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The charge trapping characteristics of silicon (Si) substrates covered with a self-assembled monolayer (SAM) were studied using on a local biasing method with Kelvin-probe force microscopy. A hexadecyl SAM (HD-SAM) on a Si substrate, in which the molecules were covalently bonded to the Si substrate, was found to have no charge trapping sites at its monolayer/Si interface while an ocatadecylsilyl SAM (ODS-SAM) on a Si substrate, in which a thin oxide layer was inserted between the molecules and the Si substrate, showed a distinct charge trapping behavior. The alkyl monolayer directly fixed on Si is promising as a very thin insulating layer in Si microelectronics.

The effect of deposition rate on the superconducting properties in the manufacturing process of SmBCO superconducting thin films was investigated. The superconducting layer was deposited using the EDDC (Evaporation using Drum in Dual Chambers) deposition process. An apparatus for continuously changing the deposition rate was constructed with a shield having a triangular open area in one chamber. Sm1+xBa2Cu3+yO7 (SmBCO) superconducting thin film samples were fabricated by continuously increasing the deposition rate of the SmBCO superconducting layer in the longitudinal direction from 0 to 28 nm/min at the tape length of 12 cm in an atmosphere with a substrate temperature of 800 C. The magnetic field dependence of the critical current was measured using the PPMS in the direction of the magnetic field parallel to the c axis of the superconducting thin film to found out the optimal deposition rate under magnetic field. The TEM analysis results confirmed the flux pinning centers of rod and particle shapes, and the flux pinning density was the highest in the sample with a deposition rate of 21 nm/min. These flux pinning centers formed by the combination of rod and particle shapes improved the critical current characteristics under the magnetic field of SmBCO superconducting wire.

Static high critical current densities ( J c ) > 1 MA/cm 2 with magnetic field parallel or perpendicular to c -axis were realized in Co-doped/undoped multilayerd BaFe 2 As 2 films. We made a current bridge by FIB to allow precise measurements, and confirmed that the boundary quality using FIB was considerably better than the quality achieved using a laser. The presence of a high in-plane J c suggested the existence of c -axis correlated vortex pinning centers. To clarify the relationship between the J c performance and superstructures, we investigated the magnetic flux pinning mechanism using scaling theory of the volume pinning force F p ( H ). The J c ( H ) curves, F p / F p,max vs. h = H / H irr curves, and parameters p and q depended on the characteristics of the flux pinning mechanism. It was found that the dominant pinning mechanism of Co-doped/undoped multilayerd BaFe 2 As 2 films was Δl-pinning and the inserted undoped BaFe 2 As 2 layers remained non-superconducting. The dominant pin geometry varied when the magnetic field direction changed. It was concluded that the artificially layered BaFe 2 As 2 film is a 3-D superconductor due to its long correlation length compared to the thickness of the non-superconducting layer.

Sm1+xBa2Cu3+yO7−d (SmBCO)-coated conductors containing pinning centers were prepared by a reactive co-evaporation method using the EDDC (Evaporation using Drum in Dual Chamber) deposition system. Superconducting materials based on Sm, Ba, and Cu were evaporated in the evaporation chamber and deposited onto the drum-mounted substrate, while the deposited element reacted with oxygen and resulting in the SmBCO superconducting phase inside the reaction chamber. Tape-type samples (length = 30 cm, width = 4 mm, thickness = 0.1 mm) with the structure of Ag/SmBCO/LMO/MgO/Y2O3/Al2O3/Hastelloy were prepared, where the SmBCO film was spread along the tape length. The critical current was measured using the non-contact Hall-probe method, and the field dependences of the critical current under a high magnetic field were measured. The superconducting properties of the samples under a magnetic field were highly influenced by the composition of the SmBCO film. Furthermore, elemental mapping of the high-Jc SmBCO-coated conductor was measured by transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (TEM-EDX). Finally, we confirmed the Sm-related secondary phases take the role of pinning centers.

