Sr₂FeO₃ with Stacked Infinite Chains of FeO₄ Square Planes

Abstract

The\nsynthesis of Sr₂FeO₃ through a hydride reduction\nof the Ruddlesden–Popper layered perovskite Sr₂FeO₄ is reported. Rietveld refinements using synchrotron and neutron\npowder diffraction data revealed that the structure contains corner-shared\nFeO₄ square-planar chains running along the [010] axis,\nbeing isostructural with Sr₂CuO₃ (<i>Immm</i> space group). Fairly strong Fe–O–Fe and Fe–Fe\ninteractions along [010] and [100], respectively, make it an <i>S</i> = 2 quasi two-dimensional (2D) rectangular lattice antiferromagnet.\nThis compound represents the end-member (<i>n</i> = 1) of\nthe serial system Sr_<i>n</i>+1Fe_<i>n</i>O_2<i>n</i>+1, together with\npreviously reported Sr₃Fe₂O₅ (<i>n</i> = 2) and SrFeO₂ (<i>n</i> = ∞),\nthus giving an opportunity to study the 2D-to-3D dimensional crossover.\nNeutron diffraction and Mössbauer spectroscopy show the occurrence\nof <i>G</i>-type antiferromagnetic order below 179 K, which\nis, because of dimensional reduction, significantly lower than those\nof the other members, 296 K in Sr₃Fe₂O₅ and 468 K in SrFeO₂. However, the temperature dependence\nof magnetic moment shows a universal behavior.