Abstract: A method of producing a thin layer, high-temperature superconductor strip is disclosed. In the method, a metal salt solution is formed and coated onto a substrate including a high-temperature superconductor layer. Heat is then applied directly or indirectly to the solution. The metal salt solution may contain a metal-organic salt solution or a metal inorganic metal salt solution. When an inorganic metal salt solution is utilized, a reducing solution may also be applied to the HTSC layer prior to heating. In addition, nano-sized metal particles may be added to the metal salt solution and/or the reducing solution.

Abstract: A method and an apparatus for spraying materials onto a substrate to produce a coating thereon is described which allows very thick layers of complex metal oxides to be produced. The apparatus and method are particularly suitable for producing superconducting coatings.

Abstract: The invention provides a method for stably preparing a bismuth-based high temperature superconductor of a Bi-2223 single-phase or a Bi/Pb-2223 single phase, wherein a second phase is not allowed to reside, at a low cost and efficiently. With the method described above, mixed powders of raw materials (mixed powders of oxides and carbonates), obtained by mixing the raw materials such that a mixing ratio of constituents, Bi:Sr:Ca:Cu or (Bi, Pb):Sr:Ca:Cu, becomes identical to the stoichiometric ratio of a crystal of the superconductor Bi2Sr2Ca2Cu3Oz, or (Bi, Pb) 2Sr2Ca2Cu3Oz, respectively, are used as raw material for sintering, and the sintering is applied thereto, using KCl as a flux. In this case, the raw material for the sintering as calcinated is preferably used, and the sintering is preferably applied at a sintering temperature kept at a constant level.

Abstract: A process is provided for preparing solid superconducting mixed-metal oxides whereby the superconductor can be formed into any predetermined shape by way of viscous sol precursors. The superconductors are also formed by this process into homogeneous phases.

Abstract: The invention relates to a spray pyrolytic process for the preparation of multi-element metal oxide powders useful as precursors of high temperature superconductor ceramics. Aerosols of aqueous solutions containing corresponding metal salts admixed in the required stoichiometric proportion are sprayed through an independently operated hydrogen/oxygen flame in such a way that a flame temperature of 800.degree.-1100.degree. C. is maintained to form said powders. Any contact of the aerosols and powders generated during the process with carbon or carbon-containing compounds or materials is strictly avoided.

Abstract: A description is given of superconducting substances having a content of Bi, Sr, Ca and Cu, and of processes for their preparation from the metal oxides within a range which is specified by the overall composition Bi.sub.a (Sr,Ca).sub.b -Cu.sub.6 O.sub.x, where a=3-24 and b=3.23-24, with an Sr/Ca atomic ratio of 1:9-9:1 and a Bi:(Ca+Sr) atomic ratio of 0.3-1.5. The transition temperature is at least 60 K. The principal phase crystallizes in the orthorhombic system. The pure compounds Bi.sub.4 (Sr,Ca).sub.4 Cu.sub.2 O.apprxeq..sub.12 and Bi.sub.4 (Sr,Ca).sub.6 Cu.sub.4 O.apprxeq..sub.20.

Abstract: Uniformity of the interstitial distribution of the second phase within composite superconducting high T.sub.c ceramic compositions is achieved by infiltrating the second phase from a bath of molten, low melting point, surface wetting, metallic salt introduced after the ceramic microstructure is formed and the superconductor phase fully developed. The metal or metal oxide second phase is formed uniformly in situ by the decomposition of the infiltrated salt and liquification and/or sintering of the residual metal or metal oxide.

Abstract: The invention relates to a spray pyrolyric process for the preparation of multi-element metal oxide powders useful as precursors of high temperature superconductor ceramics. Aerosols of aqueous solutions containing corresponding metal salts admixed in the required stoichiometric proportion are sprayed through an independently operated hydrogen/oxygen flame in such a way that a flame temperature of 800.degree.-1100.degree. C. is maintained to form said powders. Any contact of the aerosols and powders generated during the process with carbon or carbon-containing compounds or materials is strictly avoided.

