In-plane aligned YBa2Cu3O7−x thin films deposited on polycrystalline metallic substrates

Abstract

C-axis oriented YBa2Cu3O7−x thin films are conventionally obtained on polycrystalline substrates, but a- and b-axes are randomly distributed. Due to the weak links at the high-angle grain boundaries in the a–b plane, the critical current density (Jc) are comparatively low, from 103 to 104 A/cm2 (77 K, 0 T), and the Jc decreases in magnetic field in a manner similar to bulk YBa2Cu3 O7−x samples. To reduce weak links at the high-angle grain boundaries, biaxially oriented buffer layers of yttrium stabilized zirconia (YSZ) were formed on polycrystalline, Ni-based alloy by ion-beam assisted deposition (IBAD), and subsequently the a–b plane aligned YBa2Cu3 O7−x film was deposited by laser ablation. Jc of 2.5×105 A/cm2 (77 K, 0 T) and 2.2×104 A/cm2 (77 K, 8.0 T) were obtained. A new method to prevent intergranular weak links has been developed for potential applications using practical polycrystalline substrates.

Advances in YBCO-coated conductor technology

“…However, to use YBCO as a conductor, a method was needed to deposit YBCO onto a polycrystalline, flexible, basemetal substrate and yet to achieve a very high degree of alignment. This was first achieved by Iijima et al [1], and almost simultaneously by Reade et al [2]. The key is to provide a single crystal-like template film upon which the YBCO can grow epitaxially.…”

Inclined Substrate Deposition of Magnesium Oxide for YBCO‐Coated Conductors

“…Research efforts in the past few years have accelerated the processing, fabrication, and manufacturing of high-temperature coated conductors to meet the needs of the U.S. electric power industry [1][2][3]7]. Several techniques, including ion-beamassisted deposition (IBAD) [8][9][10], rolling-assisted biaxially textured substrates (RABiTS) [11,12], and inclined-substrate deposition (ISD) [13][14][15], were developed. Compared to the first two processes, ISD produces textured films at high deposition rates (20-100 Å/sec) and is independent of the recrystallization properties of the metallic substrates.…”

Residual Stress Measurement in YBCO Thin Films

“…Typical processing approaches include ion-beam-assisted deposition, rolling-assisted biaxially textured substrate method, pulsed laser deposition (PLD), e-beam co-evaporation, and metal organic deposition [3][4][5][6][7]. In a coated conductor system, a metallic or ceramic substrate is coated with a ceramic superconductor (i.e., YBCO) with buffer layers in between that act as diffusion barriers between the substrate and YBCO film.…”

“…In a coated conductor system, a metallic or ceramic substrate is coated with a ceramic superconductor (i.e., YBCO) with buffer layers in between that act as diffusion barriers between the substrate and YBCO film. Various substrates such as LaAlO 3 , Hatelloy C, nickel, and silver (Ag) have been used to process coated conductors. Because the various layers in coated conductors have different expansion coefficients, residual strains (and hence stresses) develop in different layers during processing.…”