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Iron-based superconductors (IBS) have attracted intense interest from scientists around the world. The first FeSe0.5Te0.5 hybrid coil including one FeSe0.5Te0.5 single pancake coil (SPC) and eight YBCO double pancake coils (DPCs) was successfully fabricated and test in this study. The FeSe0.5Te0.5 tape used in the hybrid coil is encapsulated strengthen tape which is with 0.15 mm thickness and 10.5 mm width to withstand the high stress during the cold test. The FeSe0.5Te0.5 encapsulated tape exhibits good performance at 4.2 K cold test. YBCO DPCs were divided into two groups connected to both sides of the FeSe0.5Te0.5 SPC. The critical current of the FeSe0.5Te0.5 coil was measured under the background field increased from 0 T to 10 T. The transport critical current of the FeSe0.5Te0.5 SPC showed 108.1 A at self-field and 17.4 A at 10 T, which had almost the same performance as the short sample. The results in this study showed that the FeSe0.5Te0.5 coated conductor coil have good performance in high magnetic fields.

Using the magnetic sputtering technique, the SnO2/Ag/SnO2 tri-layer transparent films were fabricated on float glasses successfully. Compared with the commercial FTO (F-doped SnO2) film, the SnO2/Ag/SnO2 tri-layer films have higher visible-light transmittance and better conductivity. The total thickness of the SnO2/Ag/SnO2 films is one third of the commercial FTO film leading to the high visible-light transmittance. The high carrier concentration of the SnO2/Ag/SnO2 films contributes to the tri-layer films’ low resistivity. In addition, to further improve the performance of the SnO2/Ag/SnO2 tri-layer films, samples were annealed under different temperatures. The results illustrate that the lowest sheet resistance (5.92 Ω/sq) and the highest visible-light transmittance (87.0%) were obtained after annealing at 200 °C. Furthermore, the thermal stability of the films could be enhanced by a multi-step annealing process due to the recrystallization effect.

Breast cancer patients face different nutritional problems at each stage. However, the nutrition of breast cancer patients has not been taken seriously. As a result, some patients cannot tolerate treatment due to poor nutrition, thus affecting the prognosis. This study aims to introduce a typical case to explore the whole-course (started at admission and ended 5 years after surgery) and Multidisciplinary Teams (MDTs) (comprising physician, primary nurse, case manager, nutrition liaison and nutrition specialist nurse) nutritional management mode of breast cancer patients. The patient successfully completed the scheduled treatment by implementing the whole-course and multidisciplinary nutrition management. The mode can prospectively and dynamically estimate the changes in patients’ nutritional status, and provide timely nutritional intervention to promote patient outcomes.

Objective: To explore the inverted T-shaped flap nursing after breast-conserving surgery combined with the reverse double V-shaped mastoconstriction suspension for breast cancer, and summarizes the nursing methods and experience. Method: 5 patients who underwent reverse double V-shaped mastoconstriction suspension and formed inverted T-shaped flap incision were selected from the same medical group in the Department of Breast Cancer of Sun Yat-sen University’s Cancer Center from February 1, 2019 to April 30, 2019, and they were evaluated for the recovery of blood supply of skin flap, sensory function of nipple and areola, breast satisfaction, etc. Results: Among the 5 patients in this group, the flaps of them all survived smoothly. The one-year follow-up after the operation showed that they were satisfied with the appearance of the breast after the operation, with normal sensory function, and no secondary sagging. Conclusion: The most important thing about the inverted T-shaped flap after the reverse double V-shaped mastoconstriction suspension for breast cancer is the blood supply. Close observation of the condition of the skin flap after the operation, strengthening the care of the skin flap, and preventing infection are the keys to the success of the operation.

Thickness effect severely limits the performance of REBa2Cu3O7-δ coated conductors. In this work, a Y0.5Gd0.5B2C3O7-δ/LaGdZr2O7/Y0.5Gd0.5Ba2Cu3O7-δ (YGdBCO/LGZO/YGdBCO) tri-layer film was fabricated by pulse laser deposition, which successfully inhibited the thickness effect and improved the superconductivity of YGdBCO film. By investigating the microstructure of the inserted LGZO layer, it was found that LGZO interlayer can not only reduce the surface roughness of the bottom YGdBCO layer by inhibiting the continuous growth of YGdBCO crystal grains but also realize the transmission of current between superconducting layers. With the deposition of LGZO interlayer, the critical current of the YGdBCO film increased significantly by nearly 50% from 180 A of a double-layer YGdBCO film with the same thickness to 270 A. Transmission Electron Microscope (TEM) observation and Energy Dispersive Spectroscopy (EDS) analysis indicate that the incomplete oxidized particles in the LGZO layer serve as the current channels between YGdBCO layers in the samples prepared at a laser energy of more than 210 mJ.

