Ion Beam Assisted Deposition Templates Research Articles

Mechanical Properties of BaHfO3-Doped EuBCO Coated Conductors Fabricated by Hot-Wall PLD on IBAD Template

We have developed BaHfO3 (BHO)-doped EuBa2Cu3Ox (EuBCO) coated conductors (CCs) using a hot-wall type pulsed-laser-deposition (PLD) with a high throughput condition on ion-beam-assisted-deposition (IBAD) template with a thickness of 50 μm including Hastelloy substrate. Although we have investigated the in-field Jc properties, mechanical properties are also one of the most important issues for high field magnet applications. In this article, we investigated the degradation characteristics of REBa2Cu3Ox (REBCO) CCs including the BHO-doped EuBCO CCs under uniaxial tensile strain and bending strain. As a result, dependences of irreversible strain on the REBCO film thickness were clarified. In addition, longitudinal fatigue properties of the CC were investigated by repeated tensile tests, and a fatigue behavior of metallic components of the CC was confirmed in more than 100 000 cycles.

Development of Long-Length BMO-Doped REBCO Coated Conductors by Hot-Wall PLD Process

Fujikura Ltd., Chiba, Japan, has developed stable and high-throughput production techniques for REBCO coated conductors (CC) by using large-area ion-beam-assisted-deposition (IBAD), and hot-wall type pulsed-laser-deposition (PLD). Recently, we have been attempting to dope BaMO 3 (BMO, M: Zr or Hf) to REBCO layer in order to enhance in-field critical current density (J c ). In the course of optimizing deposition conditions of PLD for BaHfO 3 doped EuBCO films on IBAD templates, “high J c condition” and “high growth rate condition” were found. For samples prepared under these conditions, the magnetic field angle dependence of I c and REBCO thickness dependence were investigated. Finally, we succeeded in fabricating a 300-m-long CC with uniform I c distribution at the high-growth-rate condition. The longitudinal I c homogeneity (defined as standard deviation divided by average) at 77 K evaluated by magnetization method was 2.6%, which is comparable to nondoped conductors. Transport in-field I c for the both end points were 1756 and 1786 A/cm at 30 K, 2 T, respectively.

Self-heating technique of metallic substrate for reel-to-reel and double-sided deposition of YBa2Cu3O7−δ films

A new, simple, and highly efficient heating technology for metal tape substrates is proposed and applied to reel-to-reel and double-sided film deposition. In this technology, direct electrical current (I DC) is conducted into the metal layer of oxide-buffered metal substrate to induce heat. Different substrate surface temperatures were achieved by varying I DC from 22 to 25 A. At these temperatures, a series of 1-μm-thick and 5-cm-long YBa2Cu3O7−δ (YBCO) films were fabricated on ion-beam-assisted deposition (IBAD) templates through metal organic chemical vapor deposition. X-ray diffraction analysis on the samples revealed that the YBCO film changed its growth mode from mixed a-axis and c-axis to purely c-axis with increasing I DC. The optimal out-of-plane and in-plane texture reached ~1.4° and 3.5°, respectively. A 30-m-long and 500-nm-thick single-sided YBCO-coated conductor was also prepared through reel-to-reel deposition using the proposed heating method. The fabricated conductor presented homogeneous crystallization and texture and exhibited a critical current density at self-field and 77 K (J c 77K, 0T ) of 2.8–3.2 MA/cm2. Moreover, 500-nm-thick YBCO films were fabricated simultaneously on both sides of the double-sided IBAD template. The two sides of films demonstrated uniform texture and J c 77K, 0T of 3.2 MA/cm2. Results demonstrated that the proposed substrate heating technology can be used for reel-to-reel and double-sided deposition of YBCO-coated conductors.

MOCVD Buffer and Superconducting Layers on Non-Magnetic Biaxially Textured Tape for Coated Conductor Fabrication

In this article, we present recent developments in the metal-organic chemical vapor deposition (MOCVD) route to coated conductor fabrication made at SuperOx. Two new buffer layer architectures on nonmagnetic Ni-Cr-W biaxially textured substrates are described. With the use of these architectures we have achieved critical currents in the range of 100–140 A/cm-width for the fully MOCVD produced coated conductors on Ni-Cr-W in the reel-to-reel mode. We have also demonstrated over 10-m-long MOCVD-high temperature superconductor tapes on the ion beam assisted deposition templates with Ic exceeding 300 A/cm-width.

