The RABiTS Approach: Using Rolling-Assisted Biaxially Textured Substrates for High-Performance YBCO Superconductors

AbstractThis article provides an overview of the fabrication of epitaxial, biaxially aligned buffer layers on rolling-assisted biaxially textured substrates (RABiTS) as templates for YBCO films carrying high critical current densities.The RABiTS technique uses standard thermomechanical processing to obtain long lengths of flexible, biaxially oriented substrates with smooth surfaces.The strong biaxial texture of the metal is conferred to the superconductor by the deposition of intermediate metal and/or oxide layers that serve both as a chemical and a structural buffer.Epitaxial YBCO films with critical current densities exceeding 3 106A/cm2at 77K in self-field have been grown on RABiTS using a variety of techniques and demonstrate magnetic-field-dependent critical current values that are similar to those of epitaxial films on single-crystal ceramic substrates.The RABiTS architecture most commonly used consists of a CeO2 (sputtered)/YSZ (sputtered)/Y203 (e-beam)/Ni-W alloy.The desired texture of the base metal has been achieved in 100 m lengths and 10cm widths.Scaleable and cost-effective techniques are also being pursued to deposit the epitaxial multilayers.The results discussed here demonstrate that this technique is a viable route for the fabrication of long lengths of high-critical-current-density wire capable of carrying high currents in magnetic fields and at temperatures accessible by cooling with relatively inexpensive liquid nitrogen (up through the 77K range).

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Progress towards a low-cost commercial coated conductor

MRS Proceedings ◽

10.1557/proc-689-e7.7 ◽

2001 ◽

Vol 689 ◽

Author(s):

Suresh Annavarapu ◽

Nguyet Nguyen ◽

Sky Cui ◽

Urs Schoop ◽

Cees Thieme ◽

...

Keyword(s):

Critical Current ◽

High Performance ◽

Low Cost ◽

Critical Currents ◽

Short Length ◽

Coated Conductor ◽

High Quality ◽

Ybco Films ◽

Performance Levels ◽

Current Densities

ABSTRACTYBCO films prepared from metal trifluoroacetate (TFA) precursors on oxide-buffered textured non-magnetic substrates have achieved performance levels equaling that on oxide buffered textured Ni substrates. Critical current densities of 0.7 MA/cm2 to 1.0 MA/cm2 have been achieved in 0.4 µm thick YBCO films on short-length of CeO2/YSZ/Y2O3/Ni/Ni-13wt%Cr substrates. High-quality epitaxial buffers comprising a Ni layer, Y2O3 seed, YSZ barrier and CeO2 cap layers have been deposited over meter long tapes of deformation textured Ni and Ni-13%Cr using reel-to-reel processes. High-performance TFA-based YBCO films have been deposited on 0.1 m to 0.3 m lengths of these oxide buffered substrates using reel to reel processes. Critical current densities up to 1.0 MA/cm2 have been achieved in 0.4 µm thick YBCO films on CeO2/YSZ/Y2O3/Ni substrates. Using multiple coats of the metal trifluoroacetate precursors, thicker YBCO films have been demonstrated on oxide buffered substrates. Critical currents in excess of 100A/cm-width have been achieved for 1.2 µm -1.6 µm thick YBCO films on short lengths of CeO2/YSZ/Y2O3/Ni substrates.

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Chemical Solution Deposition of Lanthanum Zirconate Buffer Layers on Biaxially Textured Ni–1.7% Fe–3% W Alloy Substrates for Coated-conductor Fabrication

Journal of Materials Research ◽

10.1557/jmr.2002.0229 ◽

2002 ◽

Vol 17 (6) ◽

pp. 1543-1549 ◽

Cited By ~ 39

Author(s):

S. Sathyamurthy ◽

M. Paranthaman ◽

T. Aytug ◽

B. W. Kang ◽

P. M. Martin ◽

...

