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Micro‐mechanical resonators are building blocks of a variety of applications in basic science and consumer electronics. This device technology is mainly based on well‐established and reproducible silicon‐based fabrication processes with outstanding performances in term of mechanical Q‐factor and sensitivity to external perturbations. Broadening the functionalities of micro‐electro‐mechanical systems (MEMS) by the integration of functional materials is a key step for both applied and fundamental science. However, combining functional materials with silicon‐based devices is challenging. An alternative approach is directly fabricating MEMS based on compounds inherently showing non‐trivial functional properties, such as transition metal oxides. Here, a full‐oxide approach is reported, where a high‐Tc$\rm {T_c}$ superconductor YBa2Cu3O7 (YBCO) is integrated with high Q‐factor micro‐bridge resonators made of single‐crystal LaAlO3 (LAO) thin films. LAO resonators are tensile strained, with a stress of about 350 MPa, show a Q‐factor above 200k, and have low roughness. YBCO overlayers are grown ex situ by pulsed laser deposition and YBCO/LAO bridges show zero resistance below 78 K and mechanical properties similar to those of bare LAO resonators. These results open new possibilities toward the development of advanced transducers, such as bolometers or magnetic field detectors, as well as experiments in solid state physics, material science, and quantum opto‐mechanics. [ABSTRACT FROM AUTHOR]

We have successfully fabricated a series of the SmCaBCuO bulk superconducting ceramics with different ratios of nanoscale Boron doping into mixture powder by the solid-state reaction method. Permanent magnets (PMs) with three different values in the same form were used for magnetic levitation force (MLF) measurements. During measurement of levitation forces between small PMs and bulk high Tc superconducting ceramic materials, significant hysteretic behavior was observed as a function of the distance between the magnet and the superconductor. We focused on the effect of doping and different permanent magnets on magnetic levitation force (MLF) measurements and magnetic stiffness calculations of materials, considering zero field-cooling (ZFC) and field-cooling (FC) conditions. It was seen that MLF decreased with the increase in boron dopant in the sample under ZFC conditions. We explained this result with weak bonds between grain boundaries, cracks and grain size reduction in the samples. Under FC conditions, with the increase of permanent magnet value and nano boron doping, the levitation force, which should be effective, left its place to the attractive force. Flux trapping centers formed by doping dominate the attractive force. The increase in doping caused a decrease in magnetic stiffness values. The increase in the permanent magnet caused an increase in the stiffness values of the material. This result agrees with the literature. The MLF and magnetic stiffness data got will be useful in the technological applications of maglev and carrier systems. [ABSTRACT FROM AUTHOR]

Yttrium barium copper oxide (YBCO) is used for special applications in linear generators because of its excitation loss, lower weight, and higher efficiency. These qualities enable the compound to operate better than the conventional copper wire coil in the stator unit of the linear generator. However, the continuous use of YBCO in linear generators has a fundamental challenge that affects industrial production and material stability after prolonged use. This paper seeks to sustain the adoption of YBCO by improving its quality for linear generator applications. The yttrium cuprates modification (YBYbCO) was synthesized using the solid-state reaction technique by doping YBCO with ytterbium. The crystalline structure, microstructural pattern, and stability of the new sample were adequately measured and found to be structurally stable to ensure durability. It was reported that applying YBYbCO in the linear generator would lead to a 200% increase in energy generation. The higher number of particles and lower individual particulate resistance enable it to withstand chemical pressure, thereby prolonging the lifespan of the linear generator. [ABSTRACT FROM AUTHOR]

We investigated the effect of 0.6 MeV proton irradiation on the superconducting and normal-state properties of thin-film YBa 2 Cu 3 O 7 − δ superconductors. A thin-film YBCO superconductor (≈567 nm thick) was subject to a series of proton irradiations with a total fluence of 7.6 × 10 16   p / cm 2 . Upon irradiation, T c was drastically decreased from 89.3 K towards zero with a corresponding increase in the normal-state resistivity above T c . This increase in resistivity, which indicates an increase in defects inside the thin-film sample, can be converted to the dimensionless scattering rate. We found that the relation between T c and the dimensionless scattering rate obtained during proton irradiation approximates the generalized d-wave Abrikosov–Gor'kov theory better than the previous results obtained from electron irradiations. This is an unexpected result, since the electron irradiation is known to be most effective to suppress superconductivity over other heavier ion irradiations such as proton irradiation. In comparison with the previous irradiation studies, we found that the result can be explained by two facts. First, the dominant defects created by 0.6 MeV protons can be point-like when the implantation depth is much longer than the sample thickness. Second, the presence of defects on all element sites is important to effectively suppress T c . [ABSTRACT FROM AUTHOR]

In this research, a novel method to improve the particle size and content of Y2BaCuO5 (Y-211) in YBa2Cu3O7 − x (YBCO) bulks was demonstrated. The single-domain YBCO bulks (20 mm in diameter) have been fabricated employing the RE+011 TSIG technique with different heating rates during the liquid phase infiltration (LPI) stage. The various heating rates on Y-211 size and its content in the final YBCO samples has been investigated in detail. The findings suggest that the average size of the Y-211 particles in the Y-123 matrix initially decreases followed by an increase, while its volume fraction gradually decreases with increasing heating rate. Furthermore, it is observed that the levitation force and the trapped fields exhibit an initial increase followed by a subsequent decrease as the heating rate increases. Among all the samples, sample S3 (heating rate of 30 °C/h) has the best magnetic levitation force and trapped field performances at 77 K, i.e., the largest values are of 45.3 N and 0.41 T, respectively. The results suggest that, while employing the RE+011 TSIG technique for YBCO bulk fabrication, the average size and volume fraction of Y-211 particles in the final sample can be further enhanced by controlling the heating rates during the LPI stage, obviating any need for chemical refining agents. [ABSTRACT FROM AUTHOR]

