Synthesis and properties of a 125 K superconductor in the Tl-Ca-Ba-Cu-O system

Abstract
A method for the synthesis of a 125 K superconducting phase having a nominal composition TlCaBaCu2 Ox is described. It is shown that by sintering at 1200 K in flowing oxygen containing a controlled amount of water vapor, a zero electrical resistance state (Tcf) at temperatures as high as 125 K can be obtained. A transport critical current density (Jc ) of ∼240 A/cm2 at 77 K was obtained in this 125 K material.