We report the magnetic field and temperature dependence of the critical current density {Jc(H) and Jc(T)} flowing in a 5 μm thick sample of SmBa2Cu3O7−δ (SmBCO) film. The film is a coated conductor (CC) deposited on an IBAD-MgO textured metallic template. For a range of intermediate fields, we find J c α H - α with values of α between 0.44 and 0.49. These values are lower than those reported for other CC in the literature. The sample has a Jc of 13.6 MA/cm2 at 5 K and self-field. Such high-Jc wires should find applications in large-scale energy applications of high-temperature superconductors. The temperature dependence of Jc at self-field and different applied fields is also analyzed.

Structural and transport properties of high performance SmBa2Cu3O7−x coated conductors produced by a dual-chamber co-evaporation are presented. The 5 μm-thick SmBCO coated conductors grown on IBAD-MgO based Hastelloy metal templates show critical currents larger than 1020–1560 A/cm at 77 K and self-field. The current transport characteristics of the conductors are investigated by room-temperature thermoelectric microscopy and low-temperature bolometric microscopy. The local thermoelectric images show the tilted grains, grain boundaries, and microstructural defects on the surface of the coated conductors. The bias current-dependent bolometric response at low temperature displays the current of the local flux flow dissipation as an increasing bias. Furthermore, we measured micro-Raman scattering microscopic imaging on oxygen-related peaks of the conductors. Comparing the Raman signal images with the low temperature optical scanning maps, it is remarkable that the structural disorders represented by oxygen-related Raman peaks are closely related to the low temperature bolometric abnormalities. From this result, a nature of the dissipative current distribution in coated conductors is revealed. The scanning optical microscopic study will provide a promising method for quality assurance of coated conductors.

We report the fabrication of Gd films with dimples on the surface by vacuum evaporation method on Hastelloy substrate. The Gd films are structurally and morphologically studied by x-ray diffraction and field emission scanning electron microscope respectively and found to be hexagonal crystal structure. The magnetocaloric properties are studied and found to be well comparable with commercial Gd sheet. The calculated magnetic entropy change in Gd films is 9.57 J/kg K at Curie temperature (TC) of 294 K with second order magnetic phase transition under applied magnetic field 5 T.

Nanocrystalline ZnO powders have been synthesized by co-precipitation method and investigated planetary ball milling effects on structural and optical properties. These powders were characterized using X-ray diffraction, field emission scanning electronic microscope, Infrared spectrophotometer, UV–vis spectrophotometer and Photoluminescence. It was found that prepared ZnO powders have hexagonal close packed structure which was annealed at 500 °C for 30 min. The bandgap energy of ZnO powders varied from 3.13 to 2.85 eV. The room temperature PL spectra exhibits low intensity UV emission peak at 383 nm and green emission band around 520 nm shows shifting towards higher wavelength with decrease in intensity of peak with time of planetary ball milling. Hence, it was observed that planetary ball milling can be used to tailor the optoelectronic properties of ZnO nanostructures.

Ni doped ZnO nanopowders have been synthesized by the co-precipitation route followed by planetary ball milling. The synthesized powder was characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HR-TEM), UV–vis spectrophotometry, fluorescence spectrophotometry and Quantum Design PPMS for structural, morphological, microstructural, optical and magnetic properties measurements. All the samples show wurtzite hexagonal crystal structure. The optical absorption spectra show a shift in the position of band edge towards lower energy. The estimated band gap is found to decrease with higher nickel doping. The room temperature PL measurements illustrate UV emission centered at 390 nm (3.17 eV), which is ascribed to the near-band-edge (NBE) emissions of ZnO and broad green emission around 540 nm. Room temperature ferromagnetism in the Ni doped ZnO nanopowders has been confirmed by magnetic property measurements.

Nonuniformity of critical current, Ic is one of the most important factors to be considered for the practical applications of high-temperature superconducting (HTS) REBCO coated conductors. To investigate the variation of Ic due to mechanical strain, local critical currents were measured at various tensile strain values from 0 to 1.2% for brass-laminated GdBCO tapes at 77 K, and analyzed using the Weibull distribution function. Measured local critical currents vary and decrease significantly at strain levels above about 0.8%. The Weibull function with three parameters turned out to be applicable for describing the Ic distribution of REBCO HTS wire for the entire strain range. The statistical minimum Ic calculated from the Weibull distribution function decreased with increased tensile strain. The degree of Ic variation was observed to drastically increase when the applied tensile strain exceeded the irreversible strain of about 0.8%.

