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We report the effects of BSO addition on the crystallinity, texture, and the field dependency of critical current density (Jc) of GdBCO coated conductors (CCs) prepared by pulsed laser deposition (PLD). Undoped and BSO-doped GdBCO films showed only c-axis oriented growth, and the incorporated BSO nanorods exhibited epitaxial relationship with the GdBCO matrix. In comparison with undoped film, BSO-doped GdBCO film exhibited greatly enhanced Jc and higher pinning force densities in the entire field region of 0–5 T (H//c) at 77 and 65 K. The BSO-doped GdBCO film showed the maximum pinning force densities (Fp) of 6.5 GN/m3 (77 K, H//c) and 32.5 GN/m3 (65 K, H//c), ∼2.8 times higher than those of the undoped sample. Cross-sectional TEM analyses exhibited nano-structured BSO nanorods roughly aligned along the c-axis of the GdBCO film, which are believed effective flux pinning centers responsible for strongly improved critical current densities in magnetic fields.

The magnetic properties of high T c superconductor (HTS) SmBa 2 Cu 3 O 7− δ (SmBCO) coated conductors (CCs) which are based on IBAD (ion-beam-assisted deposition) templates were investigated. The SmBCO CCs were fabricated on LaMnO 3 (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 8.5 T. 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.

We report a successful fabrication of c -axis oriented GdBa 2 Cu 3 O 7− δ (GdBCO) films on the BaSnO 3 (BSO) buffer layers on ion-beam assisted deposition (IBAD)-MgO template by pulsed-laser deposition (PLD). The (0 0 l ) growth and in-plane textures of BSO buffer layers were found sensitive to the substrate temperature ( T s ). With increasing the BSO layer thickness up to ∼165 nm, in-plane texture (Δ ϕ ∼ 6.2°) of BSO layers was almost unaltered while completely c -axis oriented BSO layers were obtainable from samples with the thickness below ∼45 nm. On the BSO buffer layers showing in-plane texture of 6.2° and RMS surface roughness of ∼8.6 nm, GdBCO films were deposited at 780–800 °C. All GdBCO films exhibited Δ ϕ values of 4.6–4.7°, T c,zero of ∼91 K, and critical current density ( J c ) over 1 MA/cm 2 at 77 K in a self-field. The highest J c value of 1.82 MA/cm 2 ( I c of 51 A/cm-width) was achieved from the GdBCO film deposited at T s of 790 °C. These results support that BSO can be a promising buffer layer on the IBAD-MgO template for obtaining high- J c GdBCO coated conductors.

We report a successful fabrication of high-J c GdBa 2 Cu 3 O 7-δ (GdBCO) films by the metal-organic deposition process on the LaAlO 3 (LAO) (0 0 1 ) substrates. The coating solution was prepared by mixing Gd, Cu fluorine-free sources with Ba trifluoroacetate. Samples were dip-coated, pyrolized within 3 h at the temperature up to 400 °C in a humid oxygen atmosphere, and finally fired at various high temperatures in 100 ppm Ar/O 2 atmosphere. The GdBCO films fired at 775 and 800 °C exhibited J c values of ~2.1 MA/ cm 2 at 77 K in a self-field, which are attributable to both high T c,zero values of ~89 K and high in-plane textures of 1.3-1.4°. Above 800°C, however, the superconducting properties of GdBCO films are degraded due to the thermal decomposition of GdBCO film in 100 ppm Ar/O 2 atmosphere. .

High temperature superconducting GdBa 2 Cu 3 O 7 (GdBCO) thin films were grown by pulsed laser ablation. Textured MgO on metal substrates was used as a template for second generation wire applications. Growth conditions of GdBCO thin films were investigated for substrate temperature ( T s ) and oxygen partial pressure (PO 2 ) during deposition. Superconducting critical currents of the films were obtained in the films grown at 790–810 °C of T s and at 100–700 mTorr of PO 2 . Scanning electron micrographs of the films revealed uniform and well-connected grains with some outgrown structures. X-ray θ –2 θ scans of the films grown at 810 °C and 300–500 mTorr exhibited c -axis oriented texture. In-plane alignment and c -axis mosaic spread of the films were determined from X-ray Φ scans and rocking curves, respectively. Polarized Raman scattering spectroscopy was used to characterize optical phonon modes, oxygen content, cation disorder, and some possible second phases of the films. The Raman spectra of the films with large critical current density showed modes at 326–329 cm −1 , 444–447 cm −1 , 500–503 cm −1 related to vibration of oxygen atoms. Origin of small peaks near 600 cm −1 will be discussed as well. The information obtained from Raman scattering measurements will be useful for quality control of the conductors as well as optimization of the process conditions.

