GROWTH AND SUPERCONDUCTIVITY OF BI2.USR1.9CA1.0(CU(1-Y)FE(Y))2O(X) SINGLE-CRYSTAL

Fe-substituted Bi-2212 single crystals in rods of Bi2.1Sr1.9Ca1.0(Cu(1-y)Fe(y))2O(x) with y less-than-or-equal-to 0.03 have been grown successfully by the floating zone method (FZM). Fe substitution in the rods depresses the growth stability of Bi-2212 crystals and consequently reduces the size of the crystals. The maximum thickness along the c-axis of the single crystals grown from a rod with y = 0 is as large as 2 mm, but only 0.4 mm for y = 0.03. The maximum Fe solubility limit of the as-grown crystals is less than 0.03 at%. Fe substitution in the crystals decreases sharply not only the superconducting transition temperature, but also the homogeneity of the superconducting phase. The rate of T(c) decrease with actual Fe-substituted content w in the crystals is as high as 16.7 K/(Fe/(Cu + Fe)) at% for the as-grown crystals of w = 0-0.01, but only 7.3 K/(Fe/(Cu + Fe)) at% for the as-grown crystals of w = 0.01-0.022 and the annealed crystals of w = 0-0.022.