FREEZE-DRYING PREPARATION OF YBACUO - CORRELATIONS BETWEEN ELECTRICAL AND MICROSTRUCTURAL PROPERTIES

YBaCuO bulk material was prepared from freeze dried solutions of acetate salts. Various effects of the main preparation parameters on electrical and microstructural properties were observed. For instance, the samples exhibit a huge dependence of the electrical properties relative to the salt concentration in the initial solution, although this corresponds to a very early step in the process. The critical current, as high as some 10 2 A/cm 2 at 77 K, and all the other measured properties present strong correlations with the homogeneity distribution of the grain composition and crystallinity. The specific gravity of the studied samples ranges between 70% and 95% of the maximum density. © 1990.