The tunability of the oxygen stoichiometry in the BaRE(Cu0.5Fe0.5)2O5+(}(d) double-perovskite structure, stable with rare earth elements RE=Lu-Pr. was studied by both normal-pressure thermogravimetric oxidative (O2) and deoxidative (Ar) post-annealings and high-pressure heat treatments carried out in a cubic-anvil-type high-pressure apparatus. Under reducing conditions the BaRE(Cu0.5Fe0.5)2O5+(}(d) double perovskite is obtained at δ≃0 irrespective of the size of the RE constituent. In the structures with RE=Pr and Nd the oxygen stoichiometry can be continuously varied by normal-pressure post-annealings up to δ≃0.24 and 0.35, respectively, whereas with a smaller rare earth ion, i.e., RE=Lu-Sm, the amount of excess oxygen raises from δ≃0 only upon high-pressure heat treatment. (C) 2000 Elsevier Science Ltd.
- A. oxides
- C. thermogravimetric analysis
- D. superconductivity
- High pressure