Flux-Pinning Properties of BaHfO₃-Doped EuBCO-Coated Conductors Fabricated by Hot-Wall PLD

Development and large volume production of extremely high current density YBa2Cu3O7 superconducting wires for fusion

“…Indeed, our present J c (B) results are superior to many excellent results achieved with nano-columnar APC reported by other groups 7,26,[30][31][32][33][34] . We conclude, therefore, that nano-columnar defects are not indispensable for high critical current in magnetic field.…”

“…The samples differed in substrate thickness: 40, 60 and 100 µm and YBCO layer thickness: 2.55, 2.82 and 3.28 µm, respectively. In all three samples very high values of critical current were achieved, among the best reported to date for commercial 2G HTS wire 7,26,[30][31][32][33][34] . In particular, an I c at 20 K, 20 T in the 220-270 A/4 mm range and an I c at 4.2 K, 20 T in the 450-570 A/4 mm range were measured.…”

“…A common approach to enhance J c in magnetic field has been to introduce artificial pinning centres (APC) of c-axis correlated nano-columns of various perovskites [21][22][23][24][25] , a technique utilised in commercial PLD 28,29,38 and metalorganic chemical vapour deposition (MOCVD) film growth 6 . Although the highest J c (B) values have been obtained in this way [39][40][41] , the complex HTS film nanostructure results in considerable spread in commercial wire in-field performance 26,27 and greatly narrows the processing window, requiring slower deposition rates to achieve maximum J c enhancement 28,29 . For 2G HTS wire with nano-columnar APC, more typical is a faster decay of critical current with increasing magnetic field than for wire without APC 42 .…”

“…We used the so-called “lift-factor” methodology in our result analysis. This methodology is accepted among 2G HTS wire manufacturers 27 , 28 , 36 ; however, it has certain applicability constraints and thus is often criticised 26 , 27 . Lift-factor is a simple empirical I c scaling parameter: it is defined as the ratio of a sample’s I c at a specific temperature and magnetic field to the I c of the same sample at 77 K in self-field.…”

“…(2) Employ uniformly distributed Y 2 O 3 nanoparticles, native to YBCO, as vortex pinning centres, thus keeping the composition and microstructure simple to facilitate reproducible fabrication. This contrasts with the common approach of introducing extrinsic nano-columns aligned about the REBCO c-axis as pinning centres [21][22][23][24][25] , a proven challenge to industrial implementation [25][26][27][28] . (3) Take advantage of the very low neutron cross-section of Y of 1.28 b compared to those of Gd (49,000 b) and Eu (4570 b), which is particularly important for application in a fusion reactor.…”