Synthesis and characterization of a new layered cuprate LiI3Bi2Sr2CaCu2O8

A new layered cuprate with the composition LiI3Bi2Sr2Ca Cu2O8 has been synt hesized by the reaction of Bi2Sr2CaCu2O8 with lithium iodide under an atmos phere of iodine at 300 degrees C. The new cuprate is pale green and lamella r and crystallized in a tetragonal cell with the lattice parameters a = 5.4 038 and c = 44.179 Angstrom. A structural model for the cuprate is proposed in which the triiodide anions are stably intercalated in the Bi2O2 layer t o form a tilted monolayer accompanying lithium cations, XPS data show that the electronic state of the intercalated triiodide anions is significantly perturbed through the interaction,vith the surrounding atomic species and t hat the lithium-iodine intercalation results in a significant narrowing of the valence band, leading to a resistivity of the cuprate as high as 0.777 k Omega cm at 30 degrees C. Identification of the iodine species in IBi2Sr2 CaCu2O8 is also discussed. (C) 1998 Academic Press.