Properties of recent IBAD–MOCVD coated conductors relevant to their high field, low temperature magnet use

BaZrO 3 (BZO) nanorods are now incorporated into production IBAD–MOCVD coated conductors. Here we compare several examples of both BZO-free and BZO-containing coated conductors using critical current ( I c ) characterizations at 4.2 K over their full angular range up to fields of 31 T. We find that BZO nanorods do not produce any c -axis distortion of the critical current density J c (θ) curve at 4.2 K at any field, but also that pinning is nevertheless strongly enhanced compared to the non-BZO conductors. We also find that the tendency of the ab -plane J c (θ) peak to become cusp-like is moderated by BZO and we define a new figure of merit that may be helpful for magnet design—the OADI (off-axis double I c ), which clearly shows that BZO broadens the ab -plane peak and thus raises J c 5°–30° away from the tape plane, where the most critical approach to I c occurs in many coil designs. We describe some experimental procedures that may make critical current I c tests of these very high current tapes more tractable at 4.2 K, where I c exceeds 1000 A even for 4 mm wide tape with only 1 µm thickness of superconductor. A positive conclusion is that BZO is very beneficial for the J c characteristics at 4.2 K, just as it is at higher temperatures, where the correlated c -axis pinning effects of the nanorods are much more obvious.