SrTiO3 films were deposited using pulsed laser deposition (PLD) at substrate temperatures ranging from 300 °C to 700 °C on a CeO2 layer and nano-Y0.5Gd0.5Ba2Cu3O7-δ buffered CeO2 layer, respectively. The effect of the substrate temperature and substrate film on the crystallinity, preferred orientation, and surface topography were investigated. On the CeO2 layer, there were two preferred SrTiO3 orientations, (00l) and (110). By introducing a nano-Y0.5Gd0.5Ba2Cu3O7-δ layer, pure c-axis oriented SrTiO3 films were obtained at each substrate temperature. Based on the lattice mismatch, three kinds of growth modes of SrTiO3 grains were proposed that were proved by scanning electron microscopy (SEM).

To evaluate the inhibition of the REBa2Cu3O7-δ (REBCO, where RE is rare earth) film thickness effect, a series of Y0.5Gd0.5Ba2Cu3O7-δ(YGBCO)/interlayer/YGBCO tri-layer films with Gd-Cerium oxide (CeO2) film were prepared under different experimental conditions in this study. The results illustrate that the electric current from the top YGBCO layer could transmit to the bottom YGBCO layer by adding Gd into the CeO2 interlayer with the approximate thicknesses limits of 10 nm. For further increase the electric current carrying capacity, a series of YGBCO/Gd-CeO2/YGBCO tri-layers were fabricated under different oxygen partial pressures and laser energies. The better crystallinity, and texture, and the smoother surface levels completely eliminated the thickness effect. However, the samples’ superconductivity declined sharply at low laser energies. Because the Gd particles deposited on the substrate were fully oxidized, this led to particle disappearance in the interlayer film. Additionally, YGBCO samples with a Gd-CeO2 interlayer were more likely to be damaged than a pure YGBCO sample in the measurement process, which could be solved by increasing the Gd content in the CeO2+Gd target. Hence, by depositing a Gd-CeO2 interlayer, YGBCO tri-layer films with high superconductivity and low damageability were obtained.

Sandwiched between two fused silica blocks, thin-gauge samples of Ag-39.9 at.%Cu eutectic alloy were solidified over a range of undercoolings. Subsequently, the samples that consisted consistently of fully lamellar eutectic were rapidly heated to a target temperature below the eutectic temperature. Increasing the initial undercooling prior to solidification or the target temperature of heating led to more anomalous eutectic and worse orientation of phases in the final microstructure. It is conclusively indicated that the formation of anomalous eutectic in bulk samples results from remelting of the primary lamellar eutectic.

Fe(Se,Te) films of different thicknesses were deposited on metal tapes by pulsed laser deposition at different substrate temperatures. It is found that the substrate temperature dependence of superconductivity changes with the Fe(Se,Te) film thickness. When fabricating thin Fe(Se,Te) films with a thickness of about 150 nm, moderate substrate temperatures are conducive to balancing the influence of texture and stoichiometry on superconductivity, contributing to the obtainment of good superconductivity. When the Fe(Se,Te) films’ thickness is about 300 nm, the optimal substrate temperatures are lowered due to the determination of film superconductivity by the inhomogeneity of longitudinal chalcogen distribution via the cooperation of Te loss in the long-term-ablated target and the attraction of metal ions in the buffer layer. In addition, with a further increase in thickness from 300 to 600 nm, the self-field critical current of thick Fe(Se,Te) films continuously increases, but the critical current density increases first and then decreases, which is thought to be a result of the misoriented grains or non-superconducting phase due to the large deviation between the actual deposition temperature and the set substrate temperature, and the Se excess in the film. In addition, the 450-nm-thick Fe(Se,Te) film exhibits excellent self-field and in-field performances at 4.2 K: 1.308 MA/cm2 at self-field and over 0.5 MA/cm2 at 9 T. Point pinning, which is the local lattice disturbance randomly distributed in the film observed by transmission electron microscopy, dominates over the entire temperature range.

The superconducting properties of REBa2Cu3Oy (REBCO or RE123, RE = rare earth elements) coated conductors could essentially depend on the rare earth elements, which could be the premise of all potential superconducting applications. In this paper, Ho0.75RE0.25Ba2Cu3O7-σ (HoREBCO, RE = Dy, Er, Yb) high temperature superconducting films were fabricated successfully by a reel-to-reel pulsed laser deposition (PLD) system for the first time. By replacing Ho elements with heavy rare earth elements in a certain mole ratio, the critical currents of the HoREBCO superconducting films were improved significantly compared with pure HoBCO films. The lattice distortions are considered as the determinative factors of the changes. The replacement of Ho atoms by Dy, Er or Yb also influenced the structure and the surface morphology of the superconducting films. The decrease of the lattice constant in HoREBCO superconducting film and the variation of the interatomic force play the decisive role in the improvement of the superconducting property.