In this study, we utilized density functional theory (DFT) to analyze the interfacial properties of YBa2Cu3O7 (YBCO) with perovskite metal oxides LaAlO3 (LAO), KTaO3 (KTO), and SrTiO3 (STO). We focused on surface energies, lattice mismatches, strain energies, and adhesion energies to gauge the stability and compatibility of these interfaces. Our findings indicate that KTO exhibits the highest surface preference due to its lowest surface energy (0.054 eV/Å 2), suggesting superior surface stability. Moreover, LAO and STO show minor lattice mismatches with YBCO, implying effective interface integration, while YBCO/KTO interfaces experience significant strain due to extensive lattice mismatches. STO is distinguished by the lowest strain energy (0.07 eV), indicating minimal energy requirement for lattice mismatch accommodation, unlike KTO, which demonstrates high strain energy (0.42 eV) and potential structural distortions. The strongest interfacial bond, as indicated by an adhesion energy of −2.16 eV, was observed at YBCO/LAO, while the weakest was found at the YBCO/KTO interface, with an adhesion energy of −0.56 eV. Additionally, charge density difference (CDD) analysis highlighted electron density redistribution at the interfaces, predominantly around interfacial oxygen atoms, indicating a mix of ionic and covalent bonding. This study provides comparative insights into the interfacial characteristics of YBCO/ABO3 heterostructures, suggesting pathways for optimizing their design and performance.

Struts of a superconducting YBa2Cu3Oy (YBCO) foam prepared by the infiltration growth method on the base of commercial polyurethane foams were extracted from the bulk, and thoroughly characterized concerning the microstructure and the magnetoresistance, measured by the four-point technique. Optical microscopy, electron microscopy, electron backscatter diffraction and atomic force microscopy observations indicate a unique microstructure of the foam struts which shows a large amount of tiny Y2BaCuO5 (Y-211) particles (with diameters between 50 and 100 nm) being enclosed in channel-like grain boundaries between the YBCO grains and a one-of-a-kind surface of the struts covered with Ba3Cu5Oy-particles. The resistance data obtained at temperatures in the range 4.2 K ≤ T ≤ 150 K (applied magnetic fields ranging from 0 to 7 T) were analyzed in the framework of the fluctuation-induced conductivity (FIC) approach using the models of Aslamazov–Larkin (AL) and Lawrence–Doniach (LD). The resulting FIC curves reveal the presence of five distinct fluctuation regimes, namely, the short-wave (SWF), one-dimensional (1D), two-dimensional (2D), three-dimensional (3D), and critical (CR) fluctuation domains. The analysis of the FIC data enable the coherence length in the direction of the c-axis at zero-temperature ( ξ c (0) ), the irreversibility field ( B irr ), the upper critical magnetic field ( B c 2 ), the critical current density at T = 0 K ( J c (0) ) and several other parameters describing the the material's superconducting properties to be determined. The present data reveal that the minuscule Y-211 particles found along the YBCO grain boundaries alter the excess conductivity and the fluctuation behavior as compared to conventional YBCO samples, leading to a quite high value for J c (0) for a sample with a non-optimized pinning landscape. [ABSTRACT FROM AUTHOR]

We investigated the effect of 0.6 MeV proton irradiation on the superconducting and normal-state properties of thin-film YBa2Cu3O7−δ superconductors. A thin-film YBCO superconductor (≈567 nm thick) was subject to a series of proton irradiations with a total fluence of 7.6×1016 p/cm2. Upon irradiation, Tc was drastically decreased from 89.3 K towards zero with a corresponding increase in the normal-state resistivity above Tc. This increase in resistivity, which indicates an increase in defects inside the thin-film sample, can be converted to the dimensionless scattering rate. We found that the relation between Tc and the dimensionless scattering rate obtained during proton irradiation approximates the generalized d-wave Abrikosov–Gor’kov theory better than the previous results obtained from electron irradiations. This is an unexpected result, since the electron irradiation is known to be most effective to suppress superconductivity over other heavier ion irradiations such as proton irradiation. In comparison with the previous irradiation studies, we found that the result can be explained by two facts. First, the dominant defects created by 0.6 MeV protons can be point-like when the implantation depth is much longer than the sample thickness. Second, the presence of defects on all element sites is important to effectively suppress Tc.

Many applications require monitoring of increasingly high neutron flux levels. Pre‐neutron characterization is performed of a superconducting transition edge bolometric device, sensitive to neutrons by an enriched boron carbide (10B4C) layer. Heat from the absorption of neutrons is simulated using an attenuated laser, while the detector is cooled to the critical temperature, Tc. Frequency dependent (4–25 Hz) and constant input power measurements are performed on a 10B4C‐coated and a non‐coated pixel. Results are used to fit a two lumped element thermal model. The effective specific heat is highly dependent on the input pulse duration due to the interconnected stack structure. For modulated pulses, the active volume in the thermal circuit is the full depth of the substrate in the area under the pixel. For constant power input, a large portion of the substrate is heated and the interface conductivities to the cold finger are found to be important. The detectivity is D* = 3.5 × 108 cmHzW−1${{\rm cm}} \sqrt {{\rm Hz}}\,{{\rm W}^{-1}}$, and is only slightly lower than similar detectors. Understanding the dynamics of the detector better and using neutron excitation, it is expected that optimizations can lead to an equally good detector for cold to thermal neutrons at flux levels >106 n cm−2s−1. [ABSTRACT FROM AUTHOR]

