1A-M-O1 Sep 7 - Afternoon (4:30-7:00 PM)
Materials - YBCO Thin films
4:30 - 5:00 Post-processing the critical current of high temperature superconducting coated conductors using particle irradiations|
LEROUX Maxime1, KIHLSTROM Karen1, JIA Ying1, SADOVSKY Ivan1, KOSHELEV Alexei1, WELP Ulrich1, KWOK Wai-Kwong1, RUPICH Martin2, SATHYAMURTHY Srivatsan2, FLESHLER Steven2, CIVALE Leonardo3, KAYANI Asghar4
1Argonne National Laboratory, United States, 2American Superconductor Corp, United States, 3Los Alamos National Laboratory, United States, 4Western Michigan University, United States
show / hide abstract
In this presentation I will show how different types of particle irradiations can markedly enhance the in-field critical current in commercial 2nd generation superconducting tapes, and that, by selecting the type of irradiation, this enhancement can be applied to fully processed industrial production tapes without any modification of the growth process.
Tremendous improvements have been made during the past decade in the performance of high temperature superconducting wire based on YBa2Cu3O7−δ (YBCO). Superconducting wire is becoming competitive for space-limited and weight-limited applications: several projects involving urban grid, transformers, compact motors or offshore wind turbines are being developed or deployed worldwide. However, widespread deployment of superconduction cables in the electric power grid has been hindered by the high fabrication cost, while in-field coil-based applications struggle with the rapid fall of the critical current in an external magnetic field.
The large critical current densities (Jc) in these wires, now >3 MA/cm2 at 77 K self-field, are achieved by strict control over the micro- and nanostructures. The current manufacturing process involves a complex combination of highly engineered buffer layers for epitaxy, and controlled formation of defects such as dislocations, stacking faults, rare-earth nanoparticles and BaZrO3 nanorods, that act as vortex pinning centers.
Irradiation can be used to independently induce defects with well-controlled density and topology (point, cluster, column). Recently, we found very promising synergies between such defects and the preexisting pinning structure of YBCO based tapes. Crossed heavy-ion irradiations at 1.4 GeV reduce the anisotropy of Jc to ~1.3, while irradiations with light ions, such as 4 MeV protons and 6 MeV oxygen, double or triple Jc in fields of 3 to 6T. The optimal irradiation dose for maximum Jc is temperature and field dependent; large-scale time dependent Ginzburg-Landau simulations yield a good description of our results.
Irradiation of fully processed tapes with light ions requires exposure times of just a few tens of seconds per cm2, with relatively low beam currents. If higher beam currents were used, irradiation times could be reduced to levels required for a reel-to-reel manufacturing process.
This work was supported by the Center for Emergent Superconductivity, an Energy Frontier Research Center funded by the U.S. D.O.E., Office of Science, Office of Basic Energy Sciences and by the D.O.E, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
5:00 - 5:30 Pinning improvement in GdBCO coated conductors prepared by the RCE-DR process|
YOO Sang-Im1, YANG Eun Kyung1, OH Won-Jae1, LEE Jae-Hun2, LEE Hunju2, MOON Seung-Hyun2
1Seoul National University, South Korea, 22SuNAM Co., Ltd, South Korea
show / hide abstract
Long-length GdBCO coated conductors (CCs) possessing high critical current at 77 K in self field up to ~800 A/cm-width are being produced via a reactive co-evaporation deposition and reaction (RCE-DR) process by SuNAM Co. in Korea. Due to a very high conversion rate from an amorphous precursor film into the GdBCO film, an overall processing speed for producing the GdBCO film is faster than 120 m/h [J. H. Lee et al., Supercond. Sci. Technol. 27 (2014) 044018]. While this technology has been continuously improved by SuNAM for higher performance GdBCO CCs, a relatively weak pinning property has been the most challenging problem [Choi et al., IEEE Trans. Appl. Supercond. 23 (2013) 8001004]. Thus, in order to overcome this problem, we have tried to refine Gd2O3 particles trapped in the GdBCO matrix, and also to produce defects by a post-annealing process in a low oxygen pressure. While refinement of Gd2O3 particles, enabled by an optimal processing, was turned out to be very effective for Jc improvement in all field directions, representing the isotropic pinning effect, generation of stacking faults aligned along the c-axis of GdBCO, formed by the post annealing process, were found to be very effective for Jc improvement for the field parallel to the c-axis like columnar defects or nanorods. In this talk, detailed pinning effects of theses pinning centers will be presented for a discussion.
