title: Square coordinated MnO(2)-units in BiMn(7)O(12).
abstract: Room temperature high-resolution synchrotron X-ray diffraction (HRSXRD) measurements were carried out on polycrystalline samples of BiMn(7)O(12) and LaMn(7)O(12). Rietveld refinements of HRSXRD data describe the crystal structures of both compounds in the monoclinic space group I2/m. The maximum entropy method-based pattern fitting (MPF) method inversion of HRSXRD data was utilized to obtain the spatial electron density (ED) distribution. Obtained results show clear differences in ED distributions around Mn-O bonds between isomorphic BiMn(7)O(12) and LaMn(7)O(12). The scheme of ED distributions in BiMn(7)O(12) indicates the presence of orbital ordering in the MnO(2) planar arrangement that appears as prominent features in very distorted MnO(12) and MnO(6) polyhedrons in the perovskite related structure of [BiMn(3)](A-site)[Mn(4)](B-site)O(12).
authors.affiliation: Centre for Materials Science and Nanotechnology, Department of Chemistry,University of Oslo, P.O.Box 1033 Blindern, NO-0315 Oslo, Norway.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Okamoto
authors.forename: Naoki
authors.initials: N
authors.lastname: Imamura
authors.forename: Maarit
authors.initials: M
authors.lastname: Karppinen
authors.forename: Hisao
authors.initials: H
authors.lastname: Yamauchi
authors.forename: Helmer
authors.initials: H
authors.lastname: Fjellvåg
mesh_terms: D017895:Manganese Compounds / Q000737:chemistry*; D008958:Models, Molecular; D010087:Oxides / Q000737:chemistry*; D017356:Synchrotrons; D014961:X-Ray Diffraction
chemical_list: D017895:Manganese Compounds; D010087:Oxides; C016552:manganese dioxide