Tuning High-Tc Superconductors via Multistage Intercalation

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Science  06 Dec 1991:
Vol. 254, Issue 5037, pp. 1487-1489
DOI: 10.1126/science.254.5037.1487


Multistage intercalation has been used to tune the interaction between adjacent blocks of CuO2 sheets in the bigh-Tc (high superconducting transition temperature) superconductor Bi2Sr2CaCu2Ox. As revealed by atomic-resolution transmission electron microscopy images, foreign iodine atoms are intercalated into every nth BiO bilayer of the host crystal, resulting in structures of stoichiometry IBi2nSr2nCanCu2nOx with stage index n up to 4. An expansion of 3.6 angstroms for each intercalated BiO bilayer decouples the CuO2 sheets in adjacent blocks. A comparison of the superconducting transition temperatures of the pristine host material and intercalated compounds of different stages suggests that the coupling between each pair of adjacent blocks contributes ∼5 K to Tc in Bi2Sr2CaCu2Ox.