Phase relations study on the melting and crystallization regions of the Bi-2223 high temperature superconductor

Polasek, A.; Majewski, Peter; Serra, Eduardo Torres; Rizzo, F.; Aldinger, Fritz

doi:10.1590/s1516-14392004000300005

Cited by 10 publications

(4 citation statements)

References 37 publications

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“…After sintering at 830-850 °C, a further heat treatment with a partial melting step at 850-860 °C for 10 minutes, in 7.5% O 2 /N 2 , was carried out. This partial melting consists of a partial decomposition of the Bi-2223 phase into liquid and solid phases 9,11,12 . After partial melting, the samples were slowly cooled (1.2 °C/h) to about 770 °C and further cooled (1 °C/min) to room temperature.…”

Section: Resultsmentioning

confidence: 99%

“…Controlling the partial melting parameters is very critical, in order to find the optimal temperature and dwelling time where a sufficient liquid amount could be obtained without excessive decomposition of the Bi-2223 phase into secondary phases 9 . This decomposition can generate large precipitates, which tends to remain stable, being not consumed to reform Bi-2223, even after a long post-annealing 11,12 . Therefore, the partial melting has to be more intensively studied, with the aim of improving the microstructure of Bi-2223 blocks.…”

Section: Resultsmentioning

confidence: 99%

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Processing of bulk Bi-2223 high-temperature superconductor

Polasek¹,

Saléh²,

Borges

et al. 2005

Mat. Res.

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The Bi2Sr2Ca2Cu3 O10+x (Bi-2223) is one of the main high temperature superconductors for applications. One of these applications is the Superconductor Fault Current Limiter (SCFCL), which is a very promising high temperature superconducting device. SCFCL's can be improved by using bulk superconductors with high critical currents, which requires a sufficiently dense and textured material. In the present work, a process for improving the microstructure of Bi-2223 bulk samples is investigated. Pressed precursor blocks are processed by sintering with a further partial melting step, in order to enhance the Bi-2223 grain texture and to healing cracks induced by pressing. In order to improve the microstructure, the precursor is mixed with silver powder before pressing. Samples with and without silver powder have been studied, with the aim of investigating the influence of silver on the microstructure evolution. The phase contents and the microstructure obtained have been analyzed through XRD and SEM/EDS. The electromagnetic characterization has been performed by Magnetic Susceptibility Analysis. We present and discuss the process and the properties of the superconducting blocks. High fractions of textured Bi-2223 grains have been obtained

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Processing of bulk Bi-2223 high-temperature superconductor

Polasek¹,

Saléh²,

Borges

et al. 2005

Mat. Res.

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“…That the XRD patterns of quenched samples exhibited high Bi-2201 content could not be clarified in our present work. It was considered as the cause of its high crystallization rate from melt, even during quenching [8] . Perhaps the dimensions of this precipitate emerging via quenching in our specimens are too fine to be detected by EDS.…”

Section: Melting Behaviormentioning

confidence: 99%

Phase evolution during the melting and recrystallization of ceramic core in the (Bi,Pb)-2223 tape

Soubeyroux²,

Zheng

et al. 2006

Physica C: Superconductivity and its Applications

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The phase evolution during melting and recrystallization of ceramic core in Ag-sheathed (Bi,Pb)-2223 monofilamentary tape has been studied. The tape was fabricated by PIT process with powders containing nearly pure (Bi,Pb)-2223 phase. Short samples were melted at 805ºC, 808ºC, 812ºC, 816ºC and 831ºC, slowly cooled down at 1.5ºC/hr. and quenched in air at room temperature. X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) were applied for the phase identification. XRD patterns of samples show that (Bi,Pb)-2223 core is partially melted at 805ºC, 808ºC, 812ºC, and well reformed directly from the melt during the slow cooling. More (Bi,Pb)-2223 phase is decomposed at temperatures higher than 816ºC and can not recrystallize, indicating that a partial melting at some temperatures around a given temperature range is essential for (Bi,Pb)-2223 phase reformation. The results of EDS analysis show that the melt composition moves from that between "2223" and "2212" stoichiometries towards 2212-like stoichiometry with increasing temperature, and Bi-containing 2:1 phase is the main secondary phase. This seems to lead to the conclusion that (Bi,Pb)-2223 phase decomposes incongruently into a 2212-like liquid and (Ca,Sr)-cuprates. 2:1 phase plays the most important role in (Bi,Pb)-2223 meltrecrystallization process. Our results also reveal that plate-like shape (Bi,Pb)-2223 grains can be obtained via melting and recrystallization if the optimum processing conditions are used.

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“…(>100 hrs) sintering for phase growth[24][25]. On the other hand Bi-2212 is relatively easy to synthesize and hence can be obtained in majority single phase form.…”

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confidence: 99%

Enhanced superconducting performance of melt quenched Bi2Sr2CaCu2O8 (Bi-2212) superconductor

Kumar

Sharma

Ahluwalia

et al. 2013

Materials Chemistry and Physics

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We scrutinize the enhanced superconducting performance of melt quench Bismuth based Bi 2 Sr 2 CaCu 2 O 8 (Bi-2212) superconductor. The superconducting properties of melt quenched Bi-2212 (Bi2212-MQ) sample are compared with non-melted Bi2212-NM and Bi 1.4 Pb 0.6 Sr 2 Ca 2 Cu 3 O 10 (Bi-2223). Crystal structure and morphology of the samples are studied using X-ray diffraction and Scanning Electron Microscopy (SEM) techniques. The high field (14T) magneto-transport and DC/AC magnetic susceptibility techniques are extensively used to study the superconducting properties of the investigated samples. The superconducting critical temperature (T c ) and upper critical field (H c2 ) as well as thermally activated flux flow (TAFF) activation energy are estimated from the magneto-resistive [R(T)H] measurements. Both DC magnetization and amplitude dependent AC susceptibility measurements are used to determine the field and temperature dependence of critical current density (J c ) for studied samples. On the other hand, the frequency dependent AC susceptibility is used for estimating flux creep activation energy. It is found that melt quenching significantly enhances the superconducting properties of granular Bi-2212 superconductor. The results are interpreted in terms of better alignment and inter-connectivity of the grains along with reduction of grain boundaries for Bi2212-MQ sample. 2

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Phase relations study on the melting and crystallization regions of the Bi-2223 high temperature superconductor

Cited by 10 publications

References 37 publications

Processing of bulk Bi-2223 high-temperature superconductor

Processing of bulk Bi-2223 high-temperature superconductor

Phase evolution during the melting and recrystallization of ceramic core in the (Bi,Pb)-2223 tape

Enhanced superconducting performance of melt quenched Bi2Sr2CaCu2O8 (Bi-2212) superconductor

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