Processing of (Bi,Pb) SCCO superconductor in wires and tapes

Abstract

A novel process of the production and processing of high quality, high T c (Bi,Pb)SCCO superconductors starts with fabrication of a precursor article including selected intermediate phases with desired chemical and structural properties. The precursor fabrication includes introducing the reacted mixture having a dominant amount of the tetragonal BSCCO phase into a metal sheath, and sealing the reacted mixture within said sheath, heating the mixture at a second selected processing temperature in an inert atmosphere with a second selected oxygen partial pressure for a second selected time period, the second processing temperature and the second oxygen partial pressure being cooperatively selected to form a dominant amount of an orthorhombic BSCCO phase in the reacted mixture. The sealed sheath is deformed to form an elongated precursor article of a desired texture; and thereafter heated at a third selected processing temperature in an inert atmosphere with a third selected oxygen partial pressure for a third selected time period. The third processing temperature and third oxygen partial pressure are cooperatively selected to convert at least a portion of the orthorhombic BSCCO phase to the final superconducting BSCCO material.

What is claimed is:  
     
         1 . A method of manufacture of an elongated BSCCO superconducting article, comprising: 
 heating a mixture of raw materials of a desired ratio of constituent metallic elements corresponding to a final superconducting BSCCO material at a first selected processing temperature in an inert atmosphere with a first selected oxygen partial pressure for a first selected time period, said first processing temperature and said first oxygen partial pressure being cooperatively selected to form a dominant amount of a tetragonal BSCCO phaser in the reacted mixture;    forming a composite article comprised of the reacted mixture substantially surrounded by a constraining metal;    heating said article at a second selected processing temperature in an inert atmosphere with a second selected oxygen partial pressure for a second selected time period, said second processing temperature and said second oxygen partial pressure being cooperatively selected to form a dominant amount of an orthorhombic BSCCO phase in the reacted mixture;    performing texture-inducing deformation on said article to form an elongated precursor article of a desired texture; and    heating said elongated precursor article at a third selected processing temperature in and inert atmosphere with a third selected oxygen partial pressure for a third selected time period, said third processing temperature and said third oxygen partial pressure being cooperatively selected to convert at least a portion of said orthorhombic BSCCO phase to said final superconducting BSCCO material.    
     
     
         2 . A method of manufacture of an elongated BSCCO superconducting article, comprising: 
 forming a composite article comprised of a dominant amount of a tetragonal BSCCO phase substantially surrounded by a constraining metal;    heating said composite article at a first selected processing temperature in an inert atmosphere with a first selected oxygen partial pressure for a first selected time period, said first processing temperature and said first oxygen partial pressure being cooperatively selected to form a dominant amount of an orthorhombic BSCCO phase in the precursor oxide powder;    performing a texture-inducing deformation on said composite article to form an elongated precursor article of a desired texture; and    heating said elongated precursor article at a second selected processing temperature in an inert atmosphere with a second selected oxygen partial pressure for a second selected time period, said second processing temperature and said second oxygen partial pressure being cooperatively selected to convert at least a portion of said orthorhombic BSCCO phase to said final superconducting BSCCO material.    
     
     
         3 . A method of manufacture of an elongated BSCCO superconducting article, comprising: 
 heating a composite article comprising a dominant amount of a tetragonal BSCCO phase substantially surrounded by a constraining metal at a first selected processing temperature in an inert atmosphere with a first selected oxygen partial pressure for a first selected time period, said first processing temperature and said first oxygen partial pressure being cooperatively selected to form a dominant amount of an orthorhombic BSCCO phase in the precursor oxide powder;    performing a texture-inducing deformation to said composite article to form an elongated composite article of a desired texture; and    heating said elongated composite article at a second selected processing temperature in an inert atmosphere with a second selected oxygen partial pressure for a second selected time period, said second processing temperature and said second oxygen partial pressure being cooperatively selected to convert at least a portion of said orthorhombic BSCCO phase to said final superconducting BSCCO material.    
     