This paper reviews recent progress in research and development (R&D) of reactive co-evaporation for high performance REBCO coated conductors in Korea. Two types of reactive co-evaporation methods were developed for the deposition of SmBCO and GdBCO superconducting layers respectively on the IBAD (Ion Beam Assisted Deposition)-MgO template in the Korean coated conductor project. Batch type reactive co-evaporation equipment and its processing were developed for SmBCO coated conductors at Korea Electrotechnology Research Institute (KERI) in conjunction with the Korea Advanced Institute of Science and Technology (KAIST), and a very high critical current exceeding 1,000 A/cm at 77 K in the self field was achieved through the optimization of deposition parameters. Reel-to-reel type reactive co-evaporation processing with a high conversion rate was also developed, while long length GdBCO coated conductors have been routinely produced by SuNAM Co. The minimum critical current of 422 A/cm-w at 77 K in self field was confirmed for 1 km-long GdBCO tape.

R&D Center, Kolon Industries, Inc., Incheon, KoreaReceived August 31, 2012, Accepted September 27, 2012Several palladium complexes containing β-ketoiminate and β-diketiminate ligands successfully producedpoly(DCPD) possibly via vinyl addition. It was found that catalysts with β-diketiminate ligands containingbulkier aryl substituents showed the highest activity in the presence of MAO as a cocatalyst. Purity of DCPDis quite essential for the higher activity and small amount of organic solvent such as CH

A facile and rapid glycine-assisted combustion method was developed to synthesize polycrystalline La0.8Ca0.2MnO3 (LCMO) powder by dissolving lanthanum nitrate, calcium nitrate, manganese nitrate (oxidant) and glycine (fuel) as the starting materials and water as solvent and then heating the resulting solution on a heating plate. The X-ray diffraction and FTIR analyses confirmed the orthorhombic crystal structure, and a morphological study showed the polycrystalline form of the LCMO powder. The calculated lattice constants a = 5.46, b = 7.73, and c = 5.49 A agreed well with the standard values. The magnetic measurements showed a paramagnetic behavior of LCMO at room temperature. The maximum change in entropy observed for the LCMO sample was −1.95 J/kgK at an applied magnetic field of 2 T at the Curie temperature of 165 K.

Sm 1+ x Ba 2− x Cu 3+ y O 7− δ (SmBCO) films were directly deposited on the epi-MgO/IBAD-MgO/Y 2 O 3 /Al 2 O 3 /Hastelloy template by co-evaporation using the evaporation using drum in dual chambers (EDDC) system without the buffer layer in order to investigate the effect of the composition ratios on superconducting property, microstructure and texture of SmBCO film. The films with gradient composition ratios of Sm:Ba:Cu were deposited using a shield with an opening which was placed between the substrate and the boats. The highest I c of 52 A (corresponding to J c = 1.6 MA/cm 2 and a thickness of 800 nm) was observed at 77 K in self field at a composition x = 0.01–0.05 and y = −0.23 to −0.46. When the composition ratio is outside this range, the I c value rapidly decreased. The superconducting critical current was highly dependent on the composition ratio. As the composition ratio is farther away from that of the highest I c , the SmBCO (1 0 3) peak intensity increased and the amount of a -axis oriented parts increased. A dense microstructure with round-shape grains was observed in the region showing the highest I c . The optimum composition ratio can be found by analyzing films deposited with variable deposition rates of each depositing element.

In this study, in order to investigate the strain effect in the critical current, I c of coated conductor (CC) tapes under magnetic field a newly devised measurement system using a pair of permanent magnets was constructed. The level of magnetic field applied could be controlled by the distance between magnets located in parallel. The distribution of magnetic field between the permanent magnets was checked using a hall probe sensor. External magnetic field was applied perpendicular to the CC tapes surface. Uniaxial tensile strain was applied to the tape by using devised loading frame mounted on a universal testing machine and the strain induced was measured by using a Nyilas type extensometer. I c /I c0 –e t relation of the CC tape was first measured at self field. External magnetic field was then varied to investigate the dependency of critical current, I c , and its effect on the reversible strain limit under uniaxial tension. Finally, the transport property characteristic of SmBCO CC tapes under magnetic field with uniaxial tension using permanent magnet is compared to the case using superconducting magnet.

