Ba2Mn2O4Cu0.9S: A layered Oxysulfide with a New Perovskite-Related Manganese Oxide Fragment

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• 作者：Geoffrey Hyett ; Zolt&#xe1 ; n A. G&#xe1 ; l ; Catherine F. Smura ; Simon J. Clarke
• 刊名：Chemistry of Materials
• 出版年：2008
• 出版时间：January 22, 2008
• 年：2008
• 卷：20
• 期：2
• 页码：559 - 566
• 全文大小：607K
• 年卷期：v.20,no.2(January 22, 2008)
• ISSN：1520-5002

文摘

The oxysulfides Ba₂Mn₂O₄Cu_0.9S and Ba_1.3Sr_0.7Mn₂O₄CuS are reported. The compounds crystallize in space group P4/nmm with 2 formula units in the unit cell and lattice parameters a = 3.9916(1) Å and c = 19.5628(5) Å for a refined composition of Ba₂Mn₂O₄Cu_0.89(1)S and a = 3.9595(1) Å and c = 19.2227(3) Å for Ba_1.32(3)Sr_0.68(4)Mn₂O₄Cu_0.98(2)S determined, respectively, from powder neutron and X-ray single-crystal diffraction measurements. The structure consists of alkaline earth Manganite slabs composed of MnO₅ square-based pyramids sharing edges and vertexes, which are separated by CuS antifluorite-type puckered layers. The central part of the alkaline earth manganite slab is composed of MnO₅ square-based pyramidal units sharing all four of their basal edges with neighboring units in the basal plane and sharing their apical vertices with those of square-based MnO₅ pyramids in the outer part of the alkaline earth manganite slab. This is similar to a structural fragment in the as-yet-unrealized strontium iron oxide Sr₄Fe₆O₁₂, which is the oxide-poor relative of the anion-conducting Sr₄Fe₆O_13±δ phases. The intrinsic copper deficiency in semiconducting Ba₂Mn₂O₄Cu_0.9S suggests a mean manganese oxidation state of +2.55. The results of magnetic susceptibility measurements and low-temperature neutron diffraction results suggest that some moments participate in long-range antiferromagnetic order, whereas others give rise to spin-glass-like behavior.