Performance of REBa2Cu3O7−δ superconductors strongly depends on their microstructures and surface morphologies. Using a reel-to-reel pulsed laser deposition (PLD) system, the CeO2-doped YBa2Cu3O7−δ (CeO2-Y123) films were fabricated. Superconducting properties and microstructure of these films were systematically studied for the first time. The results showed that the relationship between the critical current (Ic) values and the deposition temperature depends on the doping content essentially. For all CeO2-doped films, the Ic values increase at first and then decrease with increasing the deposition temperatures. The evolution of surface morphologies should take responsibility for this phenomenon. The optimum deposition temperature of 1 and 2 mol. % CeO2-doped Y123 films is higher than that of 3 mol. % CeO2 doped ones. The substitutions of the Y atoms by Ce atoms are considered as the determinative factor. Furthermore, the in-plane rotation of the crystalline grain orientation on the surface of the CeO2-Y123 films was observed. We think that not only the lattice mismatch, but also the density of dangling bonds contributes to this distinctive phenomenon.

High critical current (Ic) has long been proved important to REBa2Cu3O7−δ (REBCO or RE123) superconductor for the practical applications. To achieve high Ic values, the primary way is to increase the thickness of superconducting layer and to enhance high critical current density (Jc). However, Jc drops precipitously with increasing the thickness of the films. This phenomenon is called the thickness effect, which can be effectively inhibited by fabricating superconductor/interlayer/superconductor tri-layer structure. In this study, a series of YGBCO/CeO2/YGBCO and YGBCO/In doped CeO2 (CeO2 + In)/YGBCO tri-layer films with different interlayer thickness were fabricated. The microstructure, surface morphology and superconducting property of these samples were measured. It was found that all the tri-layer films had pure c-axis orientation. When using CeO2 film as an interlayer, the two YGBCO layers in the tri-layer films were almost completely isolated, resulting in the low Ic values, which were equivalent to the Ic of a single YGBCO layer. While using CeO2 + In film as an interlayer, the Ic values of all the YGBCO/CeO2 + In/YGBCO trilayers were almost double the Ic of a single YGBCO layer, and the Ic values of the trilayers firstly slow increased and then decreased with increasing the thickness of CeO2 + In interlayer. Under the optimal experimental parameters, the Ic value was much higher than that of the a double YGBCO layer without interlayer. The thickness effect of superconducting layer can be effectively inhibited by inserting CeO2 + In interlayer with wide thickness range.

FeSe0.5Te0.5 coated conductor as a kind of 11-type iron-based superconductor is currently attracting much attention. Recently, the bare FeSe0.5Te0.5 coated conductor tapes were developed by Shanghai Jiao Tong University and verified their superconductivity. For the future application, the FeSe0.5Te0.5 tapes should be subjected to the high electromagnetic forces and stress–strain. In this study, the authors encapsulated the bare FeSe0.5Te0.5 coated conductor tapes with copper layers to enhance the mechanical performance. The reversible critical current performance of the bare and the copper encapsulated FeSe0.5Te0.5 tapes under uniaxial tensile strain was tested. The critical currents of two kinds of tapes were measured over a wide range of applied uniaxial tensile strain by the U-shaped bending spring, respectively. The results show the critical performance of the bare FeSe0.5Te0.5 tapes decreases linearly with respect to tensile strain. The copper encapsulated FeSe0.5Te0.5 tapes have better performance than the bare tapes, with an irreversible tensile strain limit of 0.15%. In addition, the actual irreversible tensile strain limit of the copper encapsulated FeSe0.5Te0.5 tapes reaches 0.29% after considering the influence of the cooling process.

Iron chalcogenide Fe(Se,Te) films with thicknesses of 150 nm were deposited on CeO2-buffered metal tapes via pulsed laser deposition using various laser fluences. The film crystallinity and stoichiometry improved upon increasing the laser fluence. This was explained by the ablation threshold that the superconducting performance was better at higher laser fluences and was attributed to the joint contribution of higher Te contents, better texture, and strengthened in-plane strain. In addition, the pinning mechanism was studied by analyzing the in-field performance characteristics of the Fe(Se,Te) films. The dominant pinning center remained point pinning and was independent of the magnetic field direction and temperature. A collective pinning theory-based analysis showed that the vortex pinning behavior in the Fe(Se,Te) film varied from δ l pinning to δ Tc pinning as the temperature approached the critical temperature. This was related to film superconductivity inhomogeneity, which was driven by unreacted Se and Te atoms.

