Preparation, structural and magnetic characterization of DyCrMnO5

The title compound has been first synthesized by a citrate technique followed by thermal treatments under moderate oxygen pressure conditions, and characterized by X-ray and neutron powder diffraction (NPD) and magnetization measurements. The crystal structure of DyCrMnO 5 has been refined from NPD data in the space group Pbam ; a =7.2617(6) A, b =8.5161(6) A, and c =5.7126(5) A at 295 K. This oxide is isostructural with R Mn 2 O 5 oxides ( R =rare earths) and it contains infinite chains of (Cr, Mn) 4+ O 6 octahedra-sharing edges, linked together by (Mn, Cr) 3+ O 5 pyramids and DyO 8 units. The high degree of antisite disordering exhibited by DyCrMnO 5 is noteworthy. The octahedral positions are occupied by roughly 50% of Mn and Cr cations, and the pyramidal groups contain two thirds of Mn and one third of Cr cations. We assume that Mn and Cr cations at the octahedral positions exhibit a tetravalent oxidation state, whereas the metals at the pyramidal positions are trivalent, in order to preserve the electroneutrality of this oxide. The susceptibility vs temperature curve of DyCrMnO 5 does not suggest the establishment of a long-range magnetic structure even at low temperatures; the NPD technique does not provide any signal of magnetic ordering, since the reflections do not show any magnetic contribution.