The Y1Ba4Cu2CO3O5.5±δ oxycarbonate—An interesting nonsuperconductor

Abstract

A compound with the stoichiometry of Y1Ba4Cu2CO3O5.5±δ is formed in the presence of CO2 or carbonate. Analysis techniques including oxygen overpressure, wet chemical analysis, and quenching experiments establish that this material is an oxycarbonate compound. Electrical measurements indicated no superconductive properties in the 10–298 K temperature range. The ease of formation of this compound causes it to commonly appear in synthesis in this region of the phase diagram and accounts for many of the conflicting reports of properties and solid solution formation. XRD shows evidence for the existence of some solid solution in this oxycarbonate. The compound Y1Ba4Cu3O8.5±δ, formed in the absence of CO2, and Y1Ba4Cu2CO3O5.5±δ, formed in the presence of CO2, are the only barium-rich phases seen to exist.