Layered ruthenium hexagonal perovskites: The new series [Ba{sub 2}Br{sub 2-2x}(CO{sub 3}){sub x}][Ba{sub n+1}Ru{sub n}O{sub 3n+3}] with n=2, 3, 4, 5
- UCCS, Equipe Chimie du Solide, CNRS UMR 8181, ENSC Lille-UST Lille, BP 90108, 59652 Villeneuve d'Ascq cedex (France)
Single crystals of the title compounds were prepared by solid state reactions from barium carbonate and ruthenium metal using a BaBr{sub 2} flux and investigated by X-ray diffraction method using Mo(K{alpha}) radiation and a Charge Coupled Device (CCD) detector. A structural model for the term n=2, Ba{sub 5}Ru{sub 2}Br{sub 2}O{sub 9} (1) was established in the hexagonal symmetry, space group P6{sub 3}/mmc, a=5.8344(2)A, c=25.637(2)A, Z=2. Combined refinement and maximum-entropy method (MEM) unambiguously show the presence of CO{sub 3}{sup 2-} ions in the three other compounds (2, 3, 4). Their crystal structures were solved and refined in the trigonal symmetry, space group P3-barml, a=5.8381(1)A, c=15.3083(6)A for the term n=3, Ba{sub 6}Ru{sub 3}Br{sub 1.54}(CO{sub 3}){sub 0.23}O{sub 12} (2), and space group R3-barm, a=5.7992(1)A, c=52.866(2)A and a=5.7900(1)A, c=59.819(2)A for the terms n=4, Ba{sub 7}Ru{sub 4}Br{sub 1.46}(CO{sub 3}){sub 0.27}O{sub 15} (3), and n=5, Ba{sub 8}Ru{sub 5}Br{sub 1.64}(CO{sub 3}){sub 0.18}O{sub 18} (4), respectively. The structures are formed by the periodic stacking along [001] of (n+1) hexagonal close-packed [BaO{sub 3}] layers separated by a double layer of composition [Ba{sub 2}Br{sub 2-2x}(CO{sub 3}){sub x}]. The ruthenium atoms occupy the n octahedral interstices created in the hexagonal perovskite slabs and constitute isolated dimers Ru{sub 2}O{sub 9} of face-shared octahedra (FSO) in 1 and isolated trimers Ru{sub 3}O{sub 12} of FSO in 2. In 3 and 4, the Ru{sub 2}O{sub 9} units are connected by corners either directly (3) or through a slab of isolated RuO{sub 6} octahedra (4) to form a bidimensional arrangement of RuO{sub 6} octahedra. These four oxybromocarbonates belong to the family of compounds formulated [Ba{sub 2}Br{sub 2-2x}(CO{sub 3}){sub x}][Ba{sub n+1}Ru{sub n}O{sub 3n+3}] where n represents the thickness of the octahedral string in hexagonal perovskite slabs. These compounds are compared to the oxychloride series.
- OSTI ID:
- 21015860
- Journal Information:
- Journal of Solid State Chemistry, Vol. 180, Issue 7; Other Information: DOI: 10.1016/j.jssc.2007.05.018; PII: S0022-4596(07)00199-5; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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