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.

The magnetic properties of SmBa2Cu3O7-x (SmBCO) coated conductor (CC) that was fabricated on LaMnO3(LMO)/IBAD-MgO substrates using Evaporation using Drum in Dual Chamber (EDDC), which is a batch type co-evaporation system, was investigated. LMO buffer layer was deposited on IBAD-MgO templates by PLD method. The measurements of both the magnetization M(H) and the resistance R(T) for the SmBCO CC, were carried out at temperatures between 10 and 120 K in fields up to 8.5 T, using a PPMS-9T (with both ACMS and DCR options, Quantum Design). The SmBCO CC exhibited Tc (onset temperature) of 94.7 K with a narrow transition width of 0.6 K, which indicates a good homogeneity of the superconducting properties. The upper critical field Hc2 near Tc of the SmBCO CC has been estimated by the resistance R(T) approaches. The magnetization curves M(H) are symmetric about the line M = 0 for the SmBCO CC with the field applied parallel to both the c-axis and c-axis +45°. For the SmBCO CC with the field applied parallel to the ab-plane, they are asymmetric. These symmetric and asymmetric curves can be explained by introducing the bulk pinning of 1-D flux lines and surface barrier-dominated system of 2-D pancake vortices.

In superconducting cable applications using the HTS tapes, striation of ReBCO coated conductor (CC) is being considered to reduce ac loss. The striation of ReBCO coating film with laser patterned filaments has been tried. In practical applications, the striated ReBCO CC tapes should also exhibit acceptable tolerance to mechanical stress/strains. However, reports on the electromechanical properties of striated CC tapes in bending or torsion mode are limited. In this study, the critical current degradation behavior of the striated Cu stabilized SmBCO CC tapes in pure torsion mode was investigated using a sample holder which gives torsional deformation to CC tapes. The CC tape has been laser scribed to produce multi-filaments. The Ic/Ic0 and n-value-torsional angle (θ) behaviors in the striated SmBCO CC tapes were examined and compared with the case of non-striated ones. According to the location of the coating film strip striated within the cross-section, there existed some difference in the Icf degradation behavior indicating that a non-uniform deformation was induced on each striated strip.

Sm 1+xBa 2Cu 3+y O 7−d coated conductors were fabricated by reactive co-evaporation method in the evaporation using drum in dual chambers (EDDC) deposition chamber. The effect of substrate temperature on the superconducting properties was investigated. Three samples were prepared with different substrate temperatures of 740, 780, and 800 °C. In plane and out-of-plane texture were confirmed by X-ray patterns of 2 theta and phi scan and turned out to be almost the same. Angular dependences of critical currents of those samples were measured at 0.5 and 1 T. The magnetic field dependence of critical current with the magnetic field direction parallel to the c-axis of SmBCO film was measured in the range of 0.01–1.5 T. The critical current of the sample prepared at 740 °C was slightly lower than that of other samples in the range of 0.5–1.5 T. Also we investigated the effect of thickness of superconducting layer on the magnetic field dependence. Two samples with different SmBCO film thicknesses of 0.8 and 5 μm were prepared. The magnetic field dependence of critical current in the direction parallel to the c-axis of SmBCO film was measured in the range of 0.01–1.5 T. We found that the normalized critical current of a 5 μm thick sample was higher than that of 0.8 μm thick sample possibly due to the higher pinning force of thick film than that of thin film.

Long-length (Sm1+xB2-xC3O7-y) coated conductor was fabricated using ion beam assisted deposition (IBAD)-MgO template (LaMnO3/IBAD - MgO/Y2O3/Al2O3/Hastelloy) by the reactive co-evaporation method for electric power applications. SmBCO superconducting layers with thicknesses from 1 to 3 ?m were deposited to investigate the effect of SmBCO thickness on the in-plane texture, surface morphology and superconducting properties. In this study, the optimal deposition conditions were examined to make thick SmBCO coated conductor without degradation of critical current density. The oxygen partial pressure and temperature were controlled in the range of 1~20 mTorr and 600 ~ 800°C, respectively. SmBCO/IBAD-MgO coated conductors showed high critical current densities over 2.0 MA/cm2 with small amount of degradation by increasing the thickness of superconducting layer up to 3 ?m. The critical current of 637.5 A/cm-w (JC = 2.12 MA/cm2) at 77 K in self- field was obtained in 3 ?m-thick and 1 m long coated conductor. This is the highest critical current reported so far of the coated conductor with SmBCO superconducting layer deposited by co-evaporation.

