Growth of simplified buffer template on flexible metallic substrates for YBa2Cu3O7-δ coated conductors

• Simplified buffer structure for YBCO coated conductors.
• Growth of biaxially textured MgO films on flexible amorphous substrates.
• Studying the influence of film deposition rate, ion energy and ion beam flux on the development of biaxial texture.
• Demonstrating highly oriented YBCO films with a critical current density of 2.4 MA/cm2 at self-field and 77 K.

A much simplified buffer structure, including a three-layer stack of LaMnO3/MgO/composite Y2O3–Al2O3, was proposed for high performance YBa2Cu3O7-δ (YBCO) coated conductors. In this structure, biaxially textured MgO films were prepared on solution deposition planarized amorphous substrate through ion-beam-assisted deposition (IBAD) technology. By the use of in situ reflection high-energy electron diffraction monitor, X-ray diffraction and atomic force microscope, the influence of deposition parameters, such as film deposition rate, ion penetrate energy and ion beam flux, on crystalline orientation, texture, lattice parameter and surface morphology was systematically investigated. Moreover, stopping and range of ion in mater simulation was performed to study the effects of ion bombardment on MgO films. By optimizing IBAD process parameters, the best biaxial texture showed ω-scan of (002) MgO and Φ-scan of (220) MgO yield full width at half maximum values of 2.4° and 3.7°, indicating excellent biaxial texture. Subsequently, LaMnO3 films were directly deposited on the IBAD-MgO template to improve the lattice mismatch between MgO and YBCO. Finally, YBCO films grown on this simplified buffer template exhibited a critical current density of 2.4 MA/cm2 at 77 K and self-field, demonstrating the feasibility of this buffer structure.

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