Full angular critical current characteristics of coated conductors studied using a two-axishigh current goniometer

Coated conductors are considered to be the most suitable candidates for applicationsin various devices. Recently, the critical current anisotropy of (RE)BCO (rareearth barium copper oxide) has become the focus of particular research interest,due to the changes in the angular dependence of the critical current density,Jc(φ), resulting from different tape architectures and pinning landscapes. In this work, wepresent advanced anisotropy studies of coated conductors in low magnetic fields using atwo-axis high current goniometer. Two different commercially available coated conductorswere characterized and will be discussed: the first is based on an IBAD (ion beamassisted deposition) template with the YBCO (yttrium barium copper oxide)ab planes slightly tilted, and the second is highly symmetric with a template grown by theRABiTS (rolling assisted biaxially textured substrate) method. In addition, therequirements to be met by coated conductors for applications will be discussed.

Full Vector Magnetic Field Critical Current Characterization of Coated Conductors Deposited on Solution Deposition Planarized IBAD Templates

Second generation high temperature super-conductor (HTS) wire consists of metal substrate tapes textured with intermediate buffer layers that are coated with a superconducting layer. The applications of these coated conductors require a high current in magnetic fields that are not restricted to a narrow range of angles. Ion beam assisted deposition (IBAD) template tilt, in combination with REBCO vapor deposition, results in asymmetric sample growth. This requires Vector Magnetic Field (VMF) measurement over 180 degrees to be fully described. We have developed a piece wise characterization and analysis method of the VMF using a number of Ic scaling models. Solution Deposition Planarization (SDP) permits REBCO film deposition on 100 nm rms roughness substrates. To test buffer layer effects on film growth, with and without SDP, superconducting films were deposited at Superconductor Technologies, Inc. by co-evaporation of REBCO on IBAD buffer layer templates from Los Alamos. Critical current measurements in VMF up to a magnitude of ~ 0.9 Tesla show behaviors traceable to the effects of buffer layer template on pinning. The ability to discriminate between buffer layers based on in-field Ic behavior is a useful technique for the optimization of buffer layers for future REBCO film deposition.

The behavior of the magnetic irreversibility of SmBCO coated conductor on IBAD-MgO template fabricated by EDDC

The magnetic properties of high Tc superconductor (HTS) SmBa2Cu3O7−δ (SmBCO) coated conductors (CCs) which are based on IBAD (ion-beam-assisted deposition) templates were investigated. The SmBCO CCs were fabricated on LaMnO3(LMO)/epi-MgO/IBAD-MgO/Hastelloy substrates by Evaporation using Drum in Dual Chamber (EDDC) processing. The measurements of isothermal magnetizations M(H) for the prepared SmBCO-CCs were carried out at various temperatures in magnetic fields up to 8.5T. The magnetic properties for the applied magnetic fields parallel to the ab-plane show non-conventional behaviors when compared to those parallel to both c-axis and c-axis+45°. These normal and anomalous properties can be explained by introducing the magnetic flux pinning effects related to the direction of the applied magnetic fields.

The comparative study of magnetic properties for YBCO coated conductors based on RABiTS and IBAD templates

The magnetic properties of high Tc superconductor (HTS) YBa2Cu3O7−δ (YBCO) coated conductors (CCs) which are based on RABiTS (rolling-assisted biaxially textured substrate) and IBAD (ion-beam-assisted deposition) templates were investigated. The measurement of isothermal magnetizations M(H) for the prepared YBCO-CCs was carried out at 77K and 100K in magnetic fields up to 3000G. The magnetic properties for the applied magnetic fields parallel to the ab-plane are much smaller than that perpendicular to the ab-plane. Large magnetic property in the YBCO-CC based on the RABiTS template comes from the strong ferromagnetism of the textured Ni–W alloy substrate.