This work was supported by the Power Generation and Electricity Delivery of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Trade, Industry and Energy (No. 20131010501800).
5:30 - 5:45 Use of off-stoichiometric YBCO (+Ba2YNbO6) films to give strongly correlated pinning at high rate growth rates of 10 nm/s|
KURSUMOVIC Ahmed1, BIANCHETTI Marco1, WANG Haiyan2, HUANG Jijie2, JIAN Jie2, DRISCOLL Judith1
1University of Cambridge, United Kingdom, 2Texas A&M University, United States
show / hide abstract
In Ba2YNbO6 (BYNO) - added YBCO films grown by pulsed laser deposition at 800°C, we explored the influence of off-stoichiometric YBCO starting target compositions. We found that order of magnitude higher growth rates (~ 5 - 10 nm·s-1 compared to <1 nm·s-1 for standard films) led to excellent Jc(B) behaviour. The off-stoichiometric starting composition was consistent with the presence of liquid during the growth. Jcs (77 K, 1 T) of ~ 1.2 MA·cm-2 (B||a-b) and ~ 0.5 MA·cm-2 (B||c) were measured in 0.5 micron thick films, grown in only in < 1 minute. TEM showed truncated BYNO nano-columns with densities of ~ 20 and lengths of ~ 50 nm. Comparator films containing the same BYNO pinning additions but without use of the off-stoichiometric starting composition had lower Jcs of 0.2 MA·cm-2 (B||a-b) and ~0.4 MA·cm-2 (B||c), even at low growth rates of ~ 1 nm·s-1.
The authors acknowledge funding from EUROTAPES, a collaborative project funded by the European Community's Seven Framework Programme (FP7 / 2007 - 2013) under Grant Agreement n.280432.
5:45 - 6:00 Incorporation of preformed nanocrystals in YBCO coated conductors|
DE KEUKELEERE Katrien1, CAYADO Pablo2, MELEDIN Alexander3, DE ROO Jonathan1, POLLEFEYT Glenn1, RIJCKAERT Hannes1, VAN TENDELOO Staf3, PUIG Teresa2, OBRADORS Xavier2, VAN DRIESSCHE Isabel1
1Ghent University, SCRiPTS, Belgium, 2Institut de Ciencia de Materials de Barcelona, ICM, Spain, 3Antwerp University, EMAT, Belgium
show / hide abstract
The incorporation of inert metal oxide nanocrystals in YBa2Cu3O7-x (YBCO) coated conductors can lead to a better JC dependence on the magnitude and orientation of the magnetic field, making high field applications possible. In this work, we make use of preformed nanocrystals (PNCs) as artificial pinning centers that are added to the YBCO precursor solution. The use of PNCs offers the promise of a better control over particle growth, size, size distribution and shape compared to nanocrystals that are formed during the YBCO processing.
We synthesized ZrO2 and HfO2 nanocrystals (NCs) of 7 nm and a narrow size distribution. The NCs are initially capped with hydrophobic ligands, ensuring colloidal stability in apolar solvents. However, as the YBCO precursor typically provides a more polar environment, e.g., methanol, an important aspect of this research involves ligand exchange and the appropriate stabilization procedure. We are able to stabilize the NCs in high concentration for at least 2,5 months in a TFA-YBCO precursor solution, confirmed by dynamic light scattering analysis.
Afterwards, the YBCO-PNCs suspensions were deposited on a LaAlO3 substrate through spin-coating to study the influence of the NCs in the YBCO coating. The effect of different concentrations of pinning centers in YBCO was investigated, leading to a critical current density JC of 4.5 MA/cm² at 77K in self-field, compared to a JC of 3.8 MA/cm² of pristine YBCO, a better dependency of JC versus the applied magnetic field and a pinning force increase by a factor 12 at high magnetic fields.
This new, successful approach of the incorporation of preformed nanocrystals in CSD coatings holds the promise to the effective and economically efficient application of high-temperature superconductors in high and alternating magnetic field applications, relevant in alternative energy generation.
This work was financially supported by Ghent University and Eurotapes, a collaborative project funded by the European Community’s Seven Framework Program (EU-FP7 NMP-LA-2012-280432).
