2A-M-O1 Sep 8 - Afternoon (4:30-6:30 PM)
Materials - Vortex flux pinning I
4:30 - 5:00 New nano-scale engineering strategies of solution grown YBCO nanocomposites for tuning vortex pinning landscape|
PALAU Anna1, VALLES Ferran1, STANGL Alexander1, COLL Mariona1, CAYADO Pablo1, MUNDET Bernat1, GÁZQUEZ Jaume1, ROS Josep2, RICART Susagna1, OBRADORS Xavier1, PUIG Teresa1
1Institut de Ciència de Materials de Barcelona (ICM, Spain, 2Universitat Autònoma de Barcelona, Spain
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The fabrication of nanostructured YBCO thin films by the incorporation of nanosized oxide secondary phases has been shown to strongly enhance their pinning performances, ensuing great potential for use in a broad number of power applications. It is now clear that different nanoparticle (NP) characteristics, growth processes and conditions lead to a rich zoology of defects in the film, whose effectiveness depends on the magnitude and orientation of the magnetic field and the temperature. We have demonstrated that the huge isotropic pinning forces obtained in CSD nanocomposites arise from the strains associated to intergrowths emerging from the NPs . Moreover, natural defects of many types such us, vacancies, staking faults or twin boundaries my act as pinning centers, as well.
Here we present our present understanding of an extensive research on CSD nanocomposites prepared following two different approaches. On First, the in-situ approach, where adding metalorganic salts in the precursor solution, different randomly-oriented NP (BZO, BYTO, YO2 and mixed) are segregated. The second approach named ex-situ is a radically new concept consisting on the incorporation of prefabricated NP colloids (CeO2, ZrO2, CoFe2O4, BZO) in the solution to have much better control of the NP characteristics.
Only with the full understanding of the correlation between vortex pinning and nanostructure in this complex materials, will allow to specific nano-engineering the pinning landscape for best superconducting performances. In this contribution, we report on a variety in-situ and ex-situ YBCO nanocomposites where processing conditions has enabled us to control the density, length and stoichiometry of intergrowth emerging from oxide nanoparticles. The synergetic combination of natural and engineered defects in these complex systems will be evaluated by means of in situ angular transport measurements and high resolution STEM.
 A. Llordes et al., Nature Materials, 329, 2012
We acknowledge the financial support from the EU-FP7 NMP-LA-2012-280432 EUROTAPES and COST action MP1201, and MAT2014-51778-C2-1R
5:00 - 5:30 Jc mechanism in YBa2Cu3O7+BaMO3 (M=Zr, Hf, Sn) films|
HORIDE Tomoya1, TAGUCHI Kenta1, MATSUMOTO Kaname1
1Kyushu Institute of Technology, Japan
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YBa2Cu3O7(YBCO) coated conductors are promising for superconducting magnets, superconducting cables, and ship propulsion motors, and high critical current density(Jc) is required for these applications. Nanorods improved Jc significantly in YBCO films, but further enhancement of Jc has been still desired. Nanorod density, diameter, straightness, interface sharpness, and elastic strain determine vortex pinning, but their influence on Jc is not well understood. Nanorod materials are believed to be the most crucial factor for diameter and elastic strain etc. Therefore, Jc behavior should be systematically investigated by changing nanorod material and content to understand vortex pinning mechanism, but such systematic studies have not yet been reported. In the present study, YBCO+BaSnO3(BSO), YBCO+BaZrO3(BZO), and YBCO+BaHfO3(BHO) films were prepared using pulsed laser deposition, where various content of BSO, BZO, and BHO were introduced into the films. Structure of the films was evaluated using X-ray diffraction and transmission electron microscopy. Critical temperature(Tc), Jc at 77-20 K, and irreversibility temperature were measured. In addition, density functional theory calculation was performed to understand nanorod structure in the films based on thermodynamic and elastic parameters. Tc was 91-85 K in the films, and Tc-nanorod volume fraction relation depended on nanorod material. In YBCO+BZO and YBCO+BHO films, Jc at low field was not large, but high Jc was obtained at high magnetic field at 77 K compared with BSO nanorods, showing high density of BZO and BHO nanorods in the films. Based on the systematic results, influence of nanorod density, diameter, interface sharpness, and elastic strain on Tc and Jc is analyzed, and structure for high Jc is discussed.
