EFFECT OF POROSITY ON PROPERTIES OF EXPLOSIVELY COMPACTED HIGH-T-C SUPERCONDUCTORS

A superconductor, of composition Y(Ba,K,Na)(2)Cu3Ox/F-y and a composit e, of composition Y(Ba,K,Na)(2)Cu3Ox/F-y + Ag, with changing K, Na and F content, but a constant, silver content (Ag = 10 mass percent) was prepared using a single heat treatment. The resulting material was gro und in a corundum lined mill, separated to particle size fractions of 0-40 lull, 0-63 mu m and 63-900 mu m and explosively compacted, using an explosive pressure of 10(4) MPa and subsequent heat treatment. Best results were obtained with the 63-900 mu m fraction of composition Y( Ba1.95K0.01)Cu3OxF0.05/Ag: porosity < 0.01 cm(3)/g and current density 2800 A/cm(2) at 77 K.