Abstract: A process for the preparation of amorphous precursor powders for Pb-doped Bi.sub.2 Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.x (2223) includes a freeze-drying process incorporating a splat-freezing step. The process generally includes splat freezing a nitrate solution of Bi, Pb, Sr, Ca, and Cu to form flakes of the solution without any phase separation; grinding the frozen flakes to form a powder; freeze-drying the frozen powder; heating the dried powder to form a dry green precursor powders; denitrating the green-powders; heating the denitrated powders to form phase-clean Bi-2223 powders. The grain boundaries of the 2223 grains appear to be clean, leading to good intergrain contact between 2223 grains.

Abstract: A method of producing a high-temperature oxide superconducting material, which comprises the steps of (a) preparing a material corresponding to an oxide superconductor of the perovskite type structure consisting essentially of a first member selected from the group consisting yttrium, lanthanoids, thallium and bismuth; at least one alkaline earth metal; copper; and oxygen and (b) heating the material in the presence of an alkali metal selected from the group consisting of potassium, sodium, rubidium and cesium to a temperature around the melting point of the alkali metal or to a higher temperature for a time sufficient to effect grain growth in the superconductor material, thereby to produce the superconductor containing the alkali metal in an amount not larger than 4 mole % based on the first member.

Abstract: A method is disclosed for forming polycrystalline thallium system superconductors having high current carrying capacity and high magnetic field behavior. A precursor deposit is formed comprised of silver, in an amount of about 1 to 20 mole percent of total metals in the precursor deposit, and the balance oxides of calcium, barium, and copper in ratios for forming the superconductor. The precursor deposit is annealed in an oxidizing atmosphere, and in the presence of a source of thallous oxide. The source of thallous oxide is heated to a first temperature selected to incorporate thallium into the deposit in an amount of about 6 to 22 mole percent of metals in the superconductor, and the precursor deposit is heated to a second temperature to form the superconductor.

Abstract: A method of producing a compound oxide of elements including at least one of thallium, bismuth, lead, antimony, yttrium, each of rare earth elements, each of transition metal elements, each of alkali metal elements and each of alkaline earth metal elements. The method is comprised of the steps of (i) reacting at least one of carbonate, basic carbonate, hydroxide and co-precipitates of each of the above-mentioned elements with an amount of citric acid that is less than the weight equivalent of citric acid needed to form a completely citrated compound, and (ii) calcining the partly citrated compound. The co-precipitate can be one of a carbonate, a basic carbonate and a hydroxide of each of the above-mentioned elements.

Abstract: Disclosed is a method for forming a superconductive oxide layer on a substrate. The method comprises applying a precursor solution to a major surface of the substrate such that a metal-containing layer is formed on the surface, and heat treating the substrate/layer combination such that at least a substantial portion of the layer material is transformed into superconductive oxide. Exemplarily, the precursor solution is formed by dissolving Ba--, Y--, and Cu-containing compounds in acetic acid and water, spinning the solution on a MgO substrate, driving of unwanted constituents of the resulting layer at 400.degree. C., heating the combination to about 830.degree. C. in O.sub.2 such that the (perovskite) phase that is associated with superconductivity in YBa.sub.2 Cu.sub.3 O.sub.7 is formed, and oxygenating the layer at about 400.degree. C. in O.sub.2.

Abstract: A method is provided for forming thin films, such as high temperature superconductors, on a surface of a substrate using pulsed microwaves to control substrate temperature. The method includes vaporizing a liquid source to form a series of vapor pulses, irradiating the vapor pulses and a makeup gas with pulsed microwaves, and exposing the surface of the substrate to the irradiated mixture to form a thin film on the surface. The microwaves may be pulsed to coincide with the arrival of the vapor pulses at the substrate, thus reducing the amount of material consumed and the amount of waste. Further, the plasma may be closely confined to the substrate with a dielectric waveguide to reduce the power required for irradiating the mixture and to prevent the formation of stray deposits on surfaces enclosing the substrate.