Keyword(s):

Sol Gel ◽

Rf Sputtering ◽

Cube Texture ◽

Dip Coating ◽

Buffer Layers ◽

Lanthanum Zirconate ◽

Solution Deposition ◽

Ybco Films ◽

Current Densities ◽

Gel Processing

Sol-gel processing of La2Zr2O7 (LZO) buffer layers on biaxially textured Ni–1.7% Fe–3% W alloy substrates using a continuous reel-to-reel dip-coating unit has been studied. The epitaxial LZO films obtained have a strong cube texture and uniform microstructure. The effects of increasing the annealing speed on the texture, microstructure, and carbon content retained in the film were studied. On top of the LZO films, epitaxial layers of yttria-stabilized zirconia and Ceria (CeO2) were deposited using rf sputtering, and YBa2Cu3Ox (YBCO) films were then deposited using pulsed laser deposition. Critical current densities (Jc) of 1.9 MA/cm2 at 77 K and self-field and 0.34 MA/cm2at 77 K and 0.5 T have been obtained on these films. These values are comparable to those obtained on YBCO films deposited on all-vacuum deposited buffer layers and the highest ever obtained using solution seed layers.

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Crystalline Qualities and Critical Current Densities of As-Grown Ba2YCu3OxThin Films on Silicon with Buffer Layers

Japanese Journal of Applied Physics ◽

10.1143/jjap.29.l955 ◽

1990 ◽

Vol 29 (Part 2, No. 6) ◽

pp. L955-L957 ◽

Cited By ~ 45

Author(s):

Hiroaki Myoren ◽

Yukio Nishiyama ◽

Naokazu Miyamoto ◽

Yasuaki Kai ◽

Yasushi Yamanaka ◽

...

Keyword(s):

Critical Current ◽

Buffer Layers ◽

Current Densities

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All chemical YBa2Cu3O7 superconducting multilayers: Critical role of CeO2 cap layer flatness

Journal of Materials Research ◽

10.1557/jmr.2009.0160 ◽

2009 ◽

Vol 24 (4) ◽

pp. 1446-1455 ◽

Cited By ~ 59

Author(s):

M. Coll ◽

J. Gàzquez ◽

R. Huhne ◽

B. Holzapfel ◽

Y. Morilla ◽

...

Keyword(s):

Critical Role ◽

High Energy ◽

Buffer Layers ◽

Solution Deposition ◽

Ybco Films ◽

Force Microscopy ◽

Atomic Force ◽

Current Densities ◽

Atomically Flat

New advances toward microstructural improvement of epitaxial CeO2 films grown by chemical solution deposition and their use as buffer layers for YBa2Cu3O7 (YBCO) films are presented. We demonstrate that the degree of epitaxy and the fraction of (001) atomically flat surface area are controlled by the incorporation of tetravalent (Zr4+) or trivalent (Gd3+) cations into the ceria lattice. The degree of epitaxy has been investigated by means of Rutherford backscattering spectroscopy-channeling and reflection high-energy electron diffraction, and a new methodology is also presented to quantify the fraction of (001) atomically flat area from atomic force microscopy images. Results are further correlated with the superconducting properties, microstructure, and texture of YBCO films grown by the trifluoroacetate route. A comparison with pulsed laser deposition and YBCO films grown on the same ceria layers is also presented. This growth procedure has allowed us to obtain all chemical multilayer films with controlled microstructure and critical current densities above 4 MA cm−2 at 77 K.

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Microstructural analysis of the compatibility of solution deposited buffer layers with the TFA process for YBCO

MRS Proceedings ◽

10.1557/proc-659-ii4.1 ◽

2000 ◽

Vol 659 ◽

Author(s):

K. Salama ◽

S. Sathyamurthy ◽

M. Mironova

Keyword(s):