Land use changes usually lead to the deterioration of freshwater ecosystems and reduced biodiversity. Aquatic organisms are considered valuable indicators for reflecting the conditions of freshwater ecosystems. Understanding the relationship between organisms and land use type, as well as physiochemical conditions, is beneficial for the management, monitoring and restoration of aquatic ecosystems. In this study, fish, macroinvertebrates, and diatoms were investigated at 60 sampling sites in the Wei River basin from October 2012 to April 2013 to determine the relationships between the environment and aquatic organisms. The richness, abundance, Shannon diversity, evenness, Margalef diversity, and Simpson diversity were selected as biological indices for analyzing the correlation between these communities and environmental variables according to Pearson&rsquo, s coefficient. Canonical correspondence analysis (CCA) was used to analyze the relationship between the biotic communities and environmental variables. The results showed that three diatom indices were weakly correlated with chemical oxygen demand (COD), qualitative Habitat Evaluation Index (QH), and dissolved oxygen (DO). Four macroinvertebrate indices were associated with total phosphorus (TP) while total nitrogen (TN), and agricultural land (AL) had a significant influence on assemblages, suggesting that macroinvertebrates could respond to nutrient levels in the Wei River basin. All land use types had a strong effect on fish indices except AL, indicating that fish would be better used as indicators of spatial changes in the aquatic ecosystem. In conclusion, fish and macroinvertebrates have the potential for use in routine monitoring programs in the Wei River basin.

For various practical applications, excellent superconducting properties under magnetic field of REBa2Cu3O7−δ (RE = rare earth elements (REBCO))-coated conductors are required, which can be fabricated by introducing artificial pinning centers, such as second-phase dopant. It is well known that BaMO3 (M = Zr, Sn, or Hf) can form self-organized nanorods in REBCO matrix and improve the critical current density (Jc) under applied magnetic field. However, with increasing dopant level, the critical temperature Tc and Jc at 77 K in self-field decreased. In order to inhibit the degradation of the Jc in self-field, we fabricated 5 mol% BaHfO3 (BHO)-doped Y0.5Gd0.5Ba2Cu3O7−δ (YGBCO) seed layers on CeO2-buffered IBAD-MgO tapes by pulse laser deposition (PLD) at a laser repetition of 10 Hz and different substrate temperature Tseed, and subsequently deposited 5-mol% BHO-doped YGBCO upper layers at 160 Hz and higher substrate temperature. The effect of Tseed on the quality of the 5-mol% BHO-doped YGBCO upper layer was investigated. With increasing Tseed from 710 to 820 ∘C, the Δφ value of YGBCO (103) reflection first decreased and then increased, while the Jc at 77 K increased with increasing Tseed to 790 ∘C and decreased at higher Tseed. The 5-mol% BHO-doped YGBCO layer with a seed layer deposited at 790 ∘C had the highest Jc (77 K, self-field) of 4.0 MA/cm2.

Superconductor/insulator/superconductor trilayer structure can be used to increase the superconducting properties in self-field of thick REBa 2 Cu 3 O 7-δ (RE = rare metal) films by inhibiting the thickness effect, as well as improving in-field properties through the interlayer, which acts as a flux pinning interface. The conventional trilayer structure was always prepared symmetrically, namely, the bottom superconducting layer has the same thickness with the top superconducting layer. In this paper, Y 0.5 Gd 0.5 Ba 2 Cu 3 O 7-δ /SrTiO 3 /Y 0.5 Gd 0.5 Ba 2 Cu 3 O 7-δ (YGBCO/STO/Y-GBCO) trilayer films were prepared asymmetrically by pulsed laser deposition on CeO 2 buffered IBAD-MgO tapes, which means the bottom superconducting layer has a different thickness than the top superconducting layer. YGBCO/STO/YGBCO trilayer structure had the same total YGBCO layer thickness of 720 nm and STO interlayer thickness of 80 nm, but a bottom YGBCO superconducting layer of different thickness. Microstructure, surface morphology, and self-field and in-field superconducting properties were systematically investigated. It was found that thicker bottom-layer had almost no internal residual stress, better crystalline quality, and surface morphology, which contributed to better superconducting properties of the YGBCO/STO/YGBCO trilayer sample both under self-field and magnetic field. The phenomenon was explained by the growth model. These results can provide useful information for fabricating trilayer structure with high in-field performance.

At Shanghai Jiao Tong University (SJTU), REBa2Cu3O7‐σ (REBCO) coated conductor (CC) research program started in 2007. With the support of China's First National Key Project on CC Program, SJTU successfully developed hundred meters long class CC tapes with over 300 A/cm (at 77 K, self-field) based on PLD (pulsed laser deposition)/RABiTS processes in 2011. To develop high-performance CC tapes, in 2012, we switched from RABiTS to ion beam-assisted deposition (IBAD)-MgO tape and a pilot PLD/IBAD process CC fabrication line was set up at Shanghai Superconductor Technology Corporation in 2013, and deposition processes were successfully transferred from lab to fabrication line. Under optimized conditions, the IBAD-MgO layers showed pure (001) orientation and excellent in-plane texture. Atomic force microscopy observation showed MgO layer had very smooth surface. The rms is less than 1 nm. On the textured MgO layer, single CeO2 layer showed pure (001) orientation and excellent in-plane texture of ${\text{4}}^{\circ}$ – ${\text{5}}^\circ$ . Reel-to-reel PLD process was already scaled up to >100 m/h tape speed. Kilometer (Km) long CC tapes with over 300 A/cm have been routinely fabricated. Recently, our research work focused on introducing high-density nanoscale artificial flux pinning centers into REBCO superconducting layer to improve in-field superconducting properties and further expand application areas of REBCO tapes.

