Metal oxide material

Abstract

The invention provides certain novel metal oxide materials which exhibit superconductivity at elevated temperatures and/or which are useful in electrode, electrolyte, cell and sensor applications, or as electrochemical catalysts. The metal oxide materials are generally within the formula R n+1−u−s A u M m+e Cu n O w   ( 1 ) where n≧0 and n is an integer or a non-integer, 1≦m≦2, 0≦s≦0.4, 0≦e≦4, and 2n+(1/2)<w<(5/2)n+4, with the provisos that u is 2 for n≧1, u is n+1 for 0≦n<1 and where R and A are each any of or any combination of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Ca, Sr, Ba, Li, Na, K, Rb or Cs; M is any of or any combination of Cu, Bi, Sb, Pb, Tl or any other transition metal; Cu is Cu or Cu partially substituted by any of or any combination of Bi, Sb, Pb, Tl or any other transition metal; O is 0 or O partially substituted by any of N, P, S, Se, or F; and wherein the structure of the materials is characterised by distorted or undistorted substantially square planar sheets of CuO 2 when n>0 and distorted or undistorted substantially square sheets of R for n>1.

What is claimed is:  
     
         1 . A metal oxide material having the formula 
       B x Sr 2 Ca 2 Cu 3 O 10+d   
       where 
 B is Bi partially substituted by Pb and  
 x is about 2.1.  
 
     
     
         2 . A metal oxide material as set forth in  claim 1  wherein d is fixed by annealing said metal oxide material at a temperature of 300-550 C. in air or at an oxygen pressure or partial pressure and temperature equivalent to annealing in air within said temperature range.  
     
     
         3 . A metal oxide material as set forth in  claim 2  wherein d is fixed by annealing said metal oxide material at a temperature of about 500 C. in air followed by quenching in liquid nitrogen.  
     
     
         4 . A metal oxide material having the formula 
       (Bi,Pb) 2.1 Sr 2 Ca 2 Cu 3 O 10+d   
       wherein Bi is partially substituted by Pb.  
     
     
         5 . A metal oxide material as set forth in  claim 4  wherein d is fixed by annealing said metal oxide material at a temperature of 300-550 C. in air or at an oxygen pressure or partial pressure and temperature equivalent to annealing in air within said temperature range.  
     
     
         6 . A metal oxide material as set forth in  claim 5  wherein d is fixed by annealing said metal oxide material at a temperature of about 500 C. in air followed by quenching in liquid nitrogen.  
     
     
         7 . A metal oxide material having the formula 
       Bi 2.2−x Pb x Sr 2 Ca 2 Cu 3 O 10+d   
       wherein: 0<x≦0.4.  
     
     
         8 . A metal oxide material as set forth in  claim 7  wherein: 
 0.15≦x≦0.4.  
 
     
     
         9 . A metal oxide material as set forth in  claim 8  wherein: 
 0.30≦x≦0.4.  
 
     
     
         10 . A metal oxide material as set forth in  claim 9  wherein x is about 0.35.  
     
     
         11 . A metal oxide material as set forth in  claim 7  wherein d is fixed by annealing said metal oxide material at a temperature of 300-550 C. in air or at an oxygen pressure or partial pressure and temperature equivalent to annealing in air within said temperature range.  
     
     
         12 . A metal oxide material having the composition (Bi,Pb) 2+x (Sr,Ca) 4 Cu 3 O 10+δ , where x is about 0.1, the Pb/Bi ratio is less than 1, and the Ca/Sr ratio is about 1.  
     
     
         13 . A metal oxide material according to  claim 12  wherein −1≦δ≦1.  
     
     
         14 . A metal oxide material as set forth in  claim 12  wherein the value of δ is fixed by annealing said metal oxide material at a temperature of 300-550 C. in air or at an oxygen pressure or partial pressure and temperature equivalent to annealing in air within said temperature range.