EFFECTS OF PT DOPING ON THE SIZE DISTRIBUTION AND UNIFORMITY OF Y2BACUO5 PARTICLES IN LARGE-GRAIN YBCO

Accurate and detailed image analysis of the Y2BaCuO5 (Y-211) particle distribution in large-grain Pt-doped and undoped YBa2Cu3O7-delta fabri cated by seeded peritectic solidification has been performed using sca nning electron microscopy. The size distribution of Y-211 particles al ong the a or b and c directions of doped and undoped grains has been m easured and observed to approximate well to a log-normal distribution. The mean Y-211 particle size, which is independent of growth directio n, is approximately 1 mu m and 1.5 mu m in the doped and undoped grain s, respectively. The particle size distribution is significantly narro wer for the Pt-containing material, however, corresponding to a much g reater particle size uniformity. Such a uniform dispersion of fine Y-2 11 particles is desirable since it both enhances the critical current density of melt-processed YBCO and reduces liquid loss during peritect ic solidification.