Process for producing oxide superconducting thick films by screen printing

Claim 1

A process for producing a superconducting thick film, comprising the steps of: mixing powders of oxide or carbonate of Ba, oxide or carbonate of an element "β" which is selected from a group consisting of Y, Yb, Eb, La, Nd, Gd, Dy, Ho, Er, Tm and Lu, and oxide or carbonate of Cu in such proportions that the atom ratio of said elements Ba, "β" and Cu satisfy Ba.sub.1-x β.sub.x Cu.sub.1 where x is between 0.2 and 0.8, each of said powders having an average particle size of less than 5 μm; subjecting the powder mixture to preliminary sintering at a temperature between 700° and 950° C.; pulverizing the preliminary sintered mass obtained into a powder having an average particle size of less than 10 μm; admixing the pulverized powder obtained with an organic vehicle to prepare a paste; applying said paste in a thickness between 10 and 50 μm onto a substrate by means of a screen printing technique; drying the coated paste; and then subjecting the coated paste to final sintering under an oxidative condition selected from the group consisting of air and an oxygen atmosphere having a pressure of 5 to 10 atm, at a temperature between 800° and 1,000° C., whereby a superconducting thick film of perovskite type oxide or quasi-perovskite type oxide which is represented by the formula: Ba.sub.1-x β.sub.x Cu.sub.1 O.sub.3 wherein "β" has the same definition as above, the value of x being in the range between 0.2 and 0.8 and which has an average crystal grain size of less than 15 μm, is formed on the substrate.