Abstract: There is disclosed an improved process for preparing a superconducting composition having the formula M.sub.w A.sub.z Cu.sub.v O.sub.x wherein M is selected from the group consisting if 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 77 K, 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 particulate mixture comprised of Bi.sub.2 CaSr.sub.2 Cu.sub.2 O.sub.8.+-.x where x ranges from 0 to 0.5, Ca.sub.2 CuO.sub.3, cupric oxide and lead oxide, wherein the Bi.sub.2 CaSr.sub.2 Cu.sub.2 O.sub.8.+-.x crystals are oriented with their c-axis at least sufficiently parallel to each other so as not to differ significantly from a common direction, is initially reacted producing an intermediate swollen partially reacted product which is pressed to remove the swelling and then sintered to produce a superconductive Bi.sub.2 yPb.sub.y Ca.sub.2 Sr.sub.2 Cu.sub.3 O.sub.10.+-.z body where y ranges from 0.1 to 0.5 and z ranges from zero to less than 1.
Abstract: A reactant particulate mixture comprised of Bi.sub.2 CaSr.sub.2 Cu.sub.2 O.sub.8.+-.x where x ranges from 0 to 0.5, Ca.sub.2 CuO.sub.3, cupric oxide and lead oxide is formulated and reacted to produce superconductive Bi.sub.2-y Pb.sub.y Ca.sub.2 Sr.sub.2 Cu.sub.3 O.sub.10.+-.z where y ranges from 0.1 to 0.5 and z ranges from zero to less than 1.
Abstract: A polycrystalline metal oxide such as YBa.sub.2 Cu.sub.3 O.sub.7-X (where 0<X<0.5) exhibits superconducting properties and is capable of conducting very large current densities. By aligning the two-dimensional Cu-O layers which carry the current in the superconducting state in the a- and b-directions, i.e., within the basal plane, a high degree of crystalline axes alignment is provided between adjacent grains permitting the conduction of high current densities.
Abstract: A pigment useful for coloring building materials such as bricks is a heat-stable isometric iron oxide brown pigment of .gamma.-Fe.sub.2 O.sub.3 structure which has a silicon content, expresed as SiO.sub.2, of 0.1 to 12% and an Al content, expressed as Al.sub.2 O.sub.3, of 0.02 to 5%.
Type:
Grant
Filed:
October 29, 1990
Date of Patent:
September 17, 1991
Assignee:
Bayer Aktiengesellschaft
Inventors:
Bernd Krockert, Gunter Buxbaum, Axel Westerhaus, Horst Brunn
Abstract: A superconductor metal matrix composite formable into an electrical current carrying material. A superconductive particulate is intermixed with a normal metal matrix, pressed into form and heated to form the composite. The metal matrix surrounds the superconductive particulate to prevent loss of oxygen from the superconductive particulate so the particulate retains its superconductive properties. The metal matrix also becomes superconductive due to proximity effect.
Abstract: A high temperature superconductor system is provided having the following formula: M-A-B-C-D-E, wherein, M is a metallic element, A is an element in Group 3A, B is an element in Group 2A, C is another element in Group 2A, D is an element in Group 1B, and E is an element in Group 6A. In an embodiment, the high temperature superconductor has the following formula: R-Tl-Sr-Ca-Cu-O (wherein R is chosen from the group consisting of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y). Processes for making these high temperature superconductors are also disclosed.
Abstract: This invention provides a method for producing an oxide superconductor which has a uniform texture and is markedly high in sintered density and current density.The method involves the formation of intermediate products from the starting materials. The intermediate products are then used to form the final product. Specifically, to form an oxide superconducting material having a compositional formulaYBa.sub.2 CU.sub.3 O.sub.7-8,where 8 is more than zero but less than 0.5, the method of the invention includes forming a first intermediate product of Y.sub.2 CU.sub.2 O.sub.5, forming a second intermediate product of BaCuO.sub.2, mixing the first and second intermediate products, and sintering the intermediate product mixture to form the oxide superconducting material.
Abstract: There is provided a mixture which preferably is a colloidal suspension of finely divided particles of a rare-earth oxide such as cerium oxide in a liquid. The liquid may be all water but also may include other materials such as acetic acid, 1,3-butanediol, methanol. The mixture is used as a wetting and suspending agent for opaque and build-up dental porcelains to primarily overcome the problem of discoloration of the porcelains when used with metal substrates made of dental alloys containing silver, and also to make the porcelains easier to handle and to work with.
Abstract: The pigment comprises a mixture of crystalline phase and an amorphous phase in which the crystalline phase represents from 10 to 70 wt % of the mixture and is constituted by zinc phosphate in the form of substantially spheroidal particles having a maximum size of between 0.5 to 5 microns and the amorphous phase represents from 30 to 90 wt % and comprises ferric phosphate and ferrous phosphate in a mole ratio lying between 1:001 and 1:03.The process comprises a reaction giving ferrous phosphate, partial oxidation thereof and association with zinc phosphate.
Type:
Grant
Filed:
February 22, 1989
Date of Patent:
July 9, 1991
Assignee:
Colores Hispania S.A.
