The researchers have developed yttrium-based oxide superconducting tapes that allow large critical current capacity in a strong magnetic field.

Schematic process-flow of the chemical solution deposition method (Thick precursor film is obtained by repeating coating and low-temperature heat-treatment.)

The researchers have improved the characteristics in a magnetic field of the yttrium-based oxide superconducting tapes by fabricating ultra-fine artificial pinning centers (APCs) with uniform dispersion and high density using a chemical solution decomposition method which costs less than vapor phase methods. This has achieved a maximum critical current density of 4 mega-amperes that can flow while maintaining the superconducting state (at liquid nitrogen temperature, 65 K, per 1 cm² in a magnetic field of 3T), and the critical current value exceeds 360 amperes.

A superconducting tape that can maintain high performance even in a magnetic field is necessary for superconducting magnets of equipment subjected to strong magnetic fields, including motors, generators, and medical instruments such as MRI and heavy particle accelerators. Factors of lowered superconducting characteristics include electrical resistance due to the generation of voltage caused by magnetic flux lines that have entered the conductor moving with the Lorentz force generated by the current. There is the artificial pinning effect (creating defects in crystals) as a method to suppress the movement of magnetic flux, but particle size and uniform dispersion are not yet sufficient.

SWCC Showa Cable Systems Co., Ltd. plans to develop products based on the present results. AIST and Seikei University will continue to support practical applications through technological development to improve performance.