Buffer Layer ◽

Critical Current ◽

Strontium Titanate ◽

Surface Defects ◽

Microstructural Analysis ◽

Buffer Layers ◽

Barium Zirconate ◽

Chemical Compatibility ◽

Superconducting Properties ◽

Current Densities

ABSTRACTIn this paper, the feasibility of applying solution deposition processes for the fabrication of coated conductors has been explored. The crystal and chemical compatibility of the buffer layers processed using metalorganic decomposition with the Y123 deposition using the trifluoroacetate process has been studied. Two buffer layer materials have been used, namely, barium zirconate and strontium titanate. The measured superconducting properties of these conductors were correlated with the microstructure observed on these samples using SEM and cross-sectional TEM. In case of barium zirconate buffer layers, though there exists a very good structural and chemical compatibility between the buffer layer and the Y123, the presence of surface defects in the buffer layer causes compositional heterogeneity and randomly oriented grains in the Y123 film. This leads to poor superconducting properties. In case of strontium titanate buffer layers, due to the excellent crystal and chemical compatibility, and the absence of surface defects, high critical current densities (of the order of 106A/cm2 at 77K and self field) were obtained. However, TEM cross section studies reveals the presence of a significant portions of a-oriented Y123 crystallites which could lead to lower critical current densities. Further studies of the TFA process is required to eliminate the occurrence of a-oriented Y123 in the microstructure. This could lead to further improvements in the properties.

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An evaluation of phase separated, self-assembled LaMnO3-MgO nanocomposite films directly on IBAD-MgO as buffer layers for flux pinning enhancements in YBa2Cu3O7-δ coated conductors

Journal of Materials Research ◽

10.1557/jmr.2010.0073 ◽

2010 ◽

Vol 25 (3) ◽

pp. 437-443 ◽

Cited By ~ 6

Author(s):

Özgür Polat ◽

Tolga Aytug ◽

M. Parans Paranthaman ◽

Keith J. Leonard ◽

Andrew R. Lupini ◽

...

Keyword(s):

Flux Pinning ◽

High Performance ◽

Superconducting Devices ◽

Microstructural Characterization ◽

Coated Conductors ◽

Buffer Layers ◽

Nanocomposite Films ◽

Two Phase ◽

Ybco Films ◽

Self Assembled

Technological applications of high temperature superconductors (HTS) require high critical current density, Jc, under operation at high magnetic field strengths. This requires effective flux pinning by introducing artificial defects through creative processing. In this work, we evaluated the feasibility of mixed-phase LaMnO3:MgO (LMO:MgO) films as a potential cap buffer layer for the epitaxial growth and enhanced performance of YBa2Cu3O7-δ (YBCO) films. Such composite films were sputter deposited directly on IBAD-MgO templates (with no additional homo-epitaxial MgO layer) and revealed the formation of two phase-separated, but at the same time vertically aligned, self-assembled composite nanostructures that extend throughout the entire thickness of the film. The YBCO coatings deposited on these nanostructured cap layers showed correlated c-axis pinning and improved in-field Jc performance compared to those of YBCO films fabricated on standard LMO buffers. Microstructural characterization revealed additional extended disorder in the YBCO matrix. The present results demonstrate the feasibility of novel and potentially practical approaches in the pursuit of more efficient, economical, and high performance superconducting devices.

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Fabrication of High Jc YBa2Cu3O7-δ Coated Conductors Using Sol-Gel Buffer Layers On Nickel and Nickel Alloy Substrates

MRS Proceedings ◽

10.1557/proc-689-e10.5 ◽

2001 ◽

Vol 689 ◽

Author(s):

S. Sathyamurthy ◽

M. Paranthaman ◽

B. W. Kang ◽

H. Y. Zhai ◽

T. Aytug ◽

...

Keyword(s):

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Sol Gel ◽

Rf Sputtering ◽

Cube Texture ◽

Dip Coating ◽

Coated Conductors ◽

Buffer Layers ◽

Ybco Films

Sol-gel processing of La2Zr2O7 (LZO) buffer layers on biaxially textured Ni-3 at.% W alloy substrates using a continuous reel-to-reel dip-coating unit has been studied. The epitaxial LZO films obtained have a strong cube texture and uniform microstructure. The effect of increasing the annealing speed on the texture, microstructure and the carbon content retained in the film were studied. On top of the LZO films, epitaxial layers of Yttria Stabilized Zirconia (YSZ) and Ceria (CeO2) were deposited using rf sputtering, and YBa2Cu3Ox (YBCO) films were then deposited using Pulsed Laser Deposition (PLD). A critical current density (Jc) of 1.9 MA/cm2 at 77K and self-field and 0.34 MA/cm2 at 77K and 0.5T have been obtained on these films. These values are comparable to those obtained on YBCO films deposited on all-vacuum deposited buffer layers, and are the highest ever obtained using solution seed layers. The use of all-solution buffers for coated conductor processing has also been explored. A critical current density of 1.1 MA/cm2 at 77 K and self-field was obtained on YBCO films grown be PLD on LZO buffered nickel substrates.

