Defects in Decomposed YBa2Cu4Ox(124) Superconductor after Rapid Annealing


Decomposition of 124 into 123 has been studied after rapid annealing at temperatures from 800°C to 1000°C. It was found that the superconducting transition temperature (Tc) depended on the annealing temperature and atmosphere. For decomposed samples, fine-scale defects with strong strain contrast are observed in the 123 matrix. High-resolution electron microscopy studies show that the defects are parallel to the (001) planes of the 123 matrix. The length of the defects varies andranges from 5 nm to 50 nm in the direction parallel to the (001) planes. The defects have been interpreted to be copper oxides, which could be flux pinning centers in these materials.


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This work was supported by the National Science Foundation -Office of Science and Technology Centers under contract #STC-8809854 (YL, YG) and by the U. S. Department of Energy, Offices of Basic Energy Sciences - Materials Science, and Energy Storage and Distribution, Conservation and Renewable Energy, under contract #W-31-109-ENG-38 (KLM, HS, UB). The use of the H-9000 in the Dept. of Mater. Sci. & Eng., Northwestern University is gratefully acknowledged.

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Li, Y., Gao, Y., Merkle, K.L. et al. Defects in Decomposed YBa2Cu4Ox(124) Superconductor after Rapid Annealing. MRS Online Proceedings Library 209, 813–818 (1990).

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