Material developments in Ag/Bi,Pb(2223), Ag/RE(123) and Ag/Tl(1223) tapes:texture in HTS

High energy X-ray diffraction was used to compare Bi,Pb(2223) tapes prepare d by the standard rolling technique and from a periodic pressing deformatio n process. Periodic pressing increases the critical current, although low e nergy Xrays on the tapes surface show a poorer texture. From transmission m easurements, no significant effect of the different deformation process is detected on the texture of the whole ceramic core. The key toward high crit ical currents in Bi,Pb(2223) tapes has to be found in the thermodynamics of the phase formation process rather than in further improvement of texture. To get an enhanced critical current density in the Y123 and T12223 systems, a biaxial texture is mandatory. In Ag/RE(123) systems, there is a commensu rability between the Ag surface and the superconducting cell as shown form sputtering experiments on oriented Ag single crystals. To be of industrial interest, long lengths of textured Ag ribbons have to be produced and fast deposition techniques are needed. We have shown that it is possible to cont rol the texture formation in Ag ribbons. X-rays and EBSD analysis of highly textured {110}(011) is reported. Electrodeposition of T1(1223) and spray p yrolysis of RE(123) are presented as two fast and cheap techniques for biax ially aligned coated tapes preparation on textured Ag ribbons. Pure T1(1223 ) is formed from the simultaneous deposition of all metals dissolved in DMS O followed by a phase formation process under high pressure (50 bar He/1 ba r O-2). Pure and biaxially aligned Y123 is produced from an aqueous nitrate solution in a one step process at 900 degreesC. (C) 2001 Elsevier Science B.V. All rights reserved.