Improvement of the Superconducting Transport Properties of YBa2Cu3O7− δ by BaZrO3 Doping (original) (raw)
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Physica Status Solidi (a), 1993
A preparation process for YBa2Cu3O7—δ (afterhere YBCO) superconducting ceramics is presented, in which partial substitution of the copper oxide component by metallic copper is used. The results of an investigation for improving the critical current in YBCO superconductors are also presented. These results show that the YBCO superconductors can be successfully prepared by using the partial metallic copper substitution process. The sintered superconducting ceramics all contain the same pure single phase. The critical current Jc of these samples is linearly dependent on the substituted metallic copper content up to 50 wt%. For samples substituted with about 50 wt% of the copper content Jc is improved by a factor of about 1.5, i.e. Jc > 300 A/cm2. The experimental values of Jc measured at a temperature of 77 K and zero field show that Jc is limited by the intergrain tunneling weak-link effect. The linear dependence of Jc on the normal state tunneling resistance is in good agreement with the Ambegaokar-Baratoff theory. The energy gap of YBCO superconductors is estimated based on the Ambegaokar-Baratoff theory to be as high as 2Δ = 7.84kTc.
Physica C: Superconductivity, 2004
We report systematic studies of AC magnetic susceptibility and transport properties of Y 1-x Ca x Ba 2 Cu 3 O z bulk samples with 0≤x≤0.4. Single phase materials, reduction of carrier concentration and decrease of T c to 83K were obtained at doping levels up to 20%. For Y 0.7 Ca 0.3 Ba 2 Cu 3 O z sample the improvement of grains boundary transport and screening capabilities has been observed as a result of the optimal ratio between carrier concentration and impurity phase BaCuO 2 presence. The appearance of bulk pinning and nonlinear effects starting at the highest temperature were detected also.
Journal of Modern Physics, 2011
We report the results of dc resistivity, ac susceptibility, and thermopower study of partial substitution at Y (A site by Ca) and at Cu (B site by Ni) polycrystalline superconductors. The iodometric analysis reveals that the oxygen deficiency, , for YBa 2 Cu 3 O 7- (S-I), Y 0.9 Ca 0.1 Ba 2 Cu 3 O 7- (S-II), Y 0.8 Ca 0.2 Ba 2 Cu 3 O 7- (S-III) and Y 0.9 Ca 0.1 Ba 2 (Cu 0.99 Ni 0.01) 3 O 7- (S-IV) samples are 0.16, 0.30, 0.39 and 0.29 respectively. The x-ray powder diffraction pattern indicates that all samples are in orthorhombic phase. The dc resistivity, ac susceptiblity and the thermopower measurements shows that the divalent Calcium doping at the trivalent Y site and transition metal Ni doping at Cu site causes a suppression of the superconducting transition temperature (T c) from 89 to 81 K. The ac susceptibility confirms the ferromagnetic to antiferromagnetic phases at a defined T c. The room temperature S value increases for Ca substituted YBa 2 Cu 3 O 7- while to that it decreases for Y 0.9 Ca 0.1 Ba 2 (Cu 0.99 Ni 0.01) 3 O 6.71. The above feature is an indicative of enhanced number of mobile holes for the Ca doped YBa 2 Cu 3 O 7- , while to that the charge carrier density is reduced in simultaneous A (Ca) and B (Ni) site doped sample.
The Conductivity Parameters of YBa2Cu3O6.5+Superconductor Compound
Al-Nahrain journal of science, 2022
The high-temperature superconductor like YBa2Cu3O6.5+ was prepared by solid-state reaction method at calcination temperatures (900 °C). The crystal structure was confirmed using X-ray diffraction, and it was found that YBa2Cu3O6.5+ showed orthorhombic phase with lattice parameters (a = 3.82030, b = 3.88548, and c = 11.6835 Å) with space group (Pmmm). The sample was sintered at sintering temperatures (900 °C) for (24 hr). The oxygen excess () was nearly (0.36), which was effective in the appearing superconducting properties. The sample YBa2Cu3O6.86 had a critical temperature of about (92 K). The simulation on the XRD-pattern was necessary to predicate the shape of the unit cell and the position of atoms in the unit cell. The last is very important to find some theoretical date, which are benefit in the predication the conductivity parameters through the sequence's unit cells, which are useful in the conductivity mechanism. This mechanism is depending on the concept of interlayer coupling, so the number of the layers including the unit cell is effective parameter in the conductivity mechanism through the normal resistivity created.
