Enhanced residual secondary phase dissolution by atmosphere control in Bi-2212 superconductors

Sager, D.; Koch, M.; Hallstedt, Bengt; Gauckler, Ludwig J.; Chen, M

doi:10.1016/j.physc.2004.01.030

Cited by 10 publications

(6 citation statements)

References 22 publications

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“…The XRD results show that for batch II, only sample II-1, which was heat-treated with lower T p = 845 • C and shorter t p = 16 h, has Cu-free phases, while the others have only Bi2201 and Bi2212 phases. There is no obvious peak for the ordered 4413 phase (an intermediate phase of mixed Bi2212 and Bi2201) as reported by others [39,45,46].…”

Section: Properties Of Metallic Precursorssupporting

confidence: 64%

“…Although both Bi2201 and Bi2212 form in the temperature range 650-790 • C [37], Bi2201 is more stable than Bi2212 and is thus preferred. Additionally, the stability range of Bi2201 is only slightly reduced by decreasing the oxygen partial pressure, but is further reduced by increasing the temperature [45]. Hence, with a lower heating rate, the time for heating is increased from 1.0 to 3.4 h, allowing more time for Bi2201 formation and growth.…”

Section: Effects Of Varying the Testing Rate Rmentioning

confidence: 99%

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Synthesis of Bi₂Sr₂CaCu₂O_xsuperconductors via direct oxidation of metallic precursors

Zhang¹,

Koch²,

Schwartz³

2014

Supercond. Sci. Technol.

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Bi 2 Sr 2 CaCu 2 O x (Bi2212)/Ag multifilamentary wires are manufactured via the powder-in-tube process using oxide powders. After deformation, the wires undergo a partial-melt process, resulting in a complex, heterogeneous microstructure containing multiple secondary phases and porosity, limiting the wires' electrical and mechanical performance. Here, an alternative approach using the direct conversion of metallic precursors (MPs) to Bi2212 is studied. The formation of metallic precursor powders via a mechanical alloy is discussed. The MP powder is then converted to superconducting Bi2212 through a simple two-step heat treatment. By introducing oxygen at a temperature at which Bi2212 is in a stable phase, and holding at an elevated temperature for a sufficient time, the metallic precursors are oxidized and transformed into Bi2212. Several factors that impact the formation and growth of Bi2212 grains are discussed. Peak temperature, holding time and heating rate are shown to affect the MP → Bi2212 conversion, the Bi2201 content and the Bi2212 morphology and density. It is found that Bi 2 Sr 2 CuO y (Bi2201) can be the only phase impurity after heat treatment, which is quite different from what is observed in partial-melt processed wires derived from oxide precursors. Lastly, the microstructure at the sample/silver interface suggests larger size and preferred orientation of Bi2212 grains with the aid of a silver surface. Implications for MP Bi2212 wires are discussed.

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Section: Properties Of Metallic Precursorssupporting

confidence: 64%

Section: Effects Of Varying the Testing Rate Rmentioning

confidence: 99%

Synthesis of Bi₂Sr₂CaCu₂O_xsuperconductors via direct oxidation of metallic precursors

Zhang¹,

Koch²,

Schwartz³

2014

Supercond. Sci. Technol.

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“…These experimental conditions must be carefully defined when developing Ag/Bi2212 superconducting tapes [7], [8].…”

Section: Discussionmentioning

confidence: 99%

Phase Formation and Evolution, Texturing and Current Transport in Ag/Bi2212 PIT Monofilamentary Tapes

Rodrigues

Bigansolli

Cursino

et al. 2005

IEEE Trans. Appl. Supercond.

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Superconducting tapes of ceramic material capable of transporting high current densities at high operation temperatures have been revealed as promising conductors in applied superconductivity. Tapes of Ag/Bi2212 present excellent characteristics and their processing techniques are being improved. This work presents a study on the formation of phases and the texturing behavior of Ag/Bi2212 monofilamentary tapes after several heat treatments with different cooling rates from 890 C to 830 C and silver doping, allowing an optimization of the heat treatment profiles aiming the obtainment of close to stoichiometric superconducting phases with high texturing. The tapes were fabricated using Bi2212 precursor powder and the powder-in-tube (PIT) method. The powder was pressed inside the Ag tube, and the set was mechanically deformed by swaging and rolling to the final thickness of 150 m. After heat treatment, the samples were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) equipped with Energy Dispersive Spectrometer (EDS). The results show the effect of each heat treatment profile on the microstructure and superconducting characteristics of the Ag/Bi2212 tapes, as well as they show the ways to obtain the best texturing of the samples aiming high current transport.

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“…Although reflections of both samples heat-treated at 888 C for 0.5 and 1 h showed same peak angle of 29.1 , samples heat-treated at 886 C for 0.5 and 1 h showed different peak angle. D. Sager et al explained that the shift of the peak to lower angles corresponds to an increase of the axis [11]. It is likely that the shift from 29.25 of 886 C for 0.5 h to 29.05 of 886 C for 1 h means longer soaking time increased the -axis.…”

Section: Methodsmentioning

confidence: 99%

Effect of Filament Configuration on Critical Current Density of Bi2212/Ag Wires With Low Ag Ratio

Kim

et al. 2008

IEEE Trans. Appl. Supercond.

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Effect of filament configuration and heat treatment of Bi2212/Ag round wire with low Ag ratio on the engineering critical current density ( ) was reported. We have fabricated 55 7, 85 7, and 121 7 wires with different Ag ratio and evaluated at various wire diameters. We have also changed the parameters of heat treatment. The effects of maximum process temperature ( ) and soaking time at and average filament diameter on the were also studied. 121 7 wire of 0.95 mm diameter heat-treated at = 888 C showed of 858 A/mm 2 at 4.2 K, 0 T. Index Terms-Bi2212/Ag wire, critical current density, multi-filamentary wire, powder-in-tube.

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Enhanced residual secondary phase dissolution by atmosphere control in Bi-2212 superconductors

Cited by 10 publications

References 22 publications

Synthesis of Bi₂Sr₂CaCu₂O_xsuperconductors via direct oxidation of metallic precursors

Synthesis of Bi₂Sr₂CaCu₂O_xsuperconductors via direct oxidation of metallic precursors

Phase Formation and Evolution, Texturing and Current Transport in Ag/Bi2212 PIT Monofilamentary Tapes

Effect of Filament Configuration on Critical Current Density of Bi2212/Ag Wires With Low Ag Ratio

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Enhanced residual secondary phase dissolution by atmosphere control in Bi-2212 superconductors

Cited by 10 publications

References 22 publications

Synthesis of Bi2Sr2CaCu2Oxsuperconductors via direct oxidation of metallic precursors

Synthesis of Bi2Sr2CaCu2Oxsuperconductors via direct oxidation of metallic precursors

Phase Formation and Evolution, Texturing and Current Transport in Ag/Bi2212 PIT Monofilamentary Tapes

Effect of Filament Configuration on Critical Current Density of Bi2212/Ag Wires With Low Ag Ratio

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Synthesis of Bi₂Sr₂CaCu₂O_xsuperconductors via direct oxidation of metallic precursors

Synthesis of Bi₂Sr₂CaCu₂O_xsuperconductors via direct oxidation of metallic precursors