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: An improved process for preparing a superconducting composition having the formula M.sub.W A.sub.E Cu.sub.V O.sub.K wherein M is selected from the group consisting of Bi, Tl, Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm Yb and Lu; A is at least one alkaline earth metal selected from the group consisting of Ba, Ca and Sr; x is at least 6; w is at least 1; z is at least 2 and v is at least 1; said composition having a superconducting transition temperature of above 77K, preferably above about 90 K; said process consisting essentially of (a) forming a suspension having an M:A:Cu atomic ratio of w:z:v by mixing A(OH).sub.2, AO or AO.sub.2 and M.sub.2 O.sub.3 with an aqueous solution of cupric carboxylate or cupric nitrate at a temperature from about 50.degree. C. to about 100.degree. C., or mixing A(OH).sub.2 with an aqueous solution of Cu carboxylate, nitrate or a mixture thereof and M carboxylate, nitrate or a mixture thereof at a temperature from about 50.degree. C. to about 100.degree. C.

Abstract: A method is provided for preparing a precursor of a superconductor containing atoms of oxygen, atoms of copper and atoms of at least two other metals and sufficient atoms of oxygen so that up to, but no more than, one atom of copper is in the trivalent state, in which method there are blended together, in finely divided particulate state, components containing atoms of the metals in the desired proportion with at least one of the components containing oxygen in an amount above that which would put more than one atom of copper into the trivalent state and thereafter milling the components together in a high energy system to a maximum particle size of about 5 microns for at least 99 weight percent of the blend.

Abstract: Superconducting precursors, which can be made into metal oxide superconductors such as YBa.sub.2 Cu.sub.3 O.sub.6+x, and a process for their manufacture by the coprecipitation of 1-2-3 nitrates using inexpensive precipitating agents such as alkali hydroxides, carbonates and bicarbonates. The process involves preparing a stoichiometric mixture of Y, Ba and Cu nitrates, which is then combined with a solution containing an excess of NaOH/K.sub.2 CO.sub.3, KOH/K.sub.2 CO.sub.3, NaOH/Na.sub.2 CO.sub.3, or KOH/Na.sub.2 CO.sub.3, which causes the precipitation of the precursor. The suspension containing the precipitate is filtered and then washed wiThe invention of this application was made and conceived at least in part with United States Government support and the United States Government has certain rights in the invention.

Abstract: A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed.

Abstract: A process making thin film elements of an oxide superconductor (Tl..sub.5 Pb.sub.0.5)Sr.sub.2 CaCu.sub.2 O.sub.7, (Tl..sub.5 Pb.sub.0.5)Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.9 or a mixture thereof. The process entails forming an oxide film of a mixture of oxides of Pb, Sr, Ca and Cu in preselected amounts, placing the oxide film in a container of nonreactive metal such as gold that contains a powder of (Tl..sub.5 Pb.sub.0.5)Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.9 superconductor, sealing the container, and heating the sealed container to a temperature of about 820.degree. C. to about 950.degree. C. for at least 1 minute.

Abstract: A method for forming a superconducting oxide material including introducing an oxygen or an oxidizing gas and a reactive gas or reactive solution or reactive minute particles into a plasma generating chamber; applying a magnetic field to the plasma generating chamber; supplying microwaves to the plasma generating chamber wherein the direction of the magnetic field and the propagation direction of the microwaves are parallel such that the oxygen or the oxidizing gas and the reactive gas or reactive solution or reactive minute particles are converting into the plasma; and forming the superconducting oxide material on a film forming surface positioned in the plasma generating chamber during the application of the magnetic field.

