Abstract: Provided herein is a method of efficiently preparing a thin film having a higher critical temperature as to an oxide superconducting material containing Tl. A thin film of an oxide containing Tl is formed and then heat treated at a temperature of about 850.degree. to 950.degree. C. for a short time, and thereafter further heat treated at a temperature, which is lower than the preceding heat treatment temperature, of at least about 750.degree. C. for a long time. The thin film is heat treated in an atmosphere having an oxygen partial pressure of not more than about 0.1 atm. In formation of a Tl superconducting thin film, on the other hand, a 1212 phase layer is reacted with an amorphous Ca--Cu--O layer to form a 1223 phase layer, or a layer containing volatile metal elements (Tl, Bi and Pb, for example) and oxygen is reacted with another layer containing other elements than the volatile metal elements to form a superconducting film having a high critical temperature.

Abstract: To produce tubular molded parts made of high-temperature superconductor oxide material based on bismuth, calcium, strontium and copper, a homogeneous melt of the oxide with a specified stoichiometry is allowed to run at temperatures of 900.degree. to 1100.degree. C. into a casting zone rotating about its horizontal axis. The solidified molded part is removed from the casting zone and it is annealed for 4 to 150 hours at 700.degree. to 900.degree. C. in an oxygen-containing atmosphere. A plant for producing tubular molded parts includes a rotatably arranged mold (4, 9) which is provided at least at one end face with a front plate 6 which reduces its free cross section, a runner 7 extending into the interior of the mold (4, 9) and a crucible 8 arranged above the runner 7 which is capable of feeding the runner 7 with melt (cf. FIG. 2 A).

Abstract: A precursor material is superoxidized to a superconducting oxide material in an atmosphere containing a reactive component that reacts with and removes hydroxide ion (OH.sup.-), replacing it with peroxide ion (O.sup.-). Preferred reactive components include H.sub.2 O.sub.2, N.sub.2 O, and I.sub.2. The reactive component reacts with and removes hydroxide ion from the precursor material, to reach a higher oxidation state in the superconducting oxide material than possible by oxidation in molecular oxygen. The use of such a reactive component permits both faster oxidation of the precursor material at conventional temperatures and the use of lower temperatures to achieve oxidation.

Abstract: A bismuth system oxide superconductor comprising the 110 K phase is effectively prepared by a process comprising the steps of mixing a bismuth compound, a strontium compound, a calcium compound, a copper compound and optionally a lead compound, optionally provisionally sintering the mixture, and sintering the mixture.

Abstract: High temperature superconducting oxide materials can be taken to a higher, but stable, state of oxidation by removing H-impurities, such as OH.sup.-, using I.sub.2 /O.sub.2 mixtures in a reactive atmosphere process. A higher T.sub.c and a narrower .DELTA.T-transition result.

Abstract: An improved technique for the fabrication of thallium-based superconducting oxides, and particularly Tl:Ba:Ca:Cu:O 2223 oxides, is described which allows production of very pure superconductors (>95% 2223 phase) having excellent structural characteristics. The method of the invention involves first forming a self-sustaining body of starting oxides and subjecting this body to a sintering technique wherein the temperature of the body is gradually raised to a maximum level of about 850.degree.-930.degree. C., followed by maintaining the body at this temperature for a period of about 48 hours. The body is then slowly cooled to avoid distortion and loss of superconducting character. Most preferably, the sintering is a two-stage operation, wherein the body is first heated a relatively low rate (e.g., 1.degree.-10.degree. C./min.) to a temperature of about 650.degree.-750.degree. C., followed by faster heating at a higher rate to achieve the maximum sintering temperature.

Abstract: A process for producing a high critical temperature bismuth strontium calcium copper oxide superconducting material. An intimate mixture is formed of two superconducting materials. The first material is bismuth strontium calcium copper oxide or (bismuth, lead) strontium calcium copper oxide, and has a bulk critical temperature below about 90K. The second material is a seeding powder of bismuth strontium calcium copper oxide or (bismuth, lead) strontium calcium copper oxide, and includes at least 20 volume percent 2223 phase. The amount of seeding material added to the mixture is selected to result in an amount of 2223 phase in the mixture of about 2-50 weight percent. The mixture is annealed in an oxidizing atmosphere at a temperature of at least about 845.degree. C. and below the melting temperature of the 2223 phase, for a time sufficient to increase the amount of 2223 phase in the mixture.

Abstract: In an oxide superconducting film wiring, when the line width is reduced, the evaporation of a component during firing becomes so vigorous that it becomes impossible to form a desired single crystal phase, which causes a significant lowering in the properties of the oxide superconducting wiring. This problem can be solved by preventing the evaporation of the evaporable component during the firing. Examples of this include a process wherein plate is placed above the superconductor forming material film wiring pattern on the substrate so as to face each other, the plate comprising a material having no chemical influence on the superconducting wiring, and a pattern of a material containing an evaporable component is arbitrarily formed, a process wherein a pattern having a smaller line width is sandwiched between patterns having a larger line width, and a process wherein the firing atmosphere or the concentration of the evaporable component in the pattern is varied depending upon the line width.

Abstract: Improved processes for making thin film and bulk thallium superconductors are described, as well as Tl superconductors having high critical current densities and low surface impedance. An annealing step in a reduced oxygen atmosphere is used to convert compounds containing thallium, calcium, barium and copper to a Tl-2223 superconducting phase or to convert an oxide having the nominal composition Tl.sub.2 Ca.sub.2 Ba.sub.2 Cu.sub.3 O.sub.x to a crystalline Tl-2223 phase. The oxygen pressure during annealing is controlled to be below the thermodynamic stability limit for conversion of Tl-2223 to Tl-2122 and secondary phases. Temperatures less than 880.degree. C. are used, the oxygen pressure being sufficient to prevent excess thallium loss so that the Tl content in the final Tl-2223 phase is Tl.sub.1.6-2.0. Electrical devices including SQUIDs can be made with these improved superconductors.

Abstract: A process and a precursor composition for preparing a lead-doped bismuth-strontium-calcium-copper oxide superconductor of the formula Bi.sub.a Pb.sub.b Sr.sub.c Ca.sub.d Cu.sub.e O.sub.f wherein a is from about 1.7 to about 1.9, b is from about 0.3 to about 0.45, c is from about 1.6 to about 2.2, d is from about 1.6 to about 2.2, e is from about 2.97 to about 3.2 and f is 10.+-.z by reacting a mixture of Bi.sub.4 Sr.sub.3 Ca.sub.3 Cu.sub.4 O.sub.16.+-.z, an alkaline earth metal cuprate, e.g., Sr.sub.9 Ca.sub.5 Cu.sub.24 O.sub.41, and an alkaline earth metal plumbate, e.g., Ca.sub.2-x Sr.sub.x PbO.sub.4 wherein x is about 0.5, is disclosed.