Coating processes – Electrical product produced – Superconductor
Reexamination Certificate
2002-07-30
2004-09-28
Talbot, Brian K. (Department: 1762)
Coating processes
Electrical product produced
Superconductor
C029S599000, C505S434000, C505S470000, C505S482000
Reexamination Certificate
active
06797313
ABSTRACT:
INCORPORATION BY REFERENCE
The following documents are hereby incorporated by reference: U.S. Pat. No. 5,231,074, issued on Jul. 27, 1993, and entitled “Preparation of Highly Textured Oxide Superconducting Films from MOD Precursor Solutions,” U.S. Pat. No. 6,022,832, issued Feb. 8, 2000, and entitled “Low Vacuum Process for Producing Superconductor Articles with Epitaxial Layers,” U.S. Pat. No. 6,027,564, issued Feb. 22, 2000, and entitled “Low Vacuum Process for Producing Epitaxial Layers,” U.S. Pat. No. 6,190,752, issued Feb. 20, 2001, and entitled “Thin Films Having Rock-Salt-Like Structure Deposited on Amorphous Surfaces,’ PCT Publication No. WO 00/58530, published on Oct. 5, 2000, and entitled “Alloy Materials,” PCT Publication No. WO/58044, published on Oct. 5, 2000, and entitled “Alloy Materials,” PCT Publication No. WO 99/17307, published on Apr. 8, 1999, and entitled “Substrates with Improved Oxidation Resistance,” PCT Publication No. WO 99/16941, published on Apr. 8, 1999, and entitled “Substrates for Superconductors,” PCT Publication No. WO 98/58415, published on Dec. 23, 1998, and entitled “Controlled Conversion of Metal Oxyfluorides into Superconducting Oxides,” PCT Publication No. WO 01/11428, published on Feb. 15, 2001, and entitled “Multi-Layer Articles and Methods of Making Same,” PCT Publication No. WO 01/08232, published on Feb. 1, 2001, and entitled “Multi-Layer Articles And Methods Of Making Same,” PCT Publication No. WO 01/08235, published on Feb. 1, 2001, and entitled “Methods And Compositions For Making A Multi-Layer Article,” PCT Publication No. WO 01/08236, published on Feb. 1, 2001, and entitled “Coated Conductor Thick Film Precursor”, PCT Publication No. WO 01/08169, published on Feb. 1, 2001, and entitled “Coated Conductors With Reduced A.C. Loss” PCT Publication No. WO 01/15245, published on Mar. 1, 2001, and entitled “Surface Control Alloy Substrates And Methods Of Manufacture Therefor,” PCT Publication No. WO 01/08170, published on Feb. 1, 2001, and entitled “Enhanced Purity Oxide Layer Formation,” PCT Publication No. WO 01/26164, published on Apr. 12, 2001, and entitled “Control of Oxide Layer Reaction Rates,” PCT Publication No. WO 01/26165, published on Apr. 12, 2001, and entitled “Oxide Layer Method,” PCT Publication No. WO 01/08233, published on Feb. 1, 2001, and entitled “Enhanced High Temperature Coated Superconductors,” PCT Publication No. WO 01/08231, published on Feb. 1, 2001, and entitled “Methods of Making A Superconductor,” PCT Publication No. WO 02/35615, published on Apr. 20, 2002, and entitled “Precursor Solutions and Methods of Using Same,” U.S. patent application Ser. No. 09/579,193, filed on May 26, 2000, and entitled, “Oxide Bronze Compositions And Textured Articles Manufactured In Accordance Therewith;” and U.S. Provisional Patent Application Serial No. 60/309,116, filed on Jul. 31, 2001, and entitled “Multi-Layer Superconductors And Methods Of Making Same.”
TECHNICAL FIELD
The invention relates to superconductor materials, methods of making same and reactors for making same.