6:00 - 6:15 Application of ion beam textured templates for thick YBCO films with artificial pinning centers|
PAHLKE Patrick1, SIEGER Max1, SUN Peng1, HÄNISCH Jens2, HOLZAPFEL Bernhard2, USOSKIN Alexander3, STRÖMER Jan3, LAO Mayraluna4, EISTERER Michael4, MELEDIN Alexander5, VAN TENDELOO Gustaaf5, BIANCHETTI Marco6, MACMANUS-DRISCOLL Judith6, SCHULTZ Ludwig1, HÜHNE Ruben1
1IFW Dresden, Germany, 2Karlsruhe Institute of Technology (KIT), Germany, 3Bruker HTS, Germany, 4Vienna University of Technology, Austria, 5University of Antwerp, Belgium, 6University of Cambridge, United Kingdom
show / hide abstract
So far, YBa2Cu3O7-x (YBCO) or related compounds are the most promising materials for the realization of coated conductor application. Significant effort was made within the last years to develop biaxial texture templates for such conductors, which can be manufactured in long length. One major approach is the application of ion beam based methods for the preparation of cube textured buffer layers on arbitrarily textured metal tapes as for example the ion beam assisted deposition (IBAD) or alternating beam assisted deposition (ABAD).
We deposited YBCO layers with a thickness of 1 µm and above on TiN buffered IBAD-MgO as well as on ABAD-YSZ templates using pulsed laser deposition. Additionally, artificial pinning centers such as BaHfO3 (BHO) and the mixed double-perovskite Ba2Y(Nb/Ta)O6 (BYNTO) where incorporated in these YBCO layers. X-ray diffraction confirmed epitaxial growth of the superconductor on these templates and biaxially oriented incorporation of the pinning centers in the YBCO matrix. Detailed TEM studies revealed the size and distribution of the nanoparticles. A critical current density Jc of more than 2 MA/cm² was determined at 77 K in self-field for 1 µm thick films. Transport measurements were performed in order to study the anisotropy of Jc in magnetic fields. The influence of the deposition conditions on the distribution of artificial pinning centers and the resulting transport properties will be discussed in detail.
The authors acknowledge financial support from EUROTAPES, a collaborative project funded by the European Union's Seventh Framework Programme (FP7 / 2007 - 2013) under Grant Agreement no. 280432.
6:15 - 6:30 Thick superconducting YBCO films and coated conductors at high growth rate by inkjet printing deposition of low fluorine solutions |
POP Cornelia1, VILLAREJO Bohores1, RICART Susagna1, VALLES Feran1, PALAU Anna1, CAYADO Pablo1, MUNDET Bernat1, GAZQUEZ Jaume1, MELEDIN Alexander2, TENDELOO Gustaaf Van2, USOSKIN Alexander3, PUIG Teresa1, OBRADORS Xavier1
1Institut de Ciència de Materials de Barcelona, Spain, 2University of Antwerp, Belgium, 3Bruker HTS, Germany
show / hide abstract
Superconducting YBCO coated conductors are excellent materials for high efficient and energy saving providing strategic opportunities for the new grid paradigm of the XXI century. Low cost manufacturing is however one of the most stringent requirements. For that purpose, strong efforts are being devoted to decrease cost in scalable processes and the combination of chemical solution deposition (CSD) and ink jet printing (IJP) techniques is a key player.
We will report on our successful efforts in growing YBCO films and coated conductors by CSD using low fluorine solutions (80% fluorine reduction with respect to the all-TFA route) with special emphasis in thick film growth (micron range) by IJP deposition.
Upon an intensive work on pyrolyzing thick IJP films, we have grown thick (~1µm) films optimizing growth conditions and growth rate. Standard growth rates (0.8 nm/s) have been increased up to 2.3 nm/s in single deposited IJP YBCO layers. We have identified a tendency of these thick single deposited films to segregate second phases, which needed to be minimized by optimizing growth parameters and rate, in order to obtain high performance films above 2 MA/cm2 at 77 K.
When this YBCO films are grown on flexible metallic tapes, CZOMOD/YSZABAD/SS, the typical reactivity between CeO2-based buffer layers and YBCO was avoided by minimizing growth temperatures with proper tuning of supersaturation conditions and solution formulation.
All these knowledge has been transferred to the growth of thick YBCO nanocomposites with BaZrO3 and Ba2YTaO6 nanoparticles, demonstrating the potentiality of all CSD coated conductors.
Advanced HRTEM, STEM-EELS, FIB-cross sections, x-ray and angular dependent transport measurements were extremely valuable for the understanding and optimization of the performances.
