Microstructural and magnetization studies of sintered and melt-textured Y-Ba-Cu-O

For bulk applications, high-Tc superconductors generally require high critical current density, Jc. This paper reports two methods of producing high-Tc ceramic wires. The first is an extrusion and sintering route where Jc is routinely 600--1000 A cm-2. The second is by melt texturing or directional solidification where we have achieved in excess of 7000 A cm-2 by direct measurement at 77 K in zero field. However, the ease with which wire may be extruded and sintered is attractive and functioning devices have already been manufactured using this route. Fabrication of devices is facilitated by a unique processing route that has resulted in the strongest bulk ceramic yet reported (bend strength >200 MPa). The melt-texturing route and the problems associated with it are examined and compared with the extrusion and sintering route. The processing and the microstructures associated with the directionally solidified YBa2Cu3Ox will be examined in detail as will the resultant superconducting properties, in particular the magnetization