Inventors:
Juan A. Vallvey, Oscar L. Francia, Carlos M. Sole
Abstract: A Ca carbonate powder, a Sr carbonate powder, and a Cu oxide powder are mixed in predetermined proportions, and sintered at a first predetermined temperature into a Ca-Sr-Cu--O oxide sintered body. A Bi oxide powder and a Pb oxide powder are mixed in predetermined proportions, and are sintered at a second predetermined temperature into a Bi--Pb--O oxide sintered body. The obtained Ca--Sr--Cu--O oxide sintered body and Bi--Pb--O oxide sintered body are crushed, and the resulting Ca--Sr--Cu--O oxide powder and Bi--Pb--O oxide powder are mixed in predetermined proportions. The resulting mixed powder is sintered at a third predetermined temperature into a Bi--Pb--Sr--Ca--Cu--O superconductive oxide sintered body, which is crushed into a powder of a Bi-based superconductive oxide containing Pb. A sintered body of the Bi-based superconductive oxide containing Pb is formed from the Bi-based superconductive oxide powder.
Abstract: Novel superconducting materials in the form of compounds, structures or phases are formed by performing otherwise known syntheses in a highly oxidizing atmosphere rather than that created by molecular oxygen at atmospheric pressure or below. This leads to the successful synthesis of novel superconducting compounds which are thermodynamically stable at the conditions under which they are formed. The compounds and structures thus formed are substantially nonsusceptible to variations in their oxygen content when subjected to changing temperatures, thereby forming a temperature-stable substantially single phase crystal.
Type:
Grant
Filed:
June 22, 1990
Date of Patent:
June 18, 1991
Assignee:
The Regents of the University of California
Abstract: Improved process for making Tl-Ca-Ba-CuO superconductors. A solution of the monocarboxylates (e.g., acetates) of Ca, Ba, and Cu is dried, calcined, mixed with Tl.sub.2 O.sub.3, and the mixture is heated to make a superconductor. The method minimizes introduction of contaminants. Novel compositions result.
Abstract: A metal oxide material is provided which is represented by the composition formula:A.sub.2 B.sub.x Cu.sub.y O.sub.zwherein 2.ltoreq.x.ltoreq.3.5, 2.ltoreq.y.ltoreq.3.5, x+y>4, and 4<z; A is an element or a group of elements selected from alkaline earth metal elements; and B is an element or a group of elements selected from the group of elements consisting of bismuth, lead and thallium. The material has a superconductivity transition temperature of from 4.2K to 12K.
Abstract: Compositions having the nominal formulaTl.sub.e Pb.sub.a Ca.sub.b Sr.sub.c Cu.sub.d O.sub.xwherein a is from about 1/10 to 3/2,b is from about 1 to 4,c is from about 1 to 3d is from about 1 to 5e is from about 3/10 to 1x=(a+b+c+d+e+y) where y is from about 1/2 to 3,are superconducting. Processes for manufacturing such compositions and for using them are disclosed.
Abstract: A dental porcelain having the following composition:______________________________________ Ingredient Weight by Percent ______________________________________ SiO.sub.2 52.7%-64.6% Al.sub.2 O.sub.3 6.3%-16.4% Li.sub.2 O 0%-0.5% Na.sub.2 O 3.9%-14.2% K.sub.2 O 4.5%-11.7% MgO 0%-.3% CaO 1.6%-3.3% Sro 0.9%-2.3% BaO 0.3%-8.1% TiO.sub.2 0.1%-3.6% B.sub.2 O.sub.3 0.2%-5.0% ______________________________________made by blending powdered first-fire frit with pacifiers, heating this first-fire frit to 2000.degree. F., and rapidly cooling the charge.
Type:
Grant
Filed:
July 3, 1990
Date of Patent:
April 23, 1991
Assignee:
Den-Mat Corporation
Inventors:
Robert L. Ibsen, Thomas C. Chadwick, Sally A. Pritchard
Abstract: This invention provides improved methods for the preparation of precursor powders that are used in the preparation of superconducting ceramic materials that contain thallium. A first solution that contains the hydrogen peroxide and metal cations, other than thallium, that will be part of the ceramic is quickly mixed with a second solution that contains precipitating anions and thallium (I) to form a precipitate which is dried to yield precursor powders. The precursor powders are calcined an sintered to produce superconducting materials that contain thallium.
Type:
Grant
Filed:
August 2, 1989
Date of Patent:
March 19, 1991
Assignee:
The United States Department of Energy
Inventors:
Bruce C. Bunker, Diana L. Lamppa, James A. Voigt
Abstract: An inorganic powder is vibrated while being calcined. The vibrations suspend the powder as in a conventional gas-fluidized system, without clumping, but without loss of fines. As applied to superconductor precursor powders, the treatment accelerates growth of the superconducting phase. The invention includes a novel furnace system for simultaneously heating and vibrating the powders.
Abstract: A process of making high temperature Tl-based superconductors is disclosed. The process includes the steps of reacting solid Ba-Ca-Cu-oxides with Tl.sub.2 O.sub.3 vapor. The process allows high quality Tl-based superconductors to be easily fabricated.
Abstract: Black crystal compositions having the empirical composition Bi.sub.a Sr.sub.b Cu.sub.c O.sub.d are described where a+b+c=1, A=0.36-0.557, b=0.098-0.496, c=0.1-0.4 and d=approximately 1+a/2. These compositions have a superconducting transition temperature T.sub.c for superconductivity of greater than 20 K and contain a principal phase which crystallizes in the orthorhombic system. They can be prepared from the mixture of the oxides in the atomic ratio stated by heating to 700.degree.-1000.degree. C.
Type:
Grant
Filed:
November 23, 1988
Date of Patent:
February 5, 1991
Assignee:
Hoechst Aktiengesellschaft
Inventors:
Hans-Georg von Schnering, Winfried Becker, Martin Schwarz, Leonhard Walz, Elfi Waldschmidt, Joachim Adam