Phase assemblage and morphology during the partial melt processing of Bi-2212 thick films

Lang, Th.; Buhl, D.; Al-Wakeel, S.; Schneider, Daniel; Gauckler, Ludwig J.

doi:10.1016/s0921-4534(97)01475-5

Cited by 16 publications

(9 citation statements)

References 39 publications

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“…The AEC and CF grains are prominent in the melt (figures 5 and 6) and are present as remnants in fully processed wires (figure 1). Their area fractions are high in the melt in our round wire and in many other forms of 2212 conductor, such as melt-processed 60 μm thick 2212 film on Ag foil [17]. The grains of AEC and CF cause serious problems when forming 2212 from the melt.…”

Section: Discussionmentioning

confidence: 94%

Filament to filament bridging and its influence on developing high critical current density in multifilamentary Bi₂Sr₂CaCu₂O_xround wires

Shen¹,

Jiang²,

Kametani³

et al. 2009

Supercond. Sci. Technol.

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Increasing the critical current density ( J c ) of the multifilamentary round wire Ag/Bi 2 Sr 2 CaCu 2 O x (2212) requires understanding its complicated microstructure, in which extensive bridges between filaments are prominent. In this first through-process quench study of 2212 round wire, we determined how its microstructure develops during a standard partial-melt process and how filament bridging occurs. We found that filaments can bond together in the melt state. As 2212 starts to grow on subsequent cooling, we observed that two types of 2212 bridges form. One type, which we call Type-A bridges, forms within filaments that bonded in the melt; Type-A bridges are single grains that span multiple bonded filaments. The other type, called Type-B bridges, form between discrete filaments through 2212 outgrowths that penetrate into the Ag matrix and intersect with other 2212 outgrowths from adjacent filaments. We believe the ability of these two types of bridges to carry inter-filament current is intrinsically different: Type-A bridges are high-J c inter-filament paths whereas Type-B bridges contain high-angle grain boundaries and are typically weak linked. Slow cooling leads to more filament bonding, more Type-A bridges and a doubling of J c without changing the flux pinning. We suggest that Type-A bridges create a 3D current flow that is vital to developing high J c in multifilamentary 2212 round wire.

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Section: Discussionmentioning

confidence: 94%

Filament to filament bridging and its influence on developing high critical current density in multifilamentary Bi₂Sr₂CaCu₂O_xround wires

Shen¹,

Jiang²,

Kametani³

et al. 2009

Supercond. Sci. Technol.

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“…The cooling rate from this temperature to the temperature of 850 °C and the time of permanence at 850 °C (chosen due to relatively large monophasic field of Bi-2212) should also be investigated. If these four parameters are optimized, there is a chance that the percentages and mean grain sizes of secondary phases can be decreased 11,12 . A detailed study of the influences of these four parameters on the type and percentage of secondary phases in the bulk specimens, as well as on their mean grain sizes is under way.…”

Section: Discussionmentioning

confidence: 99%

“…The technology has been under development based on the partial-melting route, which had already been used in the production of Bi-2212 thick films and tapes [11][12] . The main objective of this technology is the production of bulk Bi-2212 superconductors with high superconducting transport properties, namely critical currents (I c ) and critical current densities (J c ).…”

Section: Introductionmentioning

confidence: 99%

Development of Bulk Bi2+xSr3-yCa yCu 2O8+delta Superconductors by Partial-Melting Route for Fault Current Limiters Application

Marinković

Xia²,

Saléh³

et al. 2002

Mat. Res.

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The production of bulk Bi 2+x Sr 3-y Ca y Cu 2 O 8+∆ (Bi-2212) superconductors for fault current limiter application was developed via a partial-melting route. Aiming high I c (critical current), which is the essential superconducting characteristic for application of this material in the construction of Fault Current Limiters (FCL), the produced blocks have predominance of Bi-2212 phase (83 wt%), which characterizes with high values of zero and onset transport critical temperature of 92 K and 97.5 K, respectively. A relatively low transition width, ∆T, from the superconducting to the normal state of 5.5 K, revealed a good intergrain connectivity. Consequently, current measurements on the blocks of Bi-2212 show promising I c values of 230 A and 850 A for direct and alternate current, respectively. It is expected that further increases in the I c values will depend on the elimination of an observed amorphous phase and further reduction of amount and grain sizes of secondary phases, still present in the blocks obtained by the proposed partial-melting route. This may be achieved by a further optimization of the partial-melting processing parameters.

