Preparation and Chemical Composition of Superconducting Oxide Tl2Ba2Can-1CunO2n+4 with n=1, 2 and 3

Abstract

Superconducting oxides of Tl₂Ba₂Ca _n-1Cu _n O_2n+4 with n=1, 2 and 3 were synthesized, and their structure and chemical composition were examined by X-ray powder diffraction, EPMA, Rietveld analysis and electron microscopy. Partial substitution of Tl with Ca was confirmed, but the production of holes in Cu layers expected from this substitution was rather small for a 120 K superconductor. Charge transfer of Tl^3-δ-Cu^2+δ would provide both the hole in the Cu-O bond required for high T _c and s-like electron of Tl atoms for stabilization of layered structures.