This work was supported by Fundamental Research Developing Association for Shipbuilding and Offshore (REDAS) and KAKENHI, Grant-in-Aid for Science Research (S), Grant Number 23226014.
5:30 - 5:45 Engineered Pinning Landscapes for Enhanced 2G Coil Wire|
RUPICH Martin1, SATHYAMURTHY Srivatsan1, FLESHLER Steven1, LI Qiang2, SOLOVYOV Vyacheslav2, OZAKI Toshinori2, WELP Ulrich3, KWOK Wai-Kwong3, LEROUX Maxime3, KOSHELEV Alexei3, MILLER Dean3, KIHLSTROM Karen3, CIVALE Leonardo4, ELEY Serena4, KAYANI Asghar5
1American Superconductor Corporation, United States, 2Brookhaven National Laboratory, United States, 3Argonne National Laboratory, United States, 4Los Alamos National Laboratory, United States, 5Western Michigan University, United States
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Increasing the current carried by second generation (2G) high temperature superconducting (HTS) wire in the presence of high magnetic fields is critical for the commercialization of HTS based rotating machine applications (generators for off-shore wind turbines, hydro power and utility applications; compact, light-weight ship board motors; etc.) and various HTS magnet applications. Research over the past few years has shown that pinning landscapes based on mixed defect structures are effective in improving the 2G HTS wire performance. Although mixed pinning structures based on self-assembled BaZrO3 columns and nano-particle defects have been demonstrated in short samples of vapor phase grown Rare-Earth Barium Copper Oxide films (REBCO), it has been difficult to uniformly incorporate these highly engineered defect structures into production length conductors. Additionally, these self-assembled columnar structures are not viable options for solution-grown REBCO films using metal organic deposition (MOD). Thus we have been exploring alternate routes to fabricate precisely engineered defect structures into production length MOD-based REBCO films.
The current MOD-based growth process produces a uniform defect structure in the REBCO superconductor layer consisting of a dispersion of nano-particles, stacking faults and dislocations. Research over the past year has shown that the addition of point defects produced by irradiation significantly improves the pinning in the MOD-based REBCO films, with the critical current (Ic) more than doubling at ~30K in magnetic fields >2.5 T. In this presentation, we will describe the pinning enhancements achieved in AMSC’s production tape as a function of the irradiated species ranging from protons to heavy elements with energies in the keV to MeV range. We will also present data on the reel-to-reel irradiation of 2G tape and discuss the feasibility of extending this technique to the manufacture of long length commercial 2G wire.
This work was supported by the U.S. D.O.E through ARPA-E under contract No. DE-AR0000190, the Center for Emergent Superconductivity and the Office of Basic Energy Sciences under Contract No. DE-AC02-06CH11357.
5:45 - 6:00 Enhanced vortex-pinning features of pulsed laser deposited YBa2Cu3O7-x films with Ba2YTaO6 and Ba2YNbO6 nano-columnar inclusions in the low-temperature and high magnetic field regime. |
RIZZO Francesco1, AUGIERI Andrea1, ANGRISANI ARMENIO Achille1, GALLUZZI Valentina1, MANCINI Antonella1, PINTO Valentina1, RUFOLONI Alessandro1, VANNOZZI Angelo1, KURSUMOVIC Ahmed2, MACMANUS-DRISCOLL Judith L.2, MELEDIN Alexander3, VAN TENDELOO Gustaaf3, CELENTANO Giuseppe1
1Superconductivity Laboratory, ENEA, Italy, 2University of Cambridge, United Kingdom, 3University of Antwerp, Belgium
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The possibility of strongly improve YBa2Cu3O7-x (YBCO) films flux-pinning properties by introducing nano-scale artificial pinning centres (APCs) has attracted in recent years a remarkable interest. In fact, by enhancing the transport film performances as a function of both applied magnetic field and temperature it is possible to reach the current requirements needed in a wide range of present and future applications. In particular, the controlled growth of self-assembled nano-columns oriented along the YBCO c-axis by means of pulsed laser deposition (PLD), using composite targets, has been shown to be a promising and efficient technique for both improving the critical current density magnitude and modifying its intrinsic angular anisotropy.
