Heterostructured Bi-based cuprate high-T-c superconductors with unusually coordinated metal halides

Attempts have been made to prepare various high-T-c, superconducting interc alation compounds, M-X-Bi2Sr2Can-1Cun O2n+4+delta (M = metal; X = halogen; n = 1, 2, and 3), with the synthetic strategy of hard-soft-acid-base intera ction. The chimie douce route such as vapor transport and ionic diffusion i s found to be effective in intercalating soft Le Lewis acidic guest species (AgxIwx-w, HgI2delta-, HgBr2delta-, and AuI3delta-) into the Lewis basic B i2Sr2Can-1 CunO2n+4+delta lattice. According to the X-ray diffraction and m agnetic property measurements on these intercalates, it becomes clear that the basal increment upon intercalation (3.25-7.35 A) is governed by the int erlayer geometry of the intercalant, while the accompanying T-c change depe nds on the charge transfer between host and guest. The extended S-ray absor ption fine structure and Raman studies reveal that mercuric halides are int ercalated as linear molecules as in vapor state, while silver iodide forms a two-dimensionally extended ionic-conducting channel. In the case of new g old iodide intercalate, unique trigonal planar AuI3, species is identified as the first example of an isolated gold iodide molecule. :(C) 1999 Academi c Press.