INFLUENCE OF THE Y2BACUO5 PARTICLE-SIZE DISTRIBUTION ON THE CRACK-PROPAGATION AND THE TRAPPED MAGNETIC-FLUX IN MELT-TEXTURED YBCO

Different precursor mixtures of 123 and 211 have been used to study th e particle size distribution of the 211 phase. Melt texturing of these samples was performed by using a Sm-123 seed for preferential growth of single grain material and 211 substrates to soak the outflowing mel t. The size distribution of the 211 inclusions was determined and thei r influence on the propagation of cracks in the textured material was studied. A precursor mixture of 15 wt% small grained 211 particles (1- 5 mu m) leads to the highest content of small sized 211 inclusions (< 10 mu m). This material shows trapped magnetic fluxes up to 210 mT wit hout any additional admiring.