Abstract Many applications require monitoring of increasingly high neutron flux levels. Pre‐neutron characterization is performed of a superconducting transition edge bolometric device, sensitive to neutrons by an enriched boron carbide (10B4C) layer. Heat from the absorption of neutrons is simulated using an attenuated laser, while the detector is cooled to the critical temperature, Tc. Frequency dependent (4–25 Hz) and constant input power measurements are performed on a 10B4C‐coated and a non‐coated pixel. Results are used to fit a two lumped element thermal model. The effective specific heat is highly dependent on the input pulse duration due to the interconnected stack structure. For modulated pulses, the active volume in the thermal circuit is the full depth of the substrate in the area under the pixel. For constant power input, a large portion of the substrate is heated and the interface conductivities to the cold finger are found to be important. The detectivity is D* = 3.5 × 108 cmHzW−1, and is only slightly lower than similar detectors. Understanding the dynamics of the detector better and using neutron excitation, it is expected that optimizations can lead to an equally good detector for cold to thermal neutrons at flux levels >106 n cm−2s−1.

The interest in RBa2Cu3O7–δ (R = lanthanides) stems from its superconducting properties. These represent a very significant advance in solid-state materials physics and have been extensively studied for decades, with the aim of increasing the critical temperature by doping or external parameters such as pressure. In the present review, we briefly discuss oxygen diffusion in RBa2Cu3O7–δ with respect to its composition. We consider related compounds as a comparison. [ABSTRACT FROM AUTHOR]

With the improvement of high temperature superconducting (HTS) materials, HTS machines have shown better competitive advantages in wind power generation and other fields. However, the conventional structure of superconducting machines has led to low reliability of the machines due to the complex structures such as brush and rotating dewar. Based on the analysis of the properties of second-generation high-temperature superconducting strips — YBCO strips, a kind of rotating pole shoe superconducting machine (RPHTSM) with dual HTS coils is proposed in this paper, which avoids the use of brush and rotating dewar used in the conventional HTS machine. The three-dimensional model for magnetic field analysis of the RPHTSM is established and the structure of the RPHTSM is optimized according to the calculation. A two-dimensional simplified model was developed and based on which the output performance of the machine was calculated. By comparing with the conventional HTS machine, it is concluded that the dual-coil RPHTSM has great advantage in reducing the consumption of superconducting strips and the inertia of the rotor.

Struts of a superconducting YBa2Cu3Oy (YBCO) foam prepared by the infiltration growth method on the base of commercial polyurethane foams were extracted from the bulk, and thoroughly characterized concerning the microstructure and the magnetoresistance, measured by the four-point technique. Optical microscopy, electron microscopy, electron backscatter diffraction and atomic force microscopy observations indicate a unique microstructure of the foam struts which shows a large amount of tiny Y2BaCuO5 (Y-211) particles (with diameters between 50 and 100 nm) being enclosed in channel-like grain boundaries between the YBCO grains and a one-of-a-kind surface of the struts covered with Ba3Cu5Oy-particles. The resistance data obtained at temperatures in the range 4.2 K ≤T≤ 150 K (applied magnetic fields ranging from 0 to 7 T) were analyzed in the framework of the fluctuation-induced conductivity (FIC) approach using the models of Aslamazov–Larkin (AL) and Lawrence–Doniach (LD). The resulting FIC curves reveal the presence of five distinct fluctuation regimes, namely, the short-wave (SWF), one-dimensional (1D), two-dimensional (2D), three-dimensional (3D), and critical (CR) fluctuation domains. The analysis of the FIC data enable the coherence length in the direction of the c-axis at zero-temperature (ξc(0)), the irreversibility field (Birr), the upper critical magnetic field (Bc2), the critical current density at T= 0 K (Jc(0)) and several other parameters describing the the material’s superconducting properties to be determined. The present data reveal that the minuscule Y-211 particles found along the YBCO grain boundaries alter the excess conductivity and the fluctuation behavior as compared to conventional YBCO samples, leading to a quite high value for Jc(0) for a sample with a non-optimized pinning landscape.

Holes drilled in a type-II superconductor trap the magnetic flux. Following Clem's flux pinning model, we consider surface pinning as a mechanism for compressing the magnetic flux in the holes. Estimations of the trapped magnetic flux demonstrate that the holes with the diameter up to 2 mm are advantageous for bulk single-crystal REBCO samples. The REBCO films and tapes can be improved by the holes with diameter smaller than 10 μm. [ABSTRACT FROM AUTHOR]

We have developed a new method to measure the viscosity of micrometric films by thermomechanical analysis with a hemispherical probe of millimetric diameter. The loading curve (displacement vs. time) recorded as the probe tip crosses the whole film at constant load until it touches the substrate is fitted to a theoretical curve shape that has been obtained after solving the problem of liquid flow under the probe tip. The method has been validated by measuring the viscosity of rosin films. It has been applied to analyze the thermal evolution of unstable liquid films that appear on Ba propionate, Ce(III) propionate and a low-fluorine precursor film of YBa2Cu3O6+x. During pyrolysis of the last two films, viscosity first diminishes due to heating and then it increases as solid oxide particles are formed inside the liquid. [ABSTRACT FROM AUTHOR]

