Properties of the n = 3 Ruddlesden-Popper phases, Sr₄-Mn₃-(x)Fe(x)O(10δ) (x = 1, 1.5, 2)

We have prepared a series of Fe-substituted Sr₄Mn₃-x Fe(x)O(10-δ) strontium manganates with x = 1, 3/2, and 2. These compounds adopt the n =3 Ruddlesden-Popper structure (I4/mmm), unlike the parent compound Sr₄Mn₃O₁₀, which contains a network of face-sharing MnO₆ octahedra, with the larger Fe ion preferentially occupying the Mn/Fe (1) middle layer of the corner-sharing trioctahedra slabs. We have investigated their physical properties with X-ray diffraction, X-ray absorption near edge spectroscopy, Mossbauer spectroscopy, variable temperature resistivity, and magnetic susceptibility. In addition, for the x = 2 compound we preformed room temperature neutron diffraction experiments. These compounds need to be formed at high temperatures; as a consequence they are oxygen deficient and contain some Fe³⁺. They are insulators and exhibit spinglass-like transitions at low temperature. (C) 2000 Academic Press.