The Dependence of the Superconductivity on Intercalant Amount in Iodine Intercalation of Bi₂Sr₂Ca_(n-1)Cu_nO_y(n=2, 3) Superconductors by Using Reactant FeI₂

Abstract

We have investigated the influence on the superconductivity of X for I_xBi₂Sr₂Ca_(n-1)Cu_nO_y (n=2, 3) prepared by intercalation into Bi2212 single crystal, Bi2212 and Bi2223 polycrystalline superconductors by using FeI₂ as reactant. The coexistence of Bi2212 phase and stage-1 intercalated phase is found in the range 0.2≤X≤0.9 by using XRD of single crystal samples. The sharp slope, dT_c/dX, is also found for X≥0.9 from the measurement of the resistivity of I_xBi₂Sr₂CaCu₂O_y single crystal samples. The slope of I_xBi₂Sr₂CaCu₂O_y polycrystalline samples is different from ones of single crystal samples and I_xBi₂Sr₂Ca₂Cu₂O_y polycrystalline samples.