Development of Biaxially Textured YBa2Cu3O7 Coated Conductors in the U.S.

Abstract

Two new processes have been under development since 1991 that promise a new, cost- effective way to manufacture flexible, high current density wires made from YBa2Cu3O7 (YBCO). The key is to prepare a textured substrate, or “template,” on which the YBCO may be deposited as a biaxially aligned thick film. Ion beam assisted deposition (IBAD) of yttria stabilized zirconia or magnesium oxide on alloy tapes enables a final superconducting layer with grain-to-grain, in-plane alignment to within 3–5 degrees. Similar results are achieved on rolling-assisted, biaxially textured substrates (RABiTS) using a variety of oxide layers on textured nickel tapes. The performance of research lengths of prototype wires in strong magnetic fields at 65 K already exceeds that of NbTi and Nb3Sn in liquid helium. A scalable, ex-situ process for the YBCO coating has been demonstrated on both types of substrates. Consistent values of critical current density (Jc) greater than 1 106 A/cm2 are now obtained on RABiTS, and Jc’s in excess of 2 x 106 A/cm2 have been obtained on both substrates. A nonmagnetic variation of RABiTS (Ni-13% Cr) has also been shown to yield Jc greater than 1.5 106 A/cm2.Six private companies in the U.S. are scaling up YBCO coated conductors for power and physics applications.