YBa2Cu3O7-δ (YBCO) films with a thickness of up to 3 μm containing nano-sized BaHfO3 (BHO) have been grown on Y2O3/Y-stabilized ZrO2/CeO 2 buffered Ni-9at% W tapes by pulsed laser deposition (PLD). Structural characterization by means of X-ray diffraction confirmed that the YBCO layer grew epitaxial. A superconducting transition temperature T c of about 89 K with a transition width of 1 K was determined, decreasing with increasing BHO content. Critical current density in self-field and at 0.3 T increased with increasing dopant level

Gaitzsch, U.

Holzapfel, B.

Hänisch, J.

Hühne, R.

Iida, K.

Rodig, C.

Schultz, L.

Sieger, M.

English

Repositorium für Naturwissenschaften und Technik

Journal of Physics: Conference SeriesOPEN ACCESSPulsed laser deposition of thick BaHfO3-dopedYBa2Cu307-δ films on highly alloyed textured Ni-WtapesTo cite this article: M Sieger et al 2014 J. Phys.: Conf. Ser. 507 022032 View the article online for updates and enhancements.Related contentExperimental study in the development ofHTS NMR probeM Watanebe, S Sato, K Sato et al.-Pulsed laser deposition of carbonnanodotsG Muñoz, P Homm, F Guzmán et al.-High-performance irreversibility field andflux pinning force density in BaHfO3-dopedGdBa2Cu3Oy tape prepared by pulsedlaser depositionSatoshi Awaji, Yutaka Yoshida, TakumiSuzuki et al.-Recent citationsTailoring Microstructure andSuperconducting Properties in ThickBaHfO3 and Ba2 Y(Nb/Ta)O6 DopedYBCO Films on Technical TemplatesMax Sieger et al-Multifunctional, self-assembled oxidenanocomposite thin films and devicesWenrui Zhang et al-Thick High  YBCO Films on ABAD-YSZTemplatesPatrick Pahlke et al-This content was downloaded from IP address 194.95.157.36 on 26/10/2020 at 11:08      Pulsed laser deposition of thick BaHfO3-doped YBa2Cu3O7-δ films on highly alloyed textured Ni-W tapes M Sieger, J Hänisch, K Iida, U Gaitzsch, C Rodig, L Schultz, B Holzapfel, R Hühne Institute for Metallic Materials, IFW Dresden, PO Box 270116, 01171 Dresden, Germany  m.sieger@ifw-dresden.de Abstract. YBa2Cu3O7-δ (YBCO) films with a thickness of up to 3 µm containing nano-sized BaHfO3 (BHO) have been grown on Y2O3/Y-stabilized ZrO2/CeO2 buffered Ni-9at% W tapes by pulsed laser deposition (PLD). Structural characterization by means of X-ray diffraction confirmed that the YBCO layer grew epitaxial. A superconducting transition temperature Tc of about 89 K with a transition width of 1 K was determined, decreasing with increasing BHO content. Critical current density in self-field and at 0.3 T increased with increasing dopant level. 1.  INTRODUCTION The high-temperature superconductor YBa2Cu3O7-δ (YBCO)[1] might be used for technical applications such as superconducting transmission cables, motors and electrical power components due to its superior current  transport capability in high magnetic fields.[2] The critical current Ic can be increased by improving the critical current density Jc for a constant film thickness t or by increasing t for a constant Jc. Artificial pinning centres as nanoparticles like BaHfO3 (BHO)[3,4] form effective immobilization points for magnetic flux lines,[5] thereby increasing Jc(µ0H). One of the main approaches to realize long length coated conductors is to use Ni-W tapes with a strong cube texture, formed by heavy cold rolling and annealing.[6] Recently, Ni-9at% W (Ni9W) tapes were realized, which are non-magnetic at 77 K and therefore reduce AC losses of the conductors.[7] A suitable buffer layer architecture as for example Y2O3/Y-stabilized ZrO2 (YSZ)/CeO2[8] ensures epitaxial growth to prevent high-angle grain boundaries, which are highly detrimental to the transport current.