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Influence of Complexing Agent in Tl-Containing Sol-Gel Derived Precursor on Critical Temperature Enhancement of TI0.5Pb0.5Sr1.8Yb0•2CaCu2O7 Superconductor

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Superconducting oxide ceramics of composition I0.5Pb0.5SrI.8Yb0.2CaCu2O7 was prepared by using a single-step sol-gel process using two different complexing agents (tartaric acid and citric acid). The effect of the complexing agents (0.0-11.0% (w/w %» on superconductivity of the samples were studied. It was found that the values of critical temperature, Tc zeroי was enhanced from 88 K (for the sample without any complexing agents) to 95 K (for sample with 11 w/w % tartaric acid) and 97 K (for sample with 11 w/w% citric acid). SEM analysis showed formation of ultra-fine grains with 1-2 J.1m average grains size for the sample without complexing agents. Addition of the complexing agents induced growth of elongated grains of 5-10 J.1m in average length. The Tc enhancement was discussed in terms of changes in hole concentration and sample microstructure as a result of use of the complexing agents.

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