In this work we consider PLD grown YBCO films with the inclusion of 5at% Ba2YTaO6 (BYTO) and 2.5at% Ba2YTaO6 + 2.5at% Ba2YNbO6 (BYTO + BYNO) nano-rods. The films are deposited on (00l)-oriented SrTiO3 single crystals by using a XeCl excimers laser radiation at a wavelength of 308 nm and with a repetition rate up to 10 Hz. The transition temperature drop with respect to pristine YBCO is almost completely recovered by tuning the sample deposition temperature. Transmission electron microscopy analysis reveals a well-defined APCs growth in the YBCO matrix, with almost straight and continuous along the whole film thickness nano-rods. These columns often grow associated with nanoparticles of Y2O3. Correspondingly, transport properties exhibit an excellent flux-pinning behaviour: D.C. electrical measurements are carried out in a wide range of temperatures (from 77 K to 4.2 K) and applied magnetic field intensities (from 0 to 12 T) and directions, allowing evaluating the effect of this rich pinning landscape. In particular, the BYTO + BYNO APCs combination displays a very effective pinning also in the low temperature and high field region of the YBCO H-T phase diagram which is extremely interesting looking at fusion applications.
This work has partially received funding from the European Union’s Seventh Programme under grant agreement N. 280432 EUROTAPES
6:00 - 6:15 Solution design for ReBCO CSD-MOD films and nanocomposites |
RICART Susagna1, CAYADO Pablo1, POP Cornelia1, GARZON Alba2, MARTINEZ-ESAIN Jordi2, VILLAREJO Bohores1, ROS Josep2, YAÑEZ Ramon2, ROURA Pere3, FARJAS Jordi3, PALAU Anna1, GAZQUEZ Jaume1, MUNDET Bernat1, MARIONA Coll1, OBRADORS Xavier1, PUIG Teresa1
1ICMAB-CSIC, Spain, 2Universitat Autònoma de Barcelona, Spain, 3Departament de Fisica, Spain
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Since the production of the first electronic thin films in 1980 Chemical Solution Deposition (CSD) has emerged as a highly flexible and cost-effective technique for the fabrication of a wide variety of functional oxide films. Among the different application areas we have explored CSD-MOD technique for the production of High Temperature Superconductors (HTSC). Metal-organic decomposition has been established as the methodology to grow low cost, scalable, high performance epitaxial YBa2Cu3O7 films for coated conductors.
New designed solutions are proposed in accordance with the new requirements concerning environmental safety. Looking at these objectives we will present here our work in the preparation of precursor solutions with reduction of fluorine content, which should be adapted to the requirements of Superconducting ReBCO layers production, leading to high production rates with optimal performance. Solutions with low and non-fluorine precursors (acetates, ethylhexanoates) in different amounts of additives (thriethanolamine, propionic acid) have been stabilized and their rheology modified for substrate wetability. Thermal decomposition analysis performed directly in films, have revealed differences in decomposition and growth steps. Upon optimization of growth process parameters, Tc and Jc(77K)of around 90 K and 3 MA/cm2 are obtained.
Changes in solvent and use of inorganic salts and polymers produce changes in the rheological properties of the solution improving the thickness and homogeneity of the final layers. Besides, understanding of the thermal decomposition processes, represents a powerful tool to produce ceramic layers with improved structural properties.
This knowledge has been also used in the new approach to nanostructured YBCO layers by exploiting the capabilities of combining two materials with distinct functionalities. Preparation of solutions with mixed salt precursors or colloidal solutions of oxide nanoparticles adapted to form stable solutions with Y, Ba and Cu salts will be presented. The steps to be surpassed to produce stable and homogeneous colloidal solutions with oxide nanoparticles (CeO2, ZrO2 and BZO) and to use them in combination with TFA-YBCO solutions and Low Fluorine YBCO solutions to obtain final nanostructured superconducting layers will be discussed.
The research leading to these results has received funding from EU-FP7 NMP-LA-2012-280432 EUROTAPES project and MAT2011-28874-C02 national project.