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Superconducting Interconnections in Future High Performance Systems

MRS Proceedings ◽

10.1557/proc-108-27 ◽

1987 ◽

Vol 108 ◽

Cited By ~ 6

Author(s):

R. C. Frye

Keyword(s):

Critical Current ◽

High Speed ◽

High Performance ◽

Electronic Systems ◽

Maximum Current Density ◽

Maximum Current ◽

High Performance Systems ◽

Current Densities ◽

Very High ◽

Scaling Rule

ABSTRACTNew, high temperature superconducting materials could eventually be used for interconnections in electronic systems. Such interconnections would undoubtedly cost more to implement than conventional ones, so the most likely applications would be for complex, high-speed systems that could benefit from the performance advantages of a resistance-free interconnecting medium. The problem with conventional conductors in these systems is that the resistance of wires increases quadratically as dimensions are scaled down. The most important advantage offered by superconductors is that they are not linked to this scaling rule. Their principal limitation is the maximum current density that they will support and this determines the range of applications for which they are superior to conventional conductors. An analysis will be presented which examines the relative advantages of superconductors for different critical current densities, wire dimensions and system sizes.If their critical current densities are adequate, and if they can statisfy a number of processing criteria, then superconductors could find useful applications in a number of high performance electronic systems. The most likely applications will be those demanding very high interconnection densities. Several of these systems will be discussed.

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High-Jc YBCO coatings on reel-to-reel dip-coated Gd2O3 seed buffer layers epitaxially fabricated on biaxially textured Ni and Ni-(3at%W-1.7at%Fe) alloy tapes

MRS Proceedings ◽

10.1557/proc-689-e6.5 ◽

2001 ◽

Vol 689 ◽

Cited By ~ 1

Author(s):

Tolga Aytug ◽

M. Paranthaman ◽

S. Sathyamurthy ◽

B. W. Kang ◽

D. B. Beach ◽

...

Keyword(s):

Low Cost ◽

Dip Coating ◽

Buffer Layers ◽

Ex Situ ◽

X Ray Diffraction ◽

Ybco Films ◽

Ni Alloy ◽

Current Densities ◽

Alloy Metal

ABSTRACTA low-cost, non-vacuum reel-to reel dip-coating system has been used to continuously fabricate epitaxial Gd2O3 buffer layers on mechanically strengthened, biaxially textured Ni- (3at.%W-1.7at%Fe), defined as Ni-alloy, metal tapes. X-ray diffraction analysis of the seed Gd2O3 layers indicated that well textured films can be obtained at processing temperatures (Tp) between 1100 and 1175°C. Processing speed did not significantly affect the crystalline quality of the Gd2O3. Scanning electron microscopy revealed a continuous, dense and crack-free surface morphology for these dip-coated buffers. The Gd2O3 layer thickness led to remarkable differences in the growth characteristics of the subsequent YSZ and CeO2 layers deposited by rfmagnetron sputtering. Epitaxial YBCO films grown by pulsed laser deposition on the short prototype CeO2/YSZ/Gd2O3/Ni-(3at%W-1.7at%Fe) conductors yielded self-field critical current densities (Jc) as high as 1.2×106 A/cm2 at 77 K. Pure Ni tapes were used to asses the viability of dip-coated buffers for long length coated conductor fabrication. The YBCO films, grown on 80 cm long and 1 cm wide CeO2/YSZ/Gd2O3 buffered Ni tapes by the industrially scalable ex-situ BaF2 precursor process, exhibited end-to-end self-field Jc of 6.25×105 A/cm2 at 77 K.

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