MAGNETIC-PROPERTIES OF LARGE MELT-PROCESSED Y-BA-CU-O CYLINDERS

One of the first possible applications of bulk high-Tc superconductors are magnetic bearings, superconducting permanent magnets and shielding bodies. By a new melt process starting from reacted YBCO 123 and 211 powders large samples were prepared. Silveroxide as addition to the mixture increased the density, while PtO2 led to a reduced 211 inclusion size and a better homogeneity. For testing the overall magnetic properties of these samples magnetization and levitation force measurements were performed. In comparison to samples without PtO2 addition a strong increase in the magnetization M and the repulsion force from a magnet were observed. The maximum in the field dependence of M increased to more than 1000 G. The relaxation of a trapped field after a field cooling experiment gave an acceptable flux creep at 77 K for a long-term technical application.