6:15 - 6:30 Nano-engineering of BaHfO3 and Ba2Y(Nb/Ta)O6-doped YBa2Cu3O7-d coated conductors|
SIEGER Max1, PAHLKE Patrick1, HÄNISCH Jens2, OPHERDEN Lars1, BERGELT Paul1, IIDA Kazumasa1, SPARING Maria1, BIANCHETTI Marco3, MACMANUS-DRISCOLL Judith3, LAO Mayraluna4, EISTERER Michael4, MELEDIN Alexander5, VAN TENDELOO Gustaaf5, NAST Rainer2, SCHULTZ Ludwig1, HOLZAPFEL Bernhard2, HÜHNE Ruben1
1IFW Dresden, Germany, 2Karlsruhe Institute of Technology (KIT), Germany, 3University of Cambridge, United Kingdom, 4Vienna University of Technology, Austria, 5University Antwerp, Belgium
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The recent progress of enhancing the current carrying capability for YBa2Cu3O7-d (YBCO) coated conductors by nano-engineering makes this high-temperature superconductor a suitable candidate for many applications such as low-loss conduction cables and high-energy physics fusion magnets. The necessary immobilization of fluxoids can be achieved by artificial pinning centers such as BaHfO3 (BHO) and the mixed double-perovskite Ba2Y(Nb/Ta)O6 (BYNTO). Density, size and distribution of such pinning centers can be adjusted to yield best results for the intended application conditions in temperature and magnetic field range. The incorporation of up to 6 mol% BHO on technical substrates has already improved the in-field performance at liquid nitrogen temperature , whereas BYNTO showed an astonishing Jc(B,Q) behavior on SrTiO3 single crystals in magnetic fields up to 9 T [2,3].
In this work we present results on ~1 µm thick YBCO films with up to 15 mol% BHO and 5 mol% BYNTO, respectively, grown by pulsed laser deposition on biaxially textured metal tapes. In particular, we studied the influence of the deposition conditions on the growth of incorporated nanorods. Structural characterization carried out by X-ray diffraction and transmission electron microscopy confirms epitaxial growth of both, YBCO on the tape and homogenously distributed nanorods within the superconducting matrix. Both additions expand the YBCO lattice and thereby generate strain leading to further structural defects, e.g. stacking faults. Transport current measurements in a standard four-point assembly show significant improvement of the in-field behavior and Jc (B,Q) anisotropy for both types of additions due to the presence of nanorods.
 M. Sieger et al., IEEE Trans. Appl. Supercond. 25 (3), 6602604, 2015
 G. Ercolano et al., SUST 24 (9),095012, 2011
 L. Opherden et al., submitted to SUST
The authors acknowledge financial support from EUROTAPES, a collaborative project funded by the European Community's Seven Framework Programme (FP7 / 2007 - 2013) under Grant Agreement n.280432.
6:30 - 6:45 Investigation of the longitudinal magnetic field effect on multilayered-SmBa2Cu3Oy films fabricated on single-crystal and metal substrates|
SUGIHARA Kazuki1, ICHINO Yusuke1, YOSHIDA Yutaka1, ICHINOSE Ataru2
1Nagoya University, Japan, 2CRIEPI, Japan
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The force-free state is without large Lorentz force on flux lines because critical current is parallel to external magnetic fields. Under this state, the longitudinal magnetic field (LMF) effects which include various peculiar superconducting phenomena are observed. Especially, the critical current density (Jc) enhancement under a certain magnetic field compared with the Jc under self-field (Jcself) has been reported. For twisted Bi2Sr2Ca2Cu3Oy tapes, the Jc enhancement using the LMF effect has been reported. However, for REBa2Cu3Oy (RE = rare earth) tapes, there are only a few reports for this Jc enhancement.
So far, we have reported the Jc enhancement with a peak form under the force-free state on multilayered-SmBa2Cu3Oy (SmBCO) films which consist of pure-SmBCO and BaHfO3 (BHO)-doped SmBCO layers. The samples were prepared by pulsed laser deposition (PLD) method on LaAlO3 single crystalline substrates. These Jc peak reached a range from a few to a dozen % higher than Jcself, however the determining factor of these Jc enhancement rate is still unclear. In addition, we have investigated the effect of multilayered-film structures such as interface density and film thickness on the Jc enhancement. The interface density means number of interface of pure-SmBCO layer and BHO+SmBCO layer per thickness (the unit is planes/μm). As a result, we found that the Jc peak appearance needs certain interface density which is over 80/μm and a certain film thickness which is over 400 nm.
Investigation of the LMF effects in multilayered-films on metal substrates is important not only for designing a new power cable application using this effect but also understanding the mechanism of the LMF effect. Therefore, we will investigate the LMF effect on similar multilayered-SmBCO films fabricated on IBAD-MgO metal substrates.
This work was supported in part by Grant-in-Aid for Scientific Research (Nos. 23226014 and 25289358) from the JSPS. This work was supported by the NEDO. We would like to thank Prof. T. Matsushita belonging to Kyushu Institute of Technology for fruitful discussions.