MnO5 pyramids, forming tunnels which are in fact fully occupied by carbonate groups. The compound is antiferromagnetic with a Neel temperature T-N = 260 K. (C) 1995 Academic Press. Inc.