Abstract: A method of producing a superconductor of metal oxides which includes subjecting an organic solvent solution containing (a) an alkoxide of a rare earth element, (b) an alkoxide of an alkaline earth metal and (c) copper alkoxide or cupric nitrate to hydrolysis in the presence of water and nitrate ions, thereby forming a mixture containing a gel-like substance. The gel-like substance is, after being dried and formed into a desired shape, pyrolyzed at a temperature of 600.degree.-950.degree.C. to form a superconductor of oxides of the rare earth, the alkaline earth metal and copper.

Abstract: A superconducting ceramics elongated body comprising a flexible ceramics elongated substrate and an oxide ceramics superconducting layer formed at least on a part of the surface of the ceramics elongated substrate to longitudinally extend along the ceramics elongated substrate. The superconducting ceramics elongated body further comprises a protective layer of ceramics containing a nitride, which is provided to at least cover the surface of the superconducting layer exposed on the ceramics elongated substrate. A method of manufacturing a superconducting ceramics elongated body by forming a longitudinally continuous superconducting layer on at least a part of the surface of a flexible ceramics elongated substrate. The superconducting layer is formed on the elongated substrate by a sol-gel method, a coating/sintering method, evaporation under oxygen ions, deposition from a fluoride solution or oxidation after application of corresponding fluorides.

Abstract: Solutions containing the cations of the metals Y, Ba, Cu in the atomic ratio 1:2:3 or the cations of the metals Bi, Sr, Ca and Cu having the atomic ratios of a high-temperature superconductor bound to polyacrylic acid in water as dispersant and having a viscosity of 150-10,000 cSt (at 20.degree. C.) serve to produce superconducting filaments or coatings.To produce a superconducting filament, a solution is forced through a nozzle and the extruded filamentous strand is left to solidify in an organic solvent which is miscible with water, the filament is isolated, dried and heated to at least 800.degree. C. in the presence of oxygen, annealed at at least 800.degree. C. for at least one hour in the presence of oxygen and then cooled.

Abstract: The invention provides a process for producing high phase purity ceramic materials through the utilization of organic gelling agents. The process comprises the following steps: (a) dissolving stoichiometric amounts of metal salts in a solvent to form a solution; (b) heating the solution to a temperature sufficient to dissolve the gelling agent; (c) dissolving from about 0.1 to about 50 weight percent of an organic gelling agent into the heated solution; (d) cooling the solution to form a gel; (e) drying the gel to form a xerogel precursor; and (f) subjecting the xerogel precursor to a calcination process to produce a high phase purity ceramic material.

Abstract: A novel method for forming homogeneous silver high temperature superconductor (HTS) composites. The novel method comprises a chemical coprecipitation of silver, barium, yttrium, and copper salts solutions, followed by calcination and milling processes. The novel method has an advantage of retaining all the virtues immanent in a composite HTS, for example, increased critical current density (Jc), and improved mechanical properties, while bypassing extant and deficient methodologies for forming a composite, the deficient composites characterized by heterogeneity.

Abstract: The invention relates to a process and an apparatus for converting metal nitrate or mixed metal nitrate solutions into the corresponding metal oxides in a microwave field. The invention consists in heating, while the feed stream is being metered in, in such a manner that the solvent always evaporates within seconds and the decomposition product is obtained as a porous, sponge-like, purely oxidic material, which can be ground easily to give a powder having particle sizes of 0.5 to about 10 .mu.m. The controlled metering in of the nitrate solution simultaneously makes it possible to control the reaction temperature below the sintering temperature of the powder. The reaction of the nitrate starting solution can take place continuously/batchwise in a reaction flask or continuously in a rotating reaction pipe, which is preferably charged with grinding balls, which possibly exert a reaction-activating effect similar to that exerted very particularly by the metal oxide sponge formed during the reaction.