Physica Status Solidi (a), 1993
A preparation process for YBalCu,O, (afterhere YBCO) superconducting ceramics is presented, in which partial substitution of the copper oxide component by metallic copper is used. The results of an investigation for improving the critical current in YBCO superconductors are also presented. These results show that the YBCO superconductors can be successfully prepared by using the partial metallic copper substitution process. The sintered superconducting ceramics all contain the same pure single phase. The critical current J , of these samples is linearly dependent on the substituted metallic copper content up to 50 wt%. For samples substituted with about 50 wtoh of the copper content J , is improved by a factor of about 1.5, i.e. J , > 300 A/cm2. The experimental values of J , measured at a temperature of 77 K and zero field show that J , is limited by the intergrain tunneling weak-link effect. The linear dependence of J , on the normal state tunneling resistance is in good agreement with the Ambegaokar-Baratoff theory. The energy gap of YBCO superconductors is estimated based on the Ambegaokar-Baratoff theory to be as high as 24 = 7.84kT.
Magnetization and Susceptibility Studies on BaZrO 3 -Doped YBa 2 Cu 3 O 7 − x Bulk Superconductors
Journal of Superconductivity, 2002
We studied the YBa2Cu3O7 - x bulk superconductor doped with BaZrO3 up to 50 wt.%, obtained by solid-state reaction powder technology. From DC magnetization loops and low frequency AC susceptibility measurements we determined the influence of the BaZrO3 doping level on the critical temperature, critical current density, field for full penetration, and intergrain lower critical field. The results show that
Investigation of Lu effect on YBa2Cu3O7−δ superconducting compounds
Journal of Materials Science: Materials in Electronics, 2012
This study reports the effect of Lu addition on the microstructural and superconducting properties of YBa 2 Lu x Cu 3 O 7-d (Y123) superconducting samples with x = 0, 0.1, 0.3, 0.5 and 0.7 by means of X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), electron dispersive X-ray (EDX), electrical resistivity and transport critical current density (J c) measurements. The samples prepared by the liquid ammonium nitrate and derivatives are exposed to various annealing time (20, 40 and 60 h) and temperature (950, 960 and 970°C), and the best ambient for the sample fabrication is determined to be 970°C for 20 h. Zero resistivity transition temperatures (T c), critical current densities (J c), variation of transition temperatures, hole-carrier concentration, grain size, lattice parameter, surface morphology, element distribution, crystallinity and resistivity (at room temperature) values of the bulk superconducting samples prepared at 970°C for 20 h are compared with each other. T c and J c values of the samples are inferred from the dc resistivity and the critical current measurements, respectively. The results show that the T c value of the pure sample is about 90.6 K while the sample doped with 0.1 wt% Lu has the maximum T c value (92.5 K). However, beyond x = 0.1, the T c value is observed to decrease toward to 83.5 K with increment in the Lu addition. Similarly, the J c values measured are found to reduce from 142 to 76 A/cm 2 with the addition. Moreover, XRD measurements show that both pure and Lu-doped samples exhibit the polycrystalline superconducting phase with the changing intensity of diffraction lines and contain Y123 and Y211 phase, confirming the incorporation of Lu atoms into the crystalline structure of the samples studied. At the same time, comparing of the XRD patterns of samples, the intensity ratio of the characteristic (110) and (013) peaks on the sample doped with 0.1 wt% Lu is more than that on the other samples prepared. Additionally, SEM images display that the sample doped with 0.1 wt% Lu obtains the best crystallinity, grain connectivity and largest grain size whereas the worst surface morphology is observed for the maximum doped sample (x = 0.7). Further, EDX results demonstrate that the Lu atoms doped are successfully introduced into the microstructure of the Y123 samples studied and the maximum Cu element level is observed for the sample doped with 0.1 wt%, explaining that why this sample obtains the best superconducting properties compared to others. According to all the results obtained, it is concluded that the 0.1 wt% Lu addition into the Y123 system improves the microstructural and superconducting properties of the samples studied.
Investigation of physical and structural properties of cs doped y1ba2cu3o7 superconductors
Cumhuriyet Science Journal, 2021
In this work, YBa2‑xCsxCu3O7‑δ (x= 0.05, 0.1, 0.2 and 0.3 wt. %) samples were prepared by using solid state reaction method. Some electrical, physical and structural properties of these compounds were examined by using SEM (scanning electron microscopy), XRD (X-ray diffraction), electrical resistivity, critical current density and AC susceptibility measurements, respectively. On the basis of the SEM measurements, it would seem that increasing the amount of Cs doping, the porous structures decrease and the grain size increases up to approximately 50 μm. Unit cell parameters were calculated by employing XRD measurements. On the basis of the data obtained from X-ray diffraction, Cs atoms displaced Ba atoms in the crystal structure. From the measurements of electrical resistivity at 80 K-120 K temperature, it was determined that the highest transition temperature was 91.5 K after addition of 0.05 wt. % Cs. The critical transition temperature was decreased by increasing the amount of Cs ...