Production of a high-temperature superconducting ceramic

Previously abstracted from original as item 9111-F2-c-2426. The special featurees of the produciton of articles of Y sub 2 O sub 3 --BaO--CuO system ceramics are considered for the entire production cycle, including size reduction, synthesis, moulding and sintering. The starting materials were very pure oxides of yttrium and Cu and barium carbonate, the respective mass% in the charge being 15.1, 32.1 and 52.8. Formation of the compound YBa sub 2 Cu sub 3 O sub 7--x was studied at different synthesis temperatures (800-990 deg C). The temperature dependences of shrinkage of specimens during synthesis and of the electrical resistance of specimens synthesized at various temperatures were determined and the effects of annealing were studied. Variation of the main process parameters gave products with a transition temperature of 90-92K, a current density of 50-100 A/cm exp 2 and screening from an external alternating magnetic field of approx 0.3 mT.