Abstract: A composition and method of preparing YBa.sub.2 Cu.sub.3 O.sub.7-x superconductor. Addition of tin oxide containing compounds to YBCO superconductors results in substantial improvement of fracture toughness and other mechanical properties without affect on T.sub.c. About 5-20% additions give rise to substantially improved mechanical properties.

Abstract: Improvement in a process for producing a sintered elongated article by the steps comprising filling a metal pipe with a material powder, carrying out plastic deformation of the metal pipe and then subjecting the material powder in deformed metal pipe to sintering. In the invention, the step of the plastic deformation includes at least one deformation satge carried out under a hot condition.

Abstract: A rotationally symmetrical molded part of a high-temperature superconductor achieves a critical current density of j.sub.c .gtoreq.800 A/cm.sup.2 at a temperature of 77K, by using a powder mixture (8) having the stoichiometric composition of Bi.sub.2+x EA.sub.3 Cu.sub.2 O.sub.y, where -0.15<x<0.4; EA=an alkaline earth metal or a mixture of alkaline earth metals, in particular a mixture of Sr and Ca in the ratio of Sr:Ca=(2+z):(1-z), where 0<x<0.2; 8.ltoreq.y.ltoreq.8.3. With the aid of a conveying chute (9), the powder mixture (8) is brought uniformly at room temperature with a grain size of <50 .mu.m into a silver mold (5) which is arranged inside a rotating fusion mold (4), open at one side, in a furnace (3). Subsequently, the fusion mold (4) is accelerated, heated to 500.degree. C. and held for approximately 30 min at 500.degree. C. After subsequent partial melting at a temperature of T.sub.m K to T.sub.m +6K, where T.sub.

Abstract: A ceramic superconductor is produced by close control of oxygen partial pressure during sintering of the material. The resulting microstructure of YBa.sub.2 Cu.sub.3 O.sub.x indicates that sintering kinetics are enhanced at reduced p(O.sub.2) and that because of second phase precipitates, grain growth is prevented. The density of specimens sintered at 910.degree. C. increased from 79 to 94% theoretical when p(O.sub.2) was decreased from 0.1 to 0.0001 MPa. The increase in density with decrease in p(O.sub.2) derives from enhanced sintering kinetics, due to increased defect concentration and decreased activation energy of the rate-controlling species undergoing diffusion. Sintering at 910.degree. C resulted in a fine-grain microstructure, with an average grain size of about 4 .mu.m. Post sintering annealing in a region of stability for the desired phase converts the second phases and limits grain growth.

Abstract: In a process for producing a high-temperature superconductor from oxides of bismuth, strontium, calcium, copper and optionally of lead and including sulfates of strontium and/or barium, the oxides of bismuth, strontium, calcium, copper and optionally of lead in the desired molar ratio, and from 2 to 30% by weight of strontium sulfate and/or from 1 to 20% by weight of barium sulfate, each calculated according to the mixture of the oxides, are mixed intimately, the mixture is melted in a crucible of a platinum metal at temperatures from 870.degree. to 1600.degree. C., the melt is poured into permanent molds of desired form and size and is allowed to solidify slowly therein, and the moldings produced are freed from the permanent mold material and are annealed for from 6 to 200 hours at temperatures from 700.degree. to 900.degree. C. in an oxygen-containing atmosphere.

Abstract: To ensure a well-oriented crystal structure, there is provided a process of producing an oxide superconductor of a Y--Ba--Cu--O system with a composition having an atomic ratio Y:Ba:Cu of 1.0-2.0:2.0-2.5:3.0-3.5, the process comprising the steps of: preparing a semimelt including solid and liquid phases and consisting of Y, Ba, Cu and O in the atomic ratio; and solidifying the semimelt to form the oxide superconductor by so controlling a moving speed of a solidification front to have two components of different values in two perpendicularly intersecting directions.

Abstract: A new class of high temperature superconductive oxides is disclosed. An exemplary member of the class has nominal composition Pb.sub.2 Sr.sub.2 Y.sub.0.5 Ca.sub.0.5 Cu.sub.3 O.sub.8 and has a transition temperature T.sub.c (onset) of about 79K.

Abstract: A method of forming the superconducting body comprises forming a body comprised of a precursor deposit of an oxide superconductor on a substrate formed from a silver alloy comprised of a solute metal from the group consisting of yttrium, aluminum, lithium, zirconium, alkaline earths, lanthanides, and mixtures thereof in an effective amount to form oxide particles that increase the hardness of the substrate, and the balance silver. The body is annealed in an oxidizing atmosphere to form the oxide particles in the substrate, and the deposit into a continuous oxide superconductor.

Abstract: In order to prevent expansion of a metal sheath which is heat treated in order to form an oxide high-temperature superconductor therein, the heat treatment temperature is held at a certain level in an intermediate stage of temperature rising in a step of heat treating the metal sheath after filling raw material for an oxide high-temperature superconductor into the metal sheath. After the heat treatment temperature is thus held at the certain level, the metal sheath is again heated to a target temperature. Preferably, the heat treatment temperature is held at a level which is selected in a range of at least 500.degree. C. and not more than 750.degree. C.

