Synthesis of bi-pb-ca-sr-cu-o oriented polycrystal superconductor

Claim 1

A process according to claim 19 for producing a solid sintered body containing oriented superconductive crystalline Bi 2-y Pb y Ca 2 Sr 2 Cu 3 O 10 ±z phase where y ranges from 0.1 to 15 and z ranges from zero to less than 1 in an amount of at least 90% by weight of said body which comprises the following steps: (a) forming a slurry comprised of a particulate mixture of reactants in an organic liquid vehicle, said particulate mixture of reactants being comprised of Bi 2 CaSr 2 Cu 2 O 8 ±x where x ranges from 0 to 0.5, Ca 2 CuO 3 , cupric oxide, and lead oxide, said mixture of reactants being formulated to produce the superconductive phase and to provide an excess amount of said Ca 2 CuO 3 and cupric oxide sufficient to drive the reaction to produce the superconductive phase in said sintered body, said Ca 2 CuO 3 and cupric oxide in the mixture being present in substantially mole equivalents to each other; (b) applying an aligning magnetizing field to the slurry to align said Bi 2 CaSr 2 Cu 2 O 8 ±x crystals with their c-axis substantially parallel to each other; (c) removing the organic liquid vehicle in the aligning field producing a cast body wherein Bi 2 CaSr 2 Cu 2 O 8 ±x crystals are aligned with their c-axis substantially parallel to each other; (d) firing the cast body in an oxidizing atmosphere at a reaction temperature ranging from 820° C. to 860° C. converting the Bi 2 CaSr 2 Cu 2 O 8 ±x to superconductive crystalline Bi 2-y Pb y Ca 2 Sr 2 Cu 3 O 10 ±z phase; (e) cooling the intermediate product in an oxidizing atmosphere producing a solid intermediate product; (f) applying to the pressing surface of intermediate product a uniaxial pressure which is substantially parallel to the c-axis of said superconductive phase to produce a pressed product with a thickness which is the same or less than the thickness of the cast body; (g) finally firing the resulting pressed product in an oxidizing atmosphere at a reaction temperature ranging from 820° C. to 860° C. to produce a finally sintered reaction product wherein the superconductive phase comprises at least 90% by weight of the reaction product, said reaction temperature being below the temperature at which sufficient liquid forms to prevent production of the sintered products; and (h) cooling the finally sintered reaction product in an oxidizing atmosphere producing a solid sintered body having an open porosity ranging from 5% to less than 25% by volume of the body.