Structure and spin gap in YBa2Cu3−xGdxO7−δ superconductors

Abstract: Gd-doped poly-crystallized YBa2Cu3−xGdxO7−δ compounds with x=0–0.15 were synthesized using the solid-state reaction technique. We found that Gd3+ ions prefer to replace Cu at Cu(2) sites (CuO2 planar) within x<0.05, which may due to the ion size effect, and Gd3+ ions then begin to partially occupy Cu(1) sites (CuO chain) with increasing the doping content, which gives vital influence on superconductivity and spin-gap properties. There is no clear role on spin gap opening temperature played by magnetic element doping. [Copyright &y& Elsevier]