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: Unexpected results were obtained when Tl-1223 and Tl=-2223 superconductive materials were annealed at respectively pre-determined annealing temperatures. The optimum annealing temperatures for Tl-1223 and Tl-2223 superconductive materials are found to be 860.degree. C. and 820.degree. C., respectively. By incorporating the optimum annealing temperature and an optimum annealing envirenment, which is expressed in terms of oxygen partial pressure, into the manufacturing process, the present invention presents a method which can substantially increase the critical temperature of thallium based superconductive materials with greatly reduced annealing time and with improved reproducibility, and is thus superior to any method disclosed in the prior art.

Abstract: A high temperature superconducting material with the general formula GaSr.sub.2 Ln.sub.1-x MxCu.sub.2 O.sub.7.+-.w wherein Ln is selected from the group consisting of La, Ce, Pt, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Y and M is selected from the group consisting of Ca and Sr, 0.2.ltoreq.x.ltoreq.0.4 and w is a small fraction of one. A method of preparing this high temperature superconducting material is provided which includes heating and cooling a mixture to produce a crystalline material which is subsequently fired, ground and annealed at high pressure and temperature in oxygen to establish superconductivity.

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 single phase superconducting oxide ceramic material in the form of highly oriented platelets, and a process for the production thereof. The process involves calcining in a non-reducing atmosphere a homogeneous mixture of stoichiometric proportions of suitable precursor materials. The calcination temperature is below the peritectic melt temperature of the superconducting material, and is at or above a temperature and for a time sufficient to effect partial melting of at least one of the precursor materials to a degree sufficient to effect diffusion of at least one of the precursor materials throughout the mixture. The calcination vessel is not wetted by melts of the precursor materials at the calcination temperature. The calcined material is then annealed in a non-reducing atmosphere. A typical material produced by the process is YBa.sub.2 Cu.sub.3 O.sub.x superconducting material, at a calcination temperature of about 976.degree.-982.degree. C.

Abstract: A method of making a high critical temperature superconductive fiber by fiber drawing a material of the family Bi.sub.x Pb.sub.y Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.z where 1.9.ltoreq. x+y.ltoreq. 2.3. In the method a preform is made, fiber drawing is performed, and the resulting fiber is annealed in air, wherein said preform is constituted by a block of vitreous material having the formula Bi.sub.x P.sub.y Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.z where: 1.9.ltoreq. x+y.ltoreq. 2.3 and a tube surrounding said block and made of a vitreous material having the formula Bi.sub.x' Sr.sub.2 Ca.sub.1 Cu.sub.2 O.sub.z' with 1.5.ltoreq. x'.ltoreq. 2.2.

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: The invention comprises a process of heat treatment to produce a high T.sub.c superconductor with increased flux pinning. A precursor compound is subjected to temperature and oxygen pressure conditions at which the precursor compound decomposes or converts partially or completely to the high T.sub.c superconductor and precipitated non-superconducting compounds which are dispersed through the structure of the high T.sub.c superconductor and which are effective to pin lines of magnetic flux. The precursor compound may or may not itself be a high T.sub.c superconductor. In the YBCO system, 2-4-7 may be converted to 1-2-3 or 1-2-3 to 2-4-7 and flux pinning copper oxides dispersed through the structure, for example, various other transformations are possible.

Abstract: A method for making metal/ceramic superconductor thick film structures including the steps of preparing a silver/superconductor ink, applying the ink to a substrate, evaporating the ink's binder, decomposing a silver compound in the residue to coat the superconductor grains, sintering the coated superconductor grains, and oxygenating the superconductor grains through the silver coating. The resultant inter-granular silver increases the critical current and mechanical strength of the superconductor.

Abstract: Superconducting oxide ceramics having a high density of superconducting current are formed without making use of very high temperatures higher than 1000.degree. C. Superconducting oxide material is placed in a crucible, melted and fired at a relatively low temperature. During the melting and firing step, the partial pressure of oxygen is reduced in order to lower the melting point of the ceramic. After the firing, the partial pressure of oxygen is increased.

Abstract: A method of preparing a powder of YBaCuO [phase 123] suitable for forming by drawing-lamination, which includes:preparing a powdered reactive mixture of precursors of purity greater than 99% and with a stoichiometry accurate to within less than 1%,binding this powdered reactive mixture to form intermediate pieces less than two millimeters in thickness which are placed in an oven so that their contact with a support is as small as possible,a heat treating the intermediate pieces,dry grinding the intermediate pieces to obtain grains of said powder with an average diameter of the order of a few .mu.m.

Abstract: A superconductor material having a current density, J, of from about 30,000 to about 85,000 amps/cm.sup.2 at zero magnetic field and 77.degree. K. is disclosed. The 123 superconductor, of the formula L.sub.1 Ba.sub.2 Cu.sub.3 O.sub.6 +.delta. wherein L is preferably yttrium, is capable of entrapping sufficiently high magnetic fields and exhibits a low microwave surface resistance. The process of preparing the superconductor comprises compacting the bulk product, L.sub.1 Ba.sub.2 Cu.sub.3 O, and then sintering the reaction product at a temperature between about 40.degree. C. to about 90.degree. C. below its melting point, i.e., for Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub.6 +.delta. at a temperature of approximately 940.degree. C. The composition is then heated in a preheated chamber maintained at approximately 1090.degree. C. to about 1,200.degree. C. (approximately 1,100.degree. C. for Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub.6 +.delta.