Abstract: A preparation method for high-purity Tl-based superconductor phase of 115 K, and the precursor thereof. The process comprises a specific composition of precursors, represented by the formula:(Tl.sub.a Pb.sub.b Bi.sub.c)Sr.sub.2-x Ca.sub.2+x Cu.sub.y O.sub.z, wherein (a+b+c)=1, 0<x.ltoreq.1 and 2.ltoreq.y.ltoreq.4, for the manufacturing of Tl-based superconductor by adding oxalic acid as a chelating agent which equals to half the molar amount of total nitrate anions in the required metal nitrates aqueous solution and adjusting pH value of the solution to obtain the superconductor.

Abstract: A superconducting tape is fabricated with a composition of Bi.sub.1.81 Pb.sub.0.43 Sr.sub.1.71 Ca.sub.2.14 Cu.sub.3 O.sub.x. The powder of composition is filled into a silver tube and the silver tube is processed by rolling or pressing into a thin tape. The thin tape is heat treated and pressed for several times until the superconducting phase is formed to the tape and the thickness of the tape is equal to or less than 0.07 mm. The resulting tape is highly flexible such that it can be bent into an arc with a very small radius of curvature and nonetheless provide high critical current density.

Abstract: A fine stoichiometric superconductor powder may be co-precipitated from the addition of appropriate metal compound powders in ammonium carbonate. The co-precipitated powder is very homogeneous because the reaction progresses in liquid solution. For example, YBa.sub.2 Cu.sub.3 O.sub.7-x superconducting powder may be prepared by the co-precipitation of yttrium oxide, copper (I) acetate, copper (II) acetate and barium acetate. The acetates precipitate by nucleating on the yttrium oxide particles. The process permits a relatively wide window of starting reactant proportions yet still produce ceramics having superconductive properties.

Abstract: A process of forming on a substrate a coating of a precursor of a crystalline rear earth alkaline earth copper oxide or heavy pnictide mixed alkaline earth copper oxide electrical conductor and converting the precursor to the crystalline electrical conductor.

Abstract: Disclosed is a process for the preparation of multi-element metal oxide, high temperature superconductor precursor powder comprising spraying a homogenous solution of a multi-element metal salt solution mixed in a stoichiometric ratio corresponding to the desired superconducting composition into a horizontal tube-like furnace being heated to a temperature of 800.degree.-1000.degree. C., transporting resulting sprayed mist along the main axis of the furnace tube by the aid of hot air and collecting resultant finely divided metal oxide powder by the aid of a filter, whereby the resultant mixed metal oxide powder is a precursor for the preparation of a high temperature superconducting ceramic.

Abstract: A method for forming a high T.sub.c metal oxide superconductor in the form of a hollow fiber. The method includes the steps of: forming a polymer-metal complex precursor; filling a decomposable hollow fiber mold with the precursor; and heating the filled mold to decompose the mold and convert the precursor to a metal oxide superconductor in the form of a hollow fiber. Ag-doped metal oxide superconductor structures can also be produced by the above method.

Abstract: A composite oxide synthesized by a citrating process and utilized in functional ceramics materials is prepared by the following process. Co-precipitants or mixtures of at least one component selected from the group consisting of carbonates, basic copper and/or hydroxides of elements which compose a composite oxide are reacted with citric acid in an aqueous solution or in an organic solvent. The elements are selected from at least one element of the group consisting of Y, rare earth elements, transition elements, and alkali metal or alkaline earth metal elements. The citrate compound formed is baked to complete the composite oxide.The composite oxide synthesized by this invention has superconduction at the most temperature of 93.degree. K. with excellent Meissner effect.

Abstract: A superconducting oxide precursor material is prepared by dissolving soluble compounds containing the non-oxygen elements of the oxide in concentrated nitric acid, in which a decomposing agent for the nitrate of the nitric acid selected from urea and sucrose and an oxidizing/reducing agent selected from hydrogen peroxide and ammonium nitrate have also been dissolved. The acid solution is concentrated by heating until the liquid component is pyrolyzed, leaving a superconducting oxide precursor material residue. The precursor material is produced with a relatively high oxidation state, but is normally further oxidized to reach a superconducting state.