To examine the effect of solvent treatments on the superconducting properties of MgB 2 , solvent-treated MgB 2 powders were prepared by mixing with water, acetone, or ethanol. No degradation of the superconductivity of MgB 2 by the acetone or ethanol treatments was observed. Appreciable change which accompanies degradation of superconducting properties was observed only when MgB 2 was mixed with water. In addition, to investigate the variation of the flux pinning effect due to the aging, the Ag 8 –MgB 2 , (SiC) 4 –MgB 2 , and sintered pure-MgB 2 pellets were kept at room temperature for two and half years in air. The aged Ag 8 –MgB 2 composite superconductor has showed degradation of flux pinning effect. The in-field superconducting properties of (SiC) 4 –MgB 2 , however, did not change after aging.

We have fabricated SmBCO coated conductor on IBAD-MgO substrates using unique co-evaporation method. The batch type co-deposition system was specially designed and was named EDDC (evaporation using drum in dual chamber) that is possible to deposit superconducting layer with optimum composition ratio of materials at temperature over 700 °C and several mTorr of oxygen. In this study, we have investigated the influence of SmBCO phase composition ratio on the critical current density of coated conductor. We have optimized the composition ratio by changing the deposition rates of Ba and Cu during co-evaporation for better critical current density. A higher critical current density was measured at the composition ratio of Ba deficiency (1.9–2.0) and Cu rich (3.2–3.4) compared to the Sm 1 Ba 2 Cu 3 O y stoichiometry. Especially, highest critical current density of 2.6 MA/cm 2 was measured at the composition of Sm 1 Ba 1.9 Cu 3.2 O y that has dense surface morphology.

SrRuO 3 thin films have been grown in situ on single crystal LaAlO 3 substrates and textured metal templates which contain an MgO layer produced by an ion-beam growth method. Deposition was made of oxygen partial pressure in a range from 50 m Torr to 250 m Torr with laser repetition rate of 5 Hz. Substrate temperature was between 600 °C and 800 °C. Dependence of out-of-plane and in-plane orientation of SrRuO 3 thin films on pressure and growth temperature was investigated by X-ray diffraction. The surface morphology and grain growth behaviors of SrRuO 3 thin films were analyzed by atomic force microscopy and scanning electron microscopy. In addition, the transverse magnetoresistance value in a field of 4 and 8 T was measured in temperature range of 50–200 K and the ferromagnetic transition at ∼140 K of SrRuO 3 films on LaAlO 3 was detected by resistivity measurement.

Highly textured long-length MgO template was successfully deposited on a polycrystalline metal tape using ion-beam-assisted deposition (IBAD). To increase the speed of the IBAD processing, tape moving system was modified from a single-turn to multi-turn system with 14-pass and five heating zones, which leads to larger deposition area. The overall process consists of reel-to-reel electro-polishing of a Hastelloy C276 tape, deposition of Al 2 O 3 diffusion layer and Y 2 O 3 seed layer, deposition of IBAD*-MgO and homo-epi MgO layer, and deposition of LaMnO 3 (LMO) buffer layer and YBa 2 Cu 3 O 7-δ (YBCO) superconducting layer using pulsed laser deposition (PLD). Recently, 100 m long IBAD-MgO tape with in-plane texture of Δ∅ < 7° has been successfully fabricated. Critical current density (J c ) of 0.94 MA/cm 2 at 77 K in self field was obtained from the YBCO coated conductor grown on 20 cm long LMO-buffered IBAD-MgO template by the PLD process.

A cross-sectional transmission electron microscope (TEM) analysis was conducted on the GdBa 2 Cu 3 O 7− δ (GdBCO) tapes, which were synthesized by depositing Al 2 O 3 /Gd 2 O 3 /IBAD–MgO/epi-MgO buffer layers on the hastelloy substrate by the ion-beam-assisted deposition (IBAD) method and subsequently depositing LaMnO 3 and GdBCO layer by pulsed laser deposition (PLD) method. The average critical current ( I c ) value was 62.5 A and the average full width at half maximum (FWHM) values of the in-plane GdBCO(1 0 2) was 4.4°. The thickness of the each stacked layer was precisely measured with TEM micrographs and the structural features were analyzed with scanning transmission electron microscope-energy dispersive X-ray spectrometer (STEM-EDS). The diffusion of the Cr ion in the hastelloy into the Al 2 O 3 layer was detected and the thickness of the diffused layer was about 10 nm.

