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Improvement in Fabrication of Hg-1223 Superconductor by Te-Doping

Published online by Cambridge University Press:  18 March 2011

K.K. Yau
Affiliation:
Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, People's, Republic of China
C.C. Lam
Affiliation:
Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, People's, Republic of China
L.J. Shen
Affiliation:
Department of Physics, Nanjing University of Chemical Technology, Nanjing 210009, People's, Republic of China
S.H. Li
Affiliation:
Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, People's, Republic of China
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Abstract

The sealed quartz tube method is one of the usual methods used for sintering mercury-based copper oxide superconductors. By this method, precursor pellets are inserted into the quartz tube together with certain mass ratio to the reagent sample pellets for controlling the mercury vapour pressure. A certain amount of excess HgO is required to ensure the fabricated sample to have the desired composition. In our research, it was found that if a small amount of TeO2 is added and mixed with the pulverized precursor after first calcination, Hg-1223 superconductors can be fabricated without using the precursor pellet and no excess HgO is required. Thus, the fabrication process can be simplified. As mercury and its oxide are toxic, if no excess Hg is involved, it is safe and good for the laboratory-environment. In this research, some amounts of 0.10 and 0.18 wt% (weigh percentage) of TeO2 were added into the precursor, it is shown that the critical temperature of the fabricated samples is comparable to that of the undoped Hg-1223 samples. For 0.10 wt% of TeO2, the Tc of the as-synthesized sample is about 116.7 K whereas the annealed Te-doped Hg-1223 is about 134.2 K. For 0.18 wt% of TeO2, the Tc of the as- synthesized and annealed samples are 115.8 K and 134.6 K, respectively. The phase structure of samples fabricated in this research has been analyzed by the X-ray diffraction technique. It shows that the Hg-1223 phase is dominated.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

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References

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