     
         4 . The method of  claim 1 , wherein, during said second heating step, said second processing temperature and said second oxygen partial pressure are cooperatively selected to form a dominant amount of an alkaline earth cuprate phase, in addition to said dominant orthorhombic BSCCO phase.  
     
     
         5 . The method of  claim 2  or  3 , wherein, during said first heating step, said first processing temperature and said first oxygen partial pressure are cooperatively selected to form a dominant amount of an alkaline earth cuprate phase, in addition to said dominant orthorhombic BSCCO phase.  
     
     
         6 . The method of  claim 1 ,  2  or  3 , wherein the texture-inducing deforming step is selected from the group consisting of rolling, pressing and isostatic pressing.  
     
     
         7 . The method of  claim 1  or  2 , wherein forming of the composite article comprises the step of extruding or drawing the metal constrained tetragonal BSCCO phase.  
     
     
         8 . The method of  claim 7 , wherein forming of the composite article comprises forming the metal constrained tetragonal BSCCO phase into an article of a narrower or of a different cross-sectional geometry.  
     
     
         9 . The method of  claim 7 , forming of the composite article comprises grouping a plurality of metal constrained tetragonal BSCCO phasecontaining articles and extruding or drawing the plurality of articles into a single article.  
     
     
         10 . The method of  claim 1 ,  2  or  3 , further comprising: 
 the steps of sequentially repeating said texture-inducing deforming step and said final oxide superconductor-forming heating steps.  
 
     
     
         11 . The method of  claim 1 , wherein the step of forming a dominant amount of a tetragonal BSCCO phase is carried out at a first temperature in the range of 700-850° C. and an oxygen partial pressure in the range of 0.04 atm to 1 atm.  
     
     
         12 . The method of  claim 1 ,  2  or  3 , wherein the step of forming a dominant amount of an orthorhombic BSCCO phase is carried out at a temperature in the range of 650° C. to 795° C. and an oxygen partial pressure in the range of 10 −5  atm O 2  to 0.04 atm O 2 .  
     
     
         13 . The method of  claim 1 , wherein said heating to form the final oxide superconductor comprises: 
 cooperatively selecting said third processing temperature and said third oxygen partial pressure, such that oxygen partial pressure is below a value at which a Ca—Pb—O phase is formed and above a value at which said dominant orthorhombic (Bi,Pb)SCCO 2212 phase decomposes.    
     
     
         14 . The method of  claim 2  or  3 , wherein said heating to form the final oxide superconductor comprises: 
 cooperatively selecting said second processing temperature and said second oxygen partial pressure, such that oxygen partial pressure is below a value at which a Ca—Pb—O phase is formed and above a value at which said dominant orthorhombic Bi,Pb)SCCO 2212 phase decomposes.  
 
     
     
         15 . The method of  claim 1 ,  2  or  3 , wherein said heating to form the final oxide superconductor comprises: 
 heating at a temperature in the range of 800° C. to 845° C. and at an oxygen pressure in the range of 0.003 to 0.21 atm O 2 .  
 
     
     
         16 . The method of  claim 1 ,  2  or  3 , wherein said heating to form the final oxide superconductor comprises: 
 heating in a first step in the range of about 810-850° C.;  
 heating in a second step in the range of about 800-840° C.; and  
 heating in a third step in the range of about 730-800° C., said first, second and third heating steps at an oxygen pressure in the range of 0.003 to 0.21 atm O 2 .  
 
     
     
         17 . The method of  claim 1 ,  2  or  3 , wherein said heating to form the final oxide superconductor comprises: 
 heating at a first temperature in the range of 650° C. to 795° C. and at a first oxygen pressure in the range of 0.0001 to 0.075 atm O 2 ; and  
 heating at a second temperature in the range of 800° C. to 845° C. and at a second oxygen pressure in the range of 0.003 to 0.21 atm O 2 .  
 