The Hall probe measurement system was used to measure the critical current distribution of superconducting coated conductor. The system consists of reel to reel moving apparatus, 7 array Hall probe, a rotary encoder and permanent magnet. The magnetic field profile across the width of superconducting coated conductor using Bean's critical state model was calculated. The effect of various parameters of the formulas on the magnetic field distribution and the effect of shape and size of artificial defects, which were formed on the surface of SmBa2Cu3O7-d(SmBCO) coated conductor using laser marking system, on the Hall probe magnetic field signal of the Hall probe measurement system was investigated.

It is environmentally important to recycle the wastewater, since paper factories use a large amount of water and equivalent amount of wastewater is generated. Conventional water treatment facilities like precipitation process need large-scale equipment and wide space to purify the wastewater of paper factory. In case of massive waste water, high gradient magnetic separation (HGMS) parts are more effective to purify it rapidly and to occupy relatively small space, since large voids at filter with HGMS are adopted. In this respect, we prepared two types of superconducting magnets in order to apply HGMS parts for wastewater purification process. We made cryo-cooled Bi-2223 (HTS) superconducting magnet parts with room temperature bore in diameter of 70 mm and 200 mm in height. Also, cryo-cooled Nb-Ti superconducting magnet with room temperature bore in diameter of 100 mm and 600 mm in height was used for magnetic separator. Magnetic filters were designed by the analysis of magnetic field distribution at superconducting magnets. The faster wastewater's flow rate was, the worse the degree of clarity in treated water was. The ability of wastewater treatment in the case of magnetic separation used with 10 of magnetite particles was better than that in the case of 5 of magnetite particles.

The deposition conditions of LaMnO3 (LMO) buffer layer on Ion Beam Assisted Deposition (IBAD)-MgO template by reactive DC sputtering were investigated. We developed a specially designed chamber for reactive DC magnetron sputtering. The deposition chamber was composed of two sputtering guns with the mixed metallic target of La (50 at%) + Mn (50 at%), halogen lamp heater, QCM (Quartz Crystal Microbalance), RGA (Residual Gas Analyzer) and reel to reel tape moving system. We investigated the effect of oxygen flow rate on the deposition rate of LMO layer. We found that there was an optimal range of oxygen flow rate to have the desired layer. Above the range, the deposition rate decreased sharply and plasma was unstable. Below the range, the deposited layer was partially metallic. We investigated the effect of substrate temperature on the texturing of LMO layer. The texturing of LMO layer was improved by increasing the substrate temperature. We investigated the effect of deposition rate on the texturing of LMO layer. The LMO layer has a good texture in the deposition rate range of 0.07–0.21 nm/s. We confirmed that deposition rate had little effect on the texturing of LMO layer in the deposition rate range. Sm1Ba2Cu3O7−d superconducting layer was deposited on the LMO(reactive)/IBAD-MgO template. Ic and Jc were 81.6 A and 1 MA/cm2. This means that LMO layer deposited by reactive DC sputtering shows a good performance in superconductor coated conductor.

We measured the magnetic hysteresis loops (M-H loop) of SmBCO coated conductor (CC) and YBCO-CC by using SQUID-magnetometer. These samples were fabricated by RABiTS method and IBAD method. We found the peak shifts of their M-B loops were qualitatively different. To understand this, we measured the magnetic field profiles, H(x), of SmBCO-CC and YBCO-CC by using scanning Hall probe method and calculated their current profiles, J(x). We found that the contrasting difference of M-B loops of the two types of CC was partly due to the inhomogeneous distributions of field and current, which depend on the sample shapes.

