THE GRAIN-ALIGNMENT AND ITS EFFECT ON THE LEVITATION FORCE OF MELT-PROCESSED YBCO SINGLE-DOMAINED BULK SUPERCONDUCTORS

Well textured single-domained YBCO bulk superconductors with different ial grain-alignment have been fabricated. The effect of grain-alignmen t on the levitation force has been investigated at Liquid nitrogen tem perature. It is found that the levitation force values are highly anis otropic depending on the field direction, the levitation force with H parallel to c-axis is about three times higher than that with H perpen dicular to c-axis; so we have to take account of this anisotropy in th e practical applications. The relation shape between a magnet and a su perconductor can be well described with a double exponential function. All the results are discussed in detail. (C) 1998 Elsevier Science B. V. All rights reserved.