The research leading to these results has received funding from EU-FP7 NMP-LA-2012-280432 EUROTAPES project, MP1201 Cost action and MAT2014-51778-C2-1-R national project.
6:30 - 6:45 Five micron crystal growth of c-axis oriented YBCO superconductor from oriented region toward non-oriented region by TFA-MOD.|
ARAKI Takeshi1, HAYASHI Mariko1, FUKE Hiroyuki1
1Toshiba Corporation, Japan
show / hide abstract
The TFA-MOD (metal-organic deposition using trifluoroacetates) process is a low-cost non-vacuum process for fabricating YBCO (YBa2Cu3O7-x) superconducting tape. However, it also requires vacuum processes for preparation of oriented intermediate layers and oriented metal substrate. These vacuum processes substantially raise the production cost for TFA-MOD. We propose a new process to eliminate these expensive vacuum processes. The architecture is YBCO superconductor (non-vacuum TFA-MOD) / oriented origin (non-vacuum process) / non-oriented oxide barrier layer (vacuum process, but low cost) / non-oriented metal substrate (as is). Furthermore, potential in-plane alignment (delta phi) of the YBCO superconducting layer may be below 1 degree.
One of the important phenomena for realizing the above-mentioned new architecture is transition of the oriented layer from on the oriented oxide strip toward on the non-oriented area. We partially covered LaAlO3 with Pt, which is not lattice-matched to YBCO superconductor. From the edge of LaAlO3, highly oriented YBCO is observed on Pt layer 5 microns from the edge. 10 microns from the edge, orientation is still confirmed by diffraction pattern of YBCO layer. 20 microns from the edge, orientation of YBCO is weak. From the results, provided oriented oxide strips are placed every 10 microns, we can obtain oriented YBCO superconducting layer having delta phi below 1 degree by TFA-MOD.
These results suggest the possibility of establishing an extremely low-cost process for TFA-MOD in the future.
6:45 - 7:00 Growth and characterization of epitaxial YBCO films prepared from Fluorine-Free chemical solutions|
SOLER BRU Laia1, MUNDET Bernat1, POP Cornelia1, FARJAS Jordi2, ROURA Pere2, GÁZQUEZ Jaume1, PUIG Teresa1, RICART Susagna1, OBRADORS Xavier1
1Institut de Ciència de Materials de Barcelona (CSI, Spain, 2University of Girona, Spain
show / hide abstract
The development of low-cost techniques for the growth of high performance YBCO coated conductors is one of the major requirements in obtaining a widespread use of superconductivity in large scale applications. Among all the techniques, chemical solution deposition (CSD) has become a very competitive cost-effective and scalable methodology to produce epitaxial thin films. Using trifluoroacetate precursors, high performance superconducting films can be obtained without carbon retention.
However, the reaction of the nanocrystalline oxide and fluorinated intermediates under a humid atmosphere limits the growth rate and has tight requirements in the gas flow control thus becoming very cumbersome to achieve at large scale a high production throughput. We have developed a new CSD approach using non-Fluorine metalorganic precursors which has less restricted gas flow conditions to form epitaxial YBCO films. Several fluorine-free metalorganic solutions and processing conditions have been analysed together with different strategies to enhance the decomposition of the barium carbonate forming as an intermediate phase to avoid the retention of carbon impurities in the epitaxial YBCO thin films. We will present how two novel processing procedures can be efficiently combined to reach this goal: rapid thermal annealing and heating under reduced pressure. Thermogravimetric analysis, Evolved Gas Analysis, X-ray diffraction and infrared measurements were used to control the intermediate phases leading to epitaxial growth of the films.
On the other hand, extensive research exploring different regions of the phase diagram has been carried out in order to control the nucleation process in order to obtain epitaxial growth at the maximum growth rate. Several processing parameters, such as total pressure, oxygen pressure, heating ramps and growth temperatures, were investigated. We have succeeded in obtaining highly epitaxial YBCO thin films of 200-500nm under processing conditions which make these films very promising for coated conductor applications. SQUID and transport measurements have shown that high critical temperatures (Tc=90-92K) and critical current densities (Jc=3MA/cm2 at self-field and 77 K) can be obtained with very appealing film microstructures comparable to high quality standard TFA films.
The research leading to these results has received funding from EU-FP7 NMP-LA-2012-280432 EUROTAPES project, MAT2011-28874 national project. L.S. and Ministerio español de Educación, Cultura y Deporte para la Formación de Profesorado Universitario.