Superconducting borate derivatives of 123 cuprates

Incorporation of BO3- 3 ion stabilizes YSr2Cu3O7, but the borate derivative is non superconducting. Superconductivity is not obtained by the partial substitution of Y by Ca in YSr2Cu3−x(BO3)x0z. Superconductivity has however been found in YSr2−yBayCu3−x(BO3)x)z as well as Y0.5Ca0.5Sr2−yBayCu3−x(BO3)xOz (y=1, x=0.25). The borate ion is coordinated to copper reducing its point group symmetry. Observation of superconductivity in borate derivatives prepared under ambient conditions is noteworthy.