In the present work, the effect of the addition of potassium niobate (KNbO3) nanoparticles (NPs) on the pinning properties of YBCO compound is investigated. The synthesis of YBCO:xKNbO3 (x = 0–1 wt%) nanocomposites were carried out using a two-step process, firstly KNbO3 NPs were synthesized via hydrothermal process, and later on, the nanocomposites were synthesized via solid-state reaction method containing various concentrations of NPs from 0 to 1 wt%. The effect of NPs of KNbO3 in YBCO is studied using structural, morphological, transport, and magnetic measurements. From XRD spectra, the crystal structure of YBCO was found to be orthorhombic, which remained invariant even in the nanocomposites. Magnetic properties of YBCO and its nanocomposites over the range of − 6 T to + 6 T were characterized using magnetic property measurement system (MPMS). The Bean model is applied to calculate the critical current density (JC), which has improved in YBCO:KNbO3 nanocomposites as compared to YBCO. The maximum enhancement of ~ 4.4 times in JC and pinning properties was found for YBCO:0.5wt%KNbO3 nanocomposites due to the creation of defects in YBCO matrix. Additionally, it is observed that for nanocomposites compared to YBCO, the rate of JC decay decreases with an increase of externally applied field, which indicates an enhancement in pinning properties of nanocomposites. [ABSTRACT FROM AUTHOR]

The influence of porosity on the trapped field achievable in 22 YBCO bulk superconductors of different sizes has been investigated and evaluated using Spearman's correlation coefficient in order to explore the significance of these critical features in a statistically significant way. The diameter of the single grain YBCO bulk sample correlates strongly with trapped field, and significantly more so than the effect of porosity. Therefore, the direct effect of porosity on the average J c was investigated as the main aim of this investigation. A correlation was found between the average J c calculated from trapped field measured at the top and bottom of the single grain and the porosity of the sample. This observation suggests that any method of reducing the porosity may significantly improve J c and trapped field. [ABSTRACT FROM AUTHOR]

High-TC superconductor thin film heterostructures were deposited using reactive co-evaporation for dual layer electronic applications. The epitaxial structure consisted of 35-nm YBa2Cu3O7-δ(YBCO), 75-nm CeO2 , 150-nm YBCO, and 20-nm CeO2 on r-plane sapphire wafers. The critical temperature was measured to be 83.6 K and 84.8 K for the bottom and top YBCO layers, respectively. Atomic force microscopy reveals smooth surfaces with RMS roughness of the top YBCO layer to be 4.7 nm. The CeO2 insulating layer exhibited hopping conduction that freezes out at low temperature, making these structures suitable for electrical circuits with isolated ground planes.

High-TC superconductor thin film heterostructures were deposited using reactive co-evaporation for dual layer electronic applications. The epitaxial structure consisted of 35-nm YBa2Cu3O7-δ(YBCO), 75-nm CeO2 , 150-nm YBCO, and 20-nm CeO2 on r-plane sapphire wafers. The critical temperature was measured to be 83.6 K and 84.8 K for the bottom and top YBCO layers, respectively. Atomic force microscopy reveals smooth surfaces with RMS roughness of the top YBCO layer to be 4.7 nm. The CeO2 insulating layer exhibited hopping conduction that freezes out at low temperature, making these structures suitable for electrical circuits with isolated ground planes.

Sm-doped YBa2Cu3O7–δ samples were prepared by conventional solid state reaction method in air. The studies of X-ray photoemission spectroscopy and X-ray absorption spectroscopy indicate that the extra electrons fill the holes in CuO2 planes, so that the hole carrier concentration decrease under Sm substitution. The X-ray absorption spectroscopy of Cu L-edge and O K-edge demonstrates that the hybridization strength between Cu 3d and O 2p decreases with increasing content of Sm, but the hybridization strength between Y 4d, Ba 5d, Sm 4f and O 2p increases with the increasing of Sm content, while the superconductivity of the Sm-doped YBa2Cu3O7–δ samples is suppressed, i.e., the superconducting transition temperature of the samples was lowered. Thus, our experimental results suggest a close relationship between the superconductivity and orbital hybridization. [ABSTRACT FROM AUTHOR]

We demonstrate an improved YBa2Cu3O7− δ -based microwave kinetic inductance detector with a quality factor Q i ∼ 2.5 × 10 4 and noise equivalent power, ∼ 10 − 12 W Hz − 1 at 10 K. Zero field cooled (ZFC) and field cooled (FC) measurements of the magnetic field dependence of the resonance characteristics, show substantially different behavior, indicating that both the screening currents and vortices play a role. The ZFC measurements exhibit a sharp decrease of the resonance frequency, f r , and Q i at low fields, up to the full penetration field, revealing the dominant role of the screening currents. In contrast, the FC measurements exhibit a moderate decrease of f r and Q i with field, revealing the role of vortices and reflecting the field dependence of the penetration depth in a d-wave superconductor. [ABSTRACT FROM AUTHOR]

Recently, the number of projects has grown connected with the application of high-temperature superconductors (HTSC) with exceptionally high current-carrying characteristics in strong magnetic fields. However, the thickness of the RBa2Cu3O7–x (R = REE, Y) superconducting layer is only 1–2% of the thickness of HTSC tape. Increasing the current-carrying characteristics owing to the thickness of the conducting layer is a promising approach. The fundamental problem of crystallite formation of a-oriented crystallites prevents the development of this approach. Such crystallites do not carry superconducting current along the substrate tape and interfere with the growth of c-oriented crystallites. This review presents existing methods of suppression of a-oriented growth, the basis of the creation of HTSC materials, and prospects of obtaining HTSC materials with high current-carrying characteristics. [ABSTRACT FROM AUTHOR]

