Accurate Determination of the Redox State in High‐Tc Superconductor Oxides

Abstract
The determination of the excess oxygen content in high‐Tc superconductors is especially important. The efficiency of two new methods by which δ is determined directly has been demonstrated using the prototypic semiconductor YBa2Cu3O6.5+δ. In one method the shift of the Fe2⊕/Fe3⊕ concentration ratio is determined, whereas in the other the O2‐pressure after reaction of the oxide ceramic with water is measured.