Influence of artificial pinning centers on structural and superconducting properties of thick YBCO films on ABAD-YSZ templates

Abstract

Recent efforts in the development of YBa2Cu3O7-x (YBCO) coated conductors are devoted to the increase of the critical current Ic in magnetic fields. This is typically realized by growing thicker YBCO layers as well as by the incorporation of artificial pinning centers. We studied the growth of doped YBCO layers with a thickness of up to 7 µm using pulsed laser deposition with a growth rate of about 1.2 nm/s. Industrially fabricated ion-beam textured YSZ templates based on metal tapes were used as substrates for this study. The incorporation of BaHfO3 (BHO) or Ba2Y(Nb0.5Ta0.5)O6 (BYNTO) secondary phase additions leads to a denser microstructure compared to undoped films. A purely c-axis-oriented YBCO growth is preserved up to a thickness of about 4 µm, whereas misoriented texture components were observed in thicker films. The critical temperature is slightly reduced compared to undoped films and independent of film thickness. The critical current density Jc of the BHO-and BYNTO-doped YBCO layers is lower at 77 K and self-field compared to pure YBCO layers; however, Ic increases up to a thickness of 5 µm. A comparison between films with a thickness of 1.3 µm revealed that the anisotropy of the critical current density Jc() strongly depends on the incorporated pinning centers. Whereas BHO nanorods lead to a strong B||c-axis peak, the overall anisotropy is significantly reduced by the incorporation of BYNTO forming a mixture of short c-axis-oriented nanorods and small (a-b)oriented platelets. As a result, the Jc values of the doped films outperform the undoped samples at higher fields and lower temperatures for most magnetic field directions.

Ultrafast transient liquid assisted growth of high current density superconducting films

“…We conclude that TLAG-CSD is an ultrafast non-equilibrium and versatile process to grow epitaxial YBCO films at c axis growth rates of ∼ 100 nm s −1 from different routes. This is~10-100 times faster than most of the thin film processes presently used 8,[29][30][31][32] to grow coated conductors and it confirms fast growth rates observed in other liquid-assisted techniques, such as in REBCO single crystal growth, REBCO bulk ceramic melt-textured growth 33 or REBCO films 14 . However here, the process is not restricted to the use of an equilibrium liquid phase and we demonstrate that the transient liquid formation is compatible with high-throughput CSD film manufacturing.…”

Influence of Ba2+ consumption and intermediate dwelling during processing of YBa2Cu3O7 nanocomposite films

“…To date, superconductive‐YBCO films are often deposited through physical and chemical deposition processes such as pulsed laser deposition, electron beam evaporation and metal‐organic chemical vapor deposition (MOCVD) to meet the practical requirements for commercialization. Use of the pulsed laser deposition process has resulted in some of the thickest (>4 μm) and highest J c doped‐YBCO films (>4 MA/cm 2 at 77 K, self‐field) deposited on CeO 2 ‐buffered Y‐stabilized ZrO 2 templates, while MOCVD starting from trifluoroacetate(TFA)‐based precursors shows to be a good competitor with J c of 3 MA/cm 2 (at 77 K, self‐field) at a thickness of 2.2 μm for 20 mol‐% Zr‐doped (Gd,Y)Ba 2 Cu 3 O 7− δ films deposited on Hastelloy substrates with biaxially textured MgO templates and a LaMnO 3 cap layer . However, the physical deposition processes require high vacuum and result in higher production costs in contrast to, for example MOCVD which only requires a moderate vacuum .…”

“…Use of the pulsed laser deposition process has resulted in some of the thickest (>4 μm) and highest J c doped‐YBCO films (>4 MA/cm 2 at 77 K, self‐field) deposited on CeO 2 ‐buffered Y‐stabilized ZrO 2 templates, while MOCVD starting from trifluoroacetate(TFA)‐based precursors shows to be a good competitor with J c of 3 MA/cm 2 (at 77 K, self‐field) at a thickness of 2.2 μm for 20 mol‐% Zr‐doped (Gd,Y)Ba 2 Cu 3 O 7− δ films deposited on Hastelloy substrates with biaxially textured MgO templates and a LaMnO 3 cap layer . However, the physical deposition processes require high vacuum and result in higher production costs in contrast to, for example MOCVD which only requires a moderate vacuum . Chemical solution deposition (CSD) technology offers an economically viable synthesis route toward low‐cost medium performance as it operates under normal pressure .…”

YBa2Cu3O7−x films with Ba2Y(Nb,Ta)O6 nanoinclusions for high-field applications

“…In this paper, the mixed 2.5 mol% Ba 2 YTaO 6 (BYTO) and 2.5 mol% Ba 2 YNbO 6 (BYNO) double perovskite secondary phases in YBa 2 Cu 3 O 7−x films deposited by PLD are investigated by varying the film growth rate over two orders of magnitude, R=[0.02-1.8] nm s -1 . It is reported in previous works that mixed BYTO+BYNO phases incorporated into the YBCO film matrix as dense and a fine columnar system exhibit very remarkable improvements in J c behavior, not only at 77 K but also in lower temperatures down to 10 K [28][29][30][31]. By combining structural investigations by XRD, TEM analyses and J c transport measurements carried out in wide temperature and magnetic field ranges, two effective microstructural landscapes have been identified.…”