The resonant properties of Cold-Electron Bolometers (CEBs) located at a 0.3 K cryostat plate are measured using a 50 μm long high-temperature YBa2Cu3O 7 − δ (YBCO) Josephson junction oscillator, placed on a 2.7 K plate of the same cryostat. For these purposes, a bunch of YBCO Josephson oscillators with various lengths of dipole antennas and overlapping generation bands has been developed and investigated in 50–500 GHz frequency range. Two setups of Josephson junction placement were compared, and as a result, various narrow-band receiving systems with CEBs have been measured, demonstrating the feasibility of the presented approach. [ABSTRACT FROM AUTHOR]

• YBCO films with WO 3- x decorations were firstly prepared by CSD. • The square-dot or nanowire enhanced biaxially texture and J c. • Influence of nanostructure on the texture and J c was investigated. This study explores the influence of tungsten oxide (WO 3- x) nanostructures, decorated on LaAlO 3 (LAO) single crystal substrate, on the fabrication and superconducting performance of YBa 2 Cu 3 O y (YBCO) films. The WO 3- x in square-dot and nanowire forms, significantly enhance the biaxial texture of YBCO films, resulting in high critical current density J c (square-dot, 3.05 MA/cm2 @ 77 K, nanowire, 2.1 MA/cm2 @ 77 K). However, the presence of WO 3- x nanodots leads to a random nucleation of YBCO grains along the a/b -axis, driving a porous surface and broadening the full width at half maximum (FWHM) in both phi and omega scans. This poor texture deteriorates the film's J c to 0.71 MA/cm2 @ 77 K. Therefore, optimizing the WO 3- x interface is crucial for enhancing the epitaxial growth and critical current density of YBCO film. This study provides an effective approach to optimize the superconducting performance of YBCO film by tailoring nanostructure interface. [ABSTRACT FROM AUTHOR]

Our study explores the relationship between BZO nanorod density and magnetic flux pinning in YBCO thin films on coated conductor templates. We identified an optimal BZO doping level of 8%–10%, which maximizes flux pinning and enables the highest critical current densities to be achieved across various temperatures and magnetic field ranges, especially in new types of multilayer structures. Additionally, the formation of a c -axis peak in the angular-dependent critical current curves at high BZO concentrations underscores the significance of collective pinning mechanisms. These results are discussed using a simple pinning model that considers the effects of nanorod spacing and fragmentation. Overall, our findings contribute to the development of high-performance coated conductor layer structures for future power applications, where maximizing flux pinning is essential. • Maximal flux pinning is discovered in BZO-doped YBCO films on metal template. • The critical upper limit for optimal BZO content is determined to be 10 wt.%. • The highest critical current density does not correlate with maximum flux pinning. • Optimal flux pinning is explained by the nanorod spacing and fragmentation. • A bilayer structure yields best structure with maximum flux pinning. [ABSTRACT FROM AUTHOR]

Y1Ba2Cu3O7-δ (YBCO) was doped with thermally stable graphene oxide (TS-GO) and thermally unstable graphene oxide (TU-GO) in the following %wt. concentrations: 0.1, 0.5 and 0.7. TS-GO and TU-GO was characterized using RAMAN, fourier transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDX). The critical transition temperature (TCmid) increased in all TU-GO and TS-GO doped samples. The highest TCmid of 101 K was that of the 0.7 %wt. TU-GO doped sample. The increase in TCmid was greater for the samples doped with TU-GO. Non-stoichiometric oxygen content (δ) was seen to increase with an increase in doping concentration of both TS-GO and TU-GO. X-ray diffraction (XRD) analysis was carried out to determine the lattice parameters and phase characterization of the TU-GO and TS-GO doped samples. Lattice parameters show an increase in the copper oxide (CuO2) planar area with TCmid for TS-GO and TU-GO doping. To determine strain effects, the Williamson Hall method was used to determine the lattice strain (ɛ). The ɛ was seen to decrease for both TS-GO and TU-GO doped samples. The formation of magnetic manganese oxide nanoparticles in TS-GO and TU-GO doped samples was observed, and resulted from impurities found in the graphene oxide (GO) dopant material. The magnetic particles were extracted magnetically and characterized using EDX. YBCO was doped with trimanganese tetraoxide (Mn3O4) and manganese dioxide (MnO2) in a 0.1 and 0.2 %wt. concentration. The TCmid is seen to increase to 94 K and 104 K respectively for 0.1 %wt. MnO2 and Mn3O4 doped samples. The 0.2 %wt. doped Mn3O4 sample resulted in a decrease in TCmid. Magnetic susceptibility measurements confirmed a superconducting phase changes. The increase in TCmid above YBCO’s Tc = 93 K, correlates to the presence of manganese nano-impurities. This increase is hypothezied to be related to an increase in surface area of YBCO’s 2D copper oxide (CuO2) plane structure with GO doping.