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“…(4,5) Estas fases sólidas são, tipicamente, as mesmas fases observadas no presente trabalho, o que está de acordo com a literatura. (1,(3)(4)(5) do que a 2212, sendo este um dos motivos pelo qual emprega-se uma taxa de resfriamento extremamente lenta, de modo a permitir a recristalização de altas frações de 2212. As análises por DRX e por MEV/EDS mostraram frações significativas de 2201, ainda que não muito elevadas, mas que poderiam ser minimizadas pela otimização do processo.…”

Section: Bloco Precursor Composiçãounclassified

“…O óxido Bi 2 Sr 2 CaCu2O 8+x (Bi-2212) é um dos supercondutores de alta temperatura mais promissores para aplicações. Entre as características que possibilitam o seu emprego em diversos segmentos do setor elétrico destacam-se: (1) um largo campo de estabilidade química, em função da temperatura e composição; ausência de elementos altamente tóxicos; temperatura crítica de transição para o estado supercondutor (T c < 96 K) superior à temperatura do nitrogênio líquido (77 K).…”

Section: Introductionunclassified

PROCESSAMENTO DO SUPERCONDUTOR CERÂMICO Bi-2212 POR FUSÃO PARCIAL

Polasek

Sena

Sens³

et al. 2008

TMM

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O óxido Bi 2 Sr 2 CaCu 2 O 8+x (Bi-2212) é um dos principais supercondutores cerâmicos de alta temperatura para o desenvolvimento de aplicações, seja na forma de fitas ou na forma maciça. No presente trabalho, investiga-se o processamento de blocos maciços de Bi-2212 pelo método de fusão parcial. O pó precursor é prensado na forma de blocos, que são parcialmente fundidos, seguindo-se um resfriamento lento e recozimento isotérmico. Foram empregados precursores com diferentes composições e a adição de pó de prata também foi estudada. Foram realizadas análises por DRX, MEV/EDS e DTA. A corrente crítica dos blocos (I c ) foi medida em corrente contínua, à temperatura do nitrogênio líquido (77 K). A fusão parcial produz a decomposição da fase Bi-2212 em líquido e fases sólidas. O resfriamento lento tende a promover a densificação do material e o crescimento de longos grãos texturizados de Bi-2212, que favorece o transporte de corrente elétrica. Contudo, ocorre também a precipitação de fases secundárias, que podem dificultar o transporte de corrente. Foram obtidas amostras com valores de I c acima de 100 A.

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Phase assemblage and morphology during the partial melt processing of Bi-2212 thick films

Cited by 16 publications

References 39 publications

Filament to filament bridging and its influence on developing high critical current density in multifilamentary Bi₂Sr₂CaCu₂O_xround wires

Filament to filament bridging and its influence on developing high critical current density in multifilamentary Bi₂Sr₂CaCu₂O_xround wires

Development of Bulk Bi2+xSr3-yCa yCu 2O8+delta Superconductors by Partial-Melting Route for Fault Current Limiters Application

PROCESSAMENTO DO SUPERCONDUTOR CERÂMICO Bi-2212 POR FUSÃO PARCIAL

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Phase assemblage and morphology during the partial melt processing of Bi-2212 thick films

Cited by 16 publications

References 39 publications

Filament to filament bridging and its influence on developing high critical current density in multifilamentary Bi2Sr2CaCu2Oxround wires

Filament to filament bridging and its influence on developing high critical current density in multifilamentary Bi2Sr2CaCu2Oxround wires

Development of Bulk Bi2+xSr3-yCa yCu 2O8+delta Superconductors by Partial-Melting Route for Fault Current Limiters Application

PROCESSAMENTO DO SUPERCONDUTOR CERÂMICO Bi-2212 POR FUSÃO PARCIAL

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Filament to filament bridging and its influence on developing high critical current density in multifilamentary Bi₂Sr₂CaCu₂O_xround wires

Filament to filament bridging and its influence on developing high critical current density in multifilamentary Bi₂Sr₂CaCu₂O_xround wires