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首页> 外文期刊>Physica, C. Superconductivity and its applications >Synthesis, microstructural evolution and the role of substantial addition of PbO during the final processing of (Bi,Pb)-2223 superconductors
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Synthesis, microstructural evolution and the role of substantial addition of PbO during the final processing of (Bi,Pb)-2223 superconductors

机译：（Bi，Pb）-2223超导体最终加工过程中PbO的合成，微结构演变和大量添加的作用

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The evolution of the phase formation and microstructure in (Bi,Pb)-Sr-Ca-Cu-O (BPSCCO) superconducting materials have been studied through a two-cycle annealing process by X-ray diffraction and SEM observations. Samples were Pb-doped (part 0.4 of Bi substituted by Pb) during the first thermal cycle. Yet, the synthesizing efficiency of the (Bi,Pb)-2223 phase was found to be greatly re-enhanced during the second thermal cycle by a second and substantial addition of up to 20% excess of PbO in weight. No significant increase of secondary phases was observed. Pb addition was shown to be more effective at the end of a multi-step thermal cycle. Therefore the lack of Pb that arise in BPSCCO system after some heat treatment duration is shown to be one of the most important rate-limiting (Bi,Pb)-2223 transformation. The second sintering duration at 835 degreesC was optimized with respect to the weight percentage of PbO in excess. The present work attempts also to point out the complex mechanisms of the (Bi,Pb)-2223 formation reactions. Some intermediate phases are identified and the liquid phase is suggested to derive from a partial decomposition of the (Bi,Pb)-2212 phase. This decomposition is highly sensitive to Pb addition. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 29]
机译：通过X射线衍射和SEM观察，通过双循环退火工艺研究了（Bi，Pb）-Sr-Ca-Cu-O（BPSCCO）超导材料中相形成和微观结构的演变。在第一个热循环过程中，样品被掺Pb（Bi的0.4部分被Pb取代）。然而，发现通过在第二次热循环中第二次并大量添加高达20％（重量）过量的PbO，可以极大地提高（Bi，Pb）-2223相的合成效率。没有观察到次级相的显着增加。已表明，在多步热循环结束时，添加铅更为有效。因此，经过一段时间的热处理后，BPSCCO系统中缺乏的Pb被证明是最重要的限速（Bi，Pb）-2223转化之一。相对于过量的PbO的重量百分比，优化了在835℃的第二烧结持续时间。本工作还试图指出（Bi，Pb）-2223形成反应的复杂机理。鉴定出一些中间相，并建议该液相来自（Bi，Pb）-2212相的部分分解。这种分解对铅的添加高度敏感。 （C）2001 Elsevier Science B.V.保留所有权利。 [参考：29]

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