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TlBa2Ca2Cu3O9 (Tl-1223) films have promising applications due to their high critical temperature and strong magnetic flux pinning.Nevertheless,the preparation of pure phase Tl-1223 film is still a challenge.We successfully fabricate Tl-1223 thin films on LaAlO3 (001) substrates using dc magnetic sputtering and a post annealing two-step method in argon atmosphere.The crystallization temperature of Tl-1223 films in argon is reduced by 100℃ compared to that in oxygen.This greatly reduces the volatilization of Tl and improves the surface morphology of films.The lower annealing temperature can effectively improve the repeatability of the Tl-1223 film preparation.In addition,pure Tl-1223 phase can be obtained in a broad temperature zone,from 790℃ to 830℃.In our study,the films show homogenous and dense surface morphology using the presented method.The best critical temperature of Tl-1223 films is characterized to be 110K,and the critical current Jc (77K,0 T) is up to 2.13 × 106 A/cm2.