(RE)BaCuO/Ag composites: fundamentals of processing, microstructure and control of properties

We have investigated the phase equilibria in (RE)BaCuO-Ag systems, the influence of Ag on the processing of (RE)BaCuO/Ag composites and the resulting properties. YBCO/Ag composites have been grown by the modified melt crystallization process with YBa2Cu3O7, Y2O3, Pt and Ag2O in the precursor. The improved strength of the YBCO/Ag composites compared with the conventional YBCO bulk material permitted us to magnetize these materials to achieve trapped fields up to 16 T (at 24 K) in the gap of a mini-magnet. The investigation of the microstructure revealed a remarkable increase of the spacing between micro-cracks especially of those perpendicular to a-b planes when 12 wt% Ag was added. In the case of SmBaCuO/Ag composites Ag has a strong influence on processing and causes interactions between RE123 seeds and the sample. We report on the growth of single-grain SmBaCuO/Ag composites in air and we discuss the influence of post-annealing on increasing T-c and j(c).