Aligned bismuth, strontium, calcium cuprate coatings on polycrystalline substrates

Claim 1

An article comprising an oriented thick film superconducting coating on a polycrystalline substrate of MgO, alumina, mullite, SrTiO 3 , ZrO 2 , ZrTiO 4 , BaTiO 3 or mixtures thereof, the coating comprising at least two highly oriented platelet components of Bi.sub.a Sr.sub.b Ca.sub.c Cu.sub.d O.sub.x (BSCCO) wherein in one component a is 2, b is 2, c is 1, d is 2, and x=8 and, in another components a is 2, b is 2, c is 9, d is 1, and x is ≈6, oriented such that said BSCCO platelets are essentially parallel to said substrate, said coating having been produced by a process comprising the steps of: applying a powdered mixture prepared from Bi 2 O 3 , SrCO 3 , CaCO 3 , and CuO onto a polycrystalline substrate, in amount sufficient to provide, upon melting, a coating of 75 μm to about 250 μm thickness upon said substrate; rapidly heating the resultant coated substrate to a temperature ranging from about 1000°-1100° C. for a period of from about 5-30 minutes to completely melt said powder coating and thus form a molten, thick film coating of about 75 μm to about 250 μm thickness; rapidly quenching the coated substrate at a rate of at least 50° C./minute to a temperature below about 500° C., which is below that temperature at which phase transition occurs; and annealing the resultant coated substrate, by heating in an atmosphere of an oxygen-containing gas to a temperature of from about 850°-870° C.