TEXTURE EFFECT ON VORTEX-STATE TF-MU-2223 HIGH-T-C MATERIALS(SR IN BI)

The influence of texture in Bi-2223 ingots on the temperature dependen ce of the mu(+) spin relaxation rate has been investigated. Texture wa s induced during cold-isostatic-pressing by applying an additional uni axial load which tends to align single grain c axes along the stress d irection, (c) over cap. Small plates were cut with faces either parall el to or perpendicular to (z) over cap and mu SR was measured in a 15 mT transverse field (TF) during cooling from room temperature to 6 K. While for highly-textured material, low-temperature limits are substan tially smaller than expected, the large shift (55%) observed when swit ching from <(z)over cap perpendicular to TF> to <(z)over cap parallel to TF> clearly indicates that anisotropy has developed. Relaxation rat es for the weakly-textured sample lie in between. To a lesser extent, sintering also enhanced the low-temperature relaxation, but did not af fect T-C significantly All samples showed a weak onset of depolarizati on between 60 K and 90 K, most likely due to the presence of a Bi-2212 impurity phase. This impurity phase might cause the transition-temper ature smearing in the 100-110 K range in the weakly textured (and less compacted) material. Thus the sharpness of the relaxation drop might be relevant for assessment of material quality and be used as a criter ion in the improvement of the production process.