The surface morphology and internal residual stress have influence on the critical current density (Jc) of REBa2Cu3O7-σ (REBCO) coated conductor. In order to modulate them, a series of Y0.5Gd0.5Ba2Cu3O7-σ (YGBCO) films were prepared by pulsed laser deposition (PLD) through introducing a seed layer in this paper. The thicknesses of seed layer changes from about 2 nm to 30 nm. For comparison, a standard sample without seed layer was fabricated at the same deposition condition. The surface morphology was illustrated by Scanning electron microscopy (SEM). The surface roughness was scanned by Atomic force microscopy (AFM). The microstructure and internal strain were measured by X-ray Diffraction (XRD). DC four-probe method was used to measure the critical current of the samples at 77 K and self-field. As a result, all samples have high Jc of about 4 MA/cm2, while the self-field Jc of the YGBCO films can be promoted by the seed layer. The results of our research work are as follows. First of all, seed layer makes the deposition of the YGBCO layer much easier to control. By this way, we can decrease the surface roughness of the samples. Furthermore, the internal residual stress of the YGBCO films with seed layer decrease. Finally, the best thickness of the seed layer was found by summarizing and analyzing the conditions of seed layer.

Improvement in the in-filed transport properties of REBa2Cu3O7−δ (RE = rare earth elements, REBCO) coated conductor is needed to meet the performance requirements for various practical applications, which can be accomplished by introducing artificial pinning centers (APCs), such as second phase dopant. However, with increasing dopant level the critical current density Jc at 77 K in zero applied magnetic field decreases. In this paper, in order to improve Jc we propose a seed layer technique. 5 mol% BaHfO3 (BHO) doped Y0.5Gd0.5Ba2Cu3O7−δ (YGBCO) epilayer with an inserted seed layer was grown on CeO2 buffered ion beam assisted deposition MgO (IBAD-MgO) tape by pulsed laser deposition. The effect of the conditions employed to prepare the seed layer, including tape moving speed and chemical composition, on the quality of 5 mol% BHO doped YGBCO epilayer was systematically investigated by X-ray diffraction (XRD) measurements and scanning electron microscopy (SEM) observations. It was found that all the samples with seed layer have higher Jc (77 K, self-field) than the 5 mol% BHO doped YGBCO film without seed layer. The seed layer could inhibit deterioration of the Jc at 77 K and self-filed. Especially, the self-seed layer (5 mol% BHO doped YGBCO seed layer) was more effective in improving the crystal quality, surface morphology and superconducting performance. At 4.2 K, the 5 mol% BHO doped YGBCO film with 4 nm thick self-seed layer had a very high flux pinning force density Fp of 860 GN/m3 for B//c under a 9 T field, and more importantly, the peak of the Fp curve was not observed.

Homoepitaxial MgO (Homo-MgO) films, deposited by RF magnetic sputtering method in various experimental conditions, were systematically studied using growth dynamics in older to fully understand their growth mechanism. The results showed that high quality Homo-MgO films could be obtained at high oxygen partial pressure and the thickness of Homo-MgO films were seriously affected by the ratio of O2/Ar. Moreover, an interesting phenomenon we addressed was the growth mode changed with varying the sputtering power, leading to different surface morphology. Most importantly, apart from Homo-MgO films, our theory can also be appropriate for other oxide films grown by RF magnetic sputtering technology.

As an emerging technique for surface smoothing, solution deposition planarization (SDP) has recently drawn more attention on the fabrication of the second generation high temperature superconducting (2G-HTS) tapes. In our work, a number of amorphous oxide layers were deposited on electro-polished or mirror-rolled metallic substrates by chemical solution route. Topography evolution of surface defects on these two types of metallic substrates was thoroughly investigated by atomic force microscopy (AFM). It was showed that root mean square roughness values (at 50 × 50 μm 2 scanning scale) on both rough substrates reduced to ∼5 nm after coating with SDP-layer. The smoothing effect was mainly attributed to decrease of the depth at grain boundary grooving on the electro-polished metallic substrate. On the mirror-rolled metallic substrates, the amplitude and frequency of the height fluctuation perpendicular to the rolling direction were gradually reduced as depositing more numbers of SDP-layer. A high J c value of 4.17 MA cm −2 (at 77 K, s.f. ) was achieved on a full stack of YBCO/CeO 2 /IBAD-MgO/SDP-layer/C276 sample. This study enhanced understanding of the topography evolution on the surface defects covered by the SDP-layer, and demonstrated a low-cost route for fabricating IBAD-MgO based YBCO templates with a simplified architecture.