[9] H re, we demonstrate thick YBCO films grown on Ni9W. Furthermore, BHO pinning centres were incorporated into the YBCO matrix using PLD targets from mixed powders to increase the current transport capability in magnetic fields. 2.  EXPERIMENTAL DETAILS A Lambda Physics LPX305i KrF excimer laser (λ = 248 nm, tpulse = 25 ns) with an energy density of 1.6 J/cm² at the surface of the PLD target was used to grow superconducting films on 10 mm × 10 mm × 1 mm single crystalline (100) oriented SrTiO3 (STO) substrates as well as on 10 mm × 10 mm × 80 µm sized biaxially textured Ni9W tapes with a Y2O3/YSZ/CeO2 buffer layer stack on top. The details of the tape preparation and buffer layer deposition may be found in Ref. [8]. An oxygen partial pressure of 0.4 mbar was maintained during the deposition process. The deposition 11th European Conference on Applied Superconductivity (EUCAS2013) IOP PublishingJournal of Physics: Conference Series 507 (2014) 022032 doi:10.1088/1742-6596/507/2/022032Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributionof this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Published under licence by IOP Publishing Ltd 1      temperature was set to 810°C for STO substrates and to 830°C for Ni9W tapes, which were found as optimum conditions for high critical temperature and current density in previous experiments. Undoped as well as 2, 4 and 6 mol% BHO-doped YBCO films were deposited from PLD targets which were prepared from mixed powders by a conventional solid state reaction. In-situ oxygen loading of the YBCO films took place in 400 mbar O2 during cooling at 20 K min-1 in order to obtain superconducting YBCO.  The surface morphology was studied using a Philips XL 20 scanning electron microscope, and the film thickness was measured on cross sectional cuts prepared by a focused gallium ion beam in a FEI Helios 600i. The crystal structure was determined in a Bruker D8 Advance X-ray diffractometer in Θ-2Θ geometry. Pole figures were taken by a Philips X´Pert PW3040 on the YBCO (102) and BHO (110) planes. Superconducting properties, i.e. critical temperature Tc,50 (measured at midpoint of transition), the transition width ∆Tc, and the critical current densities Jcsf and Jc0.3T (Jc in self-field and in a magnetic field of 0.3 T parallel c), were measured inductively. 3.  RESULTS AND DISCUSSION 3.1.  Growth of thick YBCO films on STO single crystalline substrates The X-ray diffraction patterns of three different samples on STO are shown in figure 1(a). The deposition frequency was increased with increasing film thickness to keep the growth time nearly constant. All samples show strong (00ℓ) YBCO peaks, which is a clear sign of c-axis oriented growth on the STO substrates. Additional peaks are assigned as Y2O3 inclusions originating from excess yttrium in the target. The thickest sample shows additional a-axis oriented YBCO grains due to the presence of (h00) reflections. The (102) YBCO pole figures for the 1 µm and 3 µm thick films are given in figures 1(b) and 1(c). Whereas an undisturbed epitaxial growth was observed for the 1 µm thick film, a significant amount of a-axis oriented grains is present in the 3 µm thick film, which is visible at an angle ψ of approximately 33°. It should be noted that the a-axis oriented growth was prevented in a 3 µm thick film by employing a laser frequency of 10 Hz.  (a)    (b)    (c)  Figure 1: Structural characterization of undoped YBCO samples on STO having different thicknesses: X-ray diffraction pattern (a); YBCO (102) pole figure of a 1 µm (b) and 3 µm (c) thick layer  Table 1 summarizes the superconducting properties for this sample series. The critical temperature Tc,50 of the 1 µm thick sample is slightly increased compared to the 0.5 µm thin film. However, the critical current density Jcsf is strongly reduced from 2.7 MA/cm² (0.5 µm) to 1.8 MA/cm² (1 µm). The 11th European Conference on Applied Superconductivity (EUCAS2013) IOP PublishingJournal of Physics: Conference Series 507 (2014) 022032 doi:10.1088/1742-6596/507/2/0220322      3 µm thick sample shows a significant drop in both, Tc and Jcsf, which may have several reasons. On the one hand, a relatively long c-axis, compared to the other samples, indicates a lower oxygen content leading to a reduced critical temperature. On the other hand, high-angle grain boundaries due to a-axis oriented grains might be responsible for lower Jc values. A change to rougher morphologies with increasing thickness may also contribute to the Jc drop.[10]  Table 1: Tc,50 and critical current density in self-field, Jcsf, at liquid nitrogen temperature for undoped YBCO samples with different thicknesses grown on STO  thickness fDep Tc,50 ∆Tc Jcsf [µm] [Hz]  [K] [K] [MA/cm²] 0.5 5 90.9 1.2 2.71 ± 0.12 1 10 92.4 1.0 1.83 ± 0.62 3 50 86.4 1.8 0.38 ± 0.11 3.2.  BHO-doped YBCO samples on highly alloyed textured metal tapes  Thicker YBCO layers were grown on Ni9W in the next step, using a laser repetition rate of 10 Hz. Figure 2(a) shows a top view of a 1.8 µm thick YBCO film on a buffered Ni9W tape. The grain structure, which is transferred from metal tape via buffer layers, is clearly visible. Only a small number of Ni recrystallization twins, which are detrimental to c-axis aligned growth of YBCO, are present. The higher magnification view (figure 2(b)) shows the small YBCO islands which coalesce during film growth.[11] The cross sectional view in figure 2(c) shows the complete layer architecture with the metal tape, the threefold buffer layer stack and YBCO. Additionally, nickel oxide (NiO) and nickel tungsten oxide (NiWO4) are found at the tape/buffer interface.  (a)  (b)  (c)  Figure 2: Surface morphology of undoped YBCO on biaxially textured Ni9W tape: top view (a), higher magnification (b), lateral view of a cross section (c)  The epitaxial growth on the biaxially textured metal tape is proven by the presence of (00ℓ) peaks of the buffer layers and YBCO in figure 3(a) as well as by pole figure measurements. The YBCO (102) peaks in the pole figure in figure 3(b) show the typical broadening, already present in the Ni9W substrate. The average (4 peaks) in-plane full width at half maximum is 6.2° for YBCO, which is similar to the value of 6.4° for the substrate. Figure 3(c) shows that BHO is incorporated into the films with a biaxial, cube-on-cube relationship. The additional strong peaks at Ψ = 55° arise from the Y2O3 (222) planes, which have almost the same 2Θ value as the BHO (110) plane.  11th European Conference on Applied Superconductivity (EUCAS2013) IOP PublishingJournal of Physics: Conference Series 507 (2014) 022032 doi:10.1088/1742-6596/507/2/0220323      (a)  (b)    (c)  Figure 3: Structural characterization of YBCO samples on Ni9W: X-ray diffraction pattern of 1.8 µm thick undoped and 6 mol% BHO-doped YBCO (a); with respective YBCO (102) pole figure (b); and BHO (110) pole figure (c)  Whereas the critical temperature of the YBCO films on Ni9W decreases slightly with increasing BHO concentration, the critical current density increases in self-field and even more pronounced at 0.3 T applied parallel to the c-axis of the films (see table 2). Pinning effects in higher fields will be investigated by detailed transport Jc studies in the near future.  