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We have constructed a compact accelerator-based neutron facility at the National Institute of Advanced Industrial Science and Technology (AIST) in Japan aiming at development of structural materials of transportation vehicles for weight reduction. The facility consists of electron linear accelerator, neutron source, and a neutron beamline with a measurement hutch. Currently we are commissioning the accelerator and expecting a first neutron beam in 2019.

The neutron wavelength resolution, Bragg-edge measurement ability and future prospects regarding the neutron count rate were investigated at AISTANS. The wavelength resolution evaluated by Bragg-edge analysis using an iron powder sample is in reasonably good agreement with calculations at neutron wavelengths of 0.2–0.3 nm. Bragg-edge imaging was also performed on a steel plate sample with distinct regions of BCC and FCC crystallinity, and the different crystal structures were successfully discriminated. In addition, an aluminum sample containing a friction stir spot welding region was also measured and the 200 and 111 Bragg-edges at the two joining areas were observed. However, it was hard to characterize the difference in texture between the two areas. The neutron counting rate for Bragg-edge imaging is expected to increase by approximately a factor 50 in the near future thanks to the planned improvements of the electron beam power and the detection efficiency of the neutron detector. [ABSTRACT FROM AUTHOR]

Investigating the chemical reactions during the calcining process of the TFA-MOD is discussed. These results are consistent with the present precursor films derived from highly purified coating solution by the solvent-into-gel method.

Investigating the relationship between residual carbon content and J (sub c) of YBCO film with different calcining conditions is discussed. The J (sub c) values of the films depend on decomposition of trifluoroacetates and CuO nanocrystallites growth, rather than the influence of carbon content.

Discussing the effects of texturing and surface roughness of CeO2 layer on J (sub c) of YBCO coated conductor is presented. The grain alignment, delta phi, and surface roughness, R (sub a), of CeO2 layers are improved with increasing the thickness for both substrates of YSZ single crystal substrates and IBAD-Gd2Zr2O7 metallic substrates is concluded.

We have fabricated long buffered substrate tapes by a reel-to-reel process. The architecture is a self-epitaxial PLD-CeO2 cap layer on an IBAD-Gd2Zr2O7 buffered Hastelloy-C 276 tape. At the same time, we have investigated the effect of the deposition temperature for self-epitaxial growth of the PLO-CeO2 cap layer. We found that a deposition temperature of 500° C for the self-epitaxial PLO-CeO2 cap layer is the best in the range of 200°C and 800°C for O2 pressure of 10-30 mTorr in terms of the in-plane grain alignment. At the deposition temperature of 500°C in the reel-to-reel process, we obtained a PLO-CeO2 cap layer with Δφ values of about 5 degrees at a tape transfer speed of 6 m/h for IBAD-GZO tapes with Δφ values of about 15 degrees in 100 m class long tapes. Furthermore, we also obtained a PLO-CeO2 cap layer with better Δφ values of 3.7-4.4 degrees at a tape transfer speed of 2 m/h for a 55 m long tape. [ABSTRACT FROM AUTHOR]

Ion-beam-assisted deposition (IBAD) is a promising method for preparation of biaxially textured templates for YBa2Cu3O7-δ (YBCO) coated conductors. For the purpose of practical application, many groups make efforts to obtain long and high-performance YBCO superconducting wires based on IBAD templates. In our laboratory, long IEAD template tape fabrication using a reel-to-reel system was developed and up to now, we have fabricats a 220-m-long tape successfully and 103-220 m tapes have been obtained steadily. On these IBAD template tapes, high critical current (Ic) performances were demonstrated and a large Ic value of 182 Amps was attains with pulsed laser deposited YBCO conductors on 46 m in length. These values give a product of Ic × L over 8000 Am. [ABSTRACT FROM AUTHOR]