The present paper presents the effects of ferromagnetic La0.67Sr0.33MnO3 (LSMO) nanoparticles on the pinning characteristics of an epitaxial GdBa2Cu3O7−δ ((Gd) BCO) film deposited on top. LSMO nanoparticles with the size between 10 and 20 nm were obtained on a (001) STO substrate by RF sputtering method. The analyses of magnetic measurements revealed that the presence of a complex vortex pinning mechanism within the (Gd) BCO film deposited on the undecorated substrate. With respect to a reference (Gd) BCO film, two additional pinning effects in LSMO decorated (Gd) BCO film were observed. One is the effect of the threading dislocations due to LSMO nanoparticles, and the other one is the LSMO nanoparticles itself. Like other nanosized particles, the LSMO nanoparticles on substrate will induce threading dislocations passing through the (Gd) BCO film. These threading dislocations serve as correlated pinning centers along the c-axis, which lead to the improvement of flux pinning properties in LSMO decorated (Gd) BCO film. According to the ferromagnetic property of LSMO material, a magnetic pinning mechanism was proposed to explain the significant increase of Jc and Fp values. The flux pinning abilities of LSMO nanoparticles were evaluated. The enhanced pinning characteristics in the high field region and high temperature together with the movement of H Fpmax (the corresponding field of Fpmax) also suggest a magnetic pinning mechanism for LSMO nanoparticles existed in LSMO decorated (Gd) BCO film.

A series of SrTiO3 films were deposited on CeO2 layer by pulsed laser deposition at substrate temperature in the range of 300 °C–700 °C. It was found that the (110)-oriented and (200)-oriented SrTiO3 grains coexisted on the CeO2 layer. Although the (110)-oriented grains dominated during the deposition, the dominance was weakened with increasing substrate temperature. The competition mechanism of SrTiO3 grains along different orientations was explained in view of the diffusion energy and the evolution of dislocation density. The dependence of the film stoichiometry on the substrate temperature and the effects of residual contaminants in the chamber were also studied by X-ray photoelectron spectroscopy.

For most applications of high-temperature superconducting tapes, a high critical current ( I c ) and critical current density ( J c ) under a magnetic field are both required. The simplest way to achieve high I c is to increase the thickness of the superconducting layer. However, doing so also reduces J c , which is called the thickness effect. In this work, to inhibit the thickness effect, a series of Y 0.5 Gd 0.5 Ba 2 Cu 3 O 7-σ (YGBCO) films with different thicknesses (240–1200 nm) were deposited by multi-step pulsed laser deposition on cerium oxide (CeO 2 ) buffered substrates. The thickness dependence of the in-field J c was systematically investigated. The in-field I c at 77 K and 0–0.5 T was measured using the four-probe method, the surface morphology was observed using scanning electron microscopy, the structure and texture were measured using X-ray diffraction, and the internal residual stress was evaluated using the Williamson–Hall method. It was found that J c first increased and then decreased with increasing YGBCO film thickness. The 480-nm YGBCO film had the highest J c of 4.33 MA/cm 2 at 77 K and a self-field>1.5 MA/cm 2 under a magnetic field of 0.5 T. A 720-nm YGBCO film showed the slowest rate of J c degradation under a magnetic field. The experimental results are discussed by considering the deposition process and growth model.

CeO2 film plays an essential role in nucleation and growth of YBa2Cu3O7−x (YBCO) films. In this work, the dependence of superconducting properties of YBCO on CeO2 films with different thicknesses was investigated, in order to achieve fabrication of high-performance YBCO coated conductors in industrial scale. The crystalline structure and morphology of CeO2 films with thickness ranging from 21 to 563 nm were systematically characterized by means of X-ray diffraction (XRD), atomic force microscope (AFM) and reflection high-energy electron diffraction (RHEED). Additional focus was addressed on evolution of the surface quality of CeO2 films with thickness increasing. The results show that at the optimal thickness of 221 nm, CeO2 film exhibits sharp in-plane and out-of-plane texture with full width of half maximum (FWHM) values of 5.9° and 1.8°, respectively, and smooth surface with a mean root-mean-square (RMS) roughness value as low as 0.6 nm. Combing RHEED and transmission electron microscope (TEM) cross-sectional analysis, it is found that nucleation and growth of CeO2 films at early stage remain in island growth mode with rougher surface, while further increasing the thickness beyond the optimal thickness leads to weak surface quality, consequently resulting in degradation of superconductor layers deposited subsequently. Eventually, a critical current density (J c) as high as 4.6 × 106 A·cm−2 (77 K, self-field) is achieved on a YBCO film on a thickness-modulated CeO2/MgO/Y2O3/Al2O3/C276 architecture, demonstrating the advantages of CeO2 films as buffer layer in high-throughput manufacture of coated conductors.