Table 2: Critical temperature and critical current density of 1.8 µm thick undoped and BHO-doped YBCO samples on biaxially textured Ni9W tapes deposited with a frequency of 10 Hz  BHO content Tc,50 ∆Tc Jcsf Jc0.3T||c [mol%] [K] [K] [MA/cm²] [MA/cm²] 0 89.1 1.0 0.38 ± 0.01 0.15 ± 0.01 2 88.1 0.8 0.33 ± 0.01 0.19 ± 0.01 4 88.4 0.7 0.60 ± 0.04 0.32 ± 0.01 6 87.7 0.9 0.73 ± 0.02 0.33 ± 0.02  The authors gratefully thank J. Scheiter, U. Fiedler and M. Kühnel for technical assistance and acknowledge the financial support from EUROTAPES, a collaborative project funded by the European Community's Seven Framework Programme (FP7 / 2007 - 2013) under Grant Agreement no. 280432. References [1] Wu M et al 1987 Phys. Rev. Lett. 58 908-910 [2] Foltyn S et al 2007 Nat. Mater. 6 631-642 [3] Hänisch J et al 2006 Supercond. Sci. Technol. 19 534-540 [4] Engel S et al 2000 Appl. Phys. Lett. 90 102505 [5] Matsushita T 2000 Supercond. Sci. Technol. 13 730-737 [6] Eickemeyer J et al 2010 Supercond. Sci. Technol. 23 085012 [7] Gaitzsch U et al 2013 Supercond. Sci. Technol. 26085024 [8] Hühne R et al 2007 Supercond. Sci. Technol. 20 709-714 [9] Hilgenkamp H and Mannhart J 2002 Rev. Mod. Phys. 74 485-549 [10] Foltyn S et al 1999 Appl. Phys. Lett. 75 3692-3694 [11] Hühne R et al 2010 Supercond. Sci. Technol. 23 034015 11th European Conference on Applied Superconductivity (EUCAS2013) IOP PublishingJournal of Physics: Conference Series 507 (2014) 022032 doi:10.1088/1742-6596/507/2/0220324Corrigendum: Pulsed laser deposition of thick BaHfO3-doped YBa2Cu3O7-δ films on highly alloyed textured Ni-W tapes M Sieger, J Hänisch, K Iida, U Gaitzsch, C Rodig, L Schultz, B Holzapfel, R Hühne Institute for Metallic Materials, IFW Dresden, PO Box 270116, 01171 Dresden, Germany  m.sieger@ifw-dresden.de  CORRIGENDUM TO: JPCS 507 (2014) 022032 The presented BHO doped YBCO films on STO turned out to have a higher thickness than we expected by earlier experiments under similar conditions (pulse number, oxygen pressure, substrate temperature, laser energy). Some inductive values of the critical current density had to be recalculated and the measured thicknesses are included in the tables.  Table 1: Tc,50 and critical current density in self-field, Jcsf, at liquid nitrogen temperature for undoped YBCO samples with different thicknesses grown n STO  thickness fDep Tc,50 ∆Tc Jcsf [µm] [Hz] [K] [K] [MA/cm²] 0.5 5 90.9 1.2 2.71 ± 0.12 2.0 10 92.4 1.0 0.74 ± 0.15 3.3 50 86.4 1.8 0.35 ± 0.12  Table 2: Critical temperature and critical current density of ~2 µm thick undoped and BHO-doped YBCO samples on biaxially textured Ni9W tapes deposited with a frequency of 10 Hz  thickness BHO content Tc,50 ∆Tc Jcsf Jc0.3T||c [µm] [mol%] [K] [K] [MA/cm²] [MA/cm²] 1.8 0 89.1 1.0 0.38 ± 0.01 0.15 ± 0.01 2.1 2 88.1 0.8 0.33 ± 0.01 0.19 ± 0.01 2.0 4 88.4 0.7 0.60 ± 0.04 0.32 ± 0.01 1.8 6 87.7 0.9 0.73 ± 0.02 0.33 ± 0.02  Thereby some numbers in section 3.1 change accordingly. The conclusion is not altered by this correction. 

Pulsed laser deposition of thick BaHfO3-doped YBa 2Cu307-δ films on highly alloyed textured Ni-W tapes

https://oa.tib.eu/renate/bitstream/123456789/5855/1/Sieger2014.pdf

Pulsed laser deposition of thick BaHfO3-doped YBa 2Cu307-δ films on highly alloyed textured Ni-W tapes

Abstract

Similar works

Full text

Available Versions

Repositorium für Naturwissenschaften und Technik