Role of Rare Earth Ions (Gd, Dy, Ho and Er) in Phase Formation and Superconducting Properties of Ba1-xLnxCuO3-y Compounds

Ba–Ln–Cu–O compounds (Ln=Gd, Dy, Ho and Er) were prepared by a solid-state reaction. The optimum sintering temperature for obtaining a single phase of Ba2LnCu3O7-δ was different for each Ln element, and this temperature decreased with increasing atomic number of Ln. A single phase with the perovskite structure was obtained only around the Ba2LnCu3O7-δ composition. T c's of these compounds prepared by a solid-state reaction in air increased with increasing atomic number of Ln. T c's of samples prepared in oxygen atmosphere were almost the same. The magnetic moment of Ba1-x Ln x CuO3-y compounds is associated with each Ln, and its value is in good agreement with the Ln3+ Hund rules free ion values.