Mechanical properties of YBaCuO superconducting tape produced by a multi-stage metal-organic chemical vapor deposition (MOCVD) technique have been investigated. It is important for YBaCuO superconducting tape to tolerate stress strain and maintain flexibility in order to be used for electric power applications, magnetic applications, and so on. At this time, we have produced an approximately 0.25 μm YBaCuO layer on a pulse laser deposition (PLD)-CeO2/ion beam assisted (IBAD)-Gd2 Zr2 O7/Ni-based alloy substrate by an MOCVD technique, and approximately 4 μm Ag was sputtered on it as a protective layer. The thickness of each layer was approximately 1.0 μm, 1.0 μm and 0.1 mm respectively. Its critical current was about 50 A. The mechanical properties of YBaCuO tape formed on Ni-based alloy substrates with a CeO2 /Gd2 Zr2 O7, buffer layer will be described. Tensile or compressive bend stress tests were conducted, and normalized critical current and the value n were evaluated. The degradation of its critical current was confirmed not to be in the big problem level in manufacturing applications. In addition, the surfaces of YBaCuO layers were observed by scanning electron microscopy and no crack was observed on them. Next, axial tensile stress tests were conducted and the YBaCuO tape was compared with biaxially textured Ni-3at.%W alloy substrates and YBaCuO layers on Ag substrates. Axial tensile stress characteristics of the YBaCuO tape were confirmed to be much higher than others. The YBaCuO tape was confirmed to have adequate axial tensile stress characteristics for designing a coil which can tolerate electromagnetic force. [ABSTRACT FROM AUTHOR]

In order to scale-up high-performance YBa2Cu3O7-δ (YBCO) coated conductors, we have been investigating pulsed laser deposition (PLD) of YBCO on the "self-epitaxial" PLD-CeO2 layer on an ion-beam-assisted deposition (IBAD)-Gd2Zr2O7 (GZO) buffered Hastelloy tape. Our continuous PLD system was designed so that the laser beam scans YBCO targets during deposition and raises plural and discrete plumes (multi-plume), and the substrate was turned three times (multi-turn) around the substrate heater to enlarge its deposition area. The multi-plume and multi-turn (MPT) PLD indicated a capability to unite high rate deposition and high Jc by enlarging the deposition area under the proper condition. A 21 m long YBCO coated conductor with high end-to-end Ic of 85.0 A and Jc, of 1.13 MA/cm² was prepared by MPT-PLD. The uniformities of the grain alignment and transport property were also achieved. Furthermore, we succeeded in deposition of a 45.8 m long YBCO layer. The Ic was as high as 182 A, that the multiplication of Ic and length reached the highest value of 8.34 kA m. [ABSTRACT FROM AUTHOR]

The multiple-stage Chemical Vapor Deposition technique was developed for making a long coated conductor with high deposition speed. In this paper, a multi -coating of YBCO layer using 6-stage CVD system was described. Substrates were PLD - CeO2/IBAD - Gd2Zr2O7/Hastelloy. Thickness of each layer was about 1.0 μm, 1.0 μμm and 0.1 mm respectively. Δφ of CeO2 layer was about 9-10°. Deposition rate of YBCO layer was 25 m/h and 5 m/h. Number of passing was 10 times and 2 times respectively. Ic of the tape which has prepared at a speed of 25 m/h × 10 passes was 100 A/cm. Thickness of total YBCO layer was about 1 μm and its Jc was 1 MA/cm². Ic of the tape which was prepared at a speed of 5 m/h × 2 passes was 101 A/cm. Thickness of total YBCO layer was also 1 μm and its Jc was 1 MA/cm². [ABSTRACT FROM AUTHOR]

For fabrication of YBa2Cu3O7 -x (YBCO) coated conductors with high Jc, we have investigated pulsed laser deposition (PLD) of YBCO on the "self-epitaxial" PLD-CeO2 layer on an ion beam assisted deposition (IBAD)-Gd2Zr2O7 (GZO) buffered Hastelloy tape. A multiple coating of YBCO layer (multi-deposition) improved the uniformity in transport properties. In order to increase Ic, we investigated the proper depositing conditions for a thick YBCO layers. It was found that raising the referential deposition temperature, in accordance with the YBCO layer growths, is effective to suppress a-axis oriented grains and increase Ic. A high Ic as high as 293 A was obtained in a 10 cm long conductor. Furthermore, we succeeded in the deposition of a 0.8 m long YBCO coated conductor with the end-to-end Ic of 225 A and Jc of 1.13 MA/cm² .The latter coated conductor also exhibited good uniformity, whose standard deviation of I distribution is 2.2%. These results demonstrated that the multi-deposition applying heater temperature increase corresponding to the YRCO thickness is effective in a preparation of high Ic and uniform YBCO coated conductors. [ABSTRACT FROM AUTHOR]

