Effect of Ba Substitution on the Formation of (Tl,Bi)-1234 Superconducting Phase

초록

(Tl(1-x) Bi (x) )(Sr(2-y) Ba (y) )Ca(3)Cu(4)O (z) ((Tl,Bi)-1234) samples (x=0.1-0.3, y=0.4-1.5) were synthesized under ambient pressure by using a two-step solid-state reaction method to investigate the effect of Ba substitution on the formation and superconducting properties of the (Tl,Bi)-1234 phase. X-ray diffraction analysis shows that nearly single-phased samples are obtained for (Tl(0.8)Bi(0.2))(Sr(2-y) Ba (y) )Ca(3)Cu(4)O (z) (0.8a parts per thousand currency signya parts per thousand currency sign1.2), suggesting that control of the composition ratio of Sr and Ba in the bridging layer is a key to stabilizing the 1234-type structure. The critical temperature for the nearly single-phased samples remained between 106.9 K and 109.1 K and was not significantly affected by the change in the Ba content.

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