Biaxial Texturing of Inorganic Photovoltaic Thin Films Using Low Energy Ion Beam Irradiation During Growth

AbstractWe describe our efforts to control the grain boundary alignment in polycrystalline thin films of silicon by using a biaxially textured template layer of CaF2 for photovoltaic device applications. We have chosen CaF2 as a candidate material due to its close lattice match with silicon and its suitability as an ion beam assisted deposition (IBAD) material. We show that the CaF2 aligns biaxially at a thickness of ~10 nm and, with the addition of an epitaxial CaF2 layer, has an in-plane texture of ~15°. Deposition of a subsequent layer of Si aligns on the template layer with an in-plane texture of 10.8°. The additional improvement of in-plane texture is similar to the behavior observed in more fully characterized IBAD materials systems. A germanium buffer layer is used to assist in the epitaxial deposition of Si on CaF2 template layers and single crystal substrates. These experiments confirm that an IBAD template can be used to biaxially orient polycrystalline Si.

AC loss study of antiparallel connected YBCO coated conductors

Some applications of high temperature superconducting conductors require a non-inductivewinding, which may be constructed from antiparallel connected YBCO (yttrium bariumcopper oxide) tapes. In the case of AC applications, this antiparallel winding changes theAC losses from that of an isolated conductor. This study focuses on the effect of the spatialseparation and misalignment between conductors on their AC loss behavior for YBCOconductors on both rolling assisted biaxially textured substrate (RABiTS) and ion beamassisted deposition templates in an effort to fully understand the behavior of theseconductors in real world applications. For RABiTS samples, the study was carried out forall three possible configurations (the so-called back-to-back, front-to-front and same-wayconfigurations) to clarify the effect of the ferromagnetic substrate on the ACloss behavior in these conductor configurations. Numerical simulations were alsoemployed in some cases to compare with and elucidate experimental observations.

Single-Buffer-Architectured Coated Conductor Based on IBAD and PLD Method

In order to lower the production costs of coated conductors based on the ion-beam assisted deposition (IBAD) and pulsed laser deposition (PLD) method, we examined a single-buffered architecture (REBCO/IBAD/Hastelloy) without a second buffer layer of . While all samples exhibited similar degrees of the textures, transport current properties were found to be strongly dependent on the REBCO layer and IBAD template materials. With a structure of Ag/PLD-GdBa2Cu3O7/IBAD - Gd2Zr2O7/Hastelloy, we obtained critical currents of 165 Amps (0.8 -thick) and critical current densities of 3.4 (0.4 -thick) for short-piece samples in standard four-probe dc measurements.

Long and High Rate Production of IBAD Templates for YBCO Coated Conductors

Ion-beam-assisted deposition (IBAD) is a promising method for preparation of biaxially textured templates for YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) coated conductors. For the purpose of practical applications, many groups make efforts to obtain long and high-performance YBCO superconducting wires based on IBAD templates. In our laboratory, long IBAD template tape fabrication using a reel-to-reel system was developed and up to now, we have fabricated a 220-m-long tape successfully and 103-220 m tapes have been obtained steadily. On these IBAD template tapes, high critical current (I/sub c/) performances were demonstrated and a large I/sub c/ value of 182 Amps was attained with pulsed laser deposited YBCO conductors on 46 m in length. These values give a product of I/sub c//spl times/L over 8000 Am.