Here, we demonstrate a method of coating ferromagnetic La0.67Sr0.33MnO3 (LSMO) nanoparticles on (001) SrTiO3 (STO) single-crystal substrates by radio frequency (RF) magnetron sputtering. LSMO nanoparticles were deposited with diameters from 10 to 20 nm and heights between 20 and 50 nm. At the same time, (Gd) Ba2Cu3O7-δ ((Gd) BCO) films were fabricated on both undecorated and LSMO nanoparticle decorated STO substrates using RF magnetron sputtering. This report also describes the properties of GdBa2Cu3O7-δ/ La0.67Sr0.33MnO3 quasi-bilayer films structures (e.g., crystalline phase, morphology, chemical composition); magnetization, magneto-transport, and superconducting transport properties were also evaluated.

Here, we demonstrate a method of coating ferromagnetic La0.67Sr0.33MnO3 (LSMO) nanoparticles on (001) SrTiO3 (STO) single-crystal substrates by radio frequency (RF) magnetron sputtering. LSMO nanoparticles were deposited with diameters from 10 to 20 nm and heights between 20 and 50 nm. At the same time, (Gd) Ba2Cu3O7−δ ((Gd) BCO) films were fabricated on both undecorated and LSMO nanoparticle decorated STO substrates using RF magnetron sputtering. This report also describes the properties of GdBa2Cu3O7−δ/ La0.67Sr0.33MnO3 quasi-bilayer films structures (e.g., crystalline phase, morphology, chemical composition); magnetization, magneto-transport, and superconducting transport properties were also evaluated.

The limited critical current, attributed to the thickness effect, has been a serious restriction to the large-scale application of ReBa2Cu3O7-8 coated conductor. Hence, a YGdBCO/STO/YGdBCO tri-layer film was fabricated by pulse laser deposition method to successfully inhibit the thickness effect and improve the superconductivity of ReBa2Cu3O7-8 film. By inserting STO interlayer, the critical current of the YGdBCOfilm significantly increased from 180 A to 250 A. We found that the incompletely oxidized particles and the uncoated areas of the STO layer can serve as channels for the transmit of the current between YGdBCO layers.

Some works found that target density had not a large effects on the superconducting or structural properties of YBa2Cu3O7-δ (YBCO) films prepared by pulsed laser deposition. However, the possible effect of target density on the Y0.5Gd0.5Ba2Cu3O7-δ (YGBCO) is not clear. In this paper, YGBCO thin films were deposited on flexible metal substrates by pulsed laser deposition using target with different densities. The density of each YGBCO target was varied from to 4.0 g/cm3 to 5.5 g/cm3. The aim of this study was to determine the relationship between the microstructure and superconducting properties of YGBCO films as a function of the target density. The film structures were examined by X-ray diffraction and field emission scanning electron microscopy. The superconducting properties of the YGBCO films were evaluated using the conventional four-probe method and PPMS. It was found that all the YGBCO films had pure c-axis orientation. The target density had effect on the surface morphology and superconducting properties of the YGBCO thin films. With increasing target density, the pore became larger and the distribution density and size of the particles became higher and larger, and the critical current Ic decreased. The YGBCO film deposited at a target density of 4.0 g/cm3 exhibited the highest critical current density Jc of 5.4 MA/cm2 at 77 K and self-field, 47.2 MA/cm2 at 0 T and 8.8 MA/cm2 at 9 T at 4.2 K and B//c.

Cerium oxide (CeO2) films with a series of nanoarray superstructures were prepared via pulse laser deposition (PLD). The facets transition from (001) to (111) and (110) was found in these samples, and the growth mechanism was proposed. The facets transition could be the result of nanostructure evolution which arises from the competition between formation energy and migration energy. The room temperature photoluminescence (RTPL) and UV–visible absorption spectrum revealed that these CeO2 nanoarray films have high content of oxygen defects and absorbance by turning nanostructures, which may contribute to their application.

Sr2Nb2O7 (SNO)-doped Y0.5Gd0.5Ba2Cu3O7−x (YGBCO) and pure YGBCO thin films with pure c-axis orientation were prepared by pulsed laser deposition. Compared with a pure YGBCO film, T c and critical current density (J c) (77 K, 0 T) of the SNO-doped film decreased from 91.9 to 88.7 K and from 4.2 to 2.5 MA/cm2, respectively. SNO-doped YGBCO film exhibited significantly enhanced J c in a magnetic field up to 9 T at 4.2 K and up to 7 T at 65 K for B//C, indicating that the SNO-doped YGBCO film possessed more effective flux pinning centers, which were stacking faults, c-axis defects, and inclined defects identified by transmission electron microscopy analysis.

