RF-properties-optimized compositions of (RE)Ba2Cu3O7-delta thin film superconductors

A superconducting article with improved microwave qualities comprising:

• a substrate, and
• a thin film disposed on the substrate having the nominal composition of
• REzBayCu3Ox
• wherein RE is a rare earth and not yttrium and wherein JIMD>0.8×107 A/cm2 at 77K.

A superconducting article with improved microwave qualities comprising:

• a substrate, and
• a thin film disposed on the substrate having the nominal composition of
• REzBayCu3Ox
• wherein RE is a rare earth and not yttrium and wherein Rs<15 μΩ when measured at 1.85 GHz and 77K.

A superconducting article comprising:

• a substrate, and
• a thin film disposed on the substrate having the nominal composition of
• DyzBayCu3Ox
• wherein y is less than substantially 2.1 and the ratio of y/z is 1.65±10%.

A superconducting article comprising:

• a substrate, and
• a thin film disposed on the substrate having the nominal composition of REzBayCu3Ox
• wherein RE is a rare earth and not yttrium, and wherein the ratio of y/z is 1.65±10%,
• the article including 45-degree grain boundaries in a concentration of <1%.