Structure and Superconducting Properties of Bi-2212 Cylinders Prepared by Diffusion Process
Structure and Superconducting Properties of Bi-2212 Cylinders Prepared by Diffusion Process
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扩散法制备Bi-2212圆柱体的结构和超导性能
DOI：
10.1007/978-1-4757-9056-6_72
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
K. Tachikawa
中科院分区：
文献类型：
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作者：
Y. Yamada;F. Yamashita;K. Wada;K. Tachikawa
利用Sr-Ca-Cu氧化物衬底与Bi-Cu氧化物涂层之间的扩散反应合成了Bi-2212氧化物超导体。将Sr：Ca：Cu原子比为2：1：2的衬底通过CIP压制成圆柱形棒或管，然后烧结。具有Bi：Cu比率为2：1且添加Ag 2 O的涂层涂覆在基底的表面周围。Bi-2212扩散相具有高密度和取向结构，具有片状晶粒。在4.2K时，厚度约为150 μm的扩散层的输运IC和Je分别超过300 A和2 × 104 A/cm 2。输运J_c随温度的升高而减小，在30 K、1 T下约为1 × 104 A/cm ~ 2。在Ar和N2等惰性气体气氛中进行后退火可以提高样品的Tc。在4.2 K下，样品的主体端的总电阻率为10−8Ω. cm 2的数量级，并显示出高达Ic的欧姆关系。本工艺制备的Bi-2212氧化物圆柱体具有大的传输IC和Jc以及低的接触电阻率，似乎有希望作为超导磁体的电流引线。
Bi-2212 oxide superconductors have been synthesized by the diffusion reaction between Sr-Ca-Cu oxide substrate and Bi-Cu oxide coating layer. The substrate with Sr:Ca:Cu atomic ratio of 2:1:2 is pressed into a cylindrical rod or tube by CIP, and then sintered. The coating layer with Bi:Cu ratio of 2:1 and Ag20 addition is coated around the surface of the substrate. The Bi-2212 diffusion phase shows high density and oriented structure with plate-like grains. The transport Ic and Je of the diffusion layer, about 150 µm in thickness, exceed 300 A and 2 × 104A/cm2at 4.2 K, respectively. The transport Jc decreases with temperature, and is about 1 × 104A/cm2at 30 K under 1 T. Post annealing in inert gas atmosphere such as Ar and N2 improves Tc of the specimen. The overall resistivity of bulk ends of the specimen is in the order of 10−8Ω.cm2at 4.2 K, and shows an ohmic relationship up to Ic. Bulk Bi-2212 oxide cylinders prepared by the present process with large transport Ic and Jc as well as low contact resistivity seem to be promising as a current lead for superconducting magnets.