We report on remarkably high in-field performance at 4.2 K achieved in >4 μm thick rare earth barium copper oxide (REBCO) samples with Zr addition. Two different samples have been measured independently at Lawrence Berkeley National Laboratory and the National High Magnetic Field Laboratory, achieving critical current densities (J c) of 12.21 MA cm-2 and 12.32 MA cm-2 at 4.2 K, 14 T (), respectively, which corresponds to equivalent critical current (I c) values of 2247 and 2119 A/4 mm. These I c values are about two times higher than the best reported performance of REBCO tapes to date and more than five times higher than the commercial HTS tapes reported in a recent study. The measured J c values, with a pinning force of ∼1.7 T N m-3 are almost identical to the highest value reported for thin (∼1 μm thick) REBCO at the field and temperature, but extended to very thick (>4 μm) films. This results in an engineering current density (J e) above 5 kA mm-2 at 4.2 K, 14 T, which is more than five times higher than Nb3Sn and nearly four times higher than the highest reported value of all superconductors other than REBCO at this field and temperature. The reported results have been achieved by utilizing an advanced metal organic chemical vapor deposition system. This study demonstrates the remarkable level of in-field performance achievable with REBCO conductors at 4.2 K and strong potential for high-field magnet applications.

We report on remarkably high in-field performance at 4.2 K achieved in >4 μm thick rare earth barium copper oxide (REBCO) samples with Zr addition. Two different samples have been measured independently at Lawrence Berkeley National Laboratory and the National High Magnetic Field Laboratory, achieving critical current densities (J c) of 12.21 MA cm-2 and 12.32 MA cm-2 at 4.2 K, 14 T (), respectively, which corresponds to equivalent critical current (I c) values of 2247 and 2119 A/4 mm. These I c values are about two times higher than the best reported performance of REBCO tapes to date and more than five times higher than the commercial HTS tapes reported in a recent study. The measured J c values, with a pinning force of ∼1.7 T N m-3 are almost identical to the highest value reported for thin (∼1 μm thick) REBCO at the field and temperature, but extended to very thick (>4 μm) films. This results in an engineering current density (J e) above 5 kA mm-2 at 4.2 K, 14 T, which is more than five times higher than Nb3Sn and nearly four times higher than the highest reported value of all superconductors other than REBCO at this field and temperature. The reported results have been achieved by utilizing an advanced metal organic chemical vapor deposition system. This study demonstrates the remarkable level of in-field performance achievable with REBCO conductors at 4.2 K and strong potential for high-field magnet applications.

A bulk YBa2Cu3O7−δ (Y-123) superconductor synthesized by a thermal treatment method was added with different weight percentages (x = 0.0, 0.2, 1.0, 1.5, and 2.0 wt.%) of BiFeO3 (BFO) nanoparticle. X-ray diffraction (XRD), alternating current susceptibility (ACS), and field emission scanning electron microscopy (FESEM) were used to determine the properties of the samples. From the XRD results, all samples showed an orthorhombic crystal structure with a Pmmm space group. The sample x = 1.0 wt.% gave the highest value of Y-123. The high amounts of BFO degraded the crystallite size of the sample, showing that the addition did not promote the grain growth of Y-123. From ACS results, the Tc-onset value was shown to be enhanced by the addition of the BFO nanoparticle, where x = 1.5 wt.% gave the highest Tc value (91.91 K). The sample with 1.5 wt.% showed a high value of Tp (89.15 K). The FESEM analysis showed that the average grain size of the samples decreased as BFO was introduced. However, the small grain size was expected to fill in the boundary, which would help in enhancing the grain connectivity. Overall, the addition of the BFO nanoparticles in Y-123 helped to improve the superconducting properties, mainly for x = 1.5 wt.%. [ABSTRACT FROM AUTHOR]

The Y1–xLixBa2Cu3O7–δ polycrystalline bulk superconductors doped with Li substituting at the Y site at different concentrations (x = 0, 0.01, 0.02, 0.1) were prepared using the citrate-gel method to study the effects of doping on the superconducting temperature and critical current density. The question was whether Li addition characterized by a high Debye frequency would have any positive effects on Tc. The optimum citrate-gel and heat treatment conditions were identified as those yielding samples with a maximum grain size on the order of 50 μm (up to the optimum Li doping level, x = 0.01). Li substitution at the Y site was verified by structural, electrical, and magnetic measurements of the produced samples, whereas X-ray diffraction (XRD) analysis revealed the formation of a pure phase with no visible impurity phases. Moreover, AC magnetic susceptibility measurements showed no increase in the superconducting transition temperature Tc, consistent with the predicted results obtained by machine learning method, although it was theoretically expected to increase owing to the high Debye frequency of Li. This observation is consistent with magnetic coupling models for pairing mechanism in cuprates. Finally, because of the optimum conditions of the preparation procedure, nearly identical values of the critical current density (Jc) were recorded for samples with different Li doping levels (up to the optimum Li doping level). It was found that improved compound preparation conditions would have a critical and extensive effect on Jc enhancement, with nearly no Tc suppression. [ABSTRACT FROM AUTHOR]

A set of DC pulse devices was built to measure the 5 mm × 10 mm YBCO sheet in order to evaluate the impact of thermal effect on the superconducting I-V curve (77 K, self-field). Firstly, metal organic deposition method was used to prepare YBCO precursor film on a 5 × 10mm2 lanthanum aluminate single crystal. With the aid of a mask plate, a 15-W laser was used to graphically process the YBCO film after pyrolysis and sintering, or before oxygen absorption, so that the silver gel curing and YBCO oxygen absorption processes could be performed simultaneously. In order to realize two modes of continuous loading current and pulse loading current, a set of power supply and test equipment consisting of a Keithley 6500 multimeter, a Keithley 2280 power supply, two simple programmable controllers, a special fixture, and a stepping motor with deceleration device was designed. This equipment is used to test Tc and Ic of graphically processed YBCO film. YBCO film displayed comparable critical current values in both continuous loading current mode and pulse loading current mode at the same current loading rate. After YBCO film enters the stage of loss of superconductivity, the method of pulse loading current shows lower resistivity than that of continuous loading current, and the ratio of the two resistivities increases further with the increasing of current, which may be because the method of pulse loading current provides more sufficient heat dissipation interval for YBCO. [ABSTRACT FROM AUTHOR]

