Effect of fluorite structure between adjacent CuO2 sheets in FeSr2(Tb,Ce)2Cu2O8+δ

Abstract: The FeSr2YCu2O6+δ compound with a tetragonal Ba2YCu3O6+δ -type structure exhibits superconductivity, only when it is properly annealed in N2 and subsequently in O2. N2-annealing causes the ordering of Cu and Fe, and O2-annealing supplies the carrier on the CuO2 sheets. We have synthesized a new compound FeSr2(Tb,Ce)2Cu2O8+δ with the fluorite structure instead of the Y layer between adjacent CuO2 sheets in FeSr2YCu2O6+δ . Neutron diffraction study shows that the insertion of the fluorite structure is very effective on preparing the structure with ordering of Cu and Fe without the N2-annealing. However, enough amount of carrier is not distributed on the CuO2 sheets to exhibit superconductivity, and resultingly we have observed very weak superconductivity in FeSr2(Tb,Ce)2Cu2O8+δ . [Copyright &y& Elsevier]