We investigated the effect of film thickness on the superconducting properties of GdBa2Cu3O7 (GdBCO) films on the SrTiO3 (STO)(1 0 0) substrates which were fabricated using pulsed laser deposition (PLD) with a KrF exicmer laser (248 nm) pulses of 2.5 J/cm2. With the target-to-substrate distance of 6.5 cm, GdBCO films were deposited at the substrate temperature of 810 °C in the oxygen pressure of 400 mTorr. Optimally processed GdBCO samples exhibited Tc of 91.3 K and Jc of 5.2 MA/cm2 at 77 K in self field. When the film thickness increased from 0.15 to 2.2 μm, Jc values were decreased from 5.2 to 1.3 MA/cm2. It was considered that the Jc reduction with increasing the thickness is attributed to the increase in the average size and density of particulates, leading to decrease in superconducting phase fraction, and also to the formation of cracks, reducing the supercurrent path.

BaZrO3 nanopowder was added to YBCO powder to make (BaZrO3)x(YBCO)(100−x)mol.% (BZOx-YBCO) (0 ⩽ x ⩽ 10) composite targets for pulsed laser deposition of superconducting film in order to investigate the effect of the addition of BZO nanopowder in the YBCO target on the flux pinning properties of YBCO coated conductor. All the BZOx-YBCO films were grown on SrTiO3 single crystal substrate under the same conditions in the PLD chamber. The effect of adding BZO to YBCO targets on the flux pinning properties of BZOx-YBCO films has been investigated. No impurity phase was identified, and all the peaks could be indexed as YBCO, BZO, and STO. There were traces of strong pinning centers at low temperature and high magnetic field region (above ∼3 T) in BZO6-YBCO film with the addition of ∼6 mol.% BZO nanopowder. However, the Tc of the BZOx-YBCO films gradually decreased as the amount of BZO nanopowder added increased.

NdBa 2 Cu 3 O 7-δ (NdBCO) films were grown by pulsed-laser deposition (PLD) on SrTiO 3 (STO)(1 0 0), MgO(1 0 0), and STO-buffered MgO(1 0 0) substrates for a comparative study on the effect of substrate on the textures, microstructures, and superconducting properties of NdBCO films. All NdBCO films were deposited at the same substrate temperature of 800 °C under the same total pressure of 800 mTorr with 1%O 2 /Ar gas. The transport J c value of 3.5 MA/cm 2 at 77 K in self-field was obtained from the NdBCO/STO with T c value of 91.2 K, while the NdBCO/MgO with T c of 86.8 K exhibited the low J c value of 0.25 MA/cm 2 . On the other hand, J c value of 1.55 MA/cm 2 was obtained from NdBCO film on STO-buffered MgO(1 0 0) substrate with T c of 91.5 K. The higher J c value of the NdBCO/STO than NdBCO/STO/MgO resulted from much better in-plane and out-of-plane textures of NdBCO/STO, while the low J c value of the NdBCO/MgO can be attributed to both depressed T c value and the existence of 45°-rotated grains with [001] NdBCO ∥[110] MgO .

We report a successful fabrication of high- J c NdBa 2 Cu 3 O 7− δ (NdBCO) coated conductors on CeO 2 /IBAD-YSZ/SS templates (YSZ ∼ 2 μm thick, CeO 2 ∼ 20 nm thick). The NdBCO films were prepared by pulsed laser deposition (PLD) at the substrate temperatures ( T s ) ranging from 750 to 830 °C under the same total pressure of 800 mTorr with 1%O 2 /Ar gas. Transport J c values over 1 MA/cm 2 at 77 K in self-field were achieved for NdBCO coated conductors deposited at T s of 775–800 °C. The highest J c value of 1.8 MA/cm 2 was obtained from the NdBCO coated conductor deposited at 775 °C, implying that NdBCO is comparable to YBCO for coated conductors. These samples had T c values of 88–90 K, commonly exhibited good in- and out-of-plane textures with the FWHM values of (1 0 3) ϕ -scan and the (0 0 6) ω -scan of 7–8° and 3.5–4.5°, respectively, and the densities and sizes of outgrowth particles in the films were not apparently different from each other.

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 77 K and 100 K in magnetic fields up to 3000 G. 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.

Melt-textured Nd123 samples are heat-treated at high temperatures in various atmospheres. For the sample prepared in 1% O 2 Ar, the decrease of J c was observed after the heat-treatment, eventhough there is no change in T c . This could be explained by the agglomeration of Nd-rich region (pinning center) during the heat treatment. On the other hand, the sample prepared in air showed the increase of T c and J c by the heat-treatment at 980°C in low oxygen partial pressure (0.1% O 2 Ar), which could be understood by the partial melting of the Nd-rich phase.