We present the results of a study of the superconducting and paramagnetic properties of polycrystalline Y1–xGdxBa2Cu3O7–δ samples. The critical current density and critical temperature of YBCO were weakly decreased by the Gd doping. A peak effect, which is a nonmonotonic dependence of the critical current density on magnetic field, was detected for all samples. The peak position shifted to higher magnetic fields with increasing Gd content. This behavior is opposite to the shift of the peak effect observed for other YBCO compounds doped by magnetic ions. This unusual behavior is apparently related to the realized granular structure instead of the type of doping ion. A correlation between the peak position and the granule size was found in the investigated samples and other polycrystalline YBCO compounds. [ABSTRACT FROM AUTHOR]

We present the results of a study of the superconducting and paramagnetic properties of polycrystalline Y1–xGdxBa2Cu3O7–δ samples. The critical current density and critical temperature of YBCO were weakly decreased by the Gd doping. A peak effect, which is a nonmonotonic dependence of the critical current density on magnetic field, was detected for all samples. The peak position shifted to higher magnetic fields with increasing Gd content. This behavior is opposite to the shift of the peak effect observed for other YBCO compounds doped by magnetic ions. This unusual behavior is apparently related to the realized granular structure instead of the type of doping ion. A correlation between the peak position and the granule size was found in the investigated samples and other polycrystalline YBCO compounds. [ABSTRACT FROM AUTHOR]

Flux-Pinning Docking Interfaces (FPDI) in satellite systems were developed using bulk superconductors and permanent magnets in previous works. However, such FPDIs have limited magnetic field strength, consist of heavy-weight material, and can only be used with a single purpose, i.e., as chasing or docking satellite. Replacing the magnetic material in the FPDI by a trapped field (TF)-magnet would enable the interface to operate for both purposes, i.e., generating a (stronger) magnetic field and trapping it. We show the requirements for such a system and discuss the possible gains when using a TF-FPDI in satellites. To reduce the system weight, the use of superconducting foams as superconducting material is discussed in detail. Furthermore, the use of superconducting foams, the size of which can be easily upscaled, may also comprise the function of the damping material, so even more weight could be saved for the payload. [ABSTRACT FROM AUTHOR]

In this study, the effect of of silver nanoparticles (Ag-NPs) inclusion on the AC magnetic susceptibility of high temperature YBa2Cu3O7-δ (Y123) + x wt% Ag (x=0.00, 0.06, 0.10 and 0.30) polycrystalline superconductors was investigated. The high temperature superconductors (Y123 + x wt% Ag) were fabricated by the solid state reaction method. XRD analysis of the samples showed superconducting orthorhombic phase with symmetry of Pmmm space group. Analysis of scanning electron microscopy (SEM) images related to the surface morphology of the samples showed that increasing silver nanoparticles dopant causes a decrease in granule size of the compounds. Real magnetic susceptibility exhibited intrinsic diamagnetic behavior and grain boundary connections and imaginary components of magnetic susceptibility showed energy loss due to flux penetration and vortex movement at the grain boundary. The critical temperature of 92 K was obtained for pure Y123 by real component of magnetic susceptibility and complete diamagnetism was observed in all samples (x=0.00, 0.06, 0.10 and 0.30). Silver decreased the critical temperature and increased the critical current density. Based on the obtained values of maximum Josephson current and Josephson intergranular energy coupling, it can be concluded that x=0.10 is the best weight percentage for Ag among the Y123 doped samples. Indeed, the greater inter-granular Josephson coupling energy causes, the superior of the trapping force and consequently produces the better critical current density.

We report the local structural and superconducting properties of undoped and Ag-doped YBa2Cu3O6+x (YBCO) films with a thickness of up to 1 µm prepared by pulsed laser deposition on SrTiO3 (STO) single crystals and on ion-beam-assisted deposition (IBAD) and rolling-assisted biaxially textured substrate (RABiTS)-based metal templates. X-ray diffraction demonstrates the high crystalline quality of the films on both single crystalline substrates and metal-based templates, respectively. Although there was only a slight decrease in Tc of up to 1.5 K for the Ag-doped YBCO films on all substrates, we found significant changes in their transport characteristics. The effect of the silver doping mainly depended on the concentration of silver, the type of substrate, and the temperature and magnetic field. In general, the greatest improvement in Jc over a wide range of magnetic fields and temperatures was observed for the 5%Ag-doped YBCO films on STO substrates, showing a significant increase compared to undoped films. Furthermore, a slight Jc improvement was observed for the 2%Ag-doped YBCO films on the RABiTS templates at temperatures below 65 K, whereas Jc decreased for the Ag-doped films on IBAD-MgO-based templates compared to undoped YBCO films. Using detailed electron microscopy studies, small changes in the local microstructure of the Ag-doped YBCO films were revealed; however, no clear correlation was found with the transport properties of the films. [ABSTRACT FROM AUTHOR]

