Methods and Systems for Fabricating High Quality Superconducting Tapes

Abstract

An MOCVD system fabricates high quality superconductor tapes with variable thicknesses. The MOCVD system can include a gas flow chamber between two parallel channels in a housing. A substrate tape is heated and then passed through the MOCVD housing such that the gas flow is perpendicular to the tape's surface. Precursors are injected into the gas flow for deposition on the substrate tape. In this way, superconductor tapes can be fabricated with variable thicknesses, uniform precursor deposition, and high critical current densities.

What is claimed is: 
     
         1 . A superconductor tape prepared by metal organic chemical vapor deposition, the superconductor tape comprising a film thickness greater than approximately 1.5 μm and a critical current density greater than approximately 4 MA/cm 2  at 77 K in a zero applied magnetic field. 
     
     
         2 . The superconductor tape of  claim 1 , wherein the superconductor tape is a REBCO film. 
     
     
         3 . The superconductor tape or  claim 2 , wherein the REBCO film comprises the formula REBa 2 Cu 3 O 7 . 
     
     
         4 . The superconductor tape of  claim 1 , wherein the superconductor tape is substantially uniform. 
     
     
         5 . The superconductor tape of  claim 1 , wherein the superconductor tape comprises no observable misoriented grain growth. 
     
     
         6 . A superconductor tape prepared by metal organic chemical vapor deposition, the superconductor tape comprising a film thickness greater than approximately 2 μm and non c-axis grain orientation less than approximately 10%. 
     
     
         7 . The superconductor tape of  claim 6 , wherein the superconductor tape is a REBCO film. 
     
     
         8 . The superconductor tape or  claim 7 , wherein the REBCO film comprises the formula REBa 2 Cu 3 O 7 . 
     
     
         9 . The superconductor tape of  claim 6 , wherein the superconductor tape is substantially uniform. 
     
     
         10 . A superconductor tape prepared by metal organic chemical vapor deposition, the superconductor tape comprising a precursor to film conversion efficiency greater than approximately 20% of theoretical value. 
     
     
         11 . The superconductor tape of  claim 10 , wherein the superconductor tape is a REBCO film. 
     
     
         12 . The superconductor tape or  claim 11 , wherein the REBCO film comprises the formula REBa 2 Cu 3 O 7 . 
     
     
         13 . The superconductor tape of  claim 10 , wherein the superconductor tape is substantially uniform. 
     
     
         14 . The superconductor tape of  claim 10 , wherein the superconductor tape comprises no observable misoriented grain growth. 
     
     
         15 . A superconductor tape prepared by a metal organic chemical vapor deposition process comprising the steps of:
 preheating a superconductor substrate tape with a first roller and a second roller;   delivering the pre-heated superconductor substrate tape to a groove in a housing via the first roller and the second roller, wherein the groove is in fluid communication with a chamber; and   flowing superconductor precursors in a gas phase through the chamber, wherein the precursors are deposited on the superconductor substrate tape by thermally-activated reaction.   
     
     
         16 . The superconductor of  claim 16 , further prepared by a metal organic chemical vapor deposition process comprising the steps of:
 pre-heating the superconductor substrate tape via Ohmic heating.   
     
     
         17 . The superconductor of  claim 15 , further prepared by a metal organic chemical vapor deposition process comprising the steps of:
 sending, via one or more temperature monitoring devices positioned in optical communication with the tape in the groove, temperature readings to a controller than controls the electric power to the first roller and the second roller in a closed loop to maintain the superconductor substrate tape at a constant temperature.   
     
     
         18 . The superconductor of  claim 15 , further prepared by a metal organic chemical vapor deposition process comprising the steps of:
 flowing the gas phase in a direction of flow that is at least one of parallel to a surface of the superconductor substrate tape and perpendicular to the long axis of the superconductor substrate tape.   
     
     
         19 . The superconductor of  claim 15 , further prepared by a metal organic chemical vapor deposition process comprising the steps of:
 vaporizing the precursors from a liquid to a gas before flowing the gas phase through the chamber.   
     
     
         20 . The superconductor of  claim 15 , further prepared by a metal organic chemical vapor deposition process comprising the steps of:
 heating the chamber to a temperature between approximately 250° C. and approximately 300° C.