Abstract. The iron arsenide oxides Sr 2 CrO 3 FeAs and Ba 2 ScO 3 FeAs were synthesized by high temperature solid state reactions and their crystal structures determined by the X-ray powder diffraction. Their structures are tetragonal (P4/nmm; Sr 2 CrO 3 FeAs: a = 391.12(1) pm, c = 1579.05(3) pm; Ba 2 ScO 3 FeAs: a = 412.66(5) pm, c = 1680.0(2) pm, Z = 2) and isotypic to Sr 2 GaO 3 CuS. Iron arsenide layers are sandwiched between perowskite-like metal oxide layers and separated by ~1600 pm, which is much larger compared to the ZrCuSiAs-type '1111' iron arsenide superconductors. The bond lengths and angles within the FeAs layers are adapted to the space requirements of the oxide blocks. Measurements of the magnetic susceptibility, electrical resistivity and temperature-dependent crystal structure show no hint for a structural phase transition or magnetic anomaly in both compounds. Sr 2 CrO 3 FeAs shows Curie-Weiss paramagnetism above 160 K with an effective magnetic moment of 3.83(3) µ B in good agreement with the theoretical value of 3.87 µ B for Cr 3+ (S = 3/2).
Fe Moessbauer spectroscopy, resistivity and magnetic measurements, and DFT electronic structure calculations. The compounds crystallize isotypically in the tetragonal space group P4/nmm with Z = 2 (Sr 2 GaO 3 CuS-type structure). FeAs layers are sandwiched between perovskite-like metal oxide layers and separated by about 1600 pm. The Cr compound exhibits paramagnetism and antiferromagnetic ordering below 31 K, whereas the Sc compound is Pauli-paramagnetic. -(TEGEL, M.; HUMMEL, F.; LACKNER, S.; SCHELLENBERG, I.; POETTGEN, R.; JOHRENDT*, D
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