In the present work, the high-rate epitaxial growth for superconducting YBa2Cu3O7- δ (YBCO) films on the substrates of LaMnO3(LMO)/IBAD-MgO/Y2O3/Al2O3/Hastelloy is achieved by fluorine-free metal organic deposition (FF-MOD) by rapidly switching the partial oxygen pressure (p O2) at a fixed temperature. Further investigation into the effects of temperature and switching p O2 on the phase transition of YBCO elucidates that the growth mode and microstructural characteristics of the studied films. BaMnO3 heterogeneous particles are observed in localized regions in the films by cross-sectional transmission electron microscopy, which may be generated by the interfacial reactions between the substrate and transient liquid phases. The present work implies the feasibility of FF-MOD for the rapid growth of YBCO films on LMO buffered metallic substrates, regardless of interfacial reactions during the preparation. [ABSTRACT FROM AUTHOR]

YBa 2 Cu 3 O 7− δ (YBCO) thin films deposited on LaAlO 3 single-crystal substrates have great potential for application in microwave field due to their low microwave surface resistance (R s). In order to prepare high-performance films and facilitate adjustment of experimental parameters, we designed novel metalorganic chemical vapor deposition system. This system adopts single liquid-source pulse feed that provides facile control over film composition through the adjustment of Y, Ba, and Cu ratios in precursors. Here, we thoroughly study influence of film composition on performance. By conducting energy-dispersive spectroscopy measurements, Y, Ba, and Cu composition ranges of 21–24%, 28–31%, and 46–54%, respectively, are found to optimize YBCO film transport and microwave properties. Composition affects purity of film phase which in turns determines film performance. To confirm this observation, we adjust ratio through input–output relationship to obtain film with composition ratio within abovementioned optimal range. Obtained YBCO film has critical current density of 2.8 MA/cm2 at 77 K and 0 T and R s of 0.285 mΩ at 77 K and 10 GHz. The full width at half maximum of YBCO (005) peak and (103) plane, measured via X-ray diffraction, are 0.235° and 0.762°, respectively. [ABSTRACT FROM AUTHOR]

YBa2Cu3O7-δ(YBCO) bulk material prepared by high temperature solid state reaction was milled and dispersed through ultrasonic process in ethanol to prepare nanoscale YBCO/ethanol sol. Then it was mixed with aniline or O-phenylenediamine and the organic/YBCO hybrid materials were obtained after concentration and being dried in vacuum. The influence of the organic on YBCO’s chemical composition, phase, elemental valence and magnetic properties was studied by Fourier transform infrared spectroscopy(FT-IR), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and vibrating sample magnetometer(VSM). The results show that the infrared absorption of YBCO is not affected by the aniline or O-phenylenediamine within 0.05%-5%(mass fraction, the same below), however the intensity of the XRD peaks is significantly increased. The interaction between the N atom in aniline or O-phenylenediamine and the Y atom in YBCO is stronger compared with N-Ba or N-Cu. The superconducting transition temperature Tc and magnetization M of YBCO are significantly affected by the content of N element in the hybrid materials. When the content of N element exceeds 1%, Tc is significantly decreased and Mmin is increased accordingly.

2G HTS wires are capable of transferring huge amounts of electrical energy without loss. An increase in the current-carrying capacity in these materials is possible due to an increase in the thickness of the superconducting layer; however, there is a problem with the appearance of impurity orientations and other defects with increasing thickness. We have proposed a solution of this problem by increasing the thickness of the superconducting layer by the MOCVD method using interlayers of yttrium oxide. The aim of this study was the production of thick composite films with yttrium oxide interlayers and high critical current density. In addition, we want to show the effectiveness of the approach of introducing yttrium oxide interlayers for the reduction of the number of parasitic orientations and defects with an increase in HTS film thickness. The deposition of YBа2Cu3O7–dand Y2O3 films was carried out layer by layer using reel-to-reel MOCVD equipment. A 12 mm wire of the following architecture was used as a substrate: 200 nm CeO2 (Gd2O3)/30–50 nm LaMnO3/5–7 nm IBAD-MgO/50 nm LaMnO3/50 nm Al2O3/60 μ Hastelloy 276. The resulting films were annealed in oxygen for obtaining the orthorhombic YBCO phase. YBа2Cu3O7–d /Y2O3composites were obtained. In these composites, obtained using the MOCVD method, the amount of side (с║) orientation of the HTS layer was reduced and high values of the critical current density, exceeding 1 MA/cm at a thickness of > 2 μm remained. The efficiency of the approach of introducing yttrium oxide interlayers for the increase in the current characteristics with increasing film thickness was shown. It was found that further thickening of films with interlayers is prevented by the formation of nanopores, reducing the critical current density.

Thermodynamic parameters, such as the activation energy (Ea) and the diffusion coefficient (D0), of weakly bounded oxygen in Fe-doped YBa2Cu3O6+x (YBa2Cu3-yFeyO6+x) system were obtained utilizing the Manometric technique. It is found that under isothermal conditions, oxygen desorption in YBa2Cu3O6+x (YBCO) occurs following an exponential decay trend and in two distinct stages. During the first stage, the majority of absorbed oxygen is released, while the second stage exhibits a delayed degassing kinetics. Ea and D0 were determined for both, pressed and powdered, samples of the YBCO and YBa2Cu3-yFeyO6+x systems, from experimental kinetic curves, depicting gas release P(t) under isothermal vacuum degassing conditions. It is demonstrated that doping with Fe prevents oxygen exchange in YBCO, as evidenced by the reduction in the quantity of released oxygen with increasing iron index (y). The experimental results validate the efficacy of the Manometric method for analyzing and determining the thermodynamic and kinetic properties of the YBCO superconductor. [ABSTRACT FROM AUTHOR]