The evaporation and sputtering simultaneous deposition (ESSD) system was developed for in-situ deposition of MgB2 thin films. Mg was evaporated from the nozzle of cylinder crucible which is heated by high frequency induction heating, while B was sputtered by RF-magnetron sputtering. The nozzle-substrate distance was small enough to keep high vapor pressure of Mg on the substrate. The Mg-flux coming out of the nozzle was controlled by means of regulating the temperature of Mg source, was monitored and was calculated in detail with the variation of the distance from its nozzle. The optimal deposition condition with the variations of substrate temperature, the temperature of Mg source and the power of RF-magnetron sputtering, was investigated. MgB2 films with onset Tc of 14 K was obtained. The Tc of the film is lower than the bulk value of 39 K. Further works are in progress to improve the quality of MgB2 films by further optimization of deposition parameters and improvement of the ESSD system.

In order to investigate the possibility of using mixed rare earth (Nd1/3Eu1/3Gd1/3)Ba2Cu3O7-x (NEG123) as the superconducting layer of the HTS coated conductor, the NEG123 thin film was deposited epitaxially on LAO(100) single crystal and IBAD_YSZ metal templates by pulsed laser deposition. Systematic studies were carried out to investigate the influences of deposition parameters of PLD on the microstructure, texture and superconducting properties of NEG-123 coated conductor. Deposition at oxygen partial pressure of 600 mTorr was needed to routinely obtain high quality NEG123 films with JC's (77 K) over 2 MA/cm2 and Tc's over 90 K (DeltaT ~ 2 K) . We verified from magnetization study that the NEG123 has an improved in-field Jc as the field increases at temperatures between 10 K and 77 K compared with Gd123. The JC (77 K, self field) and the value of onset TC of NEG123 thin film on LAO substrate was 4.0 MA/cm2 and 92 K, respectively. This is the first report, to the best of our knowledge, of coated conductors with NEG123 film as the superconducting layer which have Ic and Jc over 40 A/cm-width and 1.6 MA/cm2 at 77 K, self field. This study shows the possibility of using NEG123 film as the superconducting layer of the HTS coated conductor which can be used in high magnetic field power electric devices.

To obtain realistic data on the high temperature superconducting (HTS) power cable, 3-phase 100 m long, 22.9 kV class HTS power transmission cable system have been developed by Korea Electrotechnology Research Institute (KERI) and LS cable Ltd. that is one of 21st Century Frontier Project in Korea. This cable was installed at Go-chang testing site of Korea Electric Power Corporation (KEPCO). For the application of the HTS power cable joint is very important to ensure the performance. Therefore, this paper gives some investigation of AC loss, critical current and joint resistance in jointed HTS tape. We experimentally showed that the influence of joint resistance on AC loss by using several joint methods. Finally, we are measured critical current, AC loss and jointed resistance for the manufactured mini-model cable.

Influences of bending strain on the critical current, Ic, in Cu-stabilized IBAD/EDDC processed SmBCO coated conductor (CC) tapes were investigated at 77 K and self-field using a small-scale Goldacker type bending test rig. Considering the location of the superconducting layer against the neutral axis, tensile and compressive bending strains were applied to the SmBCO coating layer and the strain effect on Ic degradation was discussed. Under tensile bending strain, the Ic decreased monotonically but recovered reversibly up to the irreversible strain limit. Under compressive bending strain, however, the Ic increased but in some cases it suddenly dropped after straightening due to the delamination of the copper stabilizer. Also, repeated bending strains were applied to Cu-stabilized SmBCO CC samples in order to observe the behavior of Ic under cyclic loading. Ic Initially decreased with the application of 0.7% bending strain, but when the tape was subjected to repeated bending up to 100 cycles, no more degradation occurred. And finally, the Ic almost recovered to Ic0 when the tape was straightened.

The important merit of Bi-2212/Ag high Tc superconducting wire is to apply cable as round wire geometry. Bi-2212/Ag wires were fabricated in order to develop Rutherford cable for SMES near the future. Various Ag ratio and various numbers of filaments for PIT (Powder-In-Tube) process were applied to investigate the workability during drawing and to improve critical current property of the wires. Rutherford cabling machine for B-2212/Ag strands was designed and manufactured. We designed and manufactured Rutherford cabling machine with 32 bobbins which had 2 km length of wire. This machine was constituted with Turks head, caterpillar tread and take-up facility. In order to obtain uniform working conditions without defects, Turks head's rolling system and Ag ratio of Bi-2212/Ag strands were modified. We tried to fabricate Rutherford cables with 20 and 30 Bi-2212 strands. Proper working conditions for without breakage strand in cable were investigated. We made successfully Bi-2212 Rutherford cable. The critical current of Bi-2212 Rutherford cable with 30 strands showed 420 A at 64 K and 4008 A at 4.2 K. The critical current of Bi-2212/Ag wire with 847 filaments was 398 A at 4.2 K and self field.

