RESUMO
We report the synthesis, structure and physical properties of a hitherto unreported brownmillerite compound Sr2ScFeO5. We have shown a new ordering sequence of the interlayer iron tetrahedral chains. Reduced dimensionality of the magnetic lattice and the frustration in the two dimensional iron tetrahedral chains originate complex magnetic and magneto-dielectric effects. Our study highlights a novel approach to tailor the magnetic lattice in bulk oxides.
RESUMO
The new iron layered oxysulfate Sr4Fe2.5O7.25(SO4)0.5 has been prepared by a solid-state reaction in closed ampules into the form of ceramics and single crystals. Its atomic structure has been solved by means of spectroscopy, diffraction techniques, and high-resolution electron microscopy. Sr4Fe2.5O7.25(SO4)0.5 is a layered structure that derives from the Ruddelsden-Popper (RP) phases with the layer stacking sequence SrO/SrFeO2.5/SrFe0.5(SO4)0.5O1.25/SrFeO2.5. Within the mixed Fe3+/SO42- layer, the sulfur atoms are slightly shifted from the B site of the perovskite and each sulfate group shares two corners with iron pyramids in the basal plan without any order phenomenon. The electronic conductivity is thermally activated, while no ionic conductivity is detected.