Abstract: The invention provides a method for forming deposits of superconducting ceramics by sequentially electrodepositing layers of metals, of a type and in proportion suitable for forming a superconducting ceramic, to form a precursor metal deposit, followed by oxidizing the precursor deposit to form a superconducting ceramic deposit. Optionally, the electroplating steps are conducted in such a manner that a patterned precursor deposit results, to obtain a patterned superconducting deposit after oxidation.

Abstract: A process for coating a superconductive film onto a substrate is provided. In the first step of this process, a solution of the reagents required to produce the superconductive material is subjected to ultrasonic sound waves to create an aerosol. Thereafter, the aerosol is contacted with plasma while being subjected to substantially atmospheric pressure and a radio frequency alternating current in excess of 100 kilohertz; a vapor is produced in this step. The vapor so produced is passed through an orifice and allowed to deposit onto a substrate, which is in contact with a substrate holder which is electrically grounded.

Abstract: The invention process provides a metal oxide, or oxides of more than one more metal, wherein the oxides have a mean particle size less than 1 micron. The oxides are made by steps including (1) reacting an aqueous solution of a metal salt (or salts) that form insoluble carbonate(s), thereby to form a carbonate precipitate, followed by (b) recovering the precipitate, e.g., by filtration; (c) redispersing the precipitate in water to form a second very dilute slurry; (d) spray-drying said second slurry; (e) calcining the spray-dried product at a low temperature (e.g., 540.degree. C.), followed by a final calcination in atmosphere consisting of flowing oxygen initially under reduced pressure (e.g., 2 Torr). The spray-dried spheroids comprise particles having a mean particle size less than one micron, a property carried over into the products of both calcinations.

Abstract: A process for preparing powder of high temperature oxide superconductors of Bi-Pb-Sr-Ca-Cu-O type. In an aqueous solution of nitrate salts of Bi, Pb, Sr, Ca, and Cu metals, an appropriate ratio of triethylamine/oxalic acid was added to form a coprecipitate. Through the process of calcination at a temperature in the range of 750.degree. C. to 800.degree. C. and sintering at a temperature of 860.degree. C., a uniform and fine powder superconductive metal oxide having a critical temperature of 110K is obtained as the final product.

Abstract: A method for the manufacture of superconducting polycrystalline ceramic materials by the decomposition of a mixture of isopropoxides.

Abstract: A process for preparing a bulk powder for an oxide superconductor which comprises mixing an alcohol solution (I) of a copper nitrate and a lanthanoid metal nitrate with an alcohol solution (II) comprising at least one compound selected from the group consisting of a barium hydroxide and a barium alkoxide to give a coprecipitate, and thermally decomposing the coprecipitate. According to the present invention, compared to the solid-state reaction, fine particles having the particle size of not more than 1 .mu.m can be easily produced because barium carbonate comparatively stable to heat is not formed on calcination, and the desired bulk powder for oxide superconductor can be produced at even lower temperature. Consequently, the obtained bulk powder for the oxide superconductor has fine particles, e.g. the particle size being not more than 1 .mu.m, therefore, the powder is excellent in stoichinometry, large in surface energy and excellent in sintering property.

Abstract: The present invention relates to an improved process to produce an essentially carbon-free nitrate of an alkali metal, alkaline earth metal, transition metal, lanthanide metal, actinide metal, metal, or mixtures thereof, which process comprises:Contacting an anhydrous composition of an alkali metal, alkaline earth metal, transition metal, lanthanide metal, actinide metal, or mixtures thereof substituted with an organic or an inorganic carbon-containing substitute with flowing nitrogen dioxide, dinitrogen tetroxide or mixtures thereof at a temperature of between about 40.degree. to 150.degree. C. under anhydrous conditions for a time and at a pressure effective to form the nitrate of the alkaline metal, alkaline earth metal, transition metal, lanthanide metal, actinide metal, or mixtures thereof, essentially free of any carbon containing contaminant. Materials produced by this improved process are useful as electrical superconductors, e.g. YBa.sub.2 Cu.sub.3 O.sub.

