COMPOSITE REACTION TEXTURING OF Bi-BASED 2212 COMPOUND

Textured Bi2Sr2Ca1Cu2O8+x (2212) conductors have been fabricated by a novel method termed Composite Reaction Texturing (CRT) that makes use of inert whiskers or fibres to align superconducting grains and control their morphology. The process has two stages, the initial alignment of fibre material in a precursor followed by a composite reaction stage to develop a textured ceramic microstructure. Although strong texture and high critical current densities have been reported previously using this method the detailed mechanism for microstructure development was not clear. In this work two different methods of achieving fibre alignment are compared, variations in the resulting microstructures after composite reaction provide information on the mechanism of microstructure development. Disc-shaped pellets of 2212 with random MgO whisker alignment in the pellet plane are compared with polymer processed material with uni-directional whisker alignment. Although the resulting textures are strikingly different, the transport current densities are high for both materials, in excess of 2.10(4) A cm(-2) at 4.5K and 12T for each material. Samples with dimensions up to 200mmx100mmx2mm have been fabricated and the method clearly has promise for the production by wind-and-react or form-and-react techniques of high critical current conductors with large cross-sections, as well as complex shapes.