Preparation of Yba 2 Cu 3 O x Superconductor Prepared with Additives of PbO and Ag 2 O
28 Feb 2009-Transactions on Electrical and Electronic Materials (The Korean Institute of Electrical and Electronic Material Engineers)-Vol. 10, Iss: 1, pp 31-34
TL;DR: In this article, the properties of YBa2Cu3Ox superconducting bulk samples were studied using sol-gel method and solid state reaction method and the effects of different powders and the additives to the density, grain alignment, and porosity of samples, that affect the critical current density of superconductor, also have been investigated.
Abstract: The improvement of preparation process of YBa2Cu3Ox superconductor and its conducting properties is important for practical applications. In this study, the additives such as Ag2O and PbO were used to improve the preparation conditions of YBa2Cu3Ox superconducting bulk samples and the properties of YBa2Cu3Ox superconductors prepared with powders using sol-gel method and solid state reaction method were studied. The effects of the different powders and the additives to the density, grain alignment, and porosity of samples, that affect the critical current density of superconductor, also have been investigated. It is found that the properties of YBa2Cu3Ox prepared with sol-gel synthesized powder and the additives showed better superconductivities than those of conventionally prepared superconductors.
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References
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TL;DR: A stable and reproducible superconductivity transition between 80 and 93 K has been unambiguously observed both resistively and magnetically in a new Y-Ba-Cu-O compound system at ambient pressure.
Abstract: A stable and reproducible superconductivity transition between 80 and 93 K has been unambiguously observed both resistively and magnetically in a new Y-Ba-Cu-O compound system at ambient pressure. An estimated upper critical field H c2(0) between 80 and 180 T was obtained.
5,965 citations
TL;DR: The present work demonstrates that problems caused by low critical current densities and significant deterioration in weak magnetic fields can be overcome through proper microstructural control using molten oxide processing.
Abstract: The progress toward major applications of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$-type high-${T}_{c}$ superconductors has been hindered by low critical current densities (${J}_{c}$) and their significant deterioration in weak magnetic fields. The present work demonstrates that these problems can successfully be overcome through proper microstructural control using molten oxide processing. Melt-textured growth of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ from a supercooled melt created an essentially 100% dense structure consisting of locally aligned, long, needle-shaped grains (typically 40--600 \ensuremath{\mu}m in length). The needles appear to have their long axes parallel to the conduction plane (basal plane) of the orthorhombic structure, with a low-angle orientation change between adjacent grains. This new microstructure, which completely replaces the previous granular and random structure of the sintered precursor, exhibits a dramatically higher transport ${J}_{c}$ (7400 A/${\mathrm{cm}}^{2}$ at 77 K) than the typical sintered materials (${J}_{c}$=150--600 A/${\mathrm{cm}}^{2}$). Even more significant is the much reduced field dependence of ${J}_{c}$(\ensuremath{\approxeq}1000 A/${\mathrm{cm}}^{2}$ at H=1 T as compared to \ensuremath{\approxeq}1 A/${\mathrm{cm}}^{2}$ in the sintered structure), indicating that the coupling between grains is much stronger in the new structure. The mechanism responsible for the suppressed weak-link behavior in the melt-textured material is inferred to be the combined effects of the densification, alignment of crystals, and formation of cleaner grain boundaries.
494 citations
TL;DR: In this paper, biaxially aligned YBa2Cu3O7−x (YBCO) films were fabricated on random Ni-based alloy tapes with yttrium stabilized-zirconia (YSZ) buffer layers deposited by ion-beam-assisted deposition (IBAD).
Abstract: Biaxially aligned YBa2Cu3O7−x (YBCO) films were fabricated on random Ni-based alloy tapes with yttrium stabilized-zirconia (YSZ) buffer layers deposited by ion-beam-assisted deposition (IBAD). Ar+ ion bombardment was found to have two significant effects on the crystalline structure of the YSZ buffer layers: to align a [100] axis with the substrate normal and a [111] axis with the bombarding beam axis. The resulting YSZ films were biaxially aligned on the random polycrystalline tapes, and the azimuthal distribution of the a- and b-axes of YBCO films on the top of the YSZ films was restricted to 10° FWHM. A critical current density (Jc) of 1.13 × 106 A/cm2 (77 K, 0 T) was obtained, and 1.1 × 105 A/cm2 was maintained at 5 T (77 K, B⊥c). The existence of both intrinsic and extrinsic pinning properties was clearly observed in the angular dependence of Jc with B⊥I. The longitudinal field effect on Jc was clearly observed, which indicated straight transport currents. This is evidence for strongly coupled current paths that demonstrate the bulk pinning properties of YBCO.
74 citations
TL;DR: In this paper, it was shown that an essentially complete recovery of the 90 K superconductivity can be achieved by partial melt processing of the material doped with Zr, Ta, Ti, Pt, Rh, and Re, which is attributed to second phase particles draining the dopant elements away from the matrix.
Abstract: Most of the transition metal elements incorporated into the lattice of YBa2Cu3O7−δ are known to severely suppress the superconducting transition temperature. In this work, we show that an essentially complete recovery of the 90 K superconductivity can be achieved by partial melt processing of the material doped with Zr, Ta, Ti, Pt, Rh, and Re, which is attributed to second phase particles draining the dopant elements away from the matrix. Such a full recovery of Tc is not obtained in the case of Nb, V, Ni, Fe, Co, Pd, and Ru. The results are of technological interest in view of the need for nonpoisonous, high melting point substrate, clad or core materials desirable for melt processing of Y‐Ba‐Cu‐O.
49 citations
TL;DR: In this article, textured and Ag doped YBCO superconductors were studied, in which Ag contents were 0-18wt% DTA method was used to determine the starting melt temperatures of YBCOs with different Ag contents, and critical current densities of the samples were compared.
Abstract: The textured and Ag doped YBCO superconductors were studied, in which Ag contents were 0–18wt% DTA method was used to determine the starting melt temperatures of YBCO with different Ag contents The critical current densities of the samples were compared It was found that doped Ag in YBCO matrix formed Ag inclusions with size 10–50 μ m observed by SEM The saturated solubility of Ag in YBCO is about 15wt%
8 citations