Abstract: A process for coating a superconductive film onto a substrate is provided. In the first step of this process, a solution of the reagents required to produce the superconductive material is subjected to ultrasonic sound waves to create an aerosol. Thereafter, the aerosol contacted with plasma while being subjected to substantially atmospheric pressure and a radio frequency alternating current in excess of 100 kilohertz; a vapor is produced in this step. The vapor so produced is passed through an orifice and allowed to deposit onto a substrate.

Abstract: An oxalate route coprecipitation process for preparing a superconducting YBaCuO system precursor powder comprises preparing an aqueous solution of nitrates of yttrium, barium and copper, which is then mixed with an organic solution containing a dibasic oxalate ester, an organic base and acetone. An ultrasound vibration is applied to the mixture to coprecipitate oxalates of yttrium, barium and copper. The decomposition of the oxalate ester is enhanced to an optimum rate as the result of the homogeneous phase contributed by acetone which is miscible with both water and the oxalate ester. The ultrasound vibration segregates the precipitate particles thereby preventing the coagulation of the particles and assuring fine and uniform particle size.

Abstract: A method for applying coatings to substrates using chemical vapor deposition with low vapor pressure reagents is disclosed which comprises the steps of: (a) placing a substrate in a furnace means; (b) directly introducing powder reagents by a powder feeder means into said furnace means; and (c) vaporizing and reacting said reagents within said furnace means resulting in the deposition from the vapor phase of a coating on said substrate, wherein said coating can be an oxide superconductor.

Abstract: A complex oxidation reaction product of two or more metals in an oxidized state is formed by positioning a suitable precursor metal adjacent to a permeable mass of a metal-containing compound in an oxidizing atmosphere and heating the assembly to form a body of molten precursor metal. The molten metal infiltrates the permeable mass and reacts therewith and with the oxidizing atmosphere to form a complex oxidation reaction product. Methods for determining the shape of the resulting article are described. The disclosed methods can be used to form superconducting perovskites.

Abstract: A two-step process for the preparation of a thallium-containing superconductive film is described.In the first step of this process, an aerosol mist containing reactants necessary to produce a calcium/barium/strontium/copper precursor material is provided. This mist is subjected to radio-frequency radiation while in the plasma region, and it thereafter is deposited onto an electrically grounded substrate.In the second step of the process, the coated substrate is contacted with thallium-containing vapor.

Abstract: A process of forming on a substrate a coating of a precursor of a crystalline rare earth alkaline earth copper oxide or heavy pnictide mixed alkaline earth copper oxide electrical conductor and converting the precursor to the crystalline electrical conductor.

Abstract: An improved method for the preparation of single phase, fine grained ceramic materials from precursor powder mixtures where at least one of the components of the mixture is an alkali earth carbonate. The process consists of heating the precursor powders in a partial vacuum under flowing oxygen and under conditions where the partial pressure of CO.sub.2 evolved during the calcination is kept to a very low level relative to the oxygen. The process has been found particularly suitable for the preparation of high temperature copper oxide superconducting materials such as YBa.sub.2 Cu.sub.3 O.sub.x "123" and YBa.sub.2 Cu.sub.4 O.sub.8 "124".

Abstract: A spray calcination process is provided for decomposing a metal nitrate solution to form fine grain multicomponent metal oxide powders of selected composition of particular utility as superconductor precursor powders. Such precursor powders are produced in bulk quantities as high purity, reproducible, intimately mixed powders for conversion to high temperature superconductors.A metal nitrate solution containing two or more metal constituents in a preselected ratio is sprayed as a finely atomized spray into a spray calcination zone where it is contacted with a hot gas stream for a residence time of less than 15 seconds at a high temperature between 200.degree. C. and 1100.degree. C. sufficient to vaporize the water of the nitrate solution and convert the metal nitrates to their corresponding oxides.