The superconducting properties and structure of Y(Ba2-xYx)Cu3O7+δ and Bi2 Sr2-x Cax Cu2O7+δ are described. In the former material the Ba sites in the YBa2Cu3O7 structure is doped by the smaller sized Y3+ ion to give a non-superconducting phase. Similar doping by Sr2+ ions can also be achieved to give a structure which shows a broadened bulk superconducting transition with Tc = 85K. When the Ba:Sr ratio is 1:1 a resistive anomaly is observed near ∼200K. The Bi -superconductor becomes superconducting near 90K with a resistive and diamagnetic transition at 112K. The structure of the ordered phase of the Bi superconductor has been obtained by high resolution electron microscope imaging and electron diffraction.
ASJC Scopus subject areas
- Condensed Matter Physics