Liquid-Assisted Growth in Non-Stoichiometric YBa 2 Cu 3 O y +BaHfO 3 Films for High-Rate Deposition with Enhanced J c

To achieve both high in-field critical current density (Jc) and high deposition rates in REBa2Cu3Oy (REBCO) coated conductors, we investigated liquid-phase-assisted crystal growth using a non-stoichiometric target composition. Conventional pulsed laser deposition (PLD) with a stoichiometric target suffers from degradation of BaHfO3 (BHO) nanorod alignment at high deposition rates, resulting in a significant reduction in Jc. In this study, a newly designed target with the composition Y:Ba:Cu = 1:2.3:3.7 was employed to induce liquid-phase formation during PLD growth. Structural and compositional analyses revealed the presence of Cu-rich precipitates and microstructural features characteristic of liquid-mediated growth. The use of a YBCO+BHO seed layer prevented the reaction between Ba species and the CeO2 surface of the substrate. Consequently, the formation of BaCeO3 was effectively suppressed at elevated substrate temperatures. Furthermore, YBCO+BHO films grown from the non-stoichiometric target maintained well-aligned nanorods even at high deposition frequencies (100 Hz), exhibiting Jc values comparable to those of films deposited at low rates. These findings demonstrate that liquid-phase-assisted growth enabled by non-stoichiometric target design is an effective strategy for achieving both high Jc and high-rate deposition in REBCO films. This approach provides new insights into the control of liquid-phase formation in PLD processes and offers a promising pathway for cost-effective fabrication of high-performance coated conductors.