So far, huge progress has been achieved in coated superconductor wires with high performance, where cerium oxides (CeO2) usually figure as superior buffer layer. However, the influence of CeO2 layer’s surface morphology on the performance of YBCO layer is still illusive. In this work, we fabricated CeO2 layers with similar texture and diverse surface characteristics by altering process parameters on IBAD-MgO substrate and then deposited YBCO layers on these CeO2 layers by a reel-to-reel pulsed laser deposition (PLD) system. The abnormal relationship between the quality of YBCO layer and the surface morphology of CeO2 layer was investigated. Instead of texture quality, the critical current density of YBCO-coated layer is highly susceptible to the surface morphology of CeO2 layer, once their surface roughness root mean square (RMS) outstrips the threshold of atomic flat. And our study indicates RMS and flat area fraction are all key issues for PLD epitaxial multilayers but play in different priority. The possible defect formation process of YBCO/CeO2 was also discussed on the basis of the SEM images.

The frequency mixing effects in terahertz parametric oscillator (TPO) with a noncollinear phase-matching scheme based on bulk lithium niobate (LiNbO3), including sum frequency generation (SFG), difference-frequency generation (DFG), optical parametric oscillation and cascaded optical processes are investigated. The analysis results indicate that the terahertz wave (THz-wave) with N-times frequency can be generated simultaneously from frequency mixing effects in TPO with noncollinear phase-matching scheme. To our best knowledge, this is the first study of the TPO generating THz-wave with N-times frequency in bulk LiNbO3. The frequency tuning characteristics of THz-waves via varying pump wavelength, phase-matching angle and working temperature are theoretically analyzed.

High-quality long REBCO-coated conductors have been successfully fabricated on flexible metal substrates by pulsed laser deposition (PLD). Although thinner REBCO films had a very high critical current density J c of 5.0 × 10 6 A/cm 2 (at 77 K, in zero magnetic field), J c of thick films decreased to less than 3.0 × 10 6 A/cm 2 as the thickness increased over 1 μm. In order to improve superconducting properties of REBCO thick films, microstructure and surface morphology of different thick REBCO films were systematically analyzed to understand the relationship between J c and epitaxial growth process. X-ray diffraction (XRD) analysis showed that thick REBCO films still had pure c-axis orientation by Gd substitution and Y 2 O 3 doping. Scanning electron microscope (SEM) images showed thick REBCO films with high J c had sub-micrometer size grains and narrow grain-boundaries. Our experimental results showed REBCO thick films with I c of 780 A/cm could be obtained. Hundred meters long coated conductor tapes with 500 A/cm have been routinely fabricated. And now, the process optimization for kilometer long coated conductor tapes is underway.

MgO thin films were grown on Y2O3/Al2O3 buffered C276 tapes by ion beam assisted deposition (IBAD) method and the effects of assisting ion beam current on their microstructure and surface morphology were investigated. In order to evaluate the quality of IBAD-MgO thin films, CeO2 cap layer was deposited directly on the IBAD-MgO template and then YBCO superconducting layer was grown by pulsed laser deposition (PLD) method. Film characterization was performed by in-situ reflection high energy electron diffraction, X-ray diffraction, and atomic force microscopy. The critical current Ic of the YBCO film was measured by the conventional four-probe method. It was found that the orientation, texture degree and surface morphology of the IBAD-MgO thin films were very sensitive to assisting ion beam current. By optimizing the assisting ion beam current, IBAD-MgO thin films had pure (002) orientation, excellent biaxial texture and very smooth surface with a root mean square surface roughness of less than 1 nm. The PLD-CeO2 layer had the best out-of-plane texture of Δω = 1.6° and in-plane texture of Δφ = 4.8° at 140 mA of assisting ion beam current. Under optimized experimental condition, high quality YBCO coated conductor with the critical current density Jc of 4.5 × 106 A/cm2 was fabricated at 77 K and self field.

We deposited epi-MgO films on the textured ion beam assisted deposition (IBAD)-MgO substrates by RF magnetic sputtering at different substrate temperatures (600–850 °C), RF powers (110–224 W) and oxygen partial pressures (19.5–58.6 mTorr). The microstructure and surface morphology of epi-MgO films were characterized by X-ray diffraction (XRD) and atom force microscope (AFM). It was found that epi-MgO films with c-axis orientation could be easily fabricated for broad parameter ranges. But the in-plane full width half maximum (FWHM) of the epi-MgO film was dependent on the parameters, and the epi-MgO film with the smallest FWHM value of 5.22° was obtained at the optimum parameters. What’s more, the GdBa2Cu3O7 films deposited on the epi-MgO/IBAD-MgO substrate by RF magnetic sputtering showed c-axis orientation.