High critical current density YBa₂Cu₃O_7-δ thick films using ion beam assisted deposition MgO bi-axially oriented template layers on nickel-based superalloy substrates

Nickel-based superalloys have been coated with magnesium oxide (MgO) using ion-beam-assisted deposition (IBAD). This technique produced a well-oriented bi-axially textured MgO template layer with a φ scan full width half maximum of 6.4°. The layer architecture for these samples was as follows: polished hastelloy C276/amorphous Si₃N₄/IBAD MgO/pulsed laser deposited (PLD) Y₂O₃-ZrO₂/PLD CeO₂/PLD YBa₂Cu₃O_7-δ. The subsequent heteroepitaxial PLD of 1.5-μm-thick YBCO showed a nominal critical current density of over 1 MA/cm² (75 K, self-field) along a microbridge and had an in-plane mosaic spread of 4.8° and an out-of-plane spread of 1.3°. These results compare well with our earlier work using IBAD yttria-stabilized zirconia (YSZ) as a template layer and indicate that IBAD MgO is a suitable substitute. Furthermore, these results suggest that IBAD MgO could be adapted to and increase the feasibility of a continuous process to fabricate longer lengths of coated conductors at speeds 100 times faster than that previously realized with IBAD YSZ.