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.

A biaxially textured Cu(2 0 0) tape was used as a substrate for YBCO coated conductors by cold rolling followed by recrystallization heat treatment. In this work, we studied the influence of annealing conditions and final tape thickness on the recrystallization process. Phi ( ϕ ) scan and omega ( ω ) scan XRD revealed that the best in-plane and out-of-plane alignment of the Cu tape (thickness 100 μm), measured in terms of full width half maximum (FWHM) values of 6.64° and 4.49°, were obtained by annealing at 800 °C for 30 min. The texture of CeO 2 buffer layer thermally-evaporated on the Cu tape was also analyzed.

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.

As a rule, high temperature superconducting coated conductors have multi-layered buffers consisting of seed, diffusion barrier and cap layers. Multi-buffer layer deposition requires longer fabrication time. This is one of main reasons which increases fabrication cost. Thus, single buffer layer deposition seems to be important for practical coated conductor process. In this study, a single layered buffer deposition of for low cost coated conductors has been tried using thermal evaporation technique. 100 nm-thick layers deposited by thermal evaporation were found to act as a diffusion layer. SmBCO superconducting layers were deposited by thermal co-evaporation on the buffered Ni-5%W substrate. Critical current of 90 A/cm was obtained for the SmBCO coated conductors.

The important merit of Bi-2212/Ag high Tc superconducting wire is to apply cable as round wire geometry. Bi-2212/Ag wires were fabricated in order to develop Rutherford cable for SMES near the future. Various Ag ratio and various numbers of filaments for PIT (powder-in-tube) process were applied to investigate the workability during drawing and to improve critical current property of the wires. In order to find proper working process, we investigated the variation of drawing stress during working. Post-annealing of Bi-2212/Ag wires at various atmospheres was carried out after main heat-treatment in order to increase critical current density. The results of post-annealing in nitrogen were better than that of post-annealing in oxygen. Jc of Bi-2212/Ag wire was increased as increased maximum temperature,Tm , for partial melting until 890degC, and highest Jc was over than 2000 A/mm2. The shape of grain was observed by SEM to investigate Bi-2212 phase formation in filaments. The critical current density increased in proportion to the increase of Bi-2212/Ag wire's filaments number.

The degree of ferromagnetism of Ni-Wy alloys decreases as W-content y increases. Both the saturation magnetization M sat and Curie temperature T c decrease linearly with W-content y, and both M sat and T c go to zero at critical concentration of yc ~9.50 at.% W. To compare with Ni-W alloys, the magnetic properties of a series of both as-rolled (non-textured) and annealed (biaxially textured) [Ni97at.%-W3at.%]100-x-Cux alloy tapes with compositions x = 0, 1, 3, 5, and 7 at.%, were studied. Characterization methods included XRD analyses to investigate the biaxial texturing of the annealed [Ni-W]-Cu alloy tapes and studies of the magnetization for both as-rolled and annealed [Ni-W]-Cu alloy tapes. Both the isothermal mass magnetizations M(H) of a series of samples at different fixed temperatures and M(T) in fixed field, were measured. The effect of Cu addition on both the saturation magnetization and Curie temperature Tc of the Ni97at.%-W3at.% alloy was investigated.

We measured the field profiles near the surface of a coated conductor (CC) under various applied fields by using the scanning Hall probe method. The field, applied in the normal direction, was increased from zero to 171.5 Oe and then decreased to −58.8 Oe. We could not analyse our data completely by the direct use of Brandt's calculation but by a modification with unusual field dependences of the introduced parameters. Since Brandt's original calculation was based on homogeneous films, it was not suitable for CCs with coarse granular structures. The modified calculations with appropriate parameters are related to the coarse granular structures. Those parameters, D, Jc, and R, represent the three characteristics of the flux penetration network: the average distance of flux penetrations, the density of critical sheet currents, and the range of meandering of the flux penetration front, respectively. The external field dependences of these parameters were different from those of the classical critical state model.