BACKGROUND
Multi-layer articles can be used in a variety of applications. For example, superconductors, including oxide superconductors, can be formed of multi-layer articles. Typically, such superconductors include one or more layers of superconductor material and a layer, commonly referred to as a substrate, which can enhance the mechanical strength of the multi-layer article.
Generally, in addition to enhancing the strength of the multi-layer superconductor, the substrate may desirably exhibit certain other properties. For example, the substrate may desirably have a low Curie temperature so that the substrate is not ferromagnetic at the superconductor's application temperature. Furthermore, it may be desirable for the chemical species within the substrate to not be able to diffuse into the layer of superconductor material. Moreover, the coefficient of thermal expansion of the substrate may desirably be about the same as the superconductor material. In addition, if the substrate is used for an oxide superconductor, it may be desirable for the substrate material to be relatively resistant to oxidation.
For some materials, such as yttrium-barium-copper-oxide (YBCO), the ability of the material to provide high transport current in its superconducting state typically depends upon the crystallographic orientation of the material. For example, such a material can exhibit a relatively high critical current density (Jc) when the material is biaxially textured.
As used herein, “biaxially textured surface” refers to a surface for which the crystal grains are in close alignment with a direction in the plane of the surface or in close alignment with both a direction in the plane of the surface and a direction perpendicular to the surface. One type of biaxially textured surface is a cube textured surface, in which the primary cubic axes of the crystal grains are in close alignment with a direction perpendicular to the surface and with the direction in the plane of the surface. An example of a cube textured surface is the (100)[001] surface, and examples of biaxially textured surfaces include the (011)[100] and (113)[211] surfaces.
For certain multi-layer superconductors, the layer of superconductor material is an epitaxial layer. As used herein, “epitaxial layer” refers to a layer of material whose crystallographic orientation is derived from the crystallographic orientation of the surface of a layer of material onto which the epitaxial layer is deposited. For example, for a multi-layer superconductor having an epitaxial layer of superconductor material deposited onto a substrate, the crystallographic orientation of the layer of superconductor material is derived from the crystallographic orientation of the substrate. Thus, in addition to the above-discussed properties of a substrate, it can be also desirable for a substrate to have a biaxially textured surface or a cube textured surface.
Some substrates do not readily exhibit all the above-noted features, so one or more intermediate layers, commonly referred to as buffer layers, can be disposed between the substrate and the superconductor layer. The buffer layer(s) can be more resistant to oxidation than the substrate, and/or reduce the diffusion of chemical species between the substrate and the superconductor layer. Moreover, the buffer layer(s) can have a coefficient of thermal expansion that is well matched with the superconductor material.
In some instance, a buffer layer is an epitaxial layer, so its crystallographic orientation is derived from the crystallographic orientation of the surface onto which the buffer layer is deposited. For example, in a multi-layer superconductor having a substrate, an epitaxial buffer layer and an epitaxial layer of superconductor material (e.g., with the bulk of the superconductor material being biaxially textured), the crystallographic orientation of the surface of the buffer layer is derived from the crystallographic orientation of the surface of the substrate, and the crystallographic orientation of the layer of superconductor material is derived from the crystallographic orientation of the surface of the buffer layer. Therefore, the superconducting properties exhibited by a multi-layer superconductor having a buffer layer can depend upon the crystallographic orientation of the buffer layer surface.
In certain instances, a buffer layer is not an epitaxial layer but can be formed using ion beam assisted deposition. Typically, ion beam assisted deposition involves exposing a surface to ions directed at a specific angle relative to the surface while simultaneously depositing a material. In instances where ion beam assisted deposition is used to form a buffer layer, the crystallographic orientation of the surface of the buffer layer can be unrelated to the crystallographic orientation of the surface of the underlying layer (e.g., a substrate, such as an untextured substrate). Generally, however, the ion beam deposition parameters such as, fo
Fritzemeier Leslie G.
Li Qi
Li Xiaoping
Rupich Martin W.
Verebelyi Darren T.
American Superconductor Corporation
Fish & Richardson P.C.
Talbot Brian K.
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