Synthesis and Characterization of the Superconductors Y3Ba5Cu8−x FexO18(0.0597 ≤ x ≤ 0.1255)

We report on a crystallographic characterization of the Y3Ba5Cu8−x Fe x O18 complex perovskite, where x = 0.0597, 0.0625, 0.0925, and 0.1225. The samples were produced by the standard solid-state reaction. A Rietveld refinement of experimental X-ray diffraction patterns allows the determination of the lattice parameters and the phase composition of the studied samples. Magnetic and transport properties of polycrystalline samples are investigated. Nearly above the superconducting transition, the resistivity shows a slight increase while the temperature decreases. We observe an anomalous behavior of the magnetization in the normal phase of the studied compounds. The observed feature reminds the effect of a minor phase having a superconducting transition at T ˜ 150 K.