Development of 100-m long Y-123 coated conductors processed by IBAD/PLD method

100-m class Y-123 coated conductors were demonstrated by using reel-to-reel vacuum apparatuses of ion-beam-assisted-deposition (IBAD) and pulsed-laser-deposition (PLD). The window for Gd 2Zr 2O 7 deposition condition was quite wide and 100-m long IBAD-Gd 2Zr 2O 7 template films were routinely obtained with Δ φ of 10° on non-textured Ni-alloy tapes. 100-m long second buffer layers of Y 2O 3 or CeO 2 were grown by PLD on the IBAD templates with Δ φ of 7–8°, or 5–6°, respectively. Y-123 films with Δ φ of 7° were formed on the substrate of Y 2O 3//IBAD-Gd 2Zr 2O 7//Hastelloy by PLD. End-to-end I c of 38 A and J c of 0.76 MA/cm 2 (77 K, self-field) were obtained in a 100-m long sample. On the other hand, Δ φ of 3° was obtained on the substrate of CeO 2//IBAD-Gd 2Zr 2O 7//Hastelloy. J c of 2.9 MA/cm 2 were obtained in a 0.1-m long Y-123 film, and J c was improved to 1.6 MA/cm 2 for an 80-m long Y-123 tape.

次世代超電導線材の開発と特性評価 ＩＢＡＤ／ＰＬＤ法による長尺ＹＢＣＯ超電導線材

We have developed 100-m class YBCO conductors using reel-to-reel vacuum apparatuses for ion-beam-assisted deposition (IBAD) and pulsed-laser deposition (PLD). IBAD-Gd2Zr2O7 films 100m long were obtained with Δφ of 10°on non-textured Hastelloy tapes. Second buffer layers of Y2O3 or CeO2 that were 100m long were grown by PLD on the IBAD templates with Δφ of 7°or 5°, respectively. YBCO films were formed on a Y2O3/Gd2Zr2O7/Hastelloy substrate using PLD. An end-to-end Ic of 38 A and Jc of 0.76 MA/cm2 (77 K, self-field) were obtained in a 100m-long sample.

Fabrication of long-Y123 coated conductors by combination of IBAD and PLD

Continuous deposition of Gd 2Zr 2O 7 films were carried out on 10 mm width Hastelloy tapes by ion-beam-assisted deposition (IBAD). They were uniformly deposited with the in-plane mosaic spread (Δ φ) of 10–14° in the 50 m long and of 16–18° in the 60 m long, at a production rate of 0.5–1.0 m/h. The 6 cm sample with the I c value of 141 A and the J c value of 1.25 MA/cm 2 were obtained by 6 repeated depositions using pulsed laser deposition (PLD). Continuous deposition of Y-123 films were performed by PLD on long IBAD template tapes at a tape speed of 4.0 m/h. The I c value of 40 A and the J c value of 0.8 MA/cm 2 were obtained at the length of 30 m. Furthermore, the 46 m YBCO coated tape with the I c value of 74 A and the n value of 32 was formed uniformly.

Development of Y-123 coated conductors by ion-beam-assisted deposition

Continuous deposition of Gd 2Zr 2O 7 films was carried out on 10 mm width Hastelloy tapes by ion-beam-assisted deposition (IBAD). They were uniformly deposited with the in-plane mosaic spread ( Δφ) of 10–12° in the 15 m length and of 16–18° in the 60 m length, at a production rate of 1.0 m/h. In an optimized sample, I c of 140 A and J c of 1.2 MA/cm 2 were obtained at the length of 8 cm. Continuous deposition of Y-123 films was performed by pulsed laser deposition on long IBAD template tapes at a tape speed of 1.0 m/h. I c of 50.0 A and J c of 0.42 MA/cm 2 were obtained at the length of 9.6 m with Δφ for the Y-123 film was 9°. Furthermore, I c of 50.0 A and J c of 1.0 MA/cm 2 were obtained in a 8 cm Y-123 sample with Δφ of 8° at a tape speed of 4.0 m/h.

Advances in YBCO-coated conductor technology

Processes for producing both the yttrium-stabilized zirconia (YSZ) template film by ion beam-assisted deposition (IBAD) and the YBa 2Cu 3O x (YBCO) superconducting film by pulsed laser deposition (PLD) at 1-m lengths have achieved I c values of 122 A and J c values of 1 MA/cm 2. Improvements have been made in all stages of the process. Variations of I c along the length of the 1-m samples stimulated development of a new in-field I c measurement capability. The use of MgO as an IBAD template film has made great progress and can potentially decrease the time to produce the template film by more than an order of magnitude. A combination of electrical and microstructural investigations is being made to understand and improve the properties of the YBCO-coated conductors.