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.

Carbon nanotubes (i.e., CNTs) are tubular carbon molecules with properties that make them potentially useful in extremely small scale electronic and mechanical applications. Because of this, CNTs are widely used in many fields such as field emission display (FED), nanoscale sensors, vacuum electronic devices, and so on. In this study, CNTs were applied for an X-ray source. CNTs were grown on the Si-wafer substrate by thermal CVD method and the length of the grown CNTs was about 30–50 μm. The electrical properties of the grown CNT emitter were tested in an X-ray tube, which has triode structure (i.e., a cathode as a CNT emitter, a grid, and an anode). Electron beam focusing characteristics as well as correlations between emission currents and grid mesh structures (or grid mesh voltage) were also studied by using OPERA 3D simulation. The detailed descriptions of the manufactured X-ray triode were reported and some preliminary X-ray images were presented.

Many high temperature superconducting (HTS) tape manufactures make an effort to reduce the transport current loss of HTS tapes. The knowledge of critical current and self-field in an HTS tape is very useful to compute the transport current losses. The spatial distribution and magnitude of self-field are variable due to the neighboring materials. In this paper, the critical currents and the transport current losses of BSCCO and YBCO tapes with paralleled magnetic material (Ni tape) and/or diamagnetic material (BSCCO tape) are experimentally investigated to improve the AC loss properties. The critical currents of HTS tapes with paralleled Ni tape are slightly decreased and the transport current losses are markedly increased. However, the critical currents and transport current losses of HTS tapes with paralleled BSCCO tape have not current carrying are more improved than single HTS tape

We have experimentally studied the dependence of quench and recovery characteristics of ReBCO coated conductors stabilized with copper or stainless steel on the amplitude of over pulse current and its duration time. Stability tests of the samples were performed in a liquid nitrogen bath cooling condition by applying a short period over pulse currents for 100 ms with amplitude up to six times of its critical current. The copper stabilized samples were also studied for the fixed amplitude of over pulse current with varying its duration time. We analyzed the quench and recovery behavior of three test samples using the current voltage characteristics. The analyses showed that copper and stainless steel were good stabilizers for the coated conductor to be used for applications like motors and resistive type fault current limiters, respectively.

Y 2 O 3 film was directly deposited on Ni-3at%W substrate by DC reactive sputtering. DC reactive sputtering was carried out using metallic Y target and water vapor for oxidizing the elements of metallic target on the substrate. The detailed conditions of DC reactive sputtering for depositions of Y 2 O 3 films were investigated. The window of water vapor for proper growth of Y 2 O 3 films was determined by sufficient oxidations of the Y 2 O 3 films and the non-oxidation of the target surface, which was required for high rate sputtering. The window turned out to be fairly wide in the chamber used. As the sputtering power was raised, the deposition rate increased without narrowing the window. The fabricated Y 2 O 3 films showed good texture qualities and surface morphologies. The YBCO film deposited directly on the Y 2 O 3 buffered Ni-3at%W substrate showed T c , I c (77 K, self field), and J c (77 K, self field) of 89 K, 64 A/cm and 1.1 MA/cm 2 , respectively.

We report the upper critical field ( H c2 ), the irreversibility field ( H irr ), and the lower critical field ( H c1 ) of a dense polycrystalline MgB 2 superconductor which was prepared by the spark plasma sintering (SPS). The isothermal magnetizations M ( H ) of MgB 2 sample was measured at temperatures between 5 and 50 K in fields up to 8 T. The H c2 ( T ) data were well fitted to the BCS-type function H c2 ( T ) = H c2 (0)[1 − ( T / T c ) α ] β , with H c2 (0) = 8.5 T, α = 1.60 and β = 1.15. The H irr (melting line) could be described by the power-law relation H irr ( T ) = H irr (0)[1 − ( T / T c )] n with n = 1.10 and H irr (0) = 8.1 T. The deduced values of H c1 approximately followed a linear temperature dependence, not following a parabolic dependence of H c1 ( T ) = H c1 (0)[1 − ( T / T c ) 2 ].