TEXTURE AND CRITICAL-CURRENT ANISOTROPY IN COMPOSITE REACTION TEXTURED MGO WHISKER BI-2212 MULTILAYER STRUCTURES

Highly textured bulk Bi-2212/MgO whisker superconducting composites ha ve been synthesised by four processing techniques followed by a partia l melting treatment termed composite reaction texturing (CRT) and post -annealing, Composites different characteristic whisker alignment resu lted in different types of textured microstructure which enabled detai led study of the critical current density, J(c), as a function of text ure. Highest J(c) values were achieved in samples with 10 wt% MgO whis kers aligned in a planar 2D arrangement, which led to strong c-axis te xture. High J(c) anisotropy along different sample directions and for different field directions was observed in the highly textured samples , a similarity to the behaviour of Bi-2212 single crystals was seen in the most highly textured materials. The J(c) of the c-axis textured s amples was self-field limited and could reach 3200 A/cm(2) at 77 and c ould reach 3200 K and 4 mT. Magnetisation measurements indicated a J(c ) in excess of 5.10(4) A/cm(2) at 5 K and 12 T.