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Role of lead substitution in the production of 110‐K superconducting single‐phase Bi‐Sr‐Ca‐Cu‐O ceramics

 

作者: L. Pierre,   J. Schneck,   D. Morin,   J. C. Tole´dano,   J. Primot,   C. Daguet,   H. Savary,  

 

期刊: Journal of Applied Physics  (AIP Available online 1990)
卷期: Volume 68, issue 5  

页码: 2296-2303

 

ISSN:0021-8979

 

年代: 1990

 

DOI:10.1063/1.346534

 

出版商: AIP

 

数据来源: AIP

 

摘要:

We have systematically investigated the influence of the three parameters (temperature of sintering, lead content, and duration of the sintering) on the growth of the (2:2:2:3) phase in ceramics of nominal composition Bi2−xPbxSr2Ca2Cu3O10−x/2, and have determined the compositions and thermal conditions leading to ceramics withTc≊110 K and containing more than 95% of this phase. We show that this result can be obtained by usual calcination near 880°C in air, without recurring to the introduction of excess in the constituants, providing that intermediate grinding are effected, in order to reactivate the formation of the (2:2:2:3) phase which otherwise saturates for long durations of sintering. The suitable nominal compositions (0.3≤x≤0.4) correspond to those that yield inside the grains a lead content in the vicinity of the limit of solubility for lead. From the results of the preceding investigations and of experiments effected on lead‐substituted single crystals of the (2:2:1:2) phase, we have clarified the role played by lead, at the microscopic level, in the enhancement of the formation of the (2:2:2:3) phase. The inferred role is the establishment of strong bonding between the slabs which are the buildings blocks of the structure of the superconducting phases, these slabs being almost independent in the lead‐free compounds. The origin of the stronger bonding is discussed.

 

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