     
     
         18 . The method of  claim 1 ,  2  or  3 , wherein said heating to form the final oxide superconductor comprises: 
 heating at a first temperature in the range of 650° C. to 795° C. and at a first oxygen pressure in the range of 0.0001 to 0.075 atm O 2 ; and  
 heating in a second step in the range of about 810-850° C.;  
 heating in a third step in the range of about 800-840° C.; and  
 heating in a fourth step in the range of about  730 -800° C., said second, third and fourth heating steps at an oxygen pressure in the range of 0.003 to 0.21 atm O 2 .  
 
     
     
         19 . The method of  claim 1 ,  2  or  3 , wherein said heating to form the final oxide superconductor comprises: 
 ramping through a temperature range and an oxygen partial pressure range, said temperature and oxygen partial pressure range cooperatively including a value at which a Ca—Pb—O phase is formed and/or a value at which said dominant orthorhombic (Bi,Pb)SCCO phase decomposes, said ramping at a rate sufficiently rapid such that the formation of the Ca—Pb—O phase and decomposition of the dominant orthorhombic (Bi,Pb)SCCO phase is kinetically disfavored.  
 
     
     
         20 . The method of  claim 19 , wherein said ramp rate is greater than 0.1° C./min.  
     
     
         21 . The method of  claim 19 , wherein said ramp rate is in the range of 0.1 to 100° C./min.  
     
     
         22 . The method of  claim 1 ,  2  or  3 , wherein said final oxide superconductor comprises (Bi,Pb)SCCO 2223,said tetragonal BSCCO phase comprises tetragonal (Bi,Pb)SCCO 2212 and said orthorhombic BSCCO phase comprises orthorhombic (Bi,Pb)SCCO 2212.  
     
     
         23 . The method of  claim 1 ,  2  or  3 , wherein said final oxide superconductor comprises BSCCO 2223, said tetragonal BSCCO phase comprises tetragonal BSCCO 2212 and said orthorhombic BSCCO phase comprises orthorhombic BSCCO 2212.  
     
     
         24 . A method of manufacture of an elongated BSCCO superconducting article, comprising: 
 heating a composite article comprising a dominant amount of an orthorhombic BSCCO phase substantially surrounded by a constraining metal at a first selected processing temperature in an inert atmosphere with a first selected oxygen partial pressure for a first selected time period, said first processing temperature and said first oxygen partial pressure which favor the presence of the orthorhombic BSCCO phase in the composite article;    performing a texture-induced deformation on said composite article to form an elongated composite article of a desired texture; and    heating said elongated composite article at a second selected processing temperature in an inert atmosphere with a second selected oxygen partial pressure for a second selected time period, said second processing temperature and said second oxygen partial pressure being cooperatively selected to convert at least a portion of said orthorhombic BSCCO phase to said final superconducting BSCCO material.    
     
     
         25 . An oxide superconducting composite comprised of a dominant amount of a BSCCO 2223 phase substantially surrounded by a constraining metal, characterized in that the BSCCO 2223 phase exhibits substantial biaxial alignment.  
     
     
         26 . A method of manufacture of an elongated BSCCO superconducting article, comprising: 
 heating a mixture of raw materials of a desired ratio of constituent metallic elements corresponding to a final superconducting BSCCO material at a first selected processing temperature in an inert atmosphere with a first selected oxygen partial pressure for a first selected time period, said first processing temperature and said first partial pressure being cooperatively selected to form a dominant of certain desired BSCCO precursor phases in the reacted mixture;    forming a composite article comprised of the reacted mixture substantially surrounded by a constraining metal;    heating said article at a second selected processing temperature in an inert atmosphere with a second selected oxygen partial pressure for a second selected time period, said second processing temperature and said second partial pressure being cooperatively selected to form a dominant amount of an orthorhombic BSCCO phase in the reacted mixture; and    performing texture-inducing deformation on said article to form an elongated precursor article of a desired texture.    
     
     
         27 . A method according to  claim 26  further comprising the step of heating said elongated precursor article at a third selected processing temperature in an inert atmosphere with a third selected oxygen partial pressure for a third selected time period, said third processing temperature and said third oxygen partial pressure being cooperatively selected to convert at least a portion of said orthorhombic BSCCO phase to said final superconducting BSCCO material, characterized in that said final BSCCO material exhibits substantial biaxial alignment.