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We have studied the thermally activated flux creep of a newly fabricated superconductor Y3Ba5Cu8O18 with the superconducting transition temperature 102 K. Analysis of the transition spread from the normal state to superconducting state in the electrical resistivity revealed that the thermally activated flux creep explains the electron share in the vicinity of the transition temperature Tc. The activation energy U in a magnetic field below 15 kOe has been calculated by the corrected thermally activated flux creep model, and the pinning energy is exponentially related to the magnetic field.

In this study we introduce a new analytical expression for the intensity distribution of the diffraction patterns from a twined sample of YBCOx ( YBa2Cu3O6+x, 0

In this paper, the density of states (DOS) of a planar d-wave Josephson junction is studied analytically. Two high temperature superconductors are separated by an interface with finite transparency coefficient. The c-axes are parallel to the interface and ab-axes have a mis-orientation. The tunneling occurs via the interface because of phase difference between superconducting bulks. The effect of reflection at the interface and mis-orientation on the DOS is investigated both analytically and numerically. It is observed that, DOS is totally different from the case of ideal transparent d-wave Josephson junctio. Also, the mid-gap states at the energies -Δ

• Depict flux motion across a current carrying HTS tape under external magnetic field. • Model combined with Law of mass action, Arrhenius equation, theory of Kim-Anderson. • Migration rate is proportional to number density of flux lines enclosed by HTS ring. • The rate is exponentially related to thermal activation energy, potential barriers. By combining the Law of mass action, Arrhenius equation and the magnetic flux creep theory of Kim-Anderson, we proposed a model to depict the flux motion across a current-carrying high temperature superconductor (HTS) ring under an external magnetic field. In this model, the rate of flux motion is exponentially related to the thermal activation energy of trapped fluxes and the level of potential barriers in HTS material. The rate is also proportional to the number density of the flux lines enclosed by HTS ring. To qualitatively validate the rightness of the model, a test was carried out with a "double eye" shaped YBaCuO tape circuit and a permanent magnet at 77 K. The experimental results proved the validity of the model. This model may be helpful for understanding the flux relaxation in HTS loops under an external magnetic field and may account for the flux dynamics of HTS as well. [ABSTRACT FROM AUTHOR]

A new optically controlled high temperature superconducting microwave variable attenuator used in high-temperature superconducting（HTS） subsystem of satellite system was proposed.The low microwave surface resistance and excellent laser response characteristics of HTS film was used to realize the favorable properties of this attenuator.The main results conclude: Insertion loss of this attenuator is about 0.2dB,which is lower one order than conventional attenuators;Variable precision about 0.01dB can be achieved,which is lower 1~2 order than conventional attenuators.When laser power is about 45mW,the response range of HTS microstrip to laser is about 0.1dB and the duration of heat influence continue 3.5s

The basic concept of superconductive magnetic gears (SMGs) is to maximize the benefits and impact of the magnetic gearing technology by highlighting the future perspective of SMGs to produce a more efficient and compact system. This paper deals with a new analytical method (AM) for the calculation of magnetic field distribution in an SMG. A 2-D AM based on Laplace's partial differential equations of magnetic scalar potential in the different subdomains of a magnetic gear is introduced and solved by considering the corresponding boundary conditions. The proposed method shows a significant reduction in the consumed calculation time compared with the finite-element method (FEM) and can be used as a basis for design optimizations. Two-dimensional AM results are compared against those obtained from 2-D FEM simulations, using an accurate, yet efficient, high-temperature superconductor (HTS) modeling, yielded by a detailed localized E-J power law approach combining the different aspects of HTS in a numerical method, so as to find out the benefits and validity of the presented AM. Finally, the effects of PMs and pole pieces' dimensions on torque density are realized. [ABSTRACT FROM AUTHOR]

In this research, we prepared different Au nanoparticles (0.1–2 wt%) doped YBCO high temperature superconductor samples by sol-gel method. To characterize the samples, we used X-Ray diffraction (XRD) and scanning electron microscope (SEM) analysis. Results show the formation of orthorhombic phase of superconductivity for all prepared samples. We observed that by adding Au nanoparticles, the grains' size of the samples reduces from 76 nm to 47 nm as well. The critical current density ( J c ) and transition temperature ( T c ) were determined using current versus voltage (I–V) and resistivity versus temperature ( ρ - T ) measurements, respectively. We found that by increasing Au nanoparticles in the compound, in comparison to the pure YBCO sample, the transition temperature, pinning energy and critical current density will increase. Also, the highest J c is for 1 wt% Au doped YBCO compound that its critical current density is about 8 times more than the J c of pure one in 0.7 T magnetic field. [ABSTRACT FROM AUTHOR]

In this paper, a high-temperature superconducting composite right/left-handed (HTS CRLH) resonator is proposed, which is constructed by microstrip spiral coupled lines and step-like microstrip lines. The dispersion characteristics of the CRLH resonator is obtained and analyzed by an equivalent circuit model and a transmission matrix method. To verify this design methodology, the HTS CRLH resonator is designed and fabricated with a compact size of 11.25 mm $\times$ 16 mm on YBa2Cu3O7 films. The power handling capability of the filter is studied. Finally, the measured and simulated results are in good agreement with each other. [ABSTRACT FROM PUBLISHER]

In this research, we have investigated the effects of three samples of carbon-base nanostructures (carbon nanoparticles, carbon nanotubes and silicon carbide nanoparticles) doping on the properties of Y 1 Ba 2 Cu 3 O 7− δ (YBCO) high temperature superconductor. The pure and doped YBCO samples were synthesized by sol–gel method and characterized by resistivity versus temperature (ρ– T ), current versus voltage ( I – V ), through X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis. The results confirmed that for all the samples, the orthorhombic phase of YBCO compound is formed. We found that the pinning energy and critical current density of samples increase by adding carbon nanostructures to YBCO compound. Also critical temperature is improved by adding carbon nanotubes to YBCO compound, while it does not change much for carbon and silicon carbide nanoparticles doped compounds. Furthermore, the samples were characterized by UV–vis spectroscopy in 300 K and the band gap of the samples was determined. We found that the carbon nanotubes doping decreases YBCO band gap in normal state from 1.90 eV to 1.68 eV, while carbon and SiC nanoparticles doping increases it to 2.20 and 3.37 eV respectively. [ABSTRACT FROM AUTHOR]