Synthesis, crystal structure and magnetism of Eu3Sc2O5Fe2As2

The iron arsenide Eu3Fe2O5Fe2As2 was synthesized at 1173-1373 K in a resistance furnace and characterized by X-ray powder diffraction with Rietveld analysis: Sr3Fe2O5Cu2S2 type, I4/mmm, a = 406.40(1) pm, c = 2646.9(1) pm. Layers of edge-sharing FeAs4/4 tetrahedra are separated by perovskite-like oxide blocks. No structural transition occurs in the temperature range from 10 to 300 K. Magnetic measurements have revealed Curie-Weiss behavior with an effective magnetic moment of 7.79 mu(B) per europium atom in agreement with the theoretical value of 7.94 mu(B) for Eu2+. A drop in the magnetic susceptibility at 5 K indicates possible antiferromagnetic ordering. Eu-151 and Fe-57 Mossbauer spectroscopic measurements have confirmed a beginning cooperative magnetic phenomenon by showing significantly broadened spectra at 4.8 K compared to those at 78 K.