J/sub c/-B characteristics of silver sheathed oxide superconductors

Thermogravimetry, differential thermal analysis, and magnetization measurements on powders and silver-sheathed Y/sub 1-x/Ca/sub x/Ba/sub 2/Cu/sub 4/O/sub 8/ (x=0 and 0.1) were carried out. The deoxidation temperature of the Ca-doped Y124 materials in the silver-sheathed wires increased from 775 degrees C to 845 degrees C with increasing oxygen partial pressure (P/sub O2/) from P/sub O2/=0.2 bar (in air) to PO/sub 2/=1.0 bar (in pure oxygen). Although the critical transport current density of 2.1*10/sup 4/ A/cm/sup 2/ was observed for silver-sheathed Y(Ca)124 wire at 4.2 K and 0 T by selecting the oxygen partial pressure and the annealing temperature the grain boundary coupling was found to be inefficient by AC susceptibility measurement. A partial melting and growth technique was applied to silver-sheathed Bi2212 wires and well oriented and contacted grains aligned parallel to the silver wall were obtained.