Activities at SRL-Nagoya Coated Conductor Center (NCCC) are presented including rapid production of 100 to 220 m buffered substrate tapes and a 46 m YBCO coated conductor using reel-to-reel equipment of both IBAD and PLD systems. A 220 m long IBAD and a 100 m long CeO2 capped substrate have been successfully and stably produced. Furthermore, the PLD-CeO2, which we call the "Self-Epitaxial" method, is found to be effective to increase a production rate. The combination of IBAD and PLD-CeO2 enhanced the overall buffer processing rate up to 2 m/h. This is much higher than the rate of 0.5 to 1 m/h of the conventional IBAD method. We also recently introduced a new PLD system for YBCO, which utilizes a multi-plume and multi-turn deposition, MPT-PLD method. This system is now successfully operating and then very recently we have achieved the record of Ic X L (critical current times length) of 8335 Am. A 45.8 m long YBCO coated conductor carried the high Ic of 182 A. The MPT-PLD method is also effective to increase the thickness of YBCO with high Jc. Consequently, Ic as high as 300 A was also obtained for a short sample test. Therefore, the new system of MPT-PLD is very promising for long YBCO tape fabrication. [ABSTRACT FROM AUTHOR]

We have proposed a self-epitaxy process for CeO2 cap buffer layer deposition by using PLD in order to improve the deposition rate in the IBAD process. The process is combined with a thin IBAD buffer layer by a short time deposition and a self-epitaxy PLD cap layer by high rate deposition. The materials for both IBAD buffer layer and PLD cap layer were studied in terms of the grain alignment. Gd2Zr2O7 (GZO) for the IBAD buffer layer and CeO2 for the PLD cap layer are the best combination. It was estimated that a deposition time of the combination process could be about one-third of the conventional IBAD process.A 55 m long PLD-CeO2 cap layer was fabricated at the tape transfer speed of 5 m/h on an IBAD-GZO tape by a reel to reel process. A PLD-CeO2 cap layer improved the Δφ value of the buffer layer and also the uniformity of the Δφ values throughout the whole length. While the Δφ values of IBAD-GZO were in the range of 13.9° and 18.8°, those of PLD-CeO2 cap layer were improved to be in the range of 5.7° and 8.7°. [Copyright &y& Elsevier]

CeO2 buffer layers were deposited on IBAD-Gd2Zr2O7 tapes by the pulsed laser deposition (PLD) method and were investigated especially in terms of the thickness dependence on the crystal grain alignment. The film thickness was varied from 10 to 1200 nm. The grain alignment of the CeO2 layer on an IBAD tape was drastically improved with increasing its thickness. The Δφ value of the in-plane grain alignment decreased from 25.4° for the Gd2Zr2O7 layer of the IBAD tape to 4.9° for the CeO2 layer. Using this result, we demonstrated that the total production rate of the buffer layers process was enhanced drastically by the combination of a thinner Gd2Zr2O7 layer by the IBAD method and a thicker CeO2 layer by the PLD method. The improved in-plane grain alignment resulted in higher Jc in YBCO on the CeO2 buffer layer. [Copyright &y& Elsevier]

High critical current density (J[sub c]) YBa[sub 2]Cu[sub 3]O[sub 7-x] films were routinely prepared by metalorganic deposition using trifluoroacetates (TFA-MOD). Although the growth scheme of the YBa[sub 2]Cu[sub 3]O[sub 7-x] films has been studied, we still have two or more unsolved problems during heat-treatments. The first problem is chemical reaction, including the carbon-expelling scheme during the calcining process. Considering Gibbs free energy changes in the related chemical reactions and electronegativity of atoms, we explain the expelling scheme. During the calcining process metal-oxygen bonds remain after the decomposition. The fluorine partially attacks and replaces oxygen linked to Y and Ba. Consequently, these metal compounds become an amorphous matrix of metal oxyfluorides. Only CuO grows to be nanocrystalline. These results are consistent with the present precursor films derived from highly purified coating solution by the Solvent-Into-Gel method. The second problem is clarification of the required conditions to obtain high J[sub c] YBCO film by TFA-MOD. Transmission electron microscopy revealed the existence of isolated Ba and Y oxides besides CuO grains within the YBa[sub 2] Cu[sub 3] O[sub 7-x] layer, which are derived from the normally purified coating solution. Optimal calcining processing, which certainly suppresses only the CuO grains, never improves the J[sub c] of the films containing Ba and Y oxides. Thus the required condition for high J[sub c] YBa[sub 2]Cu[sub 3]O [sub 7-x] films is a combination of a highly purified coating solution and an optimized calcining process. With that combination, we prepared 210-230 nm thick YBa[sub 2]Cu[sub 3]O[sub 7-x] films on CeO[sub 2] buffered YSZ for which the J[sub c]'s were 10.5-11.4 MA/cm² (77 K, 0 T) by four-probe transport measurement. [ABSTRACT FROM AUTHOR]

We investigated calcining conditions for YBa[sub 2]Cu[sub 3]O[sub 7-x] (YBCO) films by metalorganic deposition using trifluoroacetates. We measured residual carbon content by secondary ion mass spectroscopy (SIMS) and critical current density J[sub c] values of the films calcined with various heat treatments. Precursor films are decomposed in calcining duration at 200 to 250°C, and simultaneously harmful residue such as carbon content is generated. SIMS results of carbon intensity show calcination is more effective than extension of the duration at 200 to 250°C to reduce carbon content. J[sub c] values of films with the calcination varied with the duration, reaching a maximum at about 10 hours. The J[sub c] values of the films depend on decomposition of trifluoroacetates and CuO nanocrystallites growth, rather than the influence of carbon content. We have succeeded in fabricating the YBCO films of 217 to 241 nm thickness with high J[sub c] values; 1.7 to 2.9 MA/cm² (77 K, 0 T) on CeO[sub 2]/Gd[sub 2]Zr[sub 2]O[sub 7]/hastelloy -C. [ABSTRACT FROM AUTHOR]

A CeO[sub 2] buffer layer was deposited by the pulsed laser deposition (PLD) method on a YSZ single crystal substrate and an IBAD-Gd[sub 2]Zr[sub 2]O[sub 7] substrate. It was investigated in terms of the effect of the CeO[sub 2] layer thickness for YBa[sub 2] Cu[sub 3]O[sub 7-x] (YBCO) coated conductors by the metalorganic deposition method using trifluoroacetates (TFA-MOD). The grain alignment, delta phi, and surface roughness, R[sub a], of CeO[sub 2] layers were improved with increasing the thickness for both kinds of substrates of a YSZ single crystal and an IBAD-Gd[sub 2]Zr[sub 2]O[sub 7] substrate. Especially the improvement of the qualities of the CeO[sub 2] layer on the IBAD substrate was remarkable. The initial value of delta phi was 12 degree at the surface of the IBAD-Gd[sub 2]Zr[sub 2]O[sub 7] layer without a CeO[sub 2] layer while it decreased to 4 degree after 600 nm thick CeO[sub 2] layer deposition by PLD. Consequently, the J[sub c] value of the YBCO on the CeO[sub 2] buffered IBAD-Gd[sub 2]Zr[sub 2]O[sub 7] metallic substrate exhibited the value as high as 2.9 MA/cm² at 77 K and 0 T. This result implies that a high rate deposition by PLD could be used for further texture evolution even after thin film IBAD deposition which could result in shortening